tape: Correctly decode into a table destination all the time

Reviewed-on: #20

.gitignore

@@ -0,0 +1,2 @@
+/generate/test
+/debug

cmd/hopp-generate/main.go

@@ -4,6 +4,7 @@ import "os"
 import "fmt"
 import "strings"
 import "path/filepath"
+import "git.tebibyte.media/sashakoshka/goparse"
 import "git.tebibyte.media/sashakoshka/hopp/generate"
 
 func main() {
@@ -18,7 +19,7 @@ func main() {
 	input, err := os.Open(source)
 	handleErr(1, err)
 	defer input.Close()
-	protocol, err := generate.ParseReader(input)
+	protocol, err := generate.ParseReader(source, input)
 	handleErr(1, err)
 
 	absDestination, err := filepath.Abs(destination)
@@ -30,14 +31,18 @@ func main() {
 
 	output, err := os.Create(destination)
 	handleErr(1, err)
-	err = protocol.Generate(output, packageName)
+	generator := generate.Generator {
+		Output:      output,
+		PackageName: packageName,
+	}
+	_, err = generator.Generate(protocol)
 	handleErr(1, err)
 	fmt.Fprintf(os.Stderr, "%s: OK\n", name)
 }
 
 func handleErr(code int, err error) {
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], err)
+		fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], parse.Format(err))
 		os.Exit(code)
 	}
 }

codec.go

@@ -0,0 +1,47 @@
+package hopp
+
+import "fmt"
+
+type anyInt16 interface { ~uint16 | ~int16 }
+type anyInt64 interface { ~uint64 | ~int64 }
+
+// decodeI16 decodes a 16 bit integer from the given data.
+func decodeI16[T anyInt16](data []byte) (T, error) {
+	if len(data) != 2 { return 0, fmt.Errorf("decoding int16: %w", ErrWrongBufferLength) }
+	return T(data[0]) << 8 | T(data[1]), nil
+}
+
+// encodeI16 encodes a 16 bit integer into the given buffer.
+func encodeI16[T anyInt16](buffer []byte, value T) error {
+	if len(buffer) != 2 { return fmt.Errorf("encoding int16: %w", ErrWrongBufferLength) }
+	buffer[0] = byte(value >> 8)
+	buffer[1] = byte(value)
+	return nil
+}
+
+// decodeI64 decodes a 64 bit integer from the given data.
+func decodeI64[T anyInt64](data []byte) (T, error) {
+	if len(data) != 8 { return 0, fmt.Errorf("decoding int64: %w", ErrWrongBufferLength) }
+	return T(data[0]) << 56 |
+		T(data[1]) << 48 |
+		T(data[2]) << 40 |
+		T(data[3]) << 32 |
+		T(data[4]) << 24 |
+		T(data[5]) << 16 |
+		T(data[6]) <<  8 |
+		T(data[7]), nil
+}
+
+// encodeI64 encodes a 64 bit integer into the given buffer.
+func encodeI64[T anyInt64](buffer []byte, value T) error {
+	if len(buffer) != 8 { return fmt.Errorf("encoding int64: %w", ErrWrongBufferLength) }
+	buffer[0] = byte(value >> 56)
+	buffer[1] = byte(value >> 48)
+	buffer[2] = byte(value >> 40)
+	buffer[3] = byte(value >> 32)
+	buffer[4] = byte(value >> 24)
+	buffer[5] = byte(value >> 16)
+	buffer[6] = byte(value >> 8)
+	buffer[7] = byte(value)
+	return nil
+}

codec/decode.go

@@ -1,100 +0,0 @@
-package codec
-
-import "io"
-
-// Decoder wraps an [io.Reader] and decodes data from it.
-type Decoder struct {
-	io.Reader
-}
-
-// ReadFull calls [io.ReadFull] on the reader.
-func (this *Decoder) ReadFull(buffer []byte) (n int, err error) {
-	return io.ReadFull(this, buffer)
-}
-
-// ReadByte decodes a single byte from the input reader.
-func (this *Decoder) ReadByte() (value byte, n int, err error) {
-	uncasted, n, err := this.ReadUint8()
-	return byte(uncasted), n, err
-}
-
-// ReadInt8 decodes an 8-bit signed integer from the input reader.
-func (this *Decoder) ReadInt8() (value int8, n int, err error) {
-	uncasted, n, err := this.ReadUint8()
-	return int8(uncasted), n, err
-}
-
-// ReadUint8 decodes an 8-bit unsigned integer from the input reader.
-func (this *Decoder) ReadUint8() (value uint8, n int, err error) {
-	buffer := [1]byte { }
-	n, err = this.ReadFull(buffer[:])
-	return uint8(buffer[0]), n, err
-}
-
-// ReadInt16 decodes an 16-bit signed integer from the input reader.
-func (this *Decoder) ReadInt16() (value int16, n int, err error) {
-	uncasted, n, err := this.ReadUint16()
-	return int16(uncasted), n, err
-}
-
-// ReadUint16 decodes an 16-bit unsigned integer from the input reader.
-func (this *Decoder) ReadUint16() (value uint16, n int, err error) {
-	buffer := [2]byte { }
-	n, err = this.ReadFull(buffer[:])
-	return uint16(buffer[0]) << 8 |
-		uint16(buffer[1]), n, err
-}
-
-// ReadInt32 decodes an 32-bit signed integer from the input reader.
-func (this *Decoder) ReadInt32() (value int32, n int, err error) {
-	uncasted, n, err := this.ReadUint32()
-	return int32(uncasted), n, err
-}
-
-// ReadUint32 decodes an 32-bit unsigned integer from the input reader.
-func (this *Decoder) ReadUint32() (value uint32, n int, err error) {
-	buffer := [4]byte { }
-	n, err = this.ReadFull(buffer[:])
-	return uint32(buffer[0]) << 24 |
-		uint32(buffer[1]) << 16 |
-		uint32(buffer[2]) << 8 |
-		uint32(buffer[3]), n, err
-}
-
-// ReadInt64 decodes an 64-bit signed integer from the input reader.
-func (this *Decoder) ReadInt64() (value int64, n int, err error) {
-	uncasted, n, err := this.ReadUint64()
-	return int64(uncasted), n, err
-}
-
-// ReadUint64 decodes an 64-bit unsigned integer from the input reader.
-func (this *Decoder) ReadUint64() (value uint64, n int, err error) {
-	buffer := [8]byte { }
-	n, err = this.ReadFull(buffer[:])
-	return uint64(buffer[0]) << 56 |
-		uint64(buffer[1]) << 48 |
-		uint64(buffer[2]) << 48 |
-		uint64(buffer[3]) << 32 |
-		uint64(buffer[4]) << 24 |
-		uint64(buffer[5]) << 16 |
-		uint64(buffer[6]) << 8 |
-		uint64(buffer[7]), n, err
-}
-
-// ReadGBEU decodes a growing unsigned integer of up to 64 bits from the input
-// reader.
-func (this *Decoder) ReadGBEU() (value uint64, n int, err error) {
-	var fullValue uint64
-	for {
-		chunk, nn, err := this.ReadByte()
-		if err != nil { return 0, n, err }
-		n += nn
-		
-		fullValue *= 0x80
-		fullValue += uint64(chunk & 0x7F)
-		ccb := chunk >> 7
-		if ccb == 0 {
-			return fullValue, n, nil
-		}
-	}
-}

codec/encode.go

@@ -1,95 +0,0 @@
-package codec
-
-import "io"
-
-// Encoder wraps an [io.Writer] and encodes data to it.
-type Encoder struct {
-	io.Writer
-}
-
-// WriteByte encodes a single byte to the output writer.
-func (this *Encoder) WriteByte(value byte) (n int, err error) {
-	return this.WriteByte(uint8(value))
-}
-
-// WriteInt8 encodes an 8-bit signed integer to the output writer.
-func (this *Encoder) WriteInt8(value int8) (n int, err error) {
-	return this.WriteUint8(uint8(value))
-}
-
-// WriteUint8 encodes an 8-bit unsigned integer to the output writer.
-func (this *Encoder) WriteUint8(value uint8) (n int, err error) {
-	return this.Write([]byte { byte(value) })
-}
-
-// WriteInt16 encodes an 16-bit signed integer to the output writer.
-func (this *Encoder) WriteInt16(value int16) (n int, err error) {
-	return this.WriteUint16(uint16(value))
-}
-
-// WriteUint16 encodes an 16-bit unsigned integer to the output writer.
-func (this *Encoder) WriteUint16(value uint16) (n int, err error) {
-	return this.Write([]byte {
-		byte(value >> 8),
-		byte(value),
-	})
-}
-
-// WriteInt32 encodes an 32-bit signed integer to the output writer.
-func (this *Encoder) WriteInt32(value int32) (n int, err error) {
-	return this.WriteUint32(uint32(value))
-}
-
-// WriteUint32 encodes an 32-bit unsigned integer to the output writer.
-func (this *Encoder) WriteUint32(value uint32) (n int, err error) {
-	return this.Write([]byte {
-		byte(value >> 24),
-		byte(value >> 16),
-		byte(value >> 8),
-		byte(value),
-	})
-}
-
-// WriteInt64 encodes an 64-bit signed integer to the output writer.
-func (this *Encoder) WriteInt64(value int64) (n int, err error) {
-	return this.WriteUint64(uint64(value))
-}
-
-// WriteUint64 encodes an 64-bit unsigned integer to the output writer.
-func (this *Encoder) WriteUint64(value uint64) (n int, err error) {
-	return this.Write([]byte {
-		byte(value >> 56),
-		byte(value >> 48),
-		byte(value >> 40),
-		byte(value >> 32),
-		byte(value >> 24),
-		byte(value >> 16),
-		byte(value >> 8),
-		byte(value),
-	})
-}
-
-// EncodeGBEU encodes a growing unsigned integer of up to 64 bits to the output
-// writer.
-func (this *Encoder) EncodeGBEU(value uint64) (n int, err error) {
-	// increase if go somehow gets support for over 64 bit integers. we
-	// could also make an expanding int type in goutil to use here, or maybe
-	// there is one in the stdlib. keep this int64 version as well though
-	// because its ergonomic.
-	buffer := [16]byte { }
-	
-	window := (GBEUSize(value) - 1) * 7
-	index := 0
-	for window >= 0 {
-		chunk := uint8(value >> window) & 0x7F
-		if window > 0 {
-			chunk |= 0x80
-		}
-		buffer[index] = chunk
-		
-		index += 1
-		window -= 7
-	}
-	
-	return this.Write(buffer[:])
-}

codec/measure.go

@@ -1,11 +0,0 @@
-package codec
-
-// GBEUSize returns the size (in octets) of a GBEU integer.
-func GBEUSize(value uint64) int {
-	length := 0
-	for {
-		value >>= 7
-		length ++
-		if value == 0 { return length }
-	}
-}

connection.go

@@ -2,7 +2,7 @@ package hopp
 
 import "io"
 import "net"
-// import "time"
+import "time"
 
 const defaultSizeLimit int64 = 1024 * 1024 // 1 megabyte
 
@@ -23,8 +23,13 @@ type Conn interface {
 	// be called in a loop to avoid the connection locking up.
 	AcceptTrans() (Trans, error)
 
+	// SetDeadline operates is [net.Conn.SetDeadline] but for OpenTrans
+	// and AcceptTrans calls.
+	SetDeadline(t time.Time) error	
 	// SetSizeLimit sets a limit (in bytes) for how large messages can be.
-	// By default, this limit is 1 megabyte.
+	// By default, this limit is 1 megabyte. Note that this is only
+	// enforced when sending and receiving byte slices, and it does not
+	// apply to [Trans.SendWriter] or [Trans.ReceiveReader].
 	SetSizeLimit(limit int64)
 }
 
@@ -40,8 +45,6 @@ type Trans interface {
 	// unique within the connection. This method is safe for concurrent use.
 	ID() int64
 		
-	// TODO: add methods for setting send and receive deadlines
-		
 	// Send sends a message. This method is not safe for concurrent use.
 	Send(method uint16, data []byte) error
 	// SendWriter sends data written to an [io.Writer]. The writer must be
@@ -57,4 +60,12 @@ type Trans interface {
 	// previously opened through this function will be discarded. This
 	// method is not safe for concurrent use, and neither is its result.
 	ReceiveReader() (method uint16, data io.Reader, err error)
+
+	// See the documentation for [net.Conn.SetDeadline].
+	SetDeadline(time.Time) error
+	// TODO
+	// // See the documentation for [net.Conn.SetReadDeadline].
+	// SetReadDeadline(t time.Time) error
+	// // See the documentation for [net.Conn.SetWriteDeadline].
+	// SetWriteDeadline(t time.Time) error
 }

design/branched-generated-encoder.md

@@ -0,0 +1,128 @@
+# Branched Generated Decoder
+
+Pasted here because Tebitea is down
+
+## The problem
+
+TAPE is designed so that the decoder can gloss over data it does not understand.
+Technically the protocol allows for this, but I completely forgot to implement
+this in the generated decoder, oops. This would be trivial if TAPE messages were
+still flat tables, but they aren't, because those aren't useful enough. So,
+let's analyze the problem.
+
+## When it happens
+
+There are two reasons something might not match up with the expected data:
+
+The first and most obvious is unrecognized keys. If the key is not in the set of
+recognized keys for a KTV, it should leave the corresponding struct field blank.
+Once #6 has been implemented, throw an error if the data was not optional.
+
+The second is wrong types. If we are expecting KTV and get SBA, we should leave
+the data as empty. The aforementioned concern about #6 also applies here. We
+don't need to worry about special cases at the structure root, because it would
+be technically possible to make the structure root an option, so it really is
+just a normal value. Until #6, we will leave that blank too.
+
+## Preliminary ideas
+
+The first is going to be pretty simple. All we need to do is have a skimmer
+function that skims over TAPE data very, and then call that on the KTV value
+each time we run into a mystery key. It should only return an error if the
+structure of the data is malformed in such a way that it cannot continue to the
+next one. This should be stored in the tape package alongside the dynamic
+decoding functions, because they will essentially function the same way and
+could probably share lots of code.
+
+The second is a bit more complicated because of the existence of KTV and OTA
+because they are aggregate types. Go types work a bit differently, as if you
+have an array of an array of an array of ints, that information is represented
+in one place, whereas TAPE doesn't really do that. All of that information is
+sort of buried within the data structure, so we don't know what we will be
+decoding before we actually do it. Whenever we encounter a type we don't expect,
+we would need to abort decoding of the entire data structure, and then skim over
+whatever detritus is left, which would literally be in a half-decoded state. The
+fact that the code is generated flat and thus cannot use return or defer
+statements contributes to the complexity of this problem. We need to go up, but
+we can't. There is no up, only forward.
+
+Of course, the dynamic decoder does not have this problem in the first place
+because it doesn't expect anything, and constructs the destination to fit
+whatever it sees in the TAPE structure as it is decoding it. KTVs are completely
+dynamic because they are implemented as maps, so the only time it needs to
+completely comprehend a type is with OTAs. There is a function called typeOf
+that gets the type of the current tag and returns it as a reflect.Type, which
+necessitates recursion and peeking at OTAs and their elements.
+
+We could try to do the same thing in the generated decoder, comparing the
+determined type against the expected type to try to figure out whether we should
+decode an array or a table, etc. This is immediately problematic as it requires
+memory to be allocated, both for the peek buffer and the resulting tree of type
+information. If we end up with some crazy way to keep track of the types, that's
+only one half of the allocation problem and we would still be spending extra
+cycles going over all of that twice.
+
+## Performance constraints
+
+The generated decoder is supposed to blaze through data, and it can't do that if
+it does all the singing and dancing that the dynamic decoder does. It's time for
+some performance constraints:
+
+- No allocations, except as required to build the destination for the data
+- No redundant work
+- So, no freaking peeking
+- It should take well under 500 lines of generated code to decode one message of
+reasonable size (i.e. be careful not to bloat the binary)
+
+I'm not really going to do my usual thing here of making a slow version and
+speeding it up over time based on evidence and experimentation because these
+constraints inform the design so much it would be impossible to continue without
+them. I am 99% confident that these constraints will allow for an acceptable
+baseline of performance (for generated code) and we can still profile and
+micro-optimize later. This is good enough for me.
+Heavy solution
+
+There is a solution that might work very well which involves completely redoing
+the generated decoding code. We could create a function for every source type to
+destination type mapping that exists in protocol, and then compose them all
+together. The decoding methods for each message or type would be wrappers around
+the correct function for their root TAPE -> Go type mapping. The main benefit of
+this is it would make this problem a lot more manageable because the interface
+points between the data would be represented by function boundaries. This would
+allow the use of return and defer statements, and would allow more code sharing,
+producing a smaller binary. Go would probably inline these where needed.
+
+Would this work? Probably. More investigation is required to make sure. I want
+to stop re-writing things I don't need to. On the other hand, it is just the
+decoder.
+
+## Light solution
+
+TODO: find a solution that satisfies the performance constraints, keeps the same
+identical interface, and works off the same code. I am convinced this is doable,
+and it might even allow us to extract more data from an unexpected structure.
+However, continuing this way might introduce unmanageable complexity. It is
+already a little unmanageable and I am just one pony (kind of).
+
+## Implementation
+
+Heavy solution is going to work here, applied to only the points of
+`Generator.generateDecodeValue` where it decodes an aggregate data structure.
+That way, only minimal amounts of code need to be redone.
+
+Whenever a branch needs to happen, a call shall be generated, a deferred
+implementation request shall be added to a special FIFO queue within the
+generator. After generating data structures and their root decoding functions,
+the generator shall pick away at this queue until no requests remain. The
+generator shall accept new items during this process, so that recursion is
+possible. This is all to ensure it is only ever writing one function at a time
+
+The functions shall take a pointer to a type that accepts any type like (~) the
+destination's base type. We should also probably just call
+`Generator.generateDecodeValue` directly on user defined types this way, keeping
+their public `Decode` methods just for convenience.
+
+The tape package shall contain a skimming function that takes a decoder and a
+tag, and recursively consumes the decoder given the context of the tag. This
+shall be utilized by the decoder functions to skip over values if their tags
+or keys do not match up with what is expected.

design/pdl-compiler.md

@@ -0,0 +1,109 @@
+# PDL Compiler Specification
+
+Given one or more PDL files representing a protocol, the compiler shall generate
+a Go package named "protocol", which shall contain types for message and type
+definitions, as well as encoding and decoding methods.
+
+## Static Section
+
+The compiler shall write a static section alongside the generated code. It
+shall contain this text:
+
+```go
+// Table is a KTV table with an undefined schema.
+type Table map[uint16] any
+
+// Message is any message that can be sent along this protocol.
+type Message interface {
+	codec.Encodable
+	codec.Decodable
+
+	// Method returns the method code of the message.
+	Method() uint16
+}
+```
+
+## Preamble
+
+At the start of each file but after the package name, the compiler shall emit
+this text:
+
+```go
+/* # Do not edit this package by hand!
+ * 
+ * This file was automatically generated by the Holanet PDL compiler. The
+ * source file is located at <path>
+ * Please edit that file instead, and re-compile it to this location.
+ *
+ * HOPP, TAPE, METADAPT, PDL/0 (c) 2025 holanet.xyz
+ */
+```
+
+Where `<path>` is the path of the protocol definition file relative to the
+generated file.
+
+## Message Definitions
+
+For each defined message, the compiler shall generate a Go type named
+`MessageName`, where `Name` is the name of the message as written in its
+definition. The message shall be encodable, and shall have `Encode` and `Decode`
+methods as described below.
+
+All messages shall satisfy a `Message` interface, which is defined in the
+static section.
+
+## Type Definitions
+
+For each defined type, the compiler shall generate a Go type with the same name
+as written in its definition. The Go type shall be encodable, and shall have
+`EncodeValue`, `DecodeValue`, and `Tag` methods as described below.
+
+## Encoding and Decoding Methods
+
+Each message shall be given an `Encode` method and a `Decode` method,
+which shall take in a `codec.Encoder` and a `codec.Decoder` respectively. Both
+return an `(int, error)` pair describing the amount of bytes written and an
+error if the write stopped early. `Encode` shall encode the data within the
+message to the given encoder, and `Decode` shall decode data from the given
+decoder and place it in the type's value. The methods shall not retain or close
+any encoders or decoders they are given. Both methods shall have pointer
+receivers. In effect, these methods shall satisfy `codec.Encodable` and
+`codec.Decodable`.
+
+Each defined type shall be given an `EncodeValue` method and a `DecodeValue`
+method, which shall both take in a `tape.Tag`, then a `codec.Encoder` and a
+`codec.Decoder` respectively. These methods shall encode and decode the value
+according to the CN given by the tag. The TN shall be ignored. The message shall
+also have a method `Tag` that takes no arguments and returns the preferred tag
+of the type including the TN and CN.
+
+## Connection
+
+The compiler shall generate a `Conn` struct which embeds a `hopp.Conn`, which
+is the real "porcelain" of the generated code. It shall provide methods to
+create and accept transactions. Each transaction shall be a struct which embeds
+a `hopp.Trans`, and shall have methods for sending and receiving messages.
+
+### Sending
+
+To send a message along a transaction, the program shall:
+
+1. Obtain the method code from the message
+3. Obtain a writer from the connection using the method code
+4. Wrap the writer in a `codec.Encoder`
+5. Use the encoder to encode the message
+6. Close the writer
+
+### Receiving
+
+To receiving a message from a transaction, the program shall:
+
+1. Obtain a method code and reader from the connection
+2. Wrap the reader in a `codec.Decoder`
+3. Switch on the method code, and decode the correct message using the decoder
+4. Return the message to the caller as a value
+
+The recieve function must return the message as a value instead of a pointer in
+order to avoid making an allocation. Because of this, the return value must be
+`any` instead of `Message`. The caller must then use a type switch to figure out
+what message was sent.

design/pdl-language.md

@@ -0,0 +1,105 @@
+# PDL Language Definition
+
+PDL allows defining a protocol using HOPP and TAPE.
+
+## Data Types
+
+| Syntax     | TN      | CN | Description
+| ---------- | ------- | -: | -----------
+| I5         | SI      |    |   
+| I8         | LSI     |  0 | 
+| I16        | LSI     |  1 | 
+| I32        | LSI     |  3 | 
+| I64        | LSI     |  7 | 
+| I128[^2]   | LSI     | 15 | 
+| I256[^2]   | LSI     | 31 | 
+| U5         | SI      |    | 
+| U8         | LI      |  0 | 
+| U16        | LI      |  1 | 
+| U32        | LI      |  3 | 
+| U64        | LI      |  7 | 
+| U128[^2]   | LI      | 15 | 
+| U256[^2]   | LI      | 31 | 
+| F16        | FP      |  1 | 
+| F32        | FP      |  3 | 
+| F64        | FP      |  7 | 
+| F128[^2]   | FP      | 15 | 
+| F256[^2]   | FP      | 31 | 
+| String     | SBA/LBA |  * | UTF-8 string
+| Buffer     | SBA/LBA |  * | Byte array
+| []\<TYPE\> | OTA     |  * | Array of any type[^1]
+| Table      | KTV     |  * | Table with undefined schema
+| {...}      | KTV     |  * | Table with defined schema
+| Any        | *       |  * | Value of an undefined type
+
+[^1]: Excluding SI and SBA. I5 and U5 cannot be used in an array, but String and
+Buffer are simply forced to use their "long" variant.
+
+[^2]: Some systems may lack support for this.
+
+## Tokens
+
+PDL files are divided into tokens, which assemble together into larger language
+structures. They are separated by whitespace.
+
+| Name     | Syntax             | Description
+| -------- | ------------------ | -----------
+| Method   | `M[0-9A-Fa-f]{4}`  | A 16-bit hexadecimal method code.
+| Key      | `[0-9A-Fa-f]{4}`   | A 16-bit hexadecimal table key.
+| Ident    | `[A-Z][A-Za-z0-9]` | An identifier.
+| Comma    | `,`                | A comma separator.
+| LBrace   | `{`                | A left curly brace.
+| RBrace   | `}`                | A right curly brace.
+| LBracket | `[`                | A left square bracket.
+| RBracket | `]`                | A right square bracket.
+
+## Syntax
+
+Types are expressed with an Ident. A table can be used by either writing the
+name of the type (Table), or by defining a schema with curly braces. Arrays must
+be expressed using two matching square brackets before their element type.
+
+A table schema contains comma-separated fields in-between its braces. Each field
+has three parts: the key number (Key), the field name (Ident), and the field
+type. Tables, Arrays, etc. can be nested.
+
+Files directly contain messages and types, which start with a Method token and
+an Ident token respectively. A message consists of the method code (Method), the
+message name (Ident), and the message's root type. This is usually a table, but
+can be anything.
+
+Here is an example of all that:
+
+```
+M0000 Connect {
+	0000 Name String,
+	0001 Password String,
+}
+
+M0001 UserList {
+	0000 Users []User,
+}
+
+User {
+	0000 Name      String,
+	0001 Bio       String,
+	0002 Followers U32,
+}
+```
+
+## EBNF Description
+
+Below is an EBNF description of the language.
+
+```
+<file>    -> (<message> | <typedef)*
+<method>  -> /M[0-9A-Fa-f]{4}/
+<key>     -> /[0-9A-Fa-f]{4}/
+<ident>   -> /[A-Z][A-Za-z0-9]/
+<field>   -> <key> <ident> <type>
+<type> -> <ident>
+        | "[" "]" <type>
+        | "{" (<field> ",")* [<field>] "}"
+<message> -> <method> <ident> <type>
+<typedef> -> <ident> <type>
+```

design/protocol.md

@@ -46,6 +46,10 @@ bits, and the CN is 5 bits. Both are interpreted as unsigned integers. Both
 sides of the connection must agree on the semantic meaning of the values and
 their arrangement.
 
+A TAPE structure begins with one root, which consists of a tag followed by a
+payload. This is usually an aggregate data structure such as KTV to allow for
+several different values.
+
 TAPE is based on an encoding method previously developed by silt.
 
 ### Data Value Types
@@ -63,10 +67,6 @@ in detail in the following sections.
 |  6 |  110 | KTV  | Key-tag-value table
 |  7 |  111 | N/A  | Reserved
 
-#### No Value (NIL)
-NIL is used to encode the absence of a value where there would otherwise be one.
-The CN of a NIL is ignored. It has no payload.
-
 #### Small Integer (SI)
 SI encodes an integer of up to 5 bits, which are stored in the CN. It has no
 payload. Whether the bits are interpreted as unsigned or as signed two's
@@ -75,16 +75,16 @@ connection. Thus, the value may range from 0 to 31 if unsigned, and from -16 to
 17 if signed.
 
 #### Large Integer (LI)
-LI encodes an integer of up to 256 bits, which are stored in the payload. The CN
-determine the length of the payload in bytes. The integer is big-endian. Whether
+LI encodes an integer of up to 256 bits, which are stored in the payload. The
+length of the payload (in bytes) is CN + 1. The integer is big-endian. Whether
 the payload is interpreted as unsigned or as signed two's complement is semantic
 information and must be agreed upon by both sides of the connection. Thus, the
 value may range from 0 to 31 if unsigned, and from -16 to 17 if signed.
 
 #### Floating Point (FP)
 FP encodes an IEEE 754 floating point number of up to 256 bits, which are stored
-in the payload. The CN determines the length of the payload in bytes, and it may
-only be one of these values: 16, 32, 64, 128, or 256.
+in the payload. The length of the payload (in bytes) is CN + 1. The only
+supported bit widths for floats are as follows: 16, 32, 64, 128, and 256.
 
 #### Small Byte Array (SBA)
 SBA encodes an array of up to 32 bytes, which are stored in the paylod. The
@@ -98,15 +98,16 @@ in bytes is determined by the CN.
 #### One-Tag Array (OTA)
 OTA encodes an array of up to 2^256 items, which are stored in the payload after
 the length field and the item tag, where the length field comes first. Each item
-must be the same length, as they all share the same tag. The length of the data
-length field in bytes is determined by the CN.
+must be the same length, as they all share the same tag. The length of the
+length field (in bytes) is CN + 1.
 
 #### Key-Tag-Value Table (KTV)
 KTV encodes a table of up to 2^256 key/value pairs, which are stored in the
 payload after the length field. The pairs themselves consist of a 16-bit
 unsigned big-endian key followed by a tag and then the payload. Pair values can
 be of different types and sizes. The order of the pairs is not significant and
-should never be treated as such.
+should never be treated as such. The length of the length field (in bytes) is
+CN + 1.
 
 ## Transports
 A transport is a protocol that HOPP connections can run on top of. HOPP

error.go

@@ -9,6 +9,7 @@ type Error string; const (
 	ErrIntegerOverflow    Error = "integer overflow"
 	ErrMessageMalformed   Error = "message is malformed"
 	ErrTablePairMissing   Error = "required table pair is missing"
+	ErrWrongBufferLength  Error = "wrong buffer length"
 )
 
 // Error implements the error interface.

generate/generate_test.go

@@ -0,0 +1,453 @@
+package generate
+
+// import "fmt"
+import "testing"
+
+// TODO: once everything has been ironed out, test that the public API of the
+// generator is equal to something specific
+
+var exampleProtocol = defaultProtocol()
+
+func init() {
+	exampleProtocol.Messages[0x0000] = Message {
+		Name: "Connect",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "Name",      Type: TypeString { } },
+				0x0001: Field { Name: "Password",  Type: TypeString { } },
+			},
+		},
+	}
+	exampleProtocol.Messages[0x0001] = Message {
+		Name: "UserList",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "Users",  Type: TypeArray { Element: TypeNamed { Name: "User" } } },
+			},
+		},
+	}
+	exampleProtocol.Messages[0x0002] = Message {
+		Name: "Pulse",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "Index",  Type: TypeInt { Bits: 5 } },
+				0x0001: Field { Name: "Offset", Type: TypeInt { Bits: 16, Signed: true }},
+				0x0002: Field { Name: "X",      Type: TypeFloat { Bits: 16 }},
+				0x0003: Field { Name: "Y",      Type: TypeFloat { Bits: 32 }},
+				0x0004: Field { Name: "Z",      Type: TypeFloat { Bits: 64 }},
+			},
+		},
+	}
+	exampleProtocol.Messages[0x0003] = Message {
+		Name: "NestedArray",
+		Type: TypeArray { Element: TypeArray { Element: TypeInt { Bits: 8 } } },
+	}
+	exampleProtocol.Messages[0x0004] = Message {
+		Name: "Integers",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "U5",  Type: TypeInt { Bits: 5  } },
+				0x0001: Field { Name: "U8",  Type: TypeInt { Bits: 8  } },
+				0x0002: Field { Name: "U16", Type: TypeInt { Bits: 16 } },
+				0x0003: Field { Name: "U32", Type: TypeInt { Bits: 32 } },
+				0x0004: Field { Name: "U64", Type: TypeInt { Bits: 64 } },
+				0x0006: Field { Name: "I8",  Type: TypeInt { Bits: 8,  Signed: true } },
+				0x0007: Field { Name: "I16", Type: TypeInt { Bits: 16, Signed: true } },
+				0x0008: Field { Name: "I32", Type: TypeInt { Bits: 32, Signed: true } },
+				0x0009: Field { Name: "I64", Type: TypeInt { Bits: 64, Signed: true } },
+				0x000B: Field { Name: "NI8", Type: TypeInt { Bits: 8,  Signed: true } },
+				0x000C: Field { Name: "NI16",Type: TypeInt { Bits: 16, Signed: true } },
+				0x000D: Field { Name: "NI32",Type: TypeInt { Bits: 32, Signed: true } },
+				0x000E: Field { Name: "NI64",Type: TypeInt { Bits: 64, Signed: true } },
+			},
+		},
+	}
+	exampleProtocol.Messages[0x0005] = Message {
+		Name: "Dynamic",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "AU8", Type: TypeAny { } },
+				0x0001: Field { Name: "AU16", Type: TypeAny { } },
+				0x0002: Field { Name: "AU32", Type: TypeAny { } },
+				0x0003: Field { Name: "AU64", Type: TypeAny { } },
+				0x0004: Field { Name: "AI8", Type: TypeAny { } },
+				0x0005: Field { Name: "AI16", Type: TypeAny { } },
+				0x0006: Field { Name: "AI32", Type: TypeAny { } },
+				0x0007: Field { Name: "AI64", Type: TypeAny { } },
+				0x0008: Field { Name: "AF32", Type: TypeAny { } },
+				0x0009: Field { Name: "AF64", Type: TypeAny { } },
+				0x000A: Field { Name: "AString", Type: TypeAny { } },
+				0x000B: Field { Name: "AArray", Type: TypeAny { } },
+				0x000C: Field { Name: "ATable", Type: TypeAny { } },
+				0x000D: Field { Name: "T0", Type: TypeTable { } },
+			},
+		},
+	}
+	exampleProtocol.Types["User"] = TypeTableDefined {
+		Fields: map[uint16] Field {
+			0x0000: Field { Name: "Name",      Type: TypeString { } },
+			0x0001: Field { Name: "Bio",       Type: TypeString { } },
+			0x0002: Field { Name: "Followers", Type: TypeInt { Bits: 32 } },
+		},
+	}
+}
+
+func TestGenerateRunEncodeDecode(test *testing.T) {
+	testGenerateRun(test, &exampleProtocol, "encode-decode", `
+		// imports
+	`, `
+		log.Println("MessageConnect")
+		messageConnect := MessageConnect {
+			Name: "rarity",
+			Password: "gems",
+		}
+		testEncodeDecode(
+			&messageConnect,
+			tu.S(0xE0, 0x02).AddVar(
+				[]byte { 0x00, 0x00, 0x86, 'r', 'a', 'r', 'i', 't', 'y' },
+				[]byte { 0x00, 0x01, 0x84, 'g', 'e', 'm', 's' },
+				))
+		log.Println("MessageUserList")
+		messageUserList := MessageUserList {
+			Users: []User {
+				User {
+					Name: "rarity",
+					Bio: "asdjads",
+					Followers: 0x324,
+				},
+				User {
+					Name: "deez nuts",
+					Bio: "logy",
+					Followers: 0x8000,
+				},
+				User {
+					Name: "creekflow",
+					Bio: "im creekflow",
+					Followers: 0x3894,
+				},
+			},
+		}
+		testEncodeDecode(
+			&messageUserList,
+			tu.S(0xE0, 0x01, 0x00, 0x00,
+				0xC0, 0x03, 0xE0,
+					).Add(0x03).AddVar(
+						[]byte { 0x00, 0x00, 0x86, 'r', 'a', 'r', 'i', 't', 'y' },
+						[]byte { 0x00, 0x01, 0x87, 'a', 's', 'd', 'j', 'a', 'd', 's' },
+						[]byte { 0x00, 0x02, 0x23, 0x00, 0x00, 0x03, 0x24 },
+					).Add(0x03).AddVar(
+						[]byte { 0x00, 0x00, 0x89, 'd', 'e', 'e', 'z', ' ', 'n', 'u', 't', 's' },
+						[]byte { 0x00, 0x01, 0x84, 'l', 'o', 'g', 'y' },
+						[]byte { 0x00, 0x02, 0x23, 0x00, 0x00, 0x80, 0x00 },
+					).Add(0x03).AddVar(
+						[]byte { 0x00, 0x00, 0x89, 'c', 'r', 'e', 'e', 'k', 'f', 'l', 'o', 'w' },
+						[]byte { 0x00, 0x01, 0x8C, 'i', 'm', ' ', 'c', 'r', 'e', 'e', 'k', 'f',
+							'l', 'o', 'w' },
+						[]byte { 0x00, 0x02, 0x23, 0x00, 0x00, 0x38, 0x94 },
+				))
+		log.Println("MessagePulse")
+		messagePulse := MessagePulse {
+			Index: 9,
+			Offset: -0x3521,
+			X: 45.375,
+			Y: 294.1,
+			Z: 384729384.234892034,
+		}
+		testEncodeDecode(
+			&messagePulse,
+			tu.S(0xE0, 0x05).AddVar(
+				[]byte { 0x00, 0x00, 0x09 },
+				[]byte { 0x00, 0x01, 0x41, 0xCA, 0xDF },
+				[]byte { 0x00, 0x02, 0x61, 0x51, 0xAC },
+				[]byte { 0x00, 0x03, 0x63, 0x43, 0x93, 0x0C, 0xCD },
+				[]byte { 0x00, 0x04, 0x67, 0x41, 0xB6, 0xEE, 0x81, 0x28, 0x3C, 0x21, 0xE2 },
+				))
+		log.Println("MessageNestedArray")
+		uint8s := func(n int) []uint8 {
+			array := make([]uint8, n)
+			for index := range array {
+				array[index] = uint8(index + 1) | 0xF0
+			}
+			return array
+		}
+		messageNestedArray := MessageNestedArray {
+			uint8s(6),
+			uint8s(35),
+		}
+		testEncodeDecode(
+			&messageNestedArray,
+			tu.S(0xC0, 0x02, 0xC0,
+				0x06, 0x20, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6,
+				35,   0x20, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6,
+				            0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC,
+				            0xFD, 0xFE, 0xFF, 0xF0, 0xF1, 0xF2,
+				            0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
+				            0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE,
+				            0xFF, 0xF0, 0xF1, 0xF2, 0xF3))
+		log.Println("MessageIntegers")
+		messageIntegers := MessageIntegers {
+			U5:   0x13,
+			U8:   0xC9,
+			U16:  0x34C9,
+			U32:  0x10E134C9,
+			U64:  0x639109BC10E134C9,
+			I8:   0x35,
+			I16:  0x34C9,
+			I32:  0x10E134C9,
+			I64:  0x639109BC10E134C9,
+			NI8:  -0x35,
+			NI16: -0x34C9,
+			NI32: -0x10E134C9,
+			NI64: -0x639109BC10E134C9,
+		}
+		testEncodeDecode(
+			&messageIntegers,
+			tu.S(0xE0, 13).AddVar(
+				[]byte { 0x00, 0x00, 0x13 },
+				[]byte { 0x00, 0x01, 0x20, 0xC9 },
+				[]byte { 0x00, 0x02, 0x21, 0x34, 0xC9 },
+				[]byte { 0x00, 0x03, 0x23, 0x10, 0xE1, 0x34, 0xC9 },
+				[]byte { 0x00, 0x04, 0x27, 0x63, 0x91, 0x09, 0xBC, 0x10, 0xE1, 0x34, 0xC9 },
+				[]byte { 0x00, 0x06, 0x40, 0x35 },
+				[]byte { 0x00, 0x07, 0x41, 0x34, 0xC9 },
+				[]byte { 0x00, 0x08, 0x43, 0x10, 0xE1, 0x34, 0xC9 },
+				[]byte { 0x00, 0x09, 0x47, 0x63, 0x91, 0x09, 0xBC, 0x10, 0xE1, 0x34, 0xC9 },
+				[]byte { 0x00, 0x0B, 0x40, 0xCB },
+				[]byte { 0x00, 0x0C, 0x41, 0xCB, 0x37 },
+				[]byte { 0x00, 0x0D, 0x43, 0xEF, 0x1E, 0xCB, 0x37 },
+				[]byte { 0x00, 0x0E, 0x47, 0x9C, 0x6E, 0xF6, 0x43, 0xEF, 0x1E, 0xCB, 0x37 },
+				))
+		log.Println("MessageDynamic")
+		messageDynamic := MessageDynamic {
+			AU8:     uint8(0x23),
+			AU16:    uint16(0x3247),
+			AU32:    uint32(0x87324523),
+			AU64:    uint64(0x3284029034098234),
+			AI8:     int8(0x23),
+			AI16:    int16(0x3247),
+			AI32:    int32(0x57324523),
+			AI64:    int64(0x3284029034098234),
+			AF32:    float32(2342.2378),
+			AF64:    float64(324.8899992),
+			AString: "fox bed",
+			AArray:  []int16 { 0x7, 0x6, 0x5, 0x4 },
+			ATable: map[uint16] any {
+				0x0001: int8(0x8),
+				0x0002: float64(4.4),
+			},
+			T0: map[uint16] any {
+				0x0001: float32(489.5),
+				0x0002: "hi",
+				0x0003: uint16(0x3992),
+			},
+		}
+		testEncodeDecode(
+			&messageDynamic,
+			tu.S(0xE0, 14).AddVar(
+				[]byte { 0x00, 0x00, 0x20, 0x23 },
+				[]byte { 0x00, 0x01, 0x21, 0x32, 0x47 },
+				[]byte { 0x00, 0x02, 0x23, 0x87, 0x32, 0x45, 0x23 },
+				[]byte { 0x00, 0x03, 0x27, 0x32, 0x84, 0x02, 0x90, 0x34, 0x09, 0x82, 0x34 },
+				[]byte { 0x00, 0x04, 0x40, 0x23 },
+				[]byte { 0x00, 0x05, 0x41, 0x32, 0x47 },
+				[]byte { 0x00, 0x06, 0x43, 0x57, 0x32, 0x45, 0x23 },
+				[]byte { 0x00, 0x07, 0x47, 0x32, 0x84, 0x02, 0x90, 0x34, 0x09, 0x82, 0x34 },
+				[]byte { 0x00, 0x08, 0x63, 0x45, 0x12, 0x63, 0xCE },
+				[]byte { 0x00, 0x09, 0x67, 0x40, 0x74, 0x4E, 0x3D, 0x6F, 0xCD, 0x17, 0x75 },
+				[]byte { 0x00, 0x0A, 0x87, 'f', 'o', 'x', ' ', 'b', 'e', 'd' },
+				[]byte { 0x00, 0x0B, 0xC0, 0x04, 0x41,
+					0x00, 0x07,
+					0x00, 0x06,
+					0x00, 0x05,
+					0x00, 0x04 },
+				[]byte { 0x00, 0x0C, 0xE0, 0x02,
+					0x00, 0x01, 0x40, 0x08,
+					0x00, 0x02, 0x67, 0x40, 0x11, 0x99, 0x99, 0x99, 0x99, 0x99, 0x9A },
+				[]byte { 0x00, 0x0D, 0xE0, 0x03, // ERR
+					0x00, 0x01, 0x63, 0x43, 0xF4, 0xC0, 0x00,
+					0x00, 0x02, 0x82, 'h', 'i',
+					0x00, 0x03, 0x21, 0x39, 0x92 },
+				))
+	`)
+}
+
+func TestGenerateRunDecodeWrongType(test *testing.T) {
+	protocol := defaultProtocol()
+	protocol.Messages[0x0000] = Message {
+		Name: "Uint5",
+		Type: TypeInt { Bits: 5 },
+	}
+	protocol.Messages[0x0001] = Message {
+		Name: "Uint8",
+		Type: TypeInt { Bits: 8 },
+	}
+	protocol.Messages[0x0002] = Message {
+		Name: "Uint16",
+		Type: TypeInt { Bits: 16 },
+	}
+	protocol.Messages[0x0003] = Message {
+		Name: "Uint32",
+		Type: TypeInt { Bits: 32 },
+	}
+	protocol.Messages[0x0004] = Message {
+		Name: "Uint64",
+		Type: TypeInt { Bits: 64 },
+	}
+	protocol.Messages[0x0005] = Message {
+		Name: "Int8",
+		Type: TypeInt { Bits: 8 },
+	}
+	protocol.Messages[0x0006] = Message {
+		Name: "Int16",
+		Type: TypeInt { Bits: 16 },
+	}
+	protocol.Messages[0x0007] = Message {
+		Name: "Int32",
+		Type: TypeInt { Bits: 32 },
+	}
+	protocol.Messages[0x0008] = Message {
+		Name: "Int64",
+		Type: TypeInt { Bits: 64 },
+	}
+	protocol.Messages[0x0009] = Message {
+		Name: "String",
+		Type: TypeString { },
+	}
+	protocol.Messages[0x000A] = Message {
+		Name: "Buffer",
+		Type: TypeBuffer { },
+	}
+	protocol.Messages[0x000B] = Message {
+		Name: "StringArray",
+		Type: TypeArray { Element: TypeString { } },
+	}
+	protocol.Messages[0x000C] = Message {
+		Name: "Table",
+		Type: TypeTable { },
+	}
+	protocol.Messages[0x000D] = Message {
+		Name: "TableDefined",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "Name",      Type: TypeString { } },
+				0x0001: Field { Name: "Password",  Type: TypeString { } },
+			},
+		},
+	}
+	
+	testGenerateRun(test, &protocol, "decode-wrong-type", `
+		// imports
+	`, `
+		datas := [][]byte {
+			/* int8     */ []byte { byte(tape.LSI.WithCN(0)), 0x45 },
+			/* int16    */ []byte { byte(tape.LSI.WithCN(1)), 0x45, 0x67 },
+			/* int32    */ []byte { byte(tape.LSI.WithCN(3)), 0x45, 0x67, 0x89, 0xAB },
+			/* int64    */ []byte { byte(tape.LSI.WithCN(7)), 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23 },
+			/* uint5    */ []byte { byte(tape.SI.WithCN(12)) },
+			/* uint8    */ []byte { byte(tape.LI.WithCN(0)), 0x45 },
+			/* uint16   */ []byte { byte(tape.LI.WithCN(1)), 0x45, 0x67 },
+			/* uint32   */ []byte { byte(tape.LI.WithCN(3)), 0x45, 0x67, 0x89, 0xAB },
+			/* uint64   */ []byte { byte(tape.LI.WithCN(7)), 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23 },
+			/* string   */ []byte { byte(tape.SBA.WithCN(7)), 'p', 'u', 'p', 'e', 'v', 'e', 'r' },
+			/* []byte   */ []byte { byte(tape.SBA.WithCN(5)), 'b', 'l', 'a', 'r', 'g' },
+			/* []string */ []byte {
+				byte(tape.OTA.WithCN(0)), 2, byte(tape.LBA.WithCN(0)),
+				0x08, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23,
+				0x05, 0x11, 0x11, 0x11, 0x11, 0x11,
+			},
+			/* map[uint16] any */ []byte {
+				byte(tape.KTV.WithCN(0)), 2,
+				0x02, 0x23, byte(tape.LSI.WithCN(1)), 0x45, 0x67,
+				0x02, 0x23, byte(tape.LI.WithCN(3)),  0x45, 0x67, 0x89, 0xAB,
+			},
+		}
+
+		
+		for index, data := range datas {
+			log.Printf("data %2d %v [%s]", index, tape.Tag(data[0]), tu.HexBytes(data[1:]))
+			// integers should only assign to other integers
+			if index > 8 {
+				cas := func(destination Message) {
+					n, err := destination.Decode(tape.NewDecoder(bytes.NewBuffer(data)))
+					if err != nil { log.Fatalf("error: %v | n: %d", err, n) }
+					reflectValue := reflect.ValueOf(destination).Elem()
+					if reflectValue.CanInt() {
+						if reflectValue.Int() != 0 {
+							log.Fatalf(
+								"destination not zero: %v",
+								reflectValue.Elem().Interface())
+						}
+					} else {
+						if reflectValue.Uint() != 0 {
+							log.Fatalf(
+								"destination not zero: %v",
+								reflectValue.Elem().Interface())
+						}
+					}
+					if n != len(data) {
+						log.Fatalf("n not equal: %d != %d", n, len(data))
+					}
+				}
+				log.Println("- MessageInt8")
+				{ var dest MessageInt8;   cas(&dest) }
+				log.Println("- MessageInt16")
+				{ var dest MessageInt16;  cas(&dest) }
+				log.Println("- MessageInt32")
+				{ var dest MessageInt32;  cas(&dest) }
+				log.Println("- MessageInt64")
+				{ var dest MessageInt64;  cas(&dest) }
+				log.Println("- MessageUint8")
+				{ var dest MessageUint8;  cas(&dest) }
+				log.Println("- MessageUint16")
+				{ var dest MessageUint16; cas(&dest) }
+				log.Println("- MessageUint32")
+				{ var dest MessageUint32; cas(&dest) }
+				log.Println("- MessageUint64")
+				{ var dest MessageUint64; cas(&dest) }
+			}
+			arrayCase := func(destination Message) {
+				n, err := destination.Decode(tape.NewDecoder(bytes.NewBuffer(data)),)
+				if err != nil { log.Fatalf("error: %v | n: %d", err, n) }
+				reflectDestination := reflect.ValueOf(destination)
+				reflectValue := reflectDestination.Elem()
+				if reflectValue.Len() != 0 {
+					log.Fatalf("len(destination) not zero: %v", reflectValue.Interface())
+				}
+				if n != len(data) {
+					log.Fatalf("n not equal: %d != %d", n, len(data))
+				}
+			}
+			anyCase := func(destination Message) {
+				n, err := destination.Decode(tape.NewDecoder(bytes.NewBuffer(data)),)
+				if err != nil { log.Fatalf("error: %v | n: %d", err, n) }
+				reflectDestination := reflect.ValueOf(destination)
+				reflectValue := reflectDestination.Elem()
+				if reflectValue == reflect.Zero(reflectValue.Type()) {
+					log.Fatalf("len(destination) not zero: %v", reflectValue.Interface())
+				}
+				if n != len(data) {
+					log.Fatalf("n not equal: %d != %d", n, len(data))
+				}
+			}
+			// SBA/LBA types should only assign to other SBA/LBA types
+			if index != 9 && index != 10 {
+				log.Println("- MessageString")
+				{ var dest MessageString; arrayCase(&dest) }
+				log.Println("- MessageBuffer")
+				{ var dest MessageBuffer; arrayCase(&dest) }
+			}
+			// arrays should only assign to other arrays
+			if index != 11 {
+				log.Println("- MessageStringArray")
+				{ var dest MessageStringArray; arrayCase(&dest) }
+			}
+			// tables should only assign to other tables
+			if index != 12 {
+				log.Println("- MessageTable")
+				{ var dest = make(MessageTable); arrayCase(&dest) }
+				log.Println("- MessageTableDefined")
+				{ var dest MessageTableDefined; anyCase(&dest) }
+			}
+		}
+	`)
+}

generate/lex.go

@@ -0,0 +1,230 @@
+package generate
+
+import "io"
+import "bufio"
+import "unicode"
+import "unicode/utf8"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+const (
+	TokenMethod parse.TokenKind = iota
+	TokenKey
+	TokenIdent
+	TokenComma
+	TokenLBrace
+	TokenRBrace
+	TokenLBracket
+	TokenRBracket
+)
+
+var tokenNames = map[parse.TokenKind] string {
+	TokenMethod:   "Method",
+	TokenKey:      "Key",
+	TokenIdent:    "Ident",
+	TokenComma:    "Comma",
+	TokenLBrace:   "LBrace",
+	TokenRBrace:   "RBrace",
+	TokenLBracket: "LBracket",
+	TokenRBracket: "RBracket",
+}
+
+func Lex(fileName string, reader io.Reader) (parse.Lexer, error) {
+	lex := &lexer {
+		fileName: fileName,
+		lineScanner: bufio.NewScanner(reader),
+	}
+	lex.nextRune()
+	return lex, nil
+}
+
+type lexer struct {
+	fileName    string
+	lineScanner *bufio.Scanner
+	rune        rune
+	line        string
+	lineFood    string
+	
+	offset   int
+	row      int
+	column   int
+
+	eof bool
+
+}
+
+func (this *lexer) Next() (parse.Token, error) {
+	token, err := this.nextInternal()
+	if err == io.EOF { err = this.errUnexpectedEOF() }
+	return token, err
+}
+
+func (this *lexer) nextInternal() (token parse.Token, err error) {
+	err = this.skipWhitespace()
+	token.Position = this.pos()
+	if this.eof {
+		token.Kind = parse.EOF
+		err = nil
+		return
+	}
+	if err != nil { return }
+
+	appendRune := func () {
+		token.Value += string(this.rune)
+		err = this.nextRune()
+	}
+
+	doNumber := func () {
+		for isDigit(this.rune) {
+			appendRune()
+			if this.eof { err = nil; return }
+			if err != nil { return }
+		}
+	}
+
+	defer func () {
+		newPos := this.pos()
+		newPos.End -- // TODO figure out why tf we have to do this
+		token.Position = token.Position.Union(newPos)
+	} ()
+
+	switch {
+	// Method
+	case this.rune == 'M':
+		token.Kind = TokenMethod
+		err = this.nextRune()
+		if err != nil { return }
+		doNumber()
+		if this.eof { err = nil; return }
+	// Key
+	case isDigit(this.rune):
+		token.Kind = TokenKey
+		doNumber()
+		if this.eof { err = nil; return }
+	// Ident
+	case unicode.IsUpper(this.rune):
+		token.Kind = TokenIdent
+		for unicode.IsLetter(this.rune) || isDigit(this.rune) {
+			appendRune()
+			if this.eof { err = nil; return }
+			if err != nil { return }
+		}
+	// Comma
+	case this.rune == ',':
+		token.Kind = TokenComma
+		appendRune()
+		if this.eof { err = nil; return }
+	// LBrace
+	case this.rune == '{':
+		token.Kind = TokenLBrace
+		appendRune()
+		if this.eof { err = nil; return }
+	// RBrace
+	case this.rune == '}':
+		token.Kind = TokenRBrace
+		appendRune()
+		if this.eof { err = nil; return }
+	// LBracket
+	case this.rune == '[':
+		token.Kind = TokenLBracket
+		appendRune()
+		if this.eof { err = nil; return }
+	// RBracket
+	case this.rune == ']':
+		token.Kind = TokenRBracket
+		appendRune()
+		if this.eof { err = nil; return }
+	case unicode.IsPrint(this.rune):
+		err = parse.Errorf (
+			this.pos(), "unexpected rune '%c'",
+			this.rune)
+	default:
+		err = parse.Errorf (
+			this.pos(), "unexpected rune %U",
+			this.rune)
+	}
+
+	return
+}
+
+func (this *lexer) nextRune() error {
+	if this.lineFood == "" {
+		ok := this.lineScanner.Scan()
+		if ok {
+			this.line     = this.lineScanner.Text()
+			this.lineFood = this.line
+			this.rune     = '\n'
+			this.column   = 0
+			this.row      ++
+		} else {
+			err := this.lineScanner.Err()
+			if err == nil {
+				this.eof = true
+				return io.EOF
+			} else {
+				return err
+			}
+		}
+	} else {
+		var ch   rune
+		var size int
+		for ch == 0 && this.lineFood != "" {
+			ch, size = utf8.DecodeRuneInString(this.lineFood)
+			this.lineFood = this.lineFood[size:]
+		}
+		this.rune = ch
+		this.column ++
+	}
+
+	return nil
+}
+
+func (this *lexer) skipWhitespace() error {
+	err := this.skipComment()
+	if err != nil { return err }
+	for isWhitespace(this.rune) {
+		err := this.nextRune()
+		if err != nil { return err }
+		err = this.skipComment()
+		if err != nil { return err }
+	}
+	return nil
+}
+
+func (this *lexer) skipComment() error {
+	if this.rune == ';' {
+		for this.rune != '\n' {
+			err := this.nextRune()
+			if err != nil { return err }
+		}
+	}
+	return nil
+}
+
+func (this *lexer) pos() parse.Position {
+	return parse.Position {
+		File:   this.fileName,
+		Line:   this.lineScanner.Text(),
+		Row:    this.row    - 1,
+		Start:  this.column - 1,
+		End:    this.column,
+	}
+}
+
+func (this *lexer) errUnexpectedEOF() error {
+	return parse.Errorf(this.pos(), "unexpected EOF")
+}
+
+func isWhitespace(char rune) bool {
+	switch char {
+	case ' ', '\t', '\r', '\n': return true
+	default: return false
+	}
+}
+
+func isDigit(char rune) bool {
+	return char >= '0' && char <= '9'
+}
+
+func isHexDigit(char rune) bool {
+	return isDigit(char) || char >= 'a' && char <= 'f' || char >= 'A' && char <= 'F'
+}

generate/lex_test.go

@@ -0,0 +1,54 @@
+package generate
+
+import "strings"
+import "testing"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+func TestLex(test *testing.T) {
+	lexer, err := Lex("test.pdl", strings.NewReader(`
+	M0001 User {
+		0000 Name      String,
+		0001 Users []User,
+		0002 Followers U32,
+	}`))
+	if err != nil { test.Fatal(parse.Format(err)) }
+
+	correctTokens := []parse.Token {
+		tok(TokenMethod,   "0001"),
+		tok(TokenIdent,    "User"),
+		tok(TokenLBrace,   "{"),
+		tok(TokenKey,      "0000"),
+		tok(TokenIdent,    "Name"),
+		tok(TokenIdent,    "String"),
+		tok(TokenComma,    ","),
+		tok(TokenKey,      "0001"),
+		tok(TokenIdent,    "Users"),
+		tok(TokenLBracket, "["),
+		tok(TokenRBracket, "]"),
+		tok(TokenIdent,    "User"),
+		tok(TokenComma,    ","),
+		tok(TokenKey,      "0002"),
+		tok(TokenIdent,    "Followers"),
+		tok(TokenIdent,    "U32"),
+		tok(TokenComma,    ","),
+		tok(TokenRBrace,   "}"),
+		tok(parse.EOF,     ""),
+	}
+
+	for index, correct := range correctTokens {
+		got, err := lexer.Next()
+		if err != nil { test.Fatal(parse.Format(err)) }
+		if got.Kind != correct.Kind || got.Value != correct.Value {
+			test.Logf("token %d mismatch", index)
+			test.Log("GOT:", tokenNames[got.Kind], got.Value)
+			test.Fatal("CORRECT:", tokenNames[correct.Kind], correct.Value)
+		}
+	}
+}
+
+func tok(kind parse.TokenKind, value string) parse.Token {
+	return parse.Token {
+		Kind:  kind,
+		Value: value,
+	}
+}

generate/misc_test.go

@@ -0,0 +1,131 @@
+package generate
+
+import "os"
+import "fmt"
+import "os/exec"
+import "testing"
+import "path/filepath"
+
+func testGenerateRun(test *testing.T, protocol *Protocol, title, imports, testCase string) {
+	// reset data directory
+	dir := filepath.Join("test", title)
+	err := os.RemoveAll(dir)
+	if err != nil { test.Fatal(err) }
+	err = os.MkdirAll(dir, 0750)
+	if err != nil { test.Fatal(err) }
+
+	// open files
+	sourceFile, err := os.Create(filepath.Join(dir, "protocol.go"))
+	if err != nil { test.Fatal(err) }
+	defer sourceFile.Close()
+	mainFile, err := os.Create(filepath.Join(dir, "main.go"))
+	if err != nil { test.Fatal(err) }
+	defer mainFile.Close()
+
+	// generate protocol
+	generator := Generator {
+		Output: sourceFile,
+		PackageName: "main",
+	}
+	_, err = generator.Generate(protocol)
+	if err != nil { test.Fatal(err) }
+
+	// build static source files
+	imports = `
+		import "log"
+		import "bytes"
+		import "reflect"
+		import "git.tebibyte.media/sashakoshka/hopp/tape"
+		import tu "git.tebibyte.media/sashakoshka/hopp/internal/testutil"
+		` + imports
+	setup := `log.Println("*** BEGIN TEST CASE OUTPUT ***")`
+	teardown := `log.Println("--- END TEST CASE OUTPUT ---")`
+	static := `
+		func testEncode(message Message, correct tu.Snake) {
+			buffer := bytes.Buffer { }
+			encoder := tape.NewEncoder(&buffer)
+			n, err := message.Encode(encoder)
+			if err != nil { log.Fatalf("at %d: %v\n", n, err) }
+			encoder.Flush()
+			got := buffer.Bytes()
+			log.Printf("got:     [%s]", tu.HexBytes(got))
+			log.Println("correct:", correct)
+			if n != len(got) {
+				log.Fatalf("n incorrect: %d != %d\n", n, len(got))
+			}
+			if ok, n := correct.Check(got); !ok {
+				log.Fatalln("not equal at", n)
+			}
+		}
+
+		func testDecode(correct Message, data any) {
+			var flat []byte
+			switch data := data.(type) {
+			case []byte:   flat = data
+			case tu.Snake: flat = data.Flatten()
+			}
+			message := reflect.New(reflect.ValueOf(correct).Elem().Type()).Interface().(Message)
+			log.Println("before: ", message)
+			decoder := tape.NewDecoder(bytes.NewBuffer(flat))
+			n, err := message.Decode(decoder)
+			if err != nil { log.Fatalf("at %d: %v\n", n, err) }
+			log.Println("got:    ", message)
+			log.Println("correct:", correct)
+			if n != len(flat) {
+				log.Fatalf("n incorrect: %d != %d\n", n, len(flat))
+			}
+			if !reflect.DeepEqual(message, correct) {
+				log.Fatalln("not equal")
+			}
+		}
+
+		// TODO: possibly combine the two above functions into this one,
+		// also take a data parameter here (snake)
+		func testEncodeDecode(message Message, data tu.Snake) {buffer := bytes.Buffer { }
+			log.Println("encoding:")
+			encoder := tape.NewEncoder(&buffer)
+			n, err := message.Encode(encoder)
+			if err != nil { log.Fatalf("at %d: %v\n", n, err) }
+			encoder.Flush()
+			got := buffer.Bytes()
+			log.Printf("got:     [%s]", tu.HexBytes(got))
+			log.Println("correct:", data)
+			if n != len(got) {
+				log.Fatalf("n incorrect: %d != %d\n", n, len(got))
+			}
+			if ok, n := data.Check(got); !ok {
+				log.Fatalln("not equal at", n)
+			}
+		
+			log.Println("decoding:")
+			destination := reflect.New(reflect.ValueOf(message).Elem().Type()).Interface().(Message)
+			flat := data.Flatten()
+			log.Println("before: ", tu.Describe(destination))
+			decoder := tape.NewDecoder(bytes.NewBuffer(flat))
+			n, err = destination.Decode(decoder)
+			if err != nil { log.Fatalf("at %d: %v\n", n, err) }
+			log.Println("got:    ", tu.Describe(destination))
+			log.Println("correct:", tu.Describe(message))
+			if n != len(flat) {
+				log.Fatalf("n incorrect: %d != %d\n", n, len(flat))
+			}
+			if !reflect.DeepEqual(destination, message) {
+				log.Fatalln("not equal")
+			}
+			
+		}
+		`
+	fmt.Fprintf(
+		mainFile, "package main\n%s\nfunc main() {\n%s\n%s\n%s\n}\n%s",
+		imports, setup, testCase, teardown, static)
+
+	// build and run test
+	command := exec.Command("go", "run", "./" + filepath.Join("generate", dir))
+	workingDirAbs, err := filepath.Abs("..")
+	if err != nil { test.Fatal(err) }
+	command.Dir = workingDirAbs
+	command.Env = os.Environ()
+	output, err := command.CombinedOutput()
+	test.Logf("output of %v:\n%s", command, output)
+	if err != nil { test.Fatal(err) }
+}

generate/parse.go

@@ -0,0 +1,208 @@
+package generate
+
+import "io"
+import "strconv"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+func Parse(lx parse.Lexer) (*Protocol, error) {
+	protocol := defaultProtocol()
+	par := parser {
+		Parser: parse.Parser {
+			Lexer: lx,
+			TokenNames: tokenNames,
+		},
+		protocol: &protocol,
+	}
+	err := par.parse()
+	if err != nil { return nil, err }
+	return par.protocol, nil
+}
+
+func defaultProtocol() Protocol {
+	return Protocol {
+		Messages: make(map[uint16] Message),
+		Types: map[string] Type { },
+	}
+}
+
+func ParseReader(fileName string, reader io.Reader) (*Protocol, error) {
+	lx, err := Lex(fileName, reader)
+	if err != nil { return nil, err }
+	return Parse(lx)
+}
+
+type parser struct {
+	parse.Parser
+	protocol *Protocol
+}
+
+func (this *parser) parse() error {
+	err := this.Next()
+	if err != nil { return err }
+	for this.Token.Kind != parse.EOF {
+		err = this.parseTopLevel()
+		if err != nil { return err }
+	}
+	return nil
+}
+
+func (this *parser) parseTopLevel() error {
+	err := this.ExpectDesc("message or typedef", TokenMethod, TokenIdent)
+	if err != nil { return err }
+	if this.EOF() { return nil }
+
+	switch this.Kind() {
+	case TokenMethod: return this.parseMessage()
+	case TokenIdent:  return this.parseTypedef()
+	}
+	panic("bug")
+}
+
+func (this *parser) parseMessage() error {
+	err := this.Expect(TokenMethod)
+	if err != nil { return err }
+	method, err := this.parseHexNumber(this.Value(), 0xFFFF)
+	if err != nil { return err }
+	err = this.ExpectNext(TokenIdent)
+	if err != nil { return err }
+	name := this.Value()
+	err = this.Next()
+	if err != nil { return err }
+	typ, err := this.parseType()
+	if err != nil { return err }
+	this.protocol.Messages[uint16(method)] = Message {
+		Name: name,
+		Type: typ,
+	}
+	return nil
+}
+
+func (this *parser) parseTypedef() error {
+	err := this.Expect(TokenIdent)
+	if err != nil { return err }
+	name := this.Value()
+	err = this.Next()
+	if err != nil { return err }
+	typ, err := this.parseType()
+	if err != nil { return err }
+	this.protocol.Types[name] = typ
+	return nil
+}
+
+func (this *parser) parseType() (Type, error) {
+	err := this.ExpectDesc("type", TokenIdent, TokenLBracket, TokenLBrace)
+	if err != nil { return nil, err }
+
+	switch this.Kind() {
+	case TokenIdent:
+		switch this.Value() {
+		case "U8":     return TypeInt { Bits: 8   }, this.Next()
+		case "U16":    return TypeInt { Bits: 16  }, this.Next()
+		case "U32":    return TypeInt { Bits: 32  }, this.Next()
+		case "U64":    return TypeInt { Bits: 64  }, this.Next()
+		case "U128":   return TypeInt { Bits: 128 }, this.Next()
+		case "U256":   return TypeInt { Bits: 256 }, this.Next()
+		case "I8":     return TypeInt { Bits: 8,   Signed: true }, this.Next()
+		case "I16":    return TypeInt { Bits: 16,  Signed: true }, this.Next()
+		case "I32":    return TypeInt { Bits: 32,  Signed: true }, this.Next()
+		case "I64":    return TypeInt { Bits: 64,  Signed: true }, this.Next()
+		case "I128":   return TypeInt { Bits: 128, Signed: true }, this.Next()
+		case "I256":   return TypeInt { Bits: 256, Signed: true }, this.Next()
+		case "F16":    return TypeFloat { Bits: 16  }, this.Next()
+		case "F32":    return TypeFloat { Bits: 32  }, this.Next()
+		case "F64":    return TypeFloat { Bits: 64  }, this.Next()
+		case "F128":   return TypeFloat { Bits: 128 }, this.Next()
+		case "F256":   return TypeFloat { Bits: 256 }, this.Next()
+		case "String": return TypeString { }, this.Next()
+		case "Buffer": return TypeBuffer { }, this.Next()
+		case "Table":  return TypeTable { }, this.Next()
+		case "Any":    return TypeAny { }, this.Next()
+		}
+		return this.parseTypeNamed()
+	case TokenLBracket:
+		return this.parseTypeArray()
+	case TokenLBrace:
+		return this.parseTypeTable()
+	}
+	panic("bug")
+}
+
+func (this *parser) parseTypeNamed() (TypeNamed, error) {
+	err := this.Expect(TokenIdent)
+	if err != nil { return TypeNamed { }, err }
+	name := this.Value()
+	err = this.Next()
+	if err != nil { return TypeNamed { }, err }
+	return TypeNamed { Name: name }, nil
+}
+
+func (this *parser) parseTypeArray() (TypeArray, error) {
+	err := this.Expect(TokenLBracket)
+	if err != nil { return TypeArray { }, err }
+	err = this.ExpectNext(TokenRBracket)
+	if err != nil { return TypeArray { }, err }
+	err = this.Next()
+	if err != nil { return TypeArray { }, err }
+	typ, err := this.parseType()
+	if err != nil { return TypeArray { }, err }
+	return TypeArray { Element: typ }, nil
+}
+
+func (this *parser) parseTypeTable() (TypeTableDefined, error) {
+	err := this.Expect(TokenLBrace)
+	if err != nil { return TypeTableDefined { }, err }
+	err = this.Next()
+	if err != nil { return TypeTableDefined { }, err }
+	typ := TypeTableDefined {
+		Fields: make(map[uint16] Field),
+	}
+	for {
+		err := this.ExpectDesc("table field", TokenKey, TokenRBrace)
+		if err != nil { return TypeTableDefined { }, err }
+		if this.Is(TokenRBrace) {
+			break
+		}
+		key, field, err := this.parseField()
+		if err != nil { return TypeTableDefined { }, err }
+		typ.Fields[key] = field
+		err = this.Expect(TokenComma, TokenRBrace)
+		if err != nil { return TypeTableDefined { }, err }
+		if this.Is(TokenRBrace) {
+			break
+		}
+		err = this.Next()
+		if err != nil { return TypeTableDefined { }, err }
+	}
+	err = this.Next()
+	if err != nil { return TypeTableDefined { }, err }
+	return typ, nil
+}
+
+func (this *parser) parseField() (uint16, Field, error) {
+	err := this.Expect(TokenKey)
+	if err != nil { return 0, Field { }, err }
+	key, err := this.parseHexNumber(this.Value(), 0xFFFF)
+	if err != nil { return 0, Field { }, err }
+	err = this.ExpectNext(TokenIdent)
+	if err != nil { return 0, Field { }, err }
+	name := this.Value()
+	err = this.Next()
+	if err != nil { return 0, Field { }, err }
+	typ, err := this.parseType()
+	if err != nil { return 0, Field { }, err }
+	return uint16(key), Field {
+		Name: name,
+		Type: typ,
+	}, nil
+}
+
+func (this *parser) parseHexNumber(input string, maxValue int64) (int64, error) {
+	number, err := strconv.ParseInt(input, 16, 64)
+	if err != nil {
+		return 0, parse.Errorf(this.Pos(), "%v", err)
+	}
+	if maxValue > 0 && number > maxValue {
+		return 0, parse.Errorf(this.Pos(), "value too large (max %X)", maxValue)
+	}
+	return number, nil
+}

generate/parse_test.go

@@ -0,0 +1,71 @@
+package generate
+
+import "fmt"
+import "strings"
+import "testing"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+func TestParse(test *testing.T) {
+	correct := defaultProtocol()
+	correct.Messages[0x0000] = Message {
+		Name: "Connect",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "Name",      Type: TypeString { } },
+				0x0001: Field { Name: "Password",  Type: TypeString { } },
+			},
+		},
+	}
+	correct.Messages[0x0001] = Message {
+		Name: "UserList",
+		Type: TypeTableDefined {
+			Fields: map[uint16] Field {
+				0x0000: Field { Name: "Users",  Type: TypeArray { Element: TypeNamed { Name: "User" } } },
+			},
+		},
+	}
+	correct.Types["User"] = TypeTableDefined {
+		Fields: map[uint16] Field {
+			0x0000: Field { Name: "Name",      Type: TypeString { } },
+			0x0001: Field { Name: "Bio",       Type: TypeString { } },
+			0x0002: Field { Name: "Followers", Type: TypeInt { Bits: 32 } },
+		},
+	}
+	correct.Types["Anything"] = TypeAny { }
+	test.Log("CORRECT:", &correct)
+	
+	got, err := ParseReader("test.pdl", strings.NewReader(`
+	M0000 Connect {
+		0000 Name String,
+		0001 Password String,
+	}
+	
+	M0001 UserList {
+		0000 Users []User,
+	}
+	
+	User {
+		0000 Name      String,
+		0001 Bio       String,
+		0002 Followers U32,
+	}
+
+	Anything Any
+	`))
+	if err != nil { test.Fatal(parse.Format(err)) }
+	test.Log("GOT:    ", got)
+
+	correctStr := fmt.Sprint(&correct)
+	gotStr     := fmt.Sprint(got)
+
+	if correctStr != gotStr {
+		test.Error("not equal")
+		for index := range min(len(correctStr), len(gotStr)) {
+			if correctStr[index] == gotStr[index] { continue }
+			test.Log("C:", correctStr[max(0, index - 8):min(len(correctStr), index + 8)])
+			test.Log("G:", gotStr[max(0, index - 8):min(len(gotStr), index + 8)])
+			break
+		}
+		test.FailNow()
+	}
+}

generate/protocol.go

@@ -1,244 +1,113 @@
 package generate
 
-import "io"
 import "fmt"
-import "errors"
-import "strconv"
-import "strings"
-import "github.com/gomarkdown/markdown"
-import "github.com/gomarkdown/markdown/ast"
-import "github.com/gomarkdown/markdown/parser"
+import "maps"
+import "slices"
+import "crypto/md5"
 
-// Protocol describes a protocol.
 type Protocol struct {
-	Messages []Message
+	Messages map[uint16] Message
+	Types    map[string] Type
 }
 
-// Message describes a protocol message.
 type Message struct {
-	Doc    string
-	Method uint16
-	Name   string
-	Fields []Field
+	Name string
+	Type Type
+}
+
+type Type interface {
+	fmt.Stringer
+}
+
+type TypeInt struct {
+	Bits   int
+	Signed bool
+}
+
+func (typ TypeInt) String() string {
+	output := ""
+	if typ.Signed {
+		output += "I"
+	} else {
+		output += "U"
+	}
+	output += fmt.Sprint(typ.Bits)
+	return output
+}
+
+type TypeFloat struct {
+	Bits int
+}
+
+func (typ TypeFloat) String() string {
+	return fmt.Sprintf("F%d", typ.Bits)
+}
+
+type TypeString struct { }
+
+func (TypeString) String() string {
+	return "String"
+}
+
+type TypeBuffer struct { }
+
+func (TypeBuffer) String() string {
+	return "Buffer"
+}
+
+type TypeArray struct {
+	Element Type
+}
+
+func (typ TypeArray) String() string {
+	return fmt.Sprintf("[]%v", typ.Element)
+}
+
+type TypeTable struct { }
+
+func (TypeTable) String() string {
+	return "Table"
+}
+
+type TypeTableDefined struct {
+	Fields map[uint16] Field
+}
+
+func (typ TypeTableDefined) String() string {
+	output := "{"
+	for _, key := range slices.Sorted(maps.Keys(typ.Fields)) {
+		output += fmt.Sprintf("%04X %v", key, typ.Fields[key])
+	}
+	output += "}"
+	return output
 }
 
-// Field describes a named value within a message.
 type Field struct {
-	Doc      string
-	Tag      uint16
-	Name     string
-	Optional bool
-	Type     string
+	Name string
+	Type Type
 }
 
-// ParseReader parses a protocol definition from a reader.
-func ParseReader(reader io.Reader) (*Protocol, error) {
-	data, err := io.ReadAll(reader)
-	if err != nil { return nil, err }
-	protocol := new(Protocol)
-	err = protocol.UnmarshalText(data)
-	if err != nil { return nil, err }
-	return protocol, nil
+func (field Field) String() string {
+	return fmt.Sprintf("%s %v", field.Name, field.Type)
 }
 
-// UnmarshalText unmarshals markdown-formatted text data into the protocol.
-func (this *Protocol) UnmarshalText(text []byte) error {
-	var state int; const (
-		stateIdle = iota
-		stateMessage
-		stateMessageDoc
-		stateMessageField
-	)
-
-	var message *Message
-	addMessage := func(method uint16, name string) {
-		this.Messages = append(this.Messages, Message {
-			Method: method,
-			Name:   name,
-		})
-		message = &this.Messages[len(this.Messages) - 1]
-	}
-
-	root := markdown.Parse(text, parser.New())
-	for _, node := range root.GetChildren() {
-		if node, ok := node.(*ast.Heading); ok {
-			if node.Level == 2 {
-				if removeBreaks(flatten(node)) == "Messages" {
-					state = stateMessage
-					continue
-				}
-			}
-
-			if node.Level > 3 {
-				state = stateIdle
-				continue
-			}
-
-			if state != stateIdle && node.Level == 3 {
-				heading := removeBreaks(flatten(node))
-				method, name, err := splitMessageHeading(heading)
-				if err != nil { return err }
-				addMessage(method, name)
-				state = stateMessageDoc
-			}
-		}
-
-		if state == stateIdle { continue }
-		if message == nil     { continue }
-
-		// TODO when we are adding text content to the doc comment, it
-		// might be wise to do stuff like indent lists and quotes so
-		// that go doc renders them correctly
-		switch node := node.(type) {
-		case *ast.Paragraph:
-			if message.Doc != "" { message.Doc += "\n\n" }
-			message.Doc += removeBreaks(flatten(node))
-		case *ast.BlockQuote:
-			if message.Doc != "" { message.Doc += "\n\n> " }
-			message.Doc += removeBreaks(flatten(node))
-		case *ast.List:
-			// FIXME format the list
-			if message.Doc != "" { message.Doc += "\n\n" }
-			message.Doc += removeBreaks(flatten(node))
-		case *ast.Table:
-			fields, err := processFieldTable(node)
-			if err != nil { return err}
-			message.Fields = append(message.Fields, fields...)
-		}
-	}
-	
-	return nil
+type TypeNamed struct {
+	Name string
 }
 
-func processFieldTable(node *ast.Table) ([]Field, error) {
-	fields := []Field { }
-	children := node.GetChildren()
-	if len(children) != 2 {
-		return nil, errors.New("malformed field table")
-	}
-
-	// get columns
-	columns := []string { }
-	if header, ok := children[0].(*ast.TableHeader); ok {
-		children := header.GetChildren()
-		if len(children) != 1 {
-			return nil, errors.New("malformed field table header")
-		}
-		if row, ok := header.Children[0].(*ast.TableRow); ok {
-			for _, cell := range row.GetChildren() {
-				if cell, ok := cell.(*ast.TableCell); ok {
-					columns = append(columns, flatten(cell))
-				}
-			}
-		} else {
-			return nil, errors.New("malformed field table header")
-		}
-		for index, column := range columns {
-			columns[index] = strings.ToLower(column)
-		}
-	} else {
-		return nil, errors.New("malformed field table: no header")
-	}
-
-	// get data
-	if body, ok := children[1].(*ast.TableBody); ok {
-		for _, node := range body.GetChildren() {
-		if row, ok := node.(*ast.TableRow); ok {
-			children := row.GetChildren()
-			if len(children) != len(columns) {
-				return nil, errors.New (
-					"malformed field table row: wrong " +
-					"number of columns")
-			}
-
-			field := Field { }
-		
-			for index, node := range children {
-			if cell, ok := node.(*ast.TableCell); ok {
-				text := flatten(cell)
-				switch columns[index] {
-				case "tag":
-					tag, err := parseTag(text)
-					if err != nil { return nil, err }
-					field.Tag = tag
-				case "name":
-					field.Name = text
-				case "required":
-					field.Optional = !parseBool(text)
-				case "optional":
-					field.Optional = parseBool(text)
-				case "type":
-					field.Type = text
-				case "comment", "purpose", "documentation":
-					field.Doc = text
-				}
-			}}
-
-			fields = append(fields, field)
-		}}
-	} else {
-		return nil, errors.New("malformed field table: no body")
-	}
-	return fields, nil
+func (typ TypeNamed) String() string {
+	return typ.Name
 }
 
-type nodeFlattener struct {
-	text string
-}
-func (this *nodeFlattener) String() string { return this.text }
-func (this *nodeFlattener) Visit(node ast.Node, entering bool) ast.WalkStatus {
-	if entering {
-		if node := node.AsLeaf(); node != nil {
-			this.text += string(node.Literal)
-		}
-	}
-	return ast.GoToNext
-}
-func flatten(node ast.Node) string {
-	flattener := new(nodeFlattener)
-	ast.Walk(node, flattener)
-	return flattener.text
+type TypeAny struct { }
+
+func (typ TypeAny) String() string {
+	return "Any"
 }
 
-
-func removeBreaks(text string) string {
-	text = strings.ReplaceAll(text, "\n", " ")
-	text = strings.ReplaceAll(text, "\r", "")
-	return text
-}
-
-func parseBool(text string) bool {
-	switch(strings.ToLower(text)) {
-	case "yes": return true
-	case "no": return false
-	case "true": return true
-	case "false": return false
-	}
-	return false
-}
-
-func parseTag(text string) (uint16, error) {
-	tag, err := strconv.ParseUint(text, 10, 16)
-	if err != nil {
-		return 0, fmt.Errorf("malformed tag '%s': %w", text, err)
-	}
-	return uint16(tag), nil
-}
-
-func splitMessageHeading(text string) (uint16, string, error) {
-	text = strings.TrimSpace(text)
-	methodText, name, ok := strings.Cut(text, " ")
-	if !ok {
-		return 0, "", fmt.Errorf(
-			"malformed message heading '%s': no message name",
-			text)
-	}
-	method, err := strconv.ParseUint(methodText, 16, 16)
-	if err != nil {
-		return 0, "", fmt.Errorf(
-			"malformed method number '%s': %w",
-			methodText, err)
-	}
-	name = strings.TrimSpace(name)
-	return uint16(method), name, nil
+func HashType(typ Type) [16]byte {
+	// TODO: if we ever want to make the compiler more efficient, this would
+	// be a good place to start, complex string concatenation in a hot path
+	// (sorta)
+	return md5.Sum([]byte(typ.String()))
 }

go.mod

@@ -4,5 +4,5 @@ go 1.23.0
 
 require (
 	git.tebibyte.media/sashakoshka/go-util v0.9.1
-	github.com/gomarkdown/markdown v0.0.0-20241205020045-f7e15b2f3e62
+	git.tebibyte.media/sashakoshka/goparse v0.2.0
 )

go.sum

@@ -1,4 +1,4 @@
 git.tebibyte.media/sashakoshka/go-util v0.9.1 h1:eGAbLwYhOlh4aq/0w+YnJcxT83yPhXtxnYMzz6K7xGo=
 git.tebibyte.media/sashakoshka/go-util v0.9.1/go.mod h1:0Q1t+PePdx6tFYkRuJNcpM1Mru7wE6X+it1kwuOH+6Y=
-github.com/gomarkdown/markdown v0.0.0-20241205020045-f7e15b2f3e62 h1:pbAFUZisjG4s6sxvRJvf2N7vhpCvx2Oxb3PmS6pDO1g=
-github.com/gomarkdown/markdown v0.0.0-20241205020045-f7e15b2f3e62/go.mod h1:JDGcbDT52eL4fju3sZ4TeHGsQwhG9nbDV21aMyhwPoA=
+git.tebibyte.media/sashakoshka/goparse v0.2.0 h1:uQmKvOCV2AOlCHEDjg9uclZCXQZzq2PxaXfZ1aIMiQI=
+git.tebibyte.media/sashakoshka/goparse v0.2.0/go.mod h1:tSQwfuD+EujRoKr6Y1oaRy74ZynatzkRLxjE3sbpCmk=

internal/testutil/testutil.go

@@ -0,0 +1,190 @@
+package testutil
+
+import "fmt"
+import "slices"
+import "reflect"
+import "strings"
+import "unicode"
+
+// Snake lets you compare blocks of data where the ordering of certain parts may
+// be swapped every which way. It is designed for comparing the encoding of
+// maps where the ordering of individual elements is inconsistent.
+//
+// The snake is divided into sectors, which hold a number of variations. For a
+// sector to be satisfied by some data, some ordering of it must match the data
+// exactly. for the snake to be satisfied by some data, its sectors must match
+// the data in order, but the internal ordering of each sector doesn't matter.
+type Snake []    []     []byte
+//         snake sector variation
+
+// S returns a new snake.
+func S(data ...byte) Snake {
+	return (Snake { }).Add(data...)
+}
+
+// AddVar returns a new snake with the given sector added on to it. Successive
+// calls of this method can be chained together to create a big ass snake.
+func (sn Snake) AddVar(sector ...[]byte) Snake {
+	slice := make(Snake, len(sn) + 1)
+	copy(slice, sn)
+	slice[len(slice) - 1] = sector
+	return slice
+}
+
+// Add is like AddVar, but adds a sector with only one variation, which means it
+// does not vary, hence why the method is called that.
+func (sn Snake) Add(data ...byte) Snake {
+	return sn.AddVar(data)
+}
+
+// Check determines if the data satisfies the snake.
+func (sn Snake) Check(data []byte) (ok bool, n int) {
+	left := data
+	variations := map[int] []byte { }
+	for _, sector := range sn {
+		clear(variations)
+		for key, variation := range sector {
+			variations[key] = variation
+		}
+		for len(variations) > 0 {
+			found := false
+			for key, variation := range variations {
+				if len(left) < len(variation) { continue }
+				if !slices.Equal(left[:len(variation)], variation) { continue }
+				n += len(variation)
+				left = data[n:]
+				delete(variations, key)
+				found = true
+			}
+			if !found { return false, n }
+		}
+	}
+	if n < len(data) {
+		return false, n
+	}
+	return true, n
+}
+
+// Flatten returns the snake flattened to a byte array. The result of this
+// function always satisfies the snake.
+func (sn Snake) Flatten() []byte {
+	flat := []byte { }
+	for _, sector := range sn {
+		for _, variation := range sector {
+			flat = append(flat, variation...)
+		}
+	}
+	return flat
+}
+
+func (sn Snake) String() string {
+	if len(sn) == 0 || len(sn[0]) == 0 || len(sn[0][0]) == 0 {
+		return "EMPTY"
+	}
+
+	out := strings.Builder { }
+	for index, sector := range sn {
+		if index > 0 { out.WriteString(" : ") }
+		out.WriteRune('[')
+		for index, variation := range sector {
+			if index > 0 { out.WriteString(" / ") }
+			for _, byt := range variation {
+				fmt.Fprintf(&out, "%02x", byt)
+			}
+		}
+		out.WriteRune(']')
+	}
+	return out.String()
+}
+
+// HexBytes formats bytes into a hexadecimal string.
+func HexBytes(data []byte) string {
+	if len(data) == 0 { return "EMPTY" }
+	out := strings.Builder { }
+	for _, byt := range data {
+		fmt.Fprintf(&out, "%02x", byt)
+	}
+	return out.String()
+}
+
+// Describe returns a string representing the type and data of the given value.
+func Describe(value any) string {
+	desc := describer { }
+	desc.describe(reflect.ValueOf(value))
+	return desc.String()
+}
+
+type describer struct {
+	strings.Builder
+	indent int
+}
+
+func (this *describer) describe(value reflect.Value) {
+	if !value.IsValid() {
+		this.printf("<invalid>")
+		return
+	}
+	value = reflect.ValueOf(value.Interface())
+	if !value.IsValid() {
+		this.printf("<invalid>")
+		return
+	}
+	switch value.Kind() {
+	case reflect.Array, reflect.Slice:
+		this.printf("[\n")
+		this.indent += 1
+		for index := 0; index < value.Len(); index ++ {
+			this.iprintf("")
+			this.describe(value.Index(index))
+			this.iprintf("\n")
+		}
+		this.indent -= 1
+		this.iprintf("]")
+	case reflect.Struct:
+		this.printf("struct {\n")
+		this.indent += 1
+		typ := value.Type()
+		for index := range typ.NumField() {
+			indexBuffer := [1]int { index }
+			field := typ.Field(index)
+			this.iprintf("%s: ", field.Name)
+			for _, char := range field.Name {
+				if unicode.IsUpper(char) {
+					this.describe(value.FieldByIndex(indexBuffer[:]))
+				} else {
+					this.printf("<private>")
+				}
+				break
+			}
+			this.iprintf("\n")
+		}
+		this.indent -= 1
+		this.iprintf("}")
+	case reflect.Map:
+		this.printf("map {\n")
+		this.indent += 1
+		iter := value.MapRange()
+		for iter.Next() {
+			this.iprintf("")
+			this.describe(iter.Key())
+			this.printf(": ")
+			this.describe(iter.Value())
+			this.iprintf("\n")
+		}
+		this.indent -= 1
+		this.iprintf("}")
+	case reflect.Pointer:
+		this.printf("& ")
+		this.describe(value.Elem())
+	default:
+		this.printf("<%v %v>", value.Type(), value.Interface())
+	}
+}
+
+func (this *describer) printf(format string, v ...any) {
+	fmt.Fprintf(this, format, v...)
+}
+
+func (this *describer) iprintf(format string, v ...any) {
+	fmt.Fprintf(this, strings.Repeat("\t", this.indent) + format, v...)
+}

internal/testutil/testutil_test.go

@@ -0,0 +1,66 @@
+package testutil
+
+import "testing"
+
+func TestSnakeA(test *testing.T) {
+	snake := S(1, 6).AddVar(
+		[]byte { 1 },
+		[]byte { 2 },
+		[]byte { 3 },
+		[]byte { 4 },
+		[]byte { 5 },
+	).Add(9)
+
+	test.Log(snake)
+
+	ok, n := snake.Check([]byte { 1, 6, 1, 2, 3, 4, 5, 9 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 5, 4, 3, 2, 1, 9 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 3, 1, 4, 2, 5, 9 })
+	if !ok { test.Fatal("false negative:", n) }
+	
+	ok, n = snake.Check([]byte { 1, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 1, 2, 3, 4, 5, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 0, 2, 3, 4, 5, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 7, 1, 4, 2, 5, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 7, 3, 1, 4, 2, 5, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 7, 3, 1, 4, 2, 5, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 1, 2, 3, 4, 5, 9, 10})
+	if ok { test.Fatal("false positive:", n) }
+}
+
+func TestSnakeB(test *testing.T) {
+	snake := S(1, 6).AddVar(
+		[]byte { 1 },
+		[]byte { 2 },
+	).Add(9).AddVar(
+		[]byte { 3, 2 },
+		[]byte { 0 },
+		[]byte { 1, 1, 2, 3 },
+	)
+
+	test.Log(snake)
+
+	ok, n := snake.Check([]byte { 1, 6, 1, 2, 9, 3, 2, 0, 1, 1, 2, 3})
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 2, 1, 9, 0, 1, 1, 2, 3, 3, 2})
+	if !ok { test.Fatal("false negative:", n) }
+	
+	ok, n = snake.Check([]byte { 1, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 1, 2, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 9, 3, 2, 0, 1, 1, 2, 3})
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 2, 9, 0, 1, 1, 2, 3, 3, 2})
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = snake.Check([]byte { 1, 6, 1, 2, 9, 3, 2, 1, 1, 2, 3})
+	if ok { test.Fatal("false positive:", n) }
+}

message.go

@@ -1,52 +0,0 @@
-package hopp
-
-import "fmt"
-import "encoding"
-import "git.tebibyte.media/sashakoshka/hopp/tape"
-
-// Message is any object that can be sent or received over a HOPP connection.
-type Message interface {
-	// Method returns the method number of the message. This must be unique
-	// within the protocol, and should not change between calls.
-	Method() uint16
-	encoding.BinaryMarshaler
-	encoding.BinaryUnmarshaler
-}
-
-var _ Message = new(MessageData)
-
-// MessageData represents a message that organizes its data into table pairs. It
-// can be used to alter a protocol at runtime, transmit data with arbitrary
-// keys, etc. Bear in mind that is less performant than generating code because
-// it has to make extra memory allocations and such.
-type MessageData struct {
-	// Methd holds the method number. This should only be set once.
-	Methd uint16
-	// Pairs maps tags to values.
-	Pairs map[uint16] []byte
-}
-
-// Method returns the message's method field.
-func (this *MessageData) Method() uint16 {
-	return this.Methd
-}
-
-// MarshalBinary implements the [encoding.BinaryMarshaler] interface. The
-// message is encoded using TAPE (Table Pair Encoding).
-func (this *MessageData) MarshalBinary() ([]byte, error) {
-	buffer, err := tape.EncodePairs(this.Pairs)
-	if err != nil { return nil, fmt.Errorf("marshaling MessageData: %w", err) }
-	return buffer, nil
-}
-
-// UnmarshalBinary implements the [encoding.BinaryUnmarshaler] interface. The
-// message is decoded using TAPE (Table Pair Encoding).
-func (this *MessageData) UnmarshalBinary(buffer []byte) error {
-	this.Pairs = make(map[uint16] []byte)
-	pairs, err := tape.DecodePairs(buffer)
-	if err != nil { return fmt.Errorf("unmarshaling MessageData: %w", err) }
-	for key, value := range pairs {
-		this.Pairs[key] = value
-	}
-	return nil
-}

metadapta.go

@@ -1,11 +1,12 @@
 package hopp
 
 import "io"
+import "os"
 import "fmt"
 import "net"
 import "sync"
+import "time"
 import "sync/atomic"
-import "git.tebibyte.media/sashakoshka/hopp/tape"
 import "git.tebibyte.media/sashakoshka/go-util/sync"
 
 // TODO investigate why 30 never reaches the server, causing it to wait for ever
@@ -109,6 +110,10 @@ func (this *a) AcceptTrans() (Trans, error) {
 	}
 }
 
+func (this *a) SetDeadline(t time.Time) error {
+	return this.underlying.SetDeadline(t)
+}
+
 func (this *a) SetSizeLimit(limit int64) {
 	this.sizeLimit = limit
 }
@@ -213,6 +218,10 @@ type transA struct {
 	currentWriter io.Closer
 	writeBuffer   []byte
 	closed        atomic.Bool
+	closeErr      error
+	
+	deadline      *time.Timer
+	deadlineLock  sync.Mutex
 }
 
 func (this *transA) Close() error {
@@ -222,6 +231,11 @@ func (this *transA) Close() error {
 	return err
 }
 
+func (this *transA) closeWithError(err error) error {
+	this.closeErr = err
+	return this.Close()
+}
+
 func (this *transA) closeDontUnlist() (err error) {
 	// MUST be goroutine safe
 	this.incoming.Close()
@@ -270,9 +284,9 @@ func (this *transA) Receive() (method uint16, data []byte, err error) {
 }
 
 func (this *transA) ReceiveReader() (uint16, io.Reader, error) {
-	// if the transaction has been closed, return an io.EOF
-	if this.closed.Load() {
-		return 0, nil, io.EOF
+	// if the transaction has been closed, return an appropriate error.
+	if err := this.errIfClosed(); err != nil {
+		return 0, nil, err
 	}
 
 	// drain previous reader if necessary
@@ -290,6 +304,54 @@ func (this *transA) ReceiveReader() (uint16, io.Reader, error) {
 	return method, reader, nil
 }
 
+func (this *transA) SetDeadline(t time.Time) error {
+	this.deadlineLock.Lock()
+	defer this.deadlineLock.Unlock()
+
+	if t == (time.Time { }) {
+		if this.deadline != nil {
+			this.deadline.Stop()
+		}
+		return nil
+	}
+	
+	until := time.Until(t)
+	if this.deadline == nil {
+		this.deadline.Reset(until)
+		return nil
+	}
+	this.deadline = time.AfterFunc(until, func () {
+		this.closeWithError(os.ErrDeadlineExceeded)
+	})
+	return nil
+}
+
+// TODO
+// func (this *transA) SetReadDeadline(t time.Time) error {
+// 	// TODO
+// }
+// 
+// func (this *transA) SetWriteDeadline(t time.Time) error {
+// 	// TODO
+// }
+
+func (this *transA) errIfClosed() error {
+	if !this.closed.Load() {
+		return nil
+	}
+	return this.bestErr()
+}
+
+func (this *transA) bestErr() error {
+	if this.parent.err != nil {
+		return this.parent.err
+	}
+	if this.closeErr != nil {
+		return this.closeErr
+	}
+	return io.EOF
+}
+
 type readerA struct {
 	parent   *transA
 	leftover []byte
@@ -320,11 +382,7 @@ func (this *readerA) pull() (uint16, error) {
 	// close and return error on failure
 	this.eof = true
 	this.parent.Close()
-	if this.parent.parent.err == nil {
-		return 0, fmt.Errorf("could not receive message: %w", io.EOF)
-	} else {
-		return 0, this.parent.parent.err
-	}
+	return 0, fmt.Errorf("could not receive message: %w", this.parent.bestErr())
 }
 
 func (this *readerA) Read(buffer []byte) (int, error) {
@@ -406,9 +464,9 @@ func encodeMessageA(
 		return ErrPayloadTooLarge
 	}
 	buffer := make([]byte, 18 + len(data))
-	tape.EncodeI64(buffer[:8], trans)
-	tape.EncodeI16(buffer[8:10], method)
-	tape.EncodeI64(buffer[10:18], uint64(len(data)))
+	encodeI64(buffer[:8], trans)
+	encodeI16(buffer[8:10], method)
+	encodeI64(buffer[10:18], uint64(len(data)))
 	copy(buffer[18:], data)
 	_, err := writer.Write(buffer)
 	return err
@@ -427,11 +485,11 @@ func decodeMessageA(
 	headerBuffer := [18]byte { }
 	_, err = io.ReadFull(reader, headerBuffer[:])
 	if err != nil { return 0, 0, false, nil, err }
-	transID, err = tape.DecodeI64[int64](headerBuffer[:8])
+	transID, err = decodeI64[int64](headerBuffer[:8])
 	if err != nil { return 0, 0, false, nil, err }
-	method, err = tape.DecodeI16[uint16](headerBuffer[8:10])
+	method, err = decodeI16[uint16](headerBuffer[8:10])
 	if err != nil { return 0, 0, false, nil, err }
-	size, err := tape.DecodeI64[uint64](headerBuffer[10:18])
+	size, err := decodeI64[uint64](headerBuffer[10:18])
 	if err != nil { return 0, 0, false, nil, err }
 	chunked, size = splitCCBSize(size)
 	if size > uint64(sizeLimit) {

metadaptb.go

@@ -2,10 +2,10 @@ package hopp
 
 import "io"
 import "net"
+import "time"
 import "bytes"
 import "errors"
 import "context"
-import "git.tebibyte.media/sashakoshka/hopp/tape"
 
 // B implements METADAPT-B over a multiplexed stream-oriented transport such as
 // QUIC.
@@ -51,6 +51,10 @@ func (this *b) SetSizeLimit(limit int64) {
 	this.sizeLimit = limit
 }
 
+func (this *b) SetDeadline(t time.Time) error {
+	return this.underlying.SetDeadline(t)
+}
+
 func (this *b) newTrans(underlying Stream) *transB {
 	return &transB {
 		sizeLimit: this.sizeLimit,
@@ -125,6 +129,10 @@ func (this *transB) receiveReader() (uint16, int64, io.Reader, error) {
 	return method, size, data, nil
 }
 
+func (this *transB) SetDeadline(t time.Time) error {
+	return this.underlying.SetDeadline(t)
+}
+
 type writerB struct {
 	parent *transB
 	buffer bytes.Buffer
@@ -150,12 +158,16 @@ type MultiConn interface {
 	AcceptStream(context.Context) (Stream, error)
 	// OpenStream opens a new stream.
 	OpenStream() (Stream, error)
+	// See the documentation for [net.Conn.SetDeadline].
+	SetDeadline(time.Time) error
 }
 
 // Stream represents a single stream returned by a [MultiConn].
 type Stream interface {
 	// See documentation for [net.Conn].
 	io.ReadWriteCloser
+	// See the documentation for [net.Conn.SetDeadline].
+	SetDeadline(time.Time) error
 	// ID returns the stream ID
 	ID() int64
 }
@@ -165,8 +177,8 @@ func encodeMessageB(writer io.Writer, sizeLimit int64, method uint16, data []byt
 		return ErrPayloadTooLarge
 	}
 	buffer := make([]byte, 10 + len(data))
-	tape.EncodeI16(buffer[:2], method)
-	tape.EncodeI64(buffer[2:10], uint64(len(data)))
+	encodeI16(buffer[:2], method)
+	encodeI64(buffer[2:10], uint64(len(data)))
 	copy(buffer[10:], data)
 	_, err := writer.Write(buffer)
 	return err
@@ -187,9 +199,9 @@ func decodeMessageB(
 		if errors.Is(err, io.EOF) { return 0, 0, nil, io.ErrUnexpectedEOF }
 		return 0, 0, nil, err
 	}
-	method, err = tape.DecodeI16[uint16](headerBuffer[:2])
+	method, err = decodeI16[uint16](headerBuffer[:2])
 	if err != nil { return 0, 0, nil, err }
-	length, err := tape.DecodeI64[uint64](headerBuffer[2:10])
+	length, err := decodeI64[uint64](headerBuffer[2:10])
 	if err != nil { return 0, 0, nil, err }
 	if length > uint64(sizeLimit) {
 		return 0, 0, nil, ErrPayloadTooLarge

tape/array.go

@@ -1,284 +0,0 @@
-package tape
-
-import "fmt"
-import "iter"
-import "slices"
-
-// encoding and decoding functions must not make any allocations
-
-// ArrayPushFunc adds an item to an array that is being encoded.
-type ArrayPushFunc func(value []byte) (n int, err error)
-
-// ArrayPullFunc gets the next item of an array that is being decoded.
-type ArrayPullFunc func() (value []byte, n int, err error)
-
-// DecodePASTA decodes a packed single-type array.
-func DecodePASTA(data []byte, itemLength int) ArrayPullFunc {
-	n := 0
-	return func() (value []byte, n_ int, err error) {
-		if n > len(data) - itemLength {
-			return nil, 0, fmt.Errorf("decoding PASTA: %w", ErrWrongBufferLength)
-		}
-		value = data[n:n + itemLength]
-		n += itemLength
-		return value, itemLength, nil
-	}
-}
-
-// DecodePASTAIter decodes a packed single-type array and returns it as an
-// iterator.
-func DecodePASTAIter(data []byte, itemLength int) iter.Seq[[]byte] {
-	return slices.Chunk(data, itemLength)
-}
-
-// EncodePASTA encodes a packed single-type array.
-func EncodePASTA(data []byte, itemLength int) ArrayPushFunc {
-	n := 0
-	return func(value []byte) (n_ int, err error) {
-		if n > len(data) - itemLength {
-			return 0, fmt.Errorf("encoding PASTA: %w", ErrWrongBufferLength)
-		}
-		copy(data[n:], value)
-		n += itemLength
-		return itemLength, nil
-	}
-}
-
-// PASTASize returns the size of a packed single-type array.
-func PASTASize(length, itemLength int) int {
-	return length * itemLength
-}
-
-// DecodeVILA encodes a variable item length array.
-func DecodeVILA(data []byte) ArrayPullFunc {
-	n := 0
-	return func() (value []byte, n_ int, err error) {
-		if n >= len(data) { return nil, n_, fmt.Errorf("decoding VILA: %w", ErrWrongBufferLength) }
-		length, nn, err := DecodeGBEU[uint](data[n:])
-		n += nn
-		n_ += nn
-		if err != nil { return nil, n_, err }
-		
-		if n > len(data) - int(length) {
-			return nil, n_, fmt.Errorf("decoding VILA: %w", ErrWrongBufferLength)
-		}
-		value = data[n:n + int(length)]
-		n += int(length)
-		n_ += int(length)
-		return value, int(length), nil
-	}
-}
-
-// DecodeVILAIter decodes a variable item length array and returns it as an
-// iterator.
-func DecodeVILAIter(data []byte) iter.Seq[[]byte] {
-	return func(yield func([]byte) bool) {
-		pull := DecodeVILA(data)
-		for {
-			value, _, err := pull()
-			if err != nil { return }
-			if !yield(value) { return }
-		}
-	}
-}
-
-// EncodeVILA encodes a variable item length array.
-func EncodeVILA(data []byte) ArrayPushFunc {
-	n := 0
-	return func(value []byte) (n_ int, err error) {
-		if n >= len(data) { return n_, fmt.Errorf("encoding VILA: %w", ErrWrongBufferLength) }
-		nn, err := EncodeGBEU(data[n:], uint(len(value)))
-		n += nn
-		n_ += nn
-		if err != nil { return n, err }
-		
-		if n >= len(data) { return n_, fmt.Errorf("encoding VILA: %w", ErrWrongBufferLength) }
-		nn = copy(data[n:], value)
-		n += nn
-		n_ += nn
-		if nn != len(value) { return n_, fmt.Errorf("encoding VILA: %w", ErrWrongBufferLength) }
-		return n_, err
-	}
-}
-
-// VILASize returns the size of a variable item length array.
-func VILASize(items ...[]byte) int {
-	size := 0
-	for _, item := range items {
-		size += GBEUSize[uint](uint(len(item)))
-		size += len(item)
-	}
-	return size
-}
-
-// DecodeStringArray decodes a VILA string array from the given data.
-func DecodeStringArray[T String](data []byte) (result []T, n int, err error) {
-	pull := DecodeVILA(data)
-	for {
-		item, nn, err := pull()
-		n += nn
-		if err != nil { return nil, n, err }
-		result = append(result, T(item))
-	}
-	return result, n, nil
-}
-
-// EncodeStringArray encodes a VILA string array into the given buffer.
-func EncodeStringArray[T String](buffer []byte, value []T) (n int, err error) {
-	push := EncodeVILA(buffer)
-	for _, item := range value {
-		nn, err := push([]byte(item))
-		n += nn
-		if err != nil { return n, err }
-	}
-	return n, nil
-}
-
-// StringArraySize returns the size of a VILA string array.
-func StringArraySize[T String](value []T) int {
-	size := 0
-	for _, item := range value {
-		size += GBEUSize[uint](uint(len(item)))
-		size += len(item)
-	}
-	return size
-}
-
-// DecodeI8Array decodes a packed array of 8 bit integers from the given data.
-func DecodeI8Array[T Int8](data []byte) (result []T, n int, err error) {
-	result = make([]T, len(data))
-	for index, item := range data {
-		result[index] = T(item)
-	}
-	return result, len(data), nil
-}
-
-// EncodeI8Array encodes a packed array of 8 bit integers into the given buffer.
-func EncodeI8Array[T Int8](buffer []byte, value []T) (n int, err error) {
-	if len(buffer) != len(value) { return 0, fmt.Errorf("encoding []int8: %w", ErrWrongBufferLength) }
-	for index, item := range value {
-		buffer[index] = byte(item)
-	}
-	return len(buffer), nil
-}
-
-// I8ArraySize returns the size of a packed 8 bit integer array. Returns 0 and
-// an error if the size is too large.
-func I8ArraySize[T Int8](value []T) (int, error) {
-	total := len(value)
-	if total > dataMaxSize { return 0, ErrDataTooLarge }
-	return total, nil
-}
-
-// DecodeI16Array decodes a packed array of 16 bit integers from the given data.
-func DecodeI16Array[T Int16](data []byte) (value []T, n int, err error) {
-	if len(data) % 2 != 0 { return nil, 0, fmt.Errorf("decoding []int16: %w", ErrWrongBufferLength) }
-	length := len(data) / 2
-	result := make([]T, length)
-	for index := range length {
-		offset := index * 2
-		result[index] = T(data[offset]) << 8 | T(data[offset + 1])
-	}
-	return result, len(data) / 2, nil
-}
-
-// EncodeI16Array encodes a packed array of 16 bit integers into the given buffer.
-func EncodeI16Array[T Int16](buffer []byte, value []T) (n int, err error) {
-	if len(buffer) != len(value) * 2 { return 0, fmt.Errorf("encoding []int16: %w", ErrWrongBufferLength) }
-	for _, item := range value {
-		buffer[0] = byte(item >> 8)
-		buffer[1] = byte(item)
-		buffer = buffer[2:]
-	}
-	return len(value) * 2, nil
-}
-
-// I16ArraySize returns the size of a packed 16 bit integer array. Returns 0 and
-// an error if the size is too large.
-func I16ArraySize[T Int16](value []T) (int, error) {
-	total := len(value) * 2
-	if total > dataMaxSize { return 0, ErrDataTooLarge }
-	return total, nil
-}
-
-// DecodeI32Array decodes a packed array of 32 bit integers from the given data.
-func DecodeI32Array[T Int32](data []byte) (value []T, n int, err error) {
-	if len(data) % 4 != 0 { return nil, 0, fmt.Errorf("decoding []int32: %w", ErrWrongBufferLength) }
-	length := len(data) / 4
-	result := make([]T, length)
-	for index := range length {
-		offset := index * 4
-		result[index] =
-			T(data[offset + 0]) << 24 |
-			T(data[offset + 1]) << 16 |
-			T(data[offset + 2]) <<  8 |
-			T(data[offset + 3])
-	}
-	return result, len(data) / 4, nil
-}
-
-// EncodeI32Array encodes a packed array of 32 bit integers into the given buffer.
-func EncodeI32Array[T Int32](buffer []byte, value []T) (n int, err error) {
-	if len(buffer) != len(value) * 4 { return 0, fmt.Errorf("encoding []int32: %w", ErrWrongBufferLength) }
-	for _, item := range value {
-		buffer[0] = byte(item >> 24)
-		buffer[1] = byte(item >> 16)
-		buffer[2] = byte(item >> 8)
-		buffer[3] = byte(item)
-		buffer = buffer[4:]
-	}
-	return len(value) * 4, nil
-}
-
-// I32ArraySize returns the size of a packed 32 bit integer array. Returns 0 and
-// an error if the size is too large.
-func I32ArraySize[T Int32](value []T) (int, error) {
-	total := len(value) * 4
-	if total > dataMaxSize { return 0, ErrDataTooLarge }
-	return total, nil
-}
-
-// DecodeI64Array decodes a packed array of 32 bit integers from the given data.
-func DecodeI64Array[T Int64](data []byte) (value []T, n int, err error) {
-	if len(data) % 8 != 0 { return nil, 0, fmt.Errorf("decoding []int64: %w", ErrWrongBufferLength) }
-	length := len(data) / 8
-	result := make([]T, length)
-	for index := range length {
-		offset := index * 8
-		result[index] =
-			T(data[offset + 0]) << 56 |
-			T(data[offset + 1]) << 48 |
-			T(data[offset + 2]) << 40 |
-			T(data[offset + 3]) << 32 |
-			T(data[offset + 4]) << 24 |
-			T(data[offset + 5]) << 16 |
-			T(data[offset + 6]) <<  8 |
-			T(data[offset + 7])
-	}
-	return result, len(data) / 8, nil
-}
-
-// EncodeI64Array encodes a packed array of 64 bit integers into the given buffer.
-func EncodeI64Array[T Int64](buffer []byte, value []T) (n int, err error) {
-	if len(buffer) != len(value) * 8 { return 0, fmt.Errorf("encoding []int64: %w", ErrWrongBufferLength) }
-	for _, item := range value {
-		buffer[0] = byte(item >> 56)
-		buffer[1] = byte(item >> 48)
-		buffer[2] = byte(item >> 40)
-		buffer[3] = byte(item >> 32)
-		buffer[4] = byte(item >> 24)
-		buffer[5] = byte(item >> 16)
-		buffer[6] = byte(item >> 8)
-		buffer[7] = byte(item)
-		buffer = buffer[8:]
-	}
-	return len(value) * 8, nil
-}
-
-// I64ArraySize returns the size of a packed 64 bit integer array. Returns 0 and
-// an error if the size is too large.
-func I64ArraySize[T Int64](value []T) (int, error) {
-	total := len(value) * 8
-	if total > dataMaxSize { return 0, ErrDataTooLarge }
-	return total, nil
-}

tape/array_test.go

@@ -1,131 +0,0 @@
-package tape
-
-// import "fmt"
-import "slices"
-// import "errors"
-import "testing"
-import "math/rand"
-
-func TestI8Array(test *testing.T) {
-	var buffer [64]byte
-	_, err := EncodeI8Array[uint8](buffer[:], []uint8 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int8: wrong buffer length") { test.Fatal(err) }
-	_, err = EncodeI8Array[uint8](buffer[:0], []uint8 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int8: wrong buffer length") { test.Fatal(err) }
-	_, _, err = DecodeI8Array[uint8](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI8Array[uint8](buffer[:0])
-	if err != nil { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		array := randInts[uint8](rand.Intn(16))
-		length, _ := I8ArraySize(array)
-		if length != len(array) { test.Fatalf("%d != %d", length, len(array)) }
-		_, err := EncodeI8Array[uint8](buffer[:length], array)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeI8Array[uint8](buffer[:length])
-		if err != nil { test.Fatal(err) }
-		if !slices.Equal(decoded, array) {
-			test.Fatalf("%v != %v", decoded, array)
-		}
-	}
-}
-
-func TestI16Array(test *testing.T) {
-	var buffer [128]byte
-	_, err := EncodeI16Array[uint16](buffer[:], []uint16 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int16: wrong buffer length") { test.Fatal(err) }
-	_, err = EncodeI16Array[uint16](buffer[:0], []uint16 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int16: wrong buffer length") { test.Fatal(err) }
-	_, _, err = DecodeI16Array[uint16](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI16Array[uint16](buffer[:0])
-	if err != nil { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		array := randInts[uint16](rand.Intn(16))
-		length, _ := I16ArraySize(array)
-		if length != 2 * len(array) { test.Fatalf("%d != %d", length, 2 * len(array)) }
-		_, err := EncodeI16Array[uint16](buffer[:length], array)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeI16Array[uint16](buffer[:length])
-		if err != nil { test.Fatal(err) }
-		if !slices.Equal(decoded, array) {
-			test.Fatalf("%v != %v", decoded, array)
-		}
-	}
-}
-
-func TestI32Array(test *testing.T) {
-	var buffer [256]byte
-	_, err := EncodeI32Array[uint32](buffer[:], []uint32 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int32: wrong buffer length") { test.Fatal(err) }
-	_, err = EncodeI32Array[uint32](buffer[:0], []uint32 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int32: wrong buffer length") { test.Fatal(err) }
-	_, _, err = DecodeI32Array[uint32](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI32Array[uint32](buffer[:0])
-	if err != nil { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		array := randInts[uint32](rand.Intn(16))
-		length, _ := I32ArraySize(array)
-		if length != 4 * len(array) { test.Fatalf("%d != %d", length, 4 * len(array)) }
-		_, err := EncodeI32Array[uint32](buffer[:length], array)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeI32Array[uint32](buffer[:length])
-		if err != nil { test.Fatal(err) }
-		if !slices.Equal(decoded, array) {
-			test.Fatalf("%v != %v", decoded, array)
-		}
-	}
-}
-
-func TestI64Array(test *testing.T) {
-	var buffer [512]byte
-	_, err := EncodeI64Array[uint64](buffer[:], []uint64 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int64: wrong buffer length") { test.Fatal(err) }
-	_, err = EncodeI64Array[uint64](buffer[:0], []uint64 { 0, 4, 50, 19 })
-	if !errIs(err, ErrWrongBufferLength, "encoding []int64: wrong buffer length") { test.Fatal(err) }
-	_, _, err = DecodeI64Array[uint64](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI64Array[uint64](buffer[:0])
-	if err != nil { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		array := randInts[uint64](rand.Intn(16))
-		length, _ := I64ArraySize(array)
-		if length != 8 * len(array) { test.Fatalf("%d != %d", length, 8 * len(array)) }
-		_, err := EncodeI64Array[uint64](buffer[:length], array)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeI64Array[uint64](buffer[:length])
-		if err != nil { test.Fatal(err) }
-		if !slices.Equal(decoded, array) {
-			test.Fatalf("%v != %v", decoded, array)
-		}
-	}
-}
-
-func TestStringArray(test *testing.T) {
-	var buffer [8192]byte
-	_, err := EncodeStringArray[string](buffer[:], []string { "0", "4", "50", "19" })
-	if !errIs(err, ErrWrongBufferLength, "encoding []string: wrong buffer length") { test.Fatal(err) }
-	_, err = EncodeStringArray[string](buffer[:0], []string { "0", "4", "50", "19" })
-	if !errIs(err, ErrWrongBufferLength, "encoding []string: wrong buffer length") { test.Fatal(err) }
-	_, _, err = DecodeStringArray[string](buffer[:0])
-	if err != nil { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		array := randStrings[string](rand.Intn(16), 16)
-		length, _ := StringArraySize(array)
-		// TODO test length
-		_, err := EncodeStringArray[string](buffer[:length], array)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeStringArray[string](buffer[:length])
-		if err != nil { test.Fatal(err) }
-		if !slices.Equal(decoded, array) {
-			test.Fatalf("%v != %v", decoded, array)
-		}
-	}
-}
-

tape/decode.go

@@ -0,0 +1,192 @@
+package tape
+
+import "io"
+import "math"
+import "bufio"
+
+// Decodable is any type that can decode itself from a decoder.
+type Decodable interface {
+	// Decode reads data from decoder, replacing the data of the object. It
+	// returns the amount of bytes written, and an error if the write
+	// stopped early.
+	Decode(decoder *Decoder) (n int, err error)
+}
+
+// Decoder decodes data from an [io.Reader].
+type Decoder struct {
+	bufio.Reader
+}
+
+// NewDecoder creates a new decoder that reads from reader.
+func NewDecoder(reader io.Reader) *Decoder {
+	decoder := &Decoder { }
+	decoder.Reader.Reset(reader)
+	return decoder
+}
+
+// ReadFull calls [io.ReadFull] on the reader.
+func (this *Decoder) ReadFull(buffer []byte) (n int, err error) {
+	return io.ReadFull(this, buffer)
+}
+
+// ReadInt8 decodes an 8-bit signed integer from the input reader.
+func (this *Decoder) ReadInt8() (value int8, n int, err error) {
+	uncasted, n, err := this.ReadUint8()
+	return int8(uncasted), n, err
+}
+
+// ReadUint8 decodes an 8-bit unsigned integer from the input reader.
+func (this *Decoder) ReadUint8() (value uint8, n int, err error) {
+	buffer := [1]byte { }
+	n, err = this.ReadFull(buffer[:])
+	return uint8(buffer[0]), n, err
+}
+
+// ReadInt16 decodes an 16-bit signed integer from the input reader.
+func (this *Decoder) ReadInt16() (value int16, n int, err error) {
+	uncasted, n, err := this.ReadUint16()
+	return int16(uncasted), n, err
+}
+
+// ReadUint16 decodes an 16-bit unsigned integer from the input reader.
+func (this *Decoder) ReadUint16() (value uint16, n int, err error) {
+	buffer := [2]byte { }
+	n, err = this.ReadFull(buffer[:])
+	return uint16(buffer[0]) << 8 |
+		uint16(buffer[1]), n, err
+}
+
+// ReadInt32 decodes an 32-bit signed integer from the input reader.
+func (this *Decoder) ReadInt32() (value int32, n int, err error) {
+	uncasted, n, err := this.ReadUint32()
+	return int32(uncasted), n, err
+}
+
+// ReadUint32 decodes an 32-bit unsigned integer from the input reader.
+func (this *Decoder) ReadUint32() (value uint32, n int, err error) {
+	buffer := [4]byte { }
+	n, err = this.ReadFull(buffer[:])
+	return uint32(buffer[0]) << 24 |
+		uint32(buffer[1]) << 16 |
+		uint32(buffer[2]) << 8 |
+		uint32(buffer[3]), n, err
+}
+
+// ReadInt64 decodes an 64-bit signed integer from the input reader.
+func (this *Decoder) ReadInt64() (value int64, n int, err error) {
+	uncasted, n, err := this.ReadUint64()
+	return int64(uncasted), n, err
+}
+
+// ReadUint64 decodes an 64-bit unsigned integer from the input reader.
+func (this *Decoder) ReadUint64() (value uint64, n int, err error) {
+	buffer := [8]byte { }
+	n, err = this.ReadFull(buffer[:])
+	return uint64(buffer[0]) << 56 |
+		uint64(buffer[1]) << 48 |
+		uint64(buffer[2]) << 40 |
+		uint64(buffer[3]) << 32 |
+		uint64(buffer[4]) << 24 |
+		uint64(buffer[5]) << 16 |
+		uint64(buffer[6]) << 8 |
+		uint64(buffer[7]), n, err
+}
+
+// ReadIntN decodes an N-byte signed integer from the input reader.
+func (this *Decoder) ReadIntN(bytes int) (value int64, n int, err error) {
+	uncasted, n, err := this.ReadUintN(bytes)
+	return int64(uncasted), n, err
+}
+
+// ReadUintN decodes an N-byte unsigned integer from the input reader.
+func (this *Decoder) ReadUintN(bytes int) (value uint64, n int, err error) {
+	// TODO: don't make multiple read calls (without allocating)
+	buffer := [1]byte { }
+	for bytesLeft := bytes; bytesLeft > 0; bytesLeft -- {
+		nn, err := this.ReadFull(buffer[:])
+		n += nn; if err != nil { return 0, n, err }
+		value |= uint64(buffer[0]) << ((bytesLeft - 1) * 8)
+	}
+	// *read* integers too big, but don't return them.
+	if bytes > 8 { value = 0 }
+	return value, n, nil
+}
+
+// ReadFloat16 decodes a 16-bit floating point value from the input reader.
+func (this *Decoder) ReadFloat16() (value float32, n int, err error) {
+	bits, nn, err := this.ReadUint16()
+	n += nn; if err != nil { return 0, n, err }
+	return math.Float32frombits(f16bitsToF32bits(bits)), n, nil
+}
+
+// ReadFloat32 decldes a 32-bit floating point value from the input reader.
+func (this *Decoder) ReadFloat32() (value float32, n int, err error) {
+	bits, nn, err := this.ReadUint32()
+	n += nn; if err != nil { return 0, n, err }
+	return math.Float32frombits(bits), n, nil
+}
+
+// ReadFloat64 decldes a 64-bit floating point value from the input reader.
+func (this *Decoder) ReadFloat64() (value float64, n int, err error) {
+	bits, nn, err := this.ReadUint64()
+	n += nn; if err != nil { return 0, n, err }
+	return math.Float64frombits(bits), n, nil
+}
+
+// ReadTag decodes a [Tag] from the input reader.
+func (this *Decoder) ReadTag() (value Tag, n int, err error) {
+	uncasted, nn, err := this.ReadUint8()
+	n += nn; if err != nil { return 0, n, err }
+	return Tag(uncasted), n, nil
+}
+
+// f16bitsToF32bits returns uint32 (float32 bits) converted from specified uint16.
+// Taken from https://github.com/x448/float16/blob/v0.8.4/float16
+//
+// MIT License
+// 
+// Copyright (c) 2019 Montgomery Edwards⁴⁴⁸ and Faye Amacker
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+func f16bitsToF32bits(in uint16) uint32 {
+	// All 65536 conversions with this were confirmed to be correct
+	// by Montgomery Edwards⁴⁴⁸ (github.com/x448).
+	
+	sign := uint32(in&0x8000) << 16 // sign for 32-bit
+	exp := uint32(in&0x7c00) >> 10  // exponenent for 16-bit
+	coef := uint32(in&0x03ff) << 13 // significand for 32-bit
+
+	if exp == 0x1f {
+		if coef == 0 {
+			// infinity
+			return sign | 0x7f800000 | coef
+		}
+		// NaN
+		return sign | 0x7fc00000 | coef
+	}
+
+	if exp == 0 {
+		if coef == 0 {
+			// zero
+			return sign
+		}
+
+		// normalize subnormal numbers
+		exp++
+		for coef&0x7f800000 == 0 {
+			coef <<= 1
+			exp--
+		}
+		coef &= 0x007fffff
+	}
+
+	return sign | ((exp + (0x7f - 0xf)) << 23) | coef
+}

tape/dynamic.go

@@ -0,0 +1,616 @@
+package tape
+
+// dont smoke reflection, kids!!!!!!!!!
+// totally reflectric, reflectrified, etc. this is probably souper slow but
+// certainly no slower than the built in json encoder i'd imagine.
+// TODO: add support for struct tags: `tape:"0000"`, tape:"0001"` so they can get
+// transformed into tables with a defined schema
+
+// TODO: test all of these smaller functions individually
+
+// For an explanation as to why this package always treats LBA/SBA as strings,
+// refer to https://go.dev/blog/strings:
+// 
+//   It’s important to state right up front that a string holds arbitrary
+//   bytes. It is not required to hold Unicode text, UTF-8 text, or any other
+//   predefined format. As far as the content of a string is concerned, it is
+//   exactly equivalent to a slice of bytes.
+//
+// Arbitrary byte slices and blobs won't be as common of a use case as text
+// data, and if you need that anyway you can just cast it to a byte slice.
+
+import "fmt"
+import "reflect"
+
+var dummyMap map[uint16] any
+var dummyBuffer []byte
+
+type errCantAssign string
+func (err errCantAssign) Error() string {
+	return string(err)
+}
+func errCantAssignf(format string, v ...any) errCantAssign {
+	return errCantAssign(fmt.Sprintf(format, v...))
+}
+
+// EncodeAny encodes an "any" value. Returns an error if the underlying type is
+// unsupported. Supported types are:
+//
+//   - int
+//   - int<N>
+//   - uint
+//   - uint<N>
+//   - string
+//   - []<supported type>
+//   - map[uint16]<supported type>
+func EncodeAny(encoder *Encoder, value any, tag Tag) (n int, err error) {
+	// primitives
+	reflectValue := reflect.ValueOf(value)
+	switch reflectValue.Kind() {
+	case reflect.Int:     return encoder.WriteInt32(int32(reflectValue.Int()))
+	case reflect.Uint:    return encoder.WriteUint32(uint32(reflectValue.Uint()))
+	case reflect.Int8:    return encoder.WriteInt8(int8(reflectValue.Int()))
+	case reflect.Uint8:   return encoder.WriteUint8(uint8(reflectValue.Uint()))
+	case reflect.Int16:   return encoder.WriteInt16(int16(reflectValue.Int()))
+	case reflect.Uint16:  return encoder.WriteUint16(uint16(reflectValue.Uint()))
+	case reflect.Int32:   return encoder.WriteInt32(int32(reflectValue.Int()))
+	case reflect.Uint32:  return encoder.WriteUint32(uint32(reflectValue.Uint()))
+	case reflect.Int64:   return encoder.WriteInt64(int64(reflectValue.Int()))
+	case reflect.Uint64:  return encoder.WriteUint64(uint64(reflectValue.Uint()))
+	case reflect.Float32: return encoder.WriteFloat32(float32(reflectValue.Float()))
+	case reflect.Float64: return encoder.WriteFloat64(float64(reflectValue.Float()))
+	case reflect.String:
+		if reflectValue.Len() > MaxStructureLength {
+			return 0, ErrTooLong
+		}
+		return EncodeAny(encoder, []byte(reflectValue.String()), tag)
+	}
+	if reflectValue.CanConvert(reflect.TypeOf(dummyBuffer)) {
+		if reflectValue.Len() > MaxStructureLength {
+			return 0, ErrTooLong
+		}
+		if tag.Is(LBA) {
+			nn, err := encoder.WriteUintN(uint64(reflectValue.Len()), tag.CN() + 1)
+			n += nn; if err != nil { return n, err }
+		}
+		nn, err := encoder.Write(reflectValue.Bytes())
+		n += nn; if err != nil { return n, err }
+		return n, nil
+	}
+
+	// aggregates
+	reflectType := reflect.TypeOf(value)
+	switch reflectType.Kind() {
+	case reflect.Slice:
+		return encodeAnySlice(encoder, value, tag)
+	// case reflect.Array:
+		// TODO: we can encode arrays. but can we decode into them?
+		// that's the fucken question. maybe we just do the first
+		// return encodeAnySlice(encoder, reflect.ValueOf(value).Slice(0, reflectType.Len()).Interface(), tag)
+	case reflect.Map:
+		if reflectValue.Len() > MaxStructureLength {
+			return 0, ErrTooLong
+		}
+		if reflectType.Key() == reflect.TypeOf(uint16(0)) {
+			return encodeAnyMap(encoder, value, tag)
+		}
+		return n, fmt.Errorf("cannot encode map key %T, key must be uint16", value)
+	}
+	return n, fmt.Errorf("cannot encode type %T", value)
+}
+
+// DecodeAnyInto decodes data and places it into destination, which must be a
+// pointer to a supported type. See [EncodeAny] for a list of supported types.
+// The head of the decoder must be at the start of the payload.
+func DecodeAnyInto(decoder *Decoder, destination any, tag Tag) (n int, err error) {
+	reflectDestination := reflect.ValueOf(destination)
+	if reflectDestination.Kind() != reflect.Pointer {
+		return n, fmt.Errorf("expected pointer destination, not %v", destination)
+	}
+	return decodeAny(decoder, reflectDestination.Elem(), tag)
+}
+
+// DecodeAny is like [DecodeAnyInto], but it automatically creates the
+// destination from the tag and data. The head of the decoder must be at the
+// start of the payload.
+func DecodeAny(decoder *Decoder, tag Tag) (value any, n int, err error) {
+	destination, err := skeletonPointer(decoder, tag)
+	if err != nil { return nil, n, err }
+	nn, err := decodeAny(decoder, destination.Elem(), tag)
+	n += nn; if err != nil { return nil, n, err }
+	return destination.Elem().Interface(), n, err
+}
+
+// unknownSlicePlaceholder is inserted by skeletonValue and informs the program
+// that the destination for the slice needs to be generated based on the item
+// tag in the OTA.
+type unknownSlicePlaceholder struct { }
+var unknownSlicePlaceholderType = reflect.TypeOf(unknownSlicePlaceholder { })
+
+// decodeAny is internal to [DecodeAny]. It takes in an addressable
+// [reflect.Value] as the destination. If the decoded value cannot fit in the
+// destination, it skims over the payload, leaves the destination empty, and
+// returns without an error. The head of the decoder must be at the start of the
+// payload.
+func decodeAny(decoder *Decoder, destination reflect.Value, tag Tag) (n int, err error) {
+	n, err = decodeAnyOrError(decoder, destination, tag)
+	if _, ok := err.(errCantAssign); ok {
+		if n > 0 { panic(fmt.Sprintf("decodeAnyOrError decoded more than it should: %d", n)) }
+		nn, err := Skim(decoder, tag)
+		n += nn; if err != nil { return n, err }
+		return n, nil
+	}
+	return n, err
+}
+
+// decodeAnyOrError is internal to [decodeAny]. It takes in an addressable
+// [reflect.Value] as the destination. If the decoded value cannot fit in the
+// destination, it decodes nothing and returns an error of type errCantAssign,
+// except for the case of a mismatched OTA element tag, wherein it will skim
+// over the rest of the payload, leave the destination empty, and return without
+// an error. The head of the decoder must be at the start of the payload.
+func decodeAnyOrError(decoder *Decoder, destination reflect.Value, tag Tag) (n int, err error) {
+	err = canSet(destination.Type(), tag)
+	if err != nil { return n, err }
+	
+	switch tag.WithoutCN() {
+	case SI:
+		// SI: (none)
+		setUint(destination, uint64(tag.CN()), 1)
+	case LI:
+		// LI: <value: IntN>
+		nn, err := decodeAndSetUint(decoder, destination, tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+	case LSI:
+		// LSI: <value: IntN>
+		nn, err := decodeAndSetInt(decoder, destination, tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+	case FP:
+		// FP: <value: FloatN>
+		nn, err := decodeAndSetFloat(decoder, destination, tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+	case SBA:
+		// SBA: <data: U8>*
+		length := tag.CN()
+		if length > MaxStructureLength {
+			return 0, ErrTooLong
+		}
+		buffer := make([]byte, length)
+		nn, err := decoder.Read(buffer)
+		n += nn; if err != nil { return n, err }
+		setString(destination, string(buffer))
+	case LBA:
+		// LBA: <length: UN> <data: U8>*
+		length, nn, err := decoder.ReadUintN(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+		if length > uint64(MaxStructureLength) {
+			return 0, ErrTooLong
+		}
+		buffer := make([]byte, length)
+		nn, err = decoder.Read(buffer)
+		n += nn; if err != nil { return n, err }
+		setString(destination, string(buffer))
+	case OTA:
+		// OTA: <length: UN> <elementTag: tape.Tag> <values>*
+		oldDestination := destination
+		if isTypeAny(destination.Type()) {
+			// need a skeleton value if we are assigning to any.
+			value, err := skeletonValue(decoder, tag)
+			if err != nil { return n, err }
+			destination = value
+		}
+		length, nn, err := decoder.ReadUintN(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+		if length > uint64(MaxStructureLength) {
+			return 0, ErrTooLong
+		}
+		lengthCast, err := Uint64ToIntSafe(length)
+		if err != nil { return n, err }
+		oneTag, nn, err := decoder.ReadTag()
+		n += nn; if err != nil { return n, err }
+		if destination.Cap() < lengthCast {
+			destination.Grow(lengthCast - destination.Cap())
+		}
+		// skip the rest of the array if the one tag doesn't
+		// match up with the destination
+		err = canSet(destination.Type().Elem(), oneTag)
+		if _, ok := err.(errCantAssign); ok {
+			for _ = range length {
+				nn, err := Skim(decoder, oneTag)
+				n += nn; if err != nil { return n, err }
+			}
+			break
+		}
+		if err != nil { return n, err }
+		destination.SetLen(lengthCast)
+		for index := range length {
+			nn, err := decodeAny(decoder, destination.Index(int(index)), oneTag)
+			n += nn
+			if _, ok := err.(errCantAssign); ok {
+				continue
+			} else if err != nil {
+				return n, err
+			}
+		}
+		oldDestination.Set(destination)
+	case KTV:
+		// KTV: <length: UN> (<key: U16> <tag: Tag> <value>)*
+		length, nn, err := decoder.ReadUintN(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+		if length > uint64(MaxStructureLength) {
+			return 0, ErrTooLong
+		}
+		lengthCast, err := Uint64ToIntSafe(length)
+		if err != nil { return n, err }
+
+		// im fucking so done dude. im so fucking done. this was
+		// supposed to only run when we need it but i guess it runs all
+		// the time, because when we get a map destination (a valid,
+		// allocated one) we break apart on SetMapIndex because of a nil
+		// map. yeah thats right. a fucking nil map panic. on the map we
+		// just allocated. but running this unconditionally (whether or
+		// not we receive an empty any value) actually makes it fucking
+		// work. go figure().
+		//
+		// (the map allocation functionality in skeletonPointer has been
+		// removed)
+		value := reflect.MakeMapWithSize(reflect.TypeOf(dummyMap), lengthCast)
+		destination.Set(value)
+		destination = value
+		
+		destination.Clear()
+		for _ = range lengthCast {
+			key, nn, err := decoder.ReadUint16()
+			n += nn; if err != nil { return n, err }
+			itemTag, nn, err := decoder.ReadTag()
+			n += nn; if err != nil { return n, err }
+			value, err := skeletonPointer(decoder, itemTag)
+			if err != nil { return n, err }
+			nn, err = decodeAny(decoder, value.Elem(), itemTag)
+			n += nn; if err != nil { return n, err }
+			destination.SetMapIndex(reflect.ValueOf(key), value.Elem())
+		}
+	default:
+		return n, fmt.Errorf("unknown TN %d", tag.TN())
+	}
+	return n, nil
+}
+
+// TagAny returns the correct tag for an "any" value. Returns an error if the
+// underlying type is unsupported. See [EncodeAny] for a list of supported
+// types.
+func TagAny(value any) (Tag, error) {
+	return tagAny(reflect.ValueOf(value))
+}
+
+func tagAny(reflectValue reflect.Value) (Tag, error) {
+	// primitives
+	switch reflectValue.Kind() {
+	case reflect.Int:     return LSI.WithCN(3), nil
+	case reflect.Int8:    return LSI.WithCN(0), nil
+	case reflect.Int16:   return LSI.WithCN(1), nil
+	case reflect.Int32:   return LSI.WithCN(3), nil
+	case reflect.Int64:   return LSI.WithCN(7), nil
+	case reflect.Uint:    return LI.WithCN(3), nil
+	case reflect.Uint8:   return LI.WithCN(0), nil
+	case reflect.Uint16:  return LI.WithCN(1), nil
+	case reflect.Uint32:  return LI.WithCN(3), nil
+	case reflect.Uint64:  return LI.WithCN(7), nil
+	case reflect.Float32: return FP.WithCN(3), nil
+	case reflect.Float64: return FP.WithCN(7), nil
+	case reflect.String:  return bufferLenTag(reflectValue.Len()), nil
+	}
+	if reflectValue.CanConvert(reflect.TypeOf(dummyBuffer)) {
+		return bufferLenTag(reflectValue.Len()), nil
+	}
+	
+	// aggregates
+	reflectType := reflectValue.Type()
+	switch reflectType.Kind() {
+	case reflect.Slice: return OTA.WithCN(IntBytes(uint64(reflectValue.Len())) - 1), nil
+	case reflect.Array: return OTA.WithCN(reflectType.Len()), nil
+	case reflect.Map:
+		if reflectType.Key() == reflect.TypeOf(uint16(0)) {
+			return KTV.WithCN(IntBytes(uint64(reflectValue.Len())) - 1), nil
+		}
+		return 0, fmt.Errorf("cannot encode map key %v, key must be uint16", reflectType.Key())
+	}
+	return 0, fmt.Errorf("cannot get tag of type %v", reflectType)
+}
+
+func encodeAnySlice(encoder *Encoder, value any, tag Tag) (n int, err error) {
+	// OTA: <length: UN> <elementTag: tape.Tag> <values>*
+	reflectValue := reflect.ValueOf(value)
+	nn, err := encoder.WriteUintN(uint64(reflectValue.Len()), tag.CN() + 1)
+	n += nn; if err != nil { return n, err }
+	reflectType := reflect.TypeOf(value)
+	oneTag, err := tagAny(reflect.Zero(reflectType.Elem()))
+	if err != nil { return n, err }
+	for index := 0; index < reflectValue.Len(); index += 1 {
+		itemTag, err := tagAny(reflectValue.Index(index))
+		if err != nil { return n, err }
+		if itemTag.CN() > oneTag.CN() { oneTag = itemTag }
+	}
+	if oneTag.Is(SBA) { oneTag += 1 << 5 }
+	nn, err = encoder.WriteUint8(uint8(oneTag))
+	n += nn; if err != nil { return n, err }
+	for index := 0; index < reflectValue.Len(); index += 1 {
+		item := reflectValue.Index(index).Interface()
+		nn, err = EncodeAny(encoder, item, oneTag)
+		n += nn; if err != nil { return n, err }
+	}
+	return n, err
+}
+
+func encodeAnyMap(encoder *Encoder, value any, tag Tag) (n int, err error) {
+	// KTV: <length: UN> (<key: U16> <tag: Tag> <value>)*
+	reflectValue := reflect.ValueOf(value)
+	nn, err := encoder.WriteUintN(uint64(reflectValue.Len()), tag.CN() + 1)
+	n += nn; if err != nil { return n, err }
+	iter := reflectValue.MapRange()
+	for iter.Next() {
+		reflectValue := iter.Value().Elem()
+		key          := iter.Key().Interface().(uint16)
+		value        := reflectValue.Interface()
+		nn, err = encoder.WriteUint16(key)
+		n += nn; if err != nil { return n, err }
+		itemTag, err := tagAny(reflectValue)
+		if err != nil { return n, err }
+		nn, err = encoder.WriteUint8(uint8(itemTag))
+		n += nn; if err != nil { return n, err }
+		nn, err = EncodeAny(encoder, value, itemTag)
+		n += nn; if err != nil { return n, err }
+	}
+	return n, nil
+}
+
+func canSet(destination reflect.Type, tag Tag) error {
+	// anything can be assigned to `any`
+	if isTypeAny(destination) {
+		return nil
+	}
+	switch tag.WithoutCN() {
+	case SI, LI, LSI:
+		switch destination.Kind() {
+		case
+			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		default:
+			return errCantAssignf("cannot assign integer to %v", destination)
+		}
+	case FP:
+		switch destination.Kind() {
+		case reflect.Float32, reflect.Float64:
+		default:
+			return errCantAssignf("cannot assign float to %v", destination)
+		}
+	case SBA, LBA:
+		if destination.Kind() == reflect.String { return nil }
+		if destination.Kind() != reflect.Slice {
+			return errCantAssignf("cannot assign byte array to %v", destination)
+		}
+		if destination.Elem() != reflect.TypeOf(byte(0)) {
+			return errCantAssignf("cannot convert %v to *[]byte", destination)
+		}
+	case OTA:
+		if destination.Kind() != reflect.Slice {
+			return errCantAssignf("cannot assign array to %v", destination)
+		}
+	case KTV:
+		cantAssign :=
+			destination.Kind() != reflect.Map ||
+			destination.Key().Kind() != reflect.Uint16 ||
+			!isTypeAny(destination.Elem())
+		if cantAssign {
+			return errCantAssignf("cannot assign table to %v", destination)
+		}
+	default:
+		return fmt.Errorf("unknown TN %d", tag.TN())
+	}
+	return nil
+}
+
+// setInt expects a settable destination.
+func setInt(destination reflect.Value, value int64, bytes int) {
+	switch {
+	case destination.CanInt():
+		destination.Set(reflect.ValueOf(int64(value)).Convert(destination.Type()))
+	case destination.CanUint():
+		destination.Set(reflect.ValueOf(value).Convert(destination.Type()))
+	case isTypeAny(destination.Type()):
+		switch {
+		case bytes > 4: destination.Set(reflect.ValueOf(int64(value)))
+		case bytes > 2: destination.Set(reflect.ValueOf(int32(value)))
+		case bytes > 1: destination.Set(reflect.ValueOf(int16(value)))
+		default:        destination.Set(reflect.ValueOf(int8(value)))
+		}
+	default:
+		panic("setInt called on an unsupported type")
+	}
+}
+
+// setUint expects a settable destination.
+func setUint(destination reflect.Value, value uint64, bytes int) {
+	switch {
+	case destination.CanInt():
+		destination.Set(reflect.ValueOf(int64(value)).Convert(destination.Type()))
+	case destination.CanUint():
+		destination.Set(reflect.ValueOf(value).Convert(destination.Type()))
+	case isTypeAny(destination.Type()):
+		switch {
+		case bytes > 4: destination.Set(reflect.ValueOf(uint64(value)))
+		case bytes > 2: destination.Set(reflect.ValueOf(uint32(value)))
+		case bytes > 1: destination.Set(reflect.ValueOf(uint16(value)))
+		default:        destination.Set(reflect.ValueOf(uint8(value)))
+		}
+	default:
+		panic("setUint called on an unsupported type")
+	}
+}
+
+// setFloat expects a settable destination.
+func setFloat(destination reflect.Value, value float64) {
+	destination.Set(reflect.ValueOf(value).Convert(destination.Type()))
+}
+
+// setByteArrayexpects a settable destination.
+func setByteArray(destination reflect.Value, value []byte) {
+	destination.Set(reflect.ValueOf(value))
+}
+
+// setString exepctes a settable destination
+func setString(destination reflect.Value, value string) {
+	destination.Set(reflect.ValueOf(value))
+}
+
+// decodeAndSetInt expects a settable destination.
+func decodeAndSetInt(decoder *Decoder, destination reflect.Value, bytes int) (n int, err error) {
+	value, nn, err := decoder.ReadIntN(bytes)
+	n += nn; if err != nil { return n, err }
+	setInt(destination, value, bytes)
+	return n, nil
+}
+
+// decodeAndSetUint expects a settable destination.
+func decodeAndSetUint(decoder *Decoder, destination reflect.Value, bytes int) (n int, err error) {
+	value, nn, err := decoder.ReadUintN(bytes)
+	n += nn; if err != nil { return n, err }
+	setUint(destination, value, bytes)
+	return n, nil
+}
+
+// decodeAndSetInt expects a settable destination.
+func decodeAndSetFloat(decoder *Decoder, destination reflect.Value, bytes int) (n int, err error) {
+	switch bytes {
+	case 8:
+		value, nn, err := decoder.ReadFloat64()
+		n += nn; if err != nil { return n, err }
+		setFloat(destination, float64(value))
+		return n, nil
+	case 4:
+		value, nn, err := decoder.ReadFloat32()
+		n += nn; if err != nil { return n, err }
+		setFloat(destination, float64(value))
+		return n, nil
+	}
+	return n, errCantAssignf("unsupported bit width float%d", bytes * 8)
+}
+
+// skeletonValue returns an addressable value. It can be set directly. The head
+// of the decoder must be at the start of the payload when calling.
+func skeletonValue(decoder *Decoder, tag Tag) (reflect.Value, error) {
+	ptr, err := skeletonPointer(decoder, tag)
+	if err != nil { return reflect.Value { }, err }
+	return ptr.Elem(), nil
+}
+
+// skeletonPointer returns a pointer value. In order for it to be set, it must
+// be dereferenced using Elem(). The head of the decoder must be at the start of
+// the payload when calling.
+func skeletonPointer(decoder *Decoder, tag Tag) (reflect.Value, error) {
+	typ, err := typeOf(decoder, tag)
+	if err != nil { return reflect.Value { }, err }
+	value := reflect.New(typ)
+	return value, nil
+}
+
+// typeOf returns the type of the current tag being decoded. It does not use up
+// the decoder, it only peeks. The head of the decoder must be at the start of
+// the payload when calling.
+func typeOf(decoder *Decoder, tag Tag) (reflect.Type, error) {
+	switch tag.WithoutCN() {
+	case SI:
+		return reflect.TypeOf(uint8(0)), nil
+	case LI:
+		switch tag.CN() {
+		case 0: return reflect.TypeOf(uint8(0)), nil
+		case 1: return reflect.TypeOf(uint16(0)), nil
+		case 3: return reflect.TypeOf(uint32(0)), nil
+		case 7: return reflect.TypeOf(uint64(0)), nil
+		}
+		return nil, fmt.Errorf("unknown CN %d for LI", tag.CN())
+	case LSI:
+		switch tag.CN() {
+		case 0: return reflect.TypeOf(int8(0)), nil
+		case 1: return reflect.TypeOf(int16(0)), nil
+		case 3: return reflect.TypeOf(int32(0)), nil
+		case 7: return reflect.TypeOf(int64(0)), nil
+		}
+		return nil, fmt.Errorf("unknown CN %d for LSI", tag.CN())
+	case FP:
+		switch tag.CN() {
+		case 3: return reflect.TypeOf(float32(0)), nil
+		case 7: return reflect.TypeOf(float64(0)), nil
+		}
+		return nil, fmt.Errorf("unknown CN %d for FP", tag.CN())
+	case SBA: return reflect.TypeOf(""), nil
+	case LBA: return reflect.TypeOf(""), nil
+	case OTA:
+		elemTag, dimension, err := peekSlice(decoder, tag)
+		if err != nil { return nil, err }
+		if elemTag.Is(OTA) { panic("peekSlice cannot return OTA") }
+		typ, err := typeOf(decoder, elemTag)
+		if err != nil { return nil, err }
+		for _ = range dimension {
+			typ = reflect.SliceOf(typ)
+		}
+		return typ, nil
+	case KTV: return reflect.TypeOf(dummyMap), nil
+	}
+	return nil, fmt.Errorf("unknown TN %d", tag.TN())
+}
+
+// isTypeAny returns whether the given reflect.Type is an interface with no
+// methods.
+func isTypeAny(typ reflect.Type) bool {
+	return typ.Kind() == reflect.Interface && typ.NumMethod() == 0
+}
+
+// peekSlice returns the element tag and dimension count of the OTA currently
+// being decoded. It does not use up the decoder, it only peeks.
+func peekSlice(decoder *Decoder, tag Tag) (Tag, int, error) {
+	offset    := 0
+	dimension := 0
+	currentTag := tag
+	for {
+		elem, populated, n, err := peekSliceOnce(decoder, currentTag, offset)
+		if err != nil { return 0, 0, err }
+		currentTag = elem
+		offset     = n
+		dimension += 1
+		if elem.Is(OTA) {
+			if !populated {
+				// default to a large byte array, will be
+				// interpreted as a string.
+				return LBA, dimension + 1, nil
+			}
+		} else {
+			return elem, dimension, nil
+		}
+	}
+}
+
+// peekSliceOnce returns the element tag of the OTA located offset bytes ahead
+// of the current position. It does not use up the decoder, it only peeks. The n
+// return value denotes how far away from 0 it peeked. If the OTA has more than
+// zero items, populated will be set to true.
+func peekSliceOnce(decoder *Decoder, tag Tag, offset int) (elem Tag, populated bool, n int, err error) {
+	lengthStart  := offset
+	lengthEnd    := lengthStart + tag.CN() + 1
+	elemTagStart := lengthEnd
+	elemTagEnd   := elemTagStart + 1
+
+	headerBytes, err := decoder.Peek(elemTagEnd)
+	if err != nil { return 0, false, 0, err }
+
+	elem = Tag(headerBytes[len(headerBytes) - 1])
+	for index := lengthStart; index < lengthEnd; index += 1 {
+		if headerBytes[index] > 0 {
+			populated = true
+			break
+		}
+	}
+	n = elemTagEnd
+
+	return
+}

tape/dynamic_test.go

@@ -0,0 +1,369 @@
+package tape
+
+import "bytes"
+import "testing"
+import "reflect"
+import tu "git.tebibyte.media/sashakoshka/hopp/internal/testutil"
+
+var samplePayloads = [][]byte {
+	/* int8     */ []byte { byte(LSI.WithCN(0)), 0x45 },
+	/* int16    */ []byte { byte(LSI.WithCN(1)), 0x45, 0x67 },
+	/* int32    */ []byte { byte(LSI.WithCN(3)), 0x45, 0x67, 0x89, 0xAB },
+	/* int64    */ []byte { byte(LSI.WithCN(7)), 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23 },
+	/* uint5    */ []byte { byte(SI.WithCN(12)) },
+	/* uint8    */ []byte { byte(LI.WithCN(0)), 0x45 },
+	/* uint16   */ []byte { byte(LI.WithCN(1)), 0x45, 0x67 },
+	/* uint32   */ []byte { byte(LI.WithCN(3)), 0x45, 0x67, 0x89, 0xAB },
+	/* uint64   */ []byte { byte(LI.WithCN(7)), 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23 },
+	/* string   */ []byte { byte(SBA.WithCN(7)), 'p', 'u', 'p', 'e', 'v', 'e', 'r' },
+	/* []byte   */ []byte { byte(SBA.WithCN(5)), 'b', 'l', 'a', 'r', 'g' },
+	/* []string */ []byte {
+		byte(OTA.WithCN(0)), 2, byte(LBA.WithCN(0)),
+		0x08, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23,
+		0x05, 0x11, 0x11, 0x11, 0x11, 0x11,
+	},
+	/* map[uint16] any */ []byte {
+		byte(KTV.WithCN(0)), 2,
+		0x02, 0x23, byte(LSI.WithCN(1)), 0x45, 0x67,
+		0x02, 0x24, byte(LI.WithCN(3)),  0x45, 0x67, 0x89, 0xAB,
+	},
+	/* map[uint16] any */ []byte {
+		byte(KTV.WithCN(0)), 3,
+		0x00, 0x01, 0x63, 0x43, 0xF4, 0xC0, 0x00,
+		0x00, 0x02, 0x82, 'h', 'i',
+		0x00, 0x03, 0x21, 0x39, 0x92,
+	},
+}
+
+var sampleValues = []any {
+	/* int8     */ int8(0x45),
+	/* int16    */ int16(0x4567),
+	/* int32    */ int32(0x456789AB),
+	/* int64    */ int64(0x456789ABCDEF0123),
+	/* uint5    */ uint8(12),
+	/* uint8    */ uint8(0x45),
+	/* uint16   */ uint16(0x4567),
+	/* uint32   */ uint32(0x456789AB),
+	/* uint64   */ uint64(0x456789ABCDEF0123),
+	/* string   */ "pupever",
+	/* []byte   */ "blarg",
+	/* []string */ []string {
+		"\x45\x67\x89\xAB\xCD\xEF\x01\x23",
+		"\x11\x11\x11\x11\x11",
+	},
+	/* map[uint16] any */ map[uint16] any {
+		0x0223: int16(0x4567),
+		0x0224: uint32(0x456789AB),
+	},
+	/* map[uint16] any */ map[uint16] any {
+		0x0001: float32(489.5),
+		0x0002: "hi",
+		0x0003: uint16(0x3992),
+	},
+}
+
+type userDefinedInteger int16
+
+func TestEncodeAnyInt(test *testing.T) {
+	err := testEncodeAny(test, uint8(0xCA), LI.WithCN(0), tu.S(0xCA))
+	if err != nil { test.Fatal(err) }
+	err = testEncodeAny(test, 400, LSI.WithCN(3), tu.S(
+		0, 0, 0x1, 0x90,
+	))
+	if err != nil { test.Fatal(err) }
+}
+
+func TestEncodeAnyTable(test *testing.T) {
+	err := testEncodeAny(test, map[uint16] any {
+		0xF3B9: 1,
+		0x0102: 2,
+		0x0000: "hi!",
+		0xFFFF: []uint16 { 0xBEE5, 0x7777 },
+		0x1234: [][]uint16 { []uint16 { 0x5 }, []uint16 { 0x17, 0xAAAA} },
+		0x2345: [][]int16 { []int16 { 0x5 }, []int16 { 0x17, -0xAAA } },
+		0x3456: userDefinedInteger(0x3921),
+		0x1F1F: float32(67.26),
+		0x0F0F: float64(5.3),
+	}, KTV.WithCN(0), tu.S(9).AddVar(
+		[]byte {
+			0xF3, 0xB9,
+			byte(LSI.WithCN(3)),
+			0, 0, 0, 1,
+		},
+		[]byte {
+			0x01, 0x02,
+			byte(LSI.WithCN(3)),
+			0, 0, 0, 2,
+		},
+		[]byte {
+			0, 0,
+			byte(SBA.WithCN(3)),
+			'h', 'i', '!',
+		},
+		[]byte {
+			0xFF, 0xFF,
+			byte(OTA.WithCN(0)), 2, byte(LI.WithCN(1)),
+			0xBE, 0xE5, 0x77, 0x77,
+		},
+		[]byte {
+			0x12, 0x34,
+			byte(OTA.WithCN(0)), 2, byte(OTA.WithCN(0)),
+			1, byte(LI.WithCN(1)),
+			0, 0x5,
+			2, byte(LI.WithCN(1)),
+			0,    0x17,
+			0xAA, 0xAA,
+		},
+		[]byte {
+			0x23, 0x45,
+			byte(OTA.WithCN(0)), 2, byte(OTA.WithCN(0)),
+			1, byte(LSI.WithCN(1)),
+			0, 0x5,
+			2, byte(LSI.WithCN(1)),
+			0,    0x17,
+			0xF5, 0x56,
+		},
+		[]byte {
+			0x34, 0x56,
+			byte(LSI.WithCN(1)),
+			0x39, 0x21,
+		},
+		[]byte {
+			0x1F, 0x1F,
+			byte(FP.WithCN(3)),
+			0x42, 0x86, 0x85, 0x1F,
+		},
+		[]byte {
+			0x0F, 0x0F,
+			byte(FP.WithCN(7)),
+			0x40, 0x15, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33,
+		},
+	))
+	if err != nil { test.Fatal(err) }
+}
+
+func TestDecodeWrongType(test *testing.T) {
+	for index, data := range samplePayloads {
+		test.Logf("data %2d %v [%s]", index, Tag(data[0]), tu.HexBytes(data[1:]))
+		// integers should only assign to other integers
+		if index > 8 {
+			cas := func(destination any) {
+				n, err := DecodeAnyInto(NewDecoder(bytes.NewBuffer(data[1:])), destination, Tag(data[0]))
+				if err != nil { test.Fatalf("error: %v | n: %d", err, n) }
+				reflectValue := reflect.ValueOf(destination).Elem()
+				if reflectValue.CanInt() {
+					if reflectValue.Int() != 0 {
+						test.Fatalf("destination not zero: %v", reflectValue.Elem().Interface())
+					}
+				} else {
+					if reflectValue.Uint() != 0 {
+						test.Fatalf("destination not zero: %v", reflectValue.Elem().Interface())
+					}
+				}
+				if n != len(data) - 1 {
+					test.Fatalf("n not equal: %d != %d", n, len(data) - 1)
+				}
+			}
+			test.Log("- int8")
+			{ var dest int8;   cas(&dest) }
+			test.Log("- int16")
+			{ var dest int16;  cas(&dest) }
+			test.Log("- int32")
+			{ var dest int32;  cas(&dest) }
+			test.Log("- int64")
+			{ var dest int64;  cas(&dest) }
+			test.Log("- uint8")
+			{ var dest uint8;  cas(&dest) }
+			test.Log("- uint16")
+			{ var dest uint16; cas(&dest) }
+			test.Log("- uint32")
+			{ var dest uint32; cas(&dest) }
+			test.Log("- uint64")
+			{ var dest uint64; cas(&dest) }
+		}
+		arrayCase := func(destination any) {
+			n, err := DecodeAnyInto(NewDecoder(bytes.NewBuffer(data[1:])), destination, Tag(data[0]))
+			if err != nil { test.Fatalf("error: %v | n: %d", err, n) }
+			reflectDestination := reflect.ValueOf(destination)
+			reflectValue := reflectDestination.Elem()
+			if reflectValue.Len() != 0 {
+				test.Fatalf("len(destination) not zero: %v", reflectValue.Interface())
+			}
+			if n != len(data) - 1 {
+				test.Fatalf("n not equal: %d != %d", n, len(data) - 1)
+			}
+		}
+		// SBA/LBA types should only assign to other SBA/LBA types
+		if index != 9 && index != 10 {
+			test.Log("- string")
+			{ var dest string; arrayCase(&dest) }
+			test.Log("- []byte")
+			{ var dest []byte; arrayCase(&dest) }
+		}
+		// arrays should only assign to other arrays
+		if index != 11 {
+			test.Log("- []string")
+			{ var dest []string; arrayCase(&dest) }
+		}
+		// tables should only assign to other tables
+		if index != 12 && index != 13 {
+			test.Log("- map[uint16] any")
+			{ var dest = map[uint16] any { }; arrayCase(&dest) }
+		}
+	}
+}
+
+func TestEncodeDecodeAnyTable(test *testing.T) {
+	err := testEncodeDecodeAny(test, map[uint16] any {
+		0xF3B9: uint32(1),
+		0x0102: uint32(2),
+		0x0103: int64(23432),
+		0x0104: int64(-88777),
+		0x0000: "hi!",
+		0xFFFF: []uint16 { 0xBEE5, 0x7777 },
+		0x1234: [][]uint16 { []uint16 { 0x5 }, []uint16 { 0x17, 0xAAAA} },
+		0x1F1F: float32(67.26),
+		0x0F0F: float64(5.3),
+	}, nil)
+	if err != nil { test.Fatal(err) }
+}
+
+func TestEncodeDecodeAnyDestination(test *testing.T) {
+	var destination any
+	for index, data := range samplePayloads {
+		tag     := Tag(data[0])
+		payload := data[1:]
+		test.Logf("data %2d %v [%s]", index, tag, tu.HexBytes(payload))
+		n, err := DecodeAnyInto(NewDecoder(bytes.NewBuffer(payload)), &destination, tag)
+		if err != nil { test.Fatalf("error: %v | n: %d", err, n) }
+		got     := destination
+		correct := sampleValues[index]
+		test.Log("got:    ", tu.Describe(got))
+		test.Log("correct:", tu.Describe(correct))
+		if !reflect.DeepEqual(got, correct) {
+			test.Fatalf("values not equal")
+		}
+		if n != len(payload) {
+			test.Fatalf("n not equal: %d != %d", n, len(payload))
+		}
+	}
+}
+
+func TestPeekSlice(test *testing.T) {
+	buffer := bytes.NewBuffer([]byte {
+		2, byte(OTA.WithCN(3)),
+		0, 0, 0, 1, byte(LI.WithCN(1)),
+		0, 0x5,
+		2, byte(LI.WithCN(1)),
+		0,    0x17,
+		0xAA, 0xAA,
+	})
+	decoder := NewDecoder(buffer)
+
+	elem, dimension, err := peekSlice(decoder, OTA.WithCN(0))
+	if err != nil { test.Fatal(err) }
+	if elem != LI.WithCN(1) {
+		test.Fatalf("wrong element tag: %v %02X", elem, byte(elem))
+	}
+	if got, correct := dimension, 2; got != correct {
+		test.Fatalf("wrong dimension: %d != %d", got, correct)
+	}
+}
+
+func TestPeekSliceOnce(test *testing.T) {
+	buffer := bytes.NewBuffer([]byte {
+		2, byte(OTA.WithCN(3)),
+		0, 0, 0, 1, byte(LI.WithCN(1)),
+		0, 0x5,
+		2, byte(LI.WithCN(1)),
+		0,    0x17,
+		0xAA, 0xAA,
+	})
+	decoder := NewDecoder(buffer)
+
+	test.Log("--- stage 1")
+	elem, populated, n, err := peekSliceOnce(decoder, OTA.WithCN(0), 0)
+	if err != nil { test.Fatal(err) }
+	if elem != OTA.WithCN(3) {
+		test.Fatal("wrong element tag:", elem)
+	}
+	if !populated {
+		test.Fatal("wrong populated:", populated)
+	}
+	if got, correct := n, 2; got != correct {
+		test.Fatalf("wrong n: %d != %d", got, correct)
+	}
+	
+	test.Log("--- stage 2")
+	elem, populated, n, err = peekSliceOnce(decoder, elem, n)
+	if err != nil { test.Fatal(err) }
+	if elem != LI.WithCN(1) {
+		test.Fatal("wrong element tag:", elem)
+	}
+	if !populated {
+		test.Fatal("wrong populated:", populated)
+	}
+	if got, correct := n, 7; got != correct {
+		test.Fatalf("wrong n: %d != %d", got, correct)
+	}
+}
+
+func TestTagAny(test *testing.T) {
+	cases := [][2]any {
+		[2]any { LSI.WithCN(3),  int(9)     },
+		[2]any { LSI.WithCN(0),  int8(9)    },
+		[2]any { LSI.WithCN(1),  int16(9)   },
+		[2]any { LSI.WithCN(3),  int32(9)   },
+		[2]any { LSI.WithCN(7),  int64(9)   },
+		[2]any { LI.WithCN(3),   uint(9)    },
+		[2]any { LI.WithCN(0),   uint8(9)   },
+		[2]any { LI.WithCN(1),   uint16(9)  },
+		[2]any { LI.WithCN(3),   uint32(9)  },
+		[2]any { LI.WithCN(7),   uint64(9)  },
+		[2]any { FP.WithCN(3),   float32(9) },
+		[2]any { FP.WithCN(7),   float64(9) },
+		[2]any { SBA.WithCN(12), "small string" },
+		[2]any { SBA.WithCN(12), []byte("small string") },
+		[2]any { LBA.WithCN(0),  "this is a very long string that is long" },
+		[2]any { LBA.WithCN(0),  []byte("this is a very long string that is long") },
+		[2]any { LBA.WithCN(1),  lipsum },
+		[2]any { OTA.WithCN(0),  []int { 1, 2, 3, 4, 5 } },
+		[2]any { OTA.WithCN(0),  []string { "1, 2, 3, 4, 5" } },
+		[2]any { KTV.WithCN(0),  map[uint16] any {
+			0:  1,
+			1:  "wow",
+			2:  10.238,
+			45: -9,
+			9:  map[uint16] any { },
+		}},
+	}
+	for _, cas := range cases {
+		test.Log(cas)
+		got, err := TagAny(cas[1])
+		if err != nil { test.Fatal(err) }
+		if correct := cas[0].(Tag); correct != got {
+			test.Fatalf("wrong tag: %v != %v", got, correct)
+		}
+	}
+}
+
+func TestDecodeAny(test *testing.T) {
+	for index, payload := range samplePayloads {
+		correctValue := sampleValues[index]
+		data := payload[1:]
+		decoder := NewDecoder(bytes.NewBuffer(data))
+		tag     := Tag(payload[0])
+		decoded, n, err := DecodeAny(decoder, tag)
+		test.Log("n:      ", n)
+		test.Log("tag:    ", tag)
+		test.Log("got:    ", tu.Describe(decoded))
+		test.Log("correct:", tu.Describe(correctValue))
+		if err != nil { test.Fatal(err) }
+		if !reflect.DeepEqual(decoded, correctValue) {
+			test.Fatal("values not equal")
+		}
+		if n != len(data) {
+			test.Fatalf("n not equal: %d != %d", n, len(data))
+		}
+	}
+}

tape/encode.go

@@ -0,0 +1,189 @@
+package tape
+
+import "io"
+import "math"
+import "bufio"
+
+// Encodable is any type that can write itself to an encoder.
+type Encodable interface {
+	// Encode sends data to encoder. It returns the amount of bytes written,
+	// and an error if the write stopped early.
+	Encode(encoder *Encoder) (n int, err error)
+}
+	
+// Encoder encodes data to an io.Writer.
+type Encoder struct {
+	bufio.Writer
+}
+
+// NewEncoder creates a new encoder that writes to writer.
+func NewEncoder(writer io.Writer) *Encoder {
+	encoder := &Encoder { }
+	encoder.Reset(writer)
+	return encoder
+}
+
+// WriteInt8 encodes an 8-bit signed integer to the output writer.
+func (this *Encoder) WriteInt8(value int8) (n int, err error) {
+	return this.WriteUint8(uint8(value))
+}
+
+// WriteUint8 encodes an 8-bit unsigned integer to the output writer.
+func (this *Encoder) WriteUint8(value uint8) (n int, err error) {
+	return this.Write([]byte { byte(value) })
+}
+
+// WriteInt16 encodes an 16-bit signed integer to the output writer.
+func (this *Encoder) WriteInt16(value int16) (n int, err error) {
+	return this.WriteUint16(uint16(value))
+}
+
+// WriteUint16 encodes an 16-bit unsigned integer to the output writer.
+func (this *Encoder) WriteUint16(value uint16) (n int, err error) {
+	return this.Write([]byte {
+		byte(value >> 8),
+		byte(value),
+	})
+}
+
+// WriteInt32 encodes an 32-bit signed integer to the output writer.
+func (this *Encoder) WriteInt32(value int32) (n int, err error) {
+	return this.WriteUint32(uint32(value))
+}
+
+// WriteUint32 encodes an 32-bit unsigned integer to the output writer.
+func (this *Encoder) WriteUint32(value uint32) (n int, err error) {
+	return this.Write([]byte {
+		byte(value >> 24),
+		byte(value >> 16),
+		byte(value >> 8),
+		byte(value),
+	})
+}
+
+// WriteInt64 encodes an 64-bit signed integer to the output writer.
+func (this *Encoder) WriteInt64(value int64) (n int, err error) {
+	return this.WriteUint64(uint64(value))
+}
+
+// WriteUint64 encodes an 64-bit unsigned integer to the output writer.
+func (this *Encoder) WriteUint64(value uint64) (n int, err error) {
+	return this.Write([]byte {
+		byte(value >> 56),
+		byte(value >> 48),
+		byte(value >> 40),
+		byte(value >> 32),
+		byte(value >> 24),
+		byte(value >> 16),
+		byte(value >> 8),
+		byte(value),
+	})
+}
+
+// WriteIntN encodes an N-byte signed integer to the output writer.
+func (this *Encoder) WriteIntN(value int64, bytes int) (n int, err error) {
+	return this.WriteUintN(uint64(value), bytes)
+}
+
+// for Write/ReadUintN, increase buffers if go somehow gets support for over 64
+// bit integers. we could also make an expanding int type in goutil to use here,
+// or maybe there is one in the stdlib. keep the int64 versions as well though
+// because its ergonomic.
+	
+// WriteUintN encodes an N-byte unsigned integer to the output writer.
+func (this *Encoder) WriteUintN(value uint64, bytes int) (n int, err error) {
+	// TODO: don't make multiple write calls (without allocating)
+	buffer := [1]byte { }
+	for bytesLeft := bytes; bytesLeft > 0; bytesLeft -- {
+		buffer[0] = byte(value) >> ((bytesLeft - 1) * 8)
+		nn, err := this.Write(buffer[:])
+		n += nn; if err != nil { return n, err }
+	}
+	return n, nil
+}
+
+// WriteFloat16 encodes a 16-bit floating point value to the output writer.
+func (this *Encoder) WriteFloat16(value float32) (n int, err error) {
+	return this.WriteUint16(f32bitsToF16bits(math.Float32bits(value)))
+}
+
+// WriteFloat32 encodes a 32-bit floating point value to the output writer.
+func (this *Encoder) WriteFloat32(value float32) (n int, err error) {
+	return this.WriteUint32(math.Float32bits(value))
+}
+
+// WriteFloat64 encodes a 64-bit floating point value to the output writer.
+func (this *Encoder) WriteFloat64(value float64) (n int, err error) {
+	return this.WriteUint64(math.Float64bits(value))
+}
+
+// WriteTag encodes a [Tag] to the output writer.
+func (this *Encoder) WriteTag(value Tag) (n int, err error) {
+	return this.WriteUint8(uint8(value))
+}
+
+// f32bitsToF16bits returns uint16 (Float16 bits) converted from the specified float32.
+// Conversion rounds to nearest integer with ties to even.
+// Taken from https://github.com/x448/float16/blob/v0.8.4/float16
+//
+// MIT License
+// 
+// Copyright (c) 2019 Montgomery Edwards⁴⁴⁸ and Faye Amacker
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+func f32bitsToF16bits(u32 uint32) uint16 {
+	// Translated from Rust to Go by Montgomery Edwards⁴⁴⁸ (github.com/x448).
+	// All 4294967296 conversions with this were confirmed to be correct by x448.
+	// Original Rust implementation is by Kathryn Long (github.com/starkat99) with MIT license.
+
+	sign := u32 & 0x80000000
+	exp := u32 & 0x7f800000
+	coef := u32 & 0x007fffff
+
+	if exp == 0x7f800000 {
+		// NaN or Infinity
+		nanBit := uint32(0)
+		if coef != 0 {
+			nanBit = uint32(0x0200)
+		}
+		return uint16((sign >> 16) | uint32(0x7c00) | nanBit | (coef >> 13))
+	}
+
+	halfSign := sign >> 16
+
+	unbiasedExp := int32(exp>>23) - 127
+	halfExp := unbiasedExp + 15
+
+	if halfExp >= 0x1f {
+		return uint16(halfSign | uint32(0x7c00))
+	}
+
+	if halfExp <= 0 {
+		if 14-halfExp > 24 {
+			return uint16(halfSign)
+		}
+		coef := coef | uint32(0x00800000)
+		halfCoef := coef >> uint32(14-halfExp)
+		roundBit := uint32(1) << uint32(13-halfExp)
+		if (coef&roundBit) != 0 && (coef&(3*roundBit-1)) != 0 {
+			halfCoef++
+		}
+		return uint16(halfSign | halfCoef)
+	}
+
+	uHalfExp := uint32(halfExp) << 10
+	halfCoef := coef >> 13
+	roundBit := uint32(0x00001000)
+	if (coef&roundBit) != 0 && (coef&(3*roundBit-1)) != 0 {
+		return uint16((halfSign | uHalfExp | halfCoef) + 1)
+	}
+	return uint16(halfSign | uHalfExp | halfCoef)
+}

tape/error.go

@@ -0,0 +1,12 @@
+package tape
+
+// Error enumerates common errors in this package.
+type Error string; const (
+	ErrTooLong  Error = "data structure too long"
+	ErrTooLarge Error = "number too large"
+)
+
+// Error implements the error interface.
+func (err Error) Error() string {
+	return string(err)
+}

tape/limits.go

@@ -0,0 +1,26 @@
+package tape
+
+// MaxStructureLength determines how long a TAPE data structure can be. This
+// applies to:
+//
+//  - OTA
+//  - SBA/LBA
+//  - KTV
+//
+// By default it is set at 2^20 (about a million).
+// You shouldn't need to change this. If you do, it should only be set once at
+// the start of the program.
+var MaxStructureLength = 1024 * 1024
+
+// MaxInt is the maximum value an int can hold. This varies depending on the
+// system.
+const MaxInt int = int(^uint(0) >> 1)
+
+// Uint64ToIntSafe casts the input to an int if it can be done without overflow,
+// or returns an error otherwise.
+func Uint64ToIntSafe(input uint64) (int, error) {
+	if input > uint64(MaxInt) {
+		return 0, ErrTooLarge
+	}
+	return int(input), nil
+}

tape/measure.go

@@ -0,0 +1,12 @@
+package tape
+
+// IntBytes returns the number of bytes required to hold a given unsigned
+// integer.
+func IntBytes(value uint64) int {
+	bytes := 0
+	for value > 0 || bytes == 0 {
+		value >>= 8;
+		bytes ++
+	}
+	return bytes
+}

tape/measure_test.go

@@ -0,0 +1,21 @@
+package tape
+
+import "testing"
+
+func TestIntBytes(test *testing.T) {
+	if correct, got := 1, IntBytes(0); correct != got {
+		test.Fatal("wrong:", got)
+	}
+	if correct, got := 1, IntBytes(1); correct != got {
+		test.Fatal("wrong:", got)
+	}
+	if correct, got := 1, IntBytes(16); correct != got {
+		test.Fatal("wrong:", got)
+	}
+	if correct, got := 1, IntBytes(255); correct != got {
+		test.Fatal("wrong:", got)
+	}
+	if correct, got := 2, IntBytes(256); correct != got {
+		test.Fatal("wrong:", got)
+	}
+}

tape/misc_test.go

@@ -0,0 +1,75 @@
+package tape
+
+import "fmt"
+import "bytes"
+import "testing"
+import "reflect"
+import tu "git.tebibyte.media/sashakoshka/hopp/internal/testutil"
+
+func encAny(value any) ([]byte, Tag, int, error) {
+	tag, err := TagAny(value)
+	if err != nil { return nil, 0, 0, err }
+	buffer := bytes.Buffer { }
+	encoder := NewEncoder(&buffer)
+	n, err := EncodeAny(encoder, value, tag)
+	if err != nil { return nil, 0, n, err }
+	encoder.Flush()
+	return buffer.Bytes(), tag, n, nil
+}
+
+func decAny(data []byte) (Tag, any, int, error) {
+	destination := map[uint16] any { }
+	tag, err := TagAny(destination)
+	if err != nil { return 0, nil, 0, err }
+	n, err := DecodeAnyInto(NewDecoder(bytes.NewBuffer(data)), &destination, tag)
+	if err != nil { return 0, nil, n, err }
+	return tag, destination, n, nil
+}
+
+func testEncodeAny(test *testing.T, value any, correctTag Tag, correctBytes tu.Snake) error {
+	bytes, tag, n, err := encAny(value)
+	if err != nil { return err }
+	test.Log("n:      ", n)
+	test.Log("tag:    ", tag)
+	test.Log("got:    ", tu.HexBytes(bytes))
+	test.Log("correct:", correctBytes)
+	if tag != correctTag {
+		return fmt.Errorf("tag not equal: %v != %v", tag, correctTag)
+	}
+	if ok, n := correctBytes.Check(bytes); !ok {
+		return fmt.Errorf("bytes not equal at index %d", n)
+	}
+	if n != len(bytes) {
+		return fmt.Errorf("n not equal: %d != %d", n, len(bytes))
+	}
+	return nil
+}
+
+func testEncodeDecodeAny(test *testing.T, value, correctValue any) error {
+	if correctValue == nil { 
+		correctValue = value
+	}
+
+	test.Log("encoding...")
+	bytes, tag, n, err := encAny(value)
+	if err != nil { return err }
+	test.Log("n:  ", n)
+	test.Log("tag:", tag)
+	test.Log("got:", tu.HexBytes(bytes))
+	test.Log("decoding...", tag)
+	if n != len(bytes) {
+		return fmt.Errorf("n not equal: %d != %d", n, len(bytes))
+	}
+	
+	_, decoded, n, err := decAny(bytes)
+	if err != nil { return err }
+	test.Log("got:    ", tu.Describe(decoded))
+	test.Log("correct:", tu.Describe(correctValue))
+	if !reflect.DeepEqual(decoded, correctValue) {
+		return fmt.Errorf("values not equal")
+	}
+	if n != len(bytes) {
+		return fmt.Errorf("n not equal: %d != %d", n, len(bytes))
+	}
+	return nil
+}

tape/skim.go

@@ -0,0 +1,54 @@
+package tape
+
+import "fmt"
+
+// Skim uses up data from a decoder to "skim" over one value (and all else
+// contained within it) without actually putting the data anywhere.
+func Skim(decoder *Decoder, tag Tag) (n int, err error) {
+	switch tag.WithoutCN() {
+	case SI:
+		// SI: (none)
+		return n, nil
+	case LI, LSI, FP:
+		// LI: <value: IntN>
+		// LSI: <value: IntN>
+		// FP: <value: FloatN>
+		nn, err := decoder.Discard(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+	case SBA:
+		// SBA: <data: U8>*
+		nn, err := decoder.Discard(tag.CN())
+		n += nn; if err != nil { return n, err }
+	case LBA:
+		// LBA: <length: UN> <data: U8>*
+		length, nn, err := decoder.ReadUintN(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+		nn, err = decoder.Discard(int(length))
+		n += nn; if err != nil { return n, err }
+	case OTA:
+		// OTA: <length: UN> <elementTag: tape.Tag> <values>*
+		length, nn, err := decoder.ReadUintN(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+		oneTag, nn, err := decoder.ReadTag()
+		n += nn; if err != nil { return n, err }
+		for _ = range length {
+			nn, err := Skim(decoder, oneTag)
+			n += nn; if err != nil { return n, err }
+		}
+	case KTV:
+		// KTV: <length: UN> (<key: U16> <tag: Tag> <value>)*
+		length, nn, err := decoder.ReadUintN(tag.CN() + 1)
+		n += nn; if err != nil { return n, err }
+		for _ = range length {
+			nn, err := decoder.Discard(2)
+			n += nn; if err != nil { return n, err }
+			itemTag, nn, err := decoder.ReadTag()
+			n += nn; if err != nil { return n, err }
+			nn, err = Skim(decoder, itemTag)
+			n += nn; if err != nil { return n, err }
+		}
+	default:
+		return n, fmt.Errorf("unknown TN %d", tag.TN())
+	}
+	return n, nil
+}

tape/skim_test.go

@@ -0,0 +1,137 @@
+package tape
+
+import "bytes"
+import "testing"
+
+func TestSkimInteger(test *testing.T) {
+	data := []byte {
+		0x12, 0x45, 0x23, 0xF9,
+	}
+	mainDataLen := len(data)
+	// extra junk
+	data = append(data, 0x00, 0x01, 0x02, 0x03,)
+
+	n, err := Skim(NewDecoder(bytes.NewBuffer(data)), LI.WithCN(3))
+	if err != nil {
+		test.Fatal(err)
+	}
+	if got, correct := n, mainDataLen; got != correct {
+		test.Fatalf("n not equal: %d != %d", got, correct)
+	}
+}
+
+func TestSkimArray(test *testing.T) {
+	data := []byte {
+		2, byte(LI.WithCN(1)),
+		0xBE, 0xE5, 0x77, 0x77,
+	}
+	mainDataLen := len(data)
+	// extra junk
+	data = append(data, 0x00, 0x01, 0x02, 0x03,)
+
+	n, err := Skim(NewDecoder(bytes.NewBuffer(data)), OTA.WithCN(0))
+	if err != nil {
+		test.Fatal(err)
+	}
+	if got, correct := n, mainDataLen; got != correct {
+		test.Fatalf("n not equal: %d != %d", got, correct)
+	}
+}
+
+func TestSkimNestedArray(test *testing.T) {
+	data := []byte {
+		2, byte(OTA.WithCN(0)),
+		1, byte(LSI.WithCN(1)),
+		0, 0x5,
+		2, byte(LSI.WithCN(1)),
+		0,    0x17,
+		0xF5, 0x56,
+	}
+	mainDataLen := len(data)
+	// extra junk
+	data = append(data, 0x00, 0x01, 0x02, 0x03,)
+
+	n, err := Skim(NewDecoder(bytes.NewBuffer(data)), OTA.WithCN(0))
+	if err != nil {
+		test.Fatal(err)
+	}
+	if got, correct := n, mainDataLen; got != correct {
+		test.Fatalf("n not equal: %d != %d", got, correct)
+	}
+}
+
+func TestSkimTable(test *testing.T) {
+	data := []byte {
+		2,
+		0xF3, 0xB9,
+		byte(LSI.WithCN(3)),
+		0, 0, 0, 1,
+	
+		0x01, 0x02,
+		byte(LSI.WithCN(3)),
+		0, 0, 0, 2,
+	}
+	mainDataLen := len(data)
+	// extra junk
+	data = append(data, 0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03)
+
+	n, err := Skim(NewDecoder(bytes.NewBuffer(data)), KTV.WithCN(0))
+	if got, correct := n, mainDataLen; got != correct {
+		test.Fatalf("n not equal: %d != %d ... (%d)", got, correct, len(data))
+	}
+	if err != nil {
+		test.Fatal(err)
+	}
+}
+
+func TestSkimTableComplex(test *testing.T) {
+	data := []byte {
+		7,
+		0xF3, 0xB9,
+		byte(LSI.WithCN(3)),
+		0, 0, 0, 1,
+	
+		0x01, 0x02,
+		byte(LSI.WithCN(3)),
+		0, 0, 0, 2,
+	
+		0, 0,
+		byte(SBA.WithCN(3)),
+		'h', 'i', '!',
+	
+		0xFF, 0xFF,
+		byte(OTA.WithCN(0)), 2, byte(LI.WithCN(1)),
+		0xBE, 0xE5, 0x77, 0x77,
+	
+		0x12, 0x34,
+		byte(OTA.WithCN(0)), 2, byte(OTA.WithCN(0)),
+		1, byte(LI.WithCN(1)),
+		0, 0x5,
+		2, byte(LI.WithCN(1)),
+		0,    0x17,
+		0xAA, 0xAA,
+	
+		0x23, 0x45,
+		byte(OTA.WithCN(0)), 2, byte(OTA.WithCN(0)),
+		1, byte(LSI.WithCN(1)),
+		0, 0x5,
+		2, byte(LSI.WithCN(1)),
+		0,    0x17,
+		0xF5, 0x56,
+	
+		0x34, 0x56,
+		byte(LSI.WithCN(1)),
+		0x39, 0x21,
+	}
+	mainDataLen := len(data)
+	// extra junk
+	data = append(data, 0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03)
+
+	n, err := Skim(NewDecoder(bytes.NewBuffer(data)), KTV.WithCN(0))
+	if got, correct := n, mainDataLen; got != correct {
+		test.Fatalf("n not equal: %d != %d ... (%d)", got, correct, len(data))
+	}
+	if err != nil {
+		test.Fatal(err)
+	}
+}

tape/strings.go

@@ -0,0 +1,11 @@
+package tape
+
+const lipsum = `Lorem ipsum dolor sit amet consectetur adipiscing elit. Quisque faucibus ex sapien vitae pellentesque sem placerat. In id cursus mi pretium tellus duis convallis. Tempus leo eu aenean sed diam urna tempor. Pulvinar vivamus fringilla lacus nec metus bibendum egestas. Iaculis massa nisl malesuada lacinia integer nunc posuere. Ut hendrerit semper vel class aptent taciti sociosqu. Ad litora torquent per conubia nostra inceptos himenaeos.
+
+Lorem ipsum dolor sit amet consectetur adipiscing elit. Quisque faucibus ex sapien vitae pellentesque sem placerat. In id cursus mi pretium tellus duis convallis. Tempus leo eu aenean sed diam urna tempor. Pulvinar vivamus fringilla lacus nec metus bibendum egestas. Iaculis massa nisl malesuada lacinia integer nunc posuere. Ut hendrerit semper vel class aptent taciti sociosqu. Ad litora torquent per conubia nostra inceptos himenaeos.
+
+Lorem ipsum dolor sit amet consectetur adipiscing elit. Quisque faucibus ex sapien vitae pellentesque sem placerat. In id cursus mi pretium tellus duis convallis. Tempus leo eu aenean sed diam urna tempor. Pulvinar vivamus fringilla lacus nec metus bibendum egestas. Iaculis massa nisl malesuada lacinia integer nunc posuere. Ut hendrerit semper vel class aptent taciti sociosqu. Ad litora torquent per conubia nostra inceptos himenaeos.
+
+Lorem ipsum dolor sit amet consectetur adipiscing elit. Quisque faucibus ex sapien vitae pellentesque sem placerat. In id cursus mi pretium tellus duis convallis. Tempus leo eu aenean sed diam urna tempor. Pulvinar vivamus fringilla lacus nec metus bibendum egestas. Iaculis massa nisl malesuada lacinia integer nunc posuere. Ut hendrerit semper vel class aptent taciti sociosqu. Ad litora torquent per conubia nostra inceptos himenaeos.
+
+Lorem ipsum dolor sit amet consectetur adipiscing elit. Quisque faucibus ex sapien vitae pellentesque sem placerat. In id cursus mi pretium tellus duis convallis. Tempus leo eu aenean sed diam urna tempor. Pulvinar vivamus fringilla lacus nec metus bibendum egestas. Iaculis massa nisl malesuada lacinia integer nunc posuere. Ut hendrerit semper vel class aptent taciti sociosqu. Ad litora torquent per conubia nostra inceptos himenaeos.`

tape/table.go

@@ -1,74 +0,0 @@
-package tape
-
-import "iter"
-
-// encoding and decoding functions must not make any allocations
-
-type TablePushFunc func(tag uint16, value []byte) (n int, err error)
-
-type TablePullFunc func() (tag uint16, value []byte, n int, err error)
-
-func DecodeTable(data []byte) TablePullFunc {
-	n := 0
-	return func() (tag uint16, value []byte, n_ int, err error) {
-		if n >= len(data) { return 0, nil, n, ErrWrongBufferLength }
-		tag, nn, err := DecodeI16[uint16](data[n:])
-		if err != nil { return 0, nil, n, err }
-		n += nn
-
-		if n >= len(data) { return 0, nil, n, ErrWrongBufferLength }
-		length, nn, err := DecodeGBEU[uint64](data[n:])
-		if err != nil { return 0, nil, n, err }
-		n += nn
-
-		end := n + int(length)
-		if end > len(data) { return 0, nil, n, ErrWrongBufferLength }
-		value = data[n:end]
-		n += int(length)
-		return tag, value, n, err
-	}
-}
-
-func DecodeTableIter(data []byte) iter.Seq2[uint16, []byte] {
-	return func(yield func(uint16, []byte) bool) {
-		pull := DecodeTable(data)
-		for {
-			tag, value, _, err := pull()
-			if err != nil { return }
-			if !yield(tag, value) { return }
-		}
-	}
-}
-
-func EncodeTable(data []byte) TablePushFunc {
-	return func(tag uint16, value []byte) (n int, err error) {
-		if n >= len(data) { return n, ErrWrongBufferLength }
-		nn, err := EncodeI16(data[n:], uint16(tag))
-		if err != nil { return n, err }
-		n += nn
-	
-		if n >= len(data) { return n, ErrWrongBufferLength }
-		nn, err = EncodeGBEU(data[n:], uint(len(value)))
-		if err != nil { return n, err }
-		n += nn
-
-		if n >= len(data) { return n, ErrWrongBufferLength }
-		nn = copy(data[n:], value)
-		n += nn
-		if nn < len(value) {
-			return n, ErrWrongBufferLength
-		}
-		
-		if n >= len(data) { return n, ErrWrongBufferLength }
-		data = data[n:]
-		return n, nil
-	}
-}
-
-func TableSize(itemLengths ...int) int {
-	sum := 0
-	for _, length := range itemLengths {
-		sum += GBEUSize(uint(length)) + length
-	}
-	return sum
-}

tape/table_test.go

@@ -1,144 +0,0 @@
-package tape
-
-import "fmt"
-import "slices"
-// import "errors"
-import "testing"
-// import "math/rand"
-
-var longText =
-`Curious, I started off in that direction, only for Prism to stop me. "Wrong way, Void. It's right over here." He trotted over to a door to the left of us. It was marked with the number '4004'. He took a key out of his saddlebags, unlocked it, and pushed it open. "You know, some say this suite is haunted. They call the ghost that lives here the 'Spirit of 4004'. Ooooh!" He made paddling motions in the air with his hooves.`
-
-func TestTable(test *testing.T) {
-	item5    := []byte("hello")
-	item7    := []byte("world")
-	item0    := []byte(longText)
-	item3249 := []byte { 0x0, 0x1, 0x2, 0x3, 0xA0, 0x5 }
-
-	buffer := [512]byte { }
-	push := EncodeTable(buffer[:])
-	_, err := push(5, item5)
-	if err != nil { test.Fatal(err)}
-	_, err = push(7, item7)
-	if err != nil { test.Fatal(err)}
-	_, err = push(0, item0)
-	if err != nil { test.Fatal(err)}
-	_, err = push(3249, item3249)
-	if err != nil { test.Fatal(err)}
-
-	test.Logf("len of longText: %d 0x%X", len(longText), len(longText))
-	correct := []byte("\x00\x05\x05hello\x00\x07\x05world\x00\x00\x83\x28" + longText)
-	if got := buffer[:len(correct)]; !slices.Equal(got, correct) {
-		if !compareHexArray(test, got, correct) { test.Fatal("failed") }
-	}
-
-	pull := DecodeTable(buffer[:len(correct)])
-
-	tag, value, _, err := pull()
-	if err != nil { test.Fatal(err) }
-	if got, correct := tag, uint16(5); got != correct {
-		test.Fatal("not equal:", got)
-	}
-	if !compareHexArray(test, value, []byte("hello")) { test.Fatal("failed") }
-
-	tag, value, _, err = pull()
-	if err != nil { test.Fatal(err) }
-	if got, correct := tag, uint16(7); got != correct {
-		test.Fatal("not equal:", got)
-	}
-	if !compareHexArray(test, value, []byte("world")) { test.Fatal("failed") }
-
-	tag, value, _, err = pull()
-	if err != nil { test.Fatal(err) }
-	if got, correct := tag, uint16(0); got != correct {
-		test.Fatal("not equal:", got)
-	}
-	if !compareHexArray(test, value, []byte(longText)) { test.Fatal("failed") }
-
-	tag, value, _, err = pull()
-	if err != nil { test.Fatal(err) }
-	if got, correct := tag, uint16(3249); got != correct {
-		test.Fatal("not equal:", got)
-	}
-	if !compareHexArray(test, value, []byte { 0x0, 0x1, 0x2, 0x3, 0xA0, 0x5 }) { test.Fatal("failed") }
-}
-
-func TestTableSmall(test *testing.T) {
-	item2    := []byte("hello")
-	item3249 := []byte { 0x0, 0x1, 0x2, 0x3, 0xA0, 0x5 }
-
-	buffer := [64]byte { }
-	push := EncodeTable(buffer[:])
-	_, err := push(2, item2)
-	if err != nil { test.Fatal(err) }
-	_, err = push(3249, item3249)
-	if err != nil { test.Fatal(err) }
-
-	correct := []byte("\x00\x02\x05hello\x0C\xB1\x06\x00\x01\x02\x03\xA0\x05")
-	if got := buffer[:len(correct)]; !slices.Equal(got, correct) {
-		if !compareHexArray(test, got, correct) { test.Fatal("failed") }
-	}
-
-	pull := DecodeTable(buffer[:len(correct)])
-
-	tag, value, _, err := pull()
-	if err != nil { test.Fatal(err) }
-	if got, correct := tag, uint16(2); got != correct {
-		test.Fatal("not equal:", got)
-	}
-	if !compareHexArray(test, value, []byte("hello")) { test.Fatal("failed") }
-
-	tag, value, _, err = pull()
-	if err != nil { test.Fatal(err) }
-	if got, correct := tag, uint16(3249); got != correct {
-		test.Fatal("not equal:", got)
-	}
-	if !compareHexArray(test, value, []byte { 0x0, 0x1, 0x2, 0x3, 0xA0, 0x5 }) { test.Fatal("failed") }
-}
-
-func dumpHexArray(data []byte) (message string) {
-	for _, item := range data {
-		message = fmt.Sprintf("%s %02X", message, item)
-	}
-	return message
-}
-
-func compareHexArray(test *testing.T, got, correct []byte) bool {
-	index := 0
-	for {
-		if index >= len(correct) {
-			if index < len(got) {
-				test.Log("correct longer than got")
-				test.Log("got:    ", dumpHexArray(got))
-				test.Log("correct:", dumpHexArray(correct))
-				return false
-			}
-			break
-		}
-		if index >= len(got) {
-			if index < len(correct) {
-				test.Log("got longer than correct")
-				test.Log("got:    ", dumpHexArray(got))
-				test.Log("correct:", dumpHexArray(correct))
-				return false
-			}
-			break
-		}
-		if correct[index] != got[index] {
-			test.Log("not equal")
-			test.Log("got:    ", dumpHexArray(got))
-			test.Log("correct:", dumpHexArray(correct))
-			partLow  := index - 8
-			partHigh := index + 8
-			test.Log("got part    ", dumpHexArray(safeSlice(got,     partLow, partHigh)))
-			test.Log("correct part", dumpHexArray(safeSlice(correct, partLow, partHigh)))
-			return false
-		}
-		index ++
-	}
-	return true
-}
-
-func safeSlice[T any](slice []T, low, high int) []T {
-	return slice[max(low, 0):min(high, len(slice))]
-}

tape/tag.go

@@ -0,0 +1,83 @@
+package tape
+
+import "fmt"
+
+// TODO: fix #7
+
+type Tag byte; const (
+	SI      Tag = 0 << 5 // Small integer
+	LI      Tag = 1 << 5 // Large unsigned integer
+	LSI     Tag = 2 << 5 // Large signed integer
+	FP      Tag = 3 << 5 // Floating point
+	SBA     Tag = 4 << 5 // Small byte array
+	LBA     Tag = 5 << 5 // Large byte array
+	OTA     Tag = 6 << 5 // One-tag array
+	KTV     Tag = 7 << 5 // Key-tag-value table
+	TNMask  Tag = 0xE0   // The entire TN bitfield
+	CNMask  Tag = 0x1F   // The entire CN bitfield
+	CNLimit Tag = 32     // All valid CNs are < CNLimit
+)
+
+// what the first nybble of a tag means:
+//
+//   0-1 : SI 
+//   2-3 : LI 
+//   4-5 : LSI
+//   6-7 : FP 
+//   8-9 : SBA
+//   A-B : LBA
+//   C-D : OTA
+//   E-F : KTV
+
+func (tag Tag) TN() int {
+	return int(tag >> 5)
+}
+
+func (tag Tag) CN() int {
+	return int(tag & CNMask)
+}
+
+func (tag Tag) WithCN(cn int) Tag {
+	return (tag & TNMask) | Tag(cn % 32)
+}
+
+func (tag Tag) WithoutCN() Tag {
+	return tag.WithCN(0)
+}
+
+func (tag Tag) Is(other Tag) bool {
+	return tag.TN() == other.TN()
+}
+
+func (tag Tag) String() string {
+	tn := fmt.Sprint(tag.TN())
+	switch tag.WithoutCN() {
+	case SI:  tn = "SI"
+	case LI:  tn = "LI"
+	case LSI: tn = "LSI"
+	case FP:  tn = "FP"
+	case SBA: tn = "SBA"
+	case LBA: tn = "LBA"
+	case OTA: tn = "OTA"
+	case KTV: tn = "KTV"
+	}
+	return fmt.Sprintf("%s:%d", tn, tag.CN())
+}
+
+// BufferTag returns the appropriate tag for a buffer.
+func BufferTag(value []byte) Tag {
+	return bufferLenTag(len(value))
+}
+
+// StringTag returns the appropriate tag for a string.
+func StringTag(value string) Tag {
+	return bufferLenTag(len(value))
+}
+
+func bufferLenTag(length int) Tag {
+	if length < int(CNLimit) {
+		return SBA.WithCN(length)
+	} else {
+		return LBA.WithCN(IntBytes(uint64(length)) - 1)
+	}
+}

tape/types.go

@@ -1,180 +0,0 @@
-// Package tape implements Table Pair Encoding.
-package tape
-
-import "fmt"
-
-// encoding and decoding functions must not make any allocations
-
-const dataMaxSize = 0xFFFF
-const uint16Max = 0xFFFF
-
-// Error enumerates common errors in this package.
-type Error string; const (
-	ErrWrongBufferLength Error = "wrong buffer length"
-	ErrDataTooLarge      Error = "data too large"
-	ErrGBEUNotTerminated Error = "GBEU not terminated"
-)
-
-// Error implements the error interface.
-func (err Error) Error() string {
-	return string(err)
-}
-
-// Int8 is any 8-bit integer.
-type Int8  interface { ~uint8  | ~int8 }
-// Int16 is any 16-bit integer.
-type Int16 interface { ~uint16 | ~int16 }
-// Int32 is any 32-bit integer.
-type Int32 interface { ~uint32 | ~int32 }
-// Int64 is any 64-bit integer.
-type Int64 interface { ~uint64 | ~int64 }
-// Uint is any unsigned integer.
-type Uint interface { ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 }
-// String is any string.
-type String interface { ~string | ~[]uint8 }
-
-// DecodeI8 decodes an 8 bit integer from the given data.
-func DecodeI8[T Int8](data []byte) (value T, n int, err error) {
-	if len(data) < 1 { return 0, 0, fmt.Errorf("decoding int8: %w", ErrWrongBufferLength) }
-	return T(data[0]), 1, nil
-}
-
-// EncodeI8 encodes an 8 bit integer into the given buffer.
-func EncodeI8[T Int8](buffer []byte, value T) (n int, err error) {
-	if len(buffer) < 1 { return 0, fmt.Errorf("encoding int8: %w", ErrWrongBufferLength) }
-	buffer[0] = byte(value)
-	return 1, nil
-}
-
-// DecodeI16 decodes a 16 bit integer from the given data.
-func DecodeI16[T Int16](data []byte) (value T, n int, err error) {
-	if len(data) < 2 { return 0, 0, fmt.Errorf("decoding int16: %w", ErrWrongBufferLength) }
-	return T(data[0]) << 8 | T(data[1]), 2, nil
-}
-
-// EncodeI16 encodes a 16 bit integer into the given buffer.
-func EncodeI16[T Int16](buffer []byte, value T) (n int, err error) {
-	if len(buffer) < 2 { return 0, fmt.Errorf("encoding int16: %w", ErrWrongBufferLength) }
-	buffer[0] = byte(value >> 8)
-	buffer[1] = byte(value)
-	return 2, nil
-}
-
-// DecodeI32 decodes a 32 bit integer from the given data.
-func DecodeI32[T Int32](data []byte) (value T, n int, err error) {
-	if len(data) < 4 { return 0, 0, fmt.Errorf("decoding int32: %w", ErrWrongBufferLength) }
-	return T(data[0]) << 24 |
-		T(data[1]) << 16 |
-		T(data[2]) <<  8 |
-		T(data[3]), 4, nil
-}
-
-// EncodeI32 encodes a 32 bit integer into the given buffer.
-func EncodeI32[T Int32](buffer []byte, value T) (n int, err error) {
-	if len(buffer) < 4 { return 0, fmt.Errorf("encoding int32: %w", ErrWrongBufferLength) }
-	buffer[0] = byte(value >> 24)
-	buffer[1] = byte(value >> 16)
-	buffer[2] = byte(value >> 8)
-	buffer[3] = byte(value)
-	return 4, nil
-}
-
-// DecodeI64 decodes a 64 bit integer from the given data.
-func DecodeI64[T Int64](data []byte) (value T, n int, err error) {
-	if len(data) < 8 { return 0, 0, fmt.Errorf("decoding int64: %w", ErrWrongBufferLength) }
-	return T(data[0]) << 56 |
-		T(data[1]) << 48 |
-		T(data[2]) << 40 |
-		T(data[3]) << 32 |
-		T(data[4]) << 24 |
-		T(data[5]) << 16 |
-		T(data[6]) <<  8 |
-		T(data[7]), 8, nil
-}
-
-// EncodeI64 encodes a 64 bit integer into the given buffer.
-func EncodeI64[T Int64](buffer []byte, value T) (n int, err error) {
-	if len(buffer) < 8 { return 0, fmt.Errorf("encoding int64: %w", ErrWrongBufferLength) }
-	buffer[0] = byte(value >> 56)
-	buffer[1] = byte(value >> 48)
-	buffer[2] = byte(value >> 40)
-	buffer[3] = byte(value >> 32)
-	buffer[4] = byte(value >> 24)
-	buffer[5] = byte(value >> 16)
-	buffer[6] = byte(value >> 8)
-	buffer[7] = byte(value)
-	return 8, nil
-}
-
-// DecodeGBEU decodes an 8 to 64 bit growing integer into the given buffer.
-func DecodeGBEU[T Uint](data []byte) (value T, n int, err error) {
-	var fullValue uint64
-	for _, chunk := range data {
-		fullValue *= 0x80
-		fullValue += uint64(chunk & 0x7F)
-		ccb := chunk >> 7
-		n += 1
-		if ccb == 0 {
-			return T(fullValue), n, nil
-		}
-	}
-	return 0, n, fmt.Errorf("decoding GBEU: %w", ErrGBEUNotTerminated)
-}
-
-// EncodeGBEU encodes an 8 to 64 bit growing integer into a given buffer.
-func EncodeGBEU[T Uint]	(buffer []byte, value T) (n int, err error) {
-	window := (GBEUSize(value) - 1) * 7
-	
-	index := 0
-	for window >= 0 {
-		if index >= len(buffer) { return index, fmt.Errorf("encoding GBEU: %w", ErrWrongBufferLength) }
-		
-		chunk := uint8(value >> window) & 0x7F
-		if window > 0 {
-			chunk |= 0x80
-		}
-		buffer[index] = chunk
-		
-		index += 1
-		window -= 7
-	}
-	return index, nil
-}
-
-// GBEUSize returns the size (in octets) of a GBEU integer.
-func GBEUSize[T Uint] (value T) int {
-	length := 0
-	for {
-		value >>= 7
-		length ++
-		if value == 0 { return length }
-	}
-}
-
-// DecodeString decodes a string from the given data.
-func DecodeString[T String](data []byte) (value T, n int, err error) {
-	return T(data), len(data), nil
-}
-
-// EncodeString encodes a string into the given buffer.
-func EncodeString[T String](data []byte, value T) (n int, err error) {
-	if len(data) != len(value) { return 0, fmt.Errorf("encoding string: %w", ErrWrongBufferLength) }
-	return copy(data, value), nil
-}
-
-// StringSize returns the size of a string. Returns 0 and an error if the size
-// is too large.
-func StringSize[T String](value T) (int, error) {
-	if len(value) > dataMaxSize { return 0, ErrDataTooLarge }
-	return len(value), nil
-}
-
-// U16CastSafe safely casts an integer to a uint16. If an overflow or underflow
-// occurs, it will return (0, false).
-func U16CastSafe(n int) (uint16, bool) {
-	if n < uint16Max && n >= 0 {
-		return uint16(n), true
-	} else {
-		return 0, false
-	}
-}

tape/types_test.go

@@ -1,326 +0,0 @@
-package tape
-
-import "fmt"
-import "slices"
-import "errors"
-import "testing"
-import "math/rand"
-
-const largeNumberNTestRounds = 2048
-const randStringBytes        = "-abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-
-func TestI8(test *testing.T) {
-	var buffer [16]byte
-	_, err := EncodeI8[uint8](buffer[:], 5)
-	if err != nil { test.Fatal(err) }
-	_, err = EncodeI8[uint8](buffer[:0], 5)
-	if err.Error() != "encoding int8: wrong buffer length" { test.Fatal(err) }
-	_, _, err = DecodeI8[uint8](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI8[uint8](buffer[:0])
-	if err.Error() != "decoding int8: wrong buffer length" { test.Fatal(err) }
-	
-	for number := range uint8(255) {
-		n, err := EncodeI8[uint8](buffer[:1], number)
-		if err != nil { test.Fatal(err) }
-		if correct, got := 1, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		decoded, n, err := DecodeI8[uint8](buffer[:1])
-		if err != nil { test.Fatal(err) }
-		if correct, got := 1, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		if decoded != number {
-			test.Fatalf("%d != %d", decoded, number)
-		}
-	}
-}
-
-func TestI16(test *testing.T) {
-	var buffer [16]byte
-	_, err := EncodeI16[uint16](buffer[:], 5)
-	if err != nil { test.Fatal(err) }
-	_, err = EncodeI16[uint16](buffer[:0], 5)
-	if err.Error() != "encoding int16: wrong buffer length" { test.Fatal(err) }
-	_, _, err = DecodeI16[uint16](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI16[uint16](buffer[:0])
-	if err.Error() != "decoding int16: wrong buffer length" { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		number := uint16(rand.Int())
-		n, err := EncodeI16[uint16](buffer[:2], number)
-		if err != nil { test.Fatal(err) }
-		if correct, got := 2, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		decoded, n, err := DecodeI16[uint16](buffer[:2])
-		if err != nil { test.Fatal(err) }
-		if correct, got := 2, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		if decoded != number {
-			test.Fatalf("%d != %d", decoded, number)
-		}
-	}
-}
-
-func TestI32(test *testing.T) {
-	var buffer [16]byte
-	_, err := EncodeI32[uint32](buffer[:], 5)
-	if err != nil { test.Fatal(err) }
-	_, err = EncodeI32[uint32](buffer[:0], 5)
-	if err.Error() != "encoding int32: wrong buffer length" { test.Fatal(err) }
-	_, _, err = DecodeI32[uint32](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI32[uint32](buffer[:0])
-	if err.Error() != "decoding int32: wrong buffer length" { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		number := uint32(rand.Int())
-		n, err := EncodeI32[uint32](buffer[:4], number)
-		if err != nil { test.Fatal(err) }
-		if correct, got := 4, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		decoded, n, err := DecodeI32[uint32](buffer[:4])
-		if err != nil { test.Fatal(err) }
-		if correct, got := 4, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		if decoded != number {
-			test.Fatalf("%d != %d", decoded, number)
-		}
-	}
-}
-
-func TestI64(test *testing.T) {
-	var buffer [16]byte
-	_, err := EncodeI64[uint64](buffer[:], 5)
-	if err != nil { test.Fatal(err) }
-	_, err = EncodeI64[uint64](buffer[:0], 5)
-	if err.Error() != "encoding int64: wrong buffer length" { test.Fatal(err) }
-	_, _, err = DecodeI64[uint64](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeI64[uint64](buffer[:0])
-	if err.Error() != "decoding int64: wrong buffer length" { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		number := uint64(rand.Int())
-		n, err := EncodeI64[uint64](buffer[:8], number)
-		if err != nil { test.Fatal(err) }
-		if correct, got := 8, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		decoded, n, err := DecodeI64[uint64](buffer[:8])
-		if err != nil { test.Fatal(err) }
-		if correct, got := 8, n; correct != got {
-			test.Fatal("not equal:", got)
-		}
-		if decoded != number {
-			test.Fatalf("%d != %d", decoded, number)
-		}
-	}
-}
-
-func TestGBEU(test *testing.T) {
-	var buffer = [16]byte {
-		255, 255, 255, 255,
-		255, 255, 255, 255,
-		255, 255, 255, 255,
-		255, 255, 255, 255,
-	}
-	_, err := EncodeGBEU[uint64](buffer[:0], 5)
-	if err == nil { test.Fatal("no error") }
-	if err.Error() != "encoding GBEU: wrong buffer length" { test.Fatal(err) }
-	_, err = EncodeGBEU[uint64](buffer[:2], 5555555)
-	if err == nil { test.Fatal("no error") }
-	if err.Error() != "encoding GBEU: wrong buffer length" { test.Fatal(err) }
-	_, _, err = DecodeGBEU[uint64](buffer[:0])
-	if err == nil { test.Fatal("no error") }
-	if err.Error() != "decoding GBEU: GBEU not terminated" { test.Fatal(err) }
-
-	n, err := EncodeGBEU[uint64](buffer[:], 0x97)
-	if err != nil { test.Fatal(err) }
-	if correct, got := 2, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := []byte { 0x81, 0x17 }, buffer[:2]; !slices.Equal(correct, got) {
-		message := "not equal:"
-		for _, item := range got {
-			message = fmt.Sprintf("%s %x", message, item)
-		}
-		test.Fatal(message)
-	}
-	decoded, n, err := DecodeGBEU[uint64](buffer[:])
-	if err != nil { test.Fatal(err) }
-	if correct, got := 2, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := uint64(0x97), decoded; correct != got {
-		test.Fatalf("not equal: %x", got)
-	}
-
-	n, err = EncodeGBEU[uint64](buffer[:], 0x123456)
-	if err != nil { test.Fatal(err) }
-	if correct, got := 3, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := []byte { 0xc8, 0xe8, 0x56 }, buffer[:3]; !slices.Equal(correct, got) {
-		message := "not equal:"
-		for _, item := range got {
-			message = fmt.Sprintf("%s %x", message, item)
-		}
-		test.Fatal(message)
-	}
-	decoded, n, err = DecodeGBEU[uint64](buffer[:])
-	if err != nil { test.Fatal(err) }
-	if correct, got := 3, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := uint64(0x123456), decoded; correct != got {
-		test.Fatalf("not equal: %x", got)
-	}
-
-	maxGBEU64 := []byte { 0x81, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x7F }
-	n, err = EncodeGBEU[uint64](buffer[:], 0xFFFFFFFFFFFFFFFF)
-	if err != nil { test.Fatal(err) }
-	if correct, got := 10, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := maxGBEU64, buffer[:10]; !slices.Equal(correct, got) {
-		message := "not equal:"
-		for _, item := range got {
-			message = fmt.Sprintf("%s %x", message, item)
-		}
-		test.Fatal(message)
-	}
-	decoded, n, err = DecodeGBEU[uint64](buffer[:])
-	if err != nil { test.Fatal(err) }
-	if correct, got := 10, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := uint64(0xFFFFFFFFFFFFFFFF), decoded; correct != got {
-		test.Fatalf("not equal: %x", got)
-	}
-
-	n, err = EncodeGBEU[uint64](buffer[:], 11)
-	if err != nil { test.Fatal(err) }
-	if correct, got := 1, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := byte(0xb), buffer[0]; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	decoded, n, err = DecodeGBEU[uint64](buffer[:])
-	if err != nil { test.Fatal(err) }
-	if correct, got := 1, n; correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := uint64(0xb), decoded; correct != got {
-		test.Fatalf("not equal: %x", got)
-	}
-	
-	for _ = range largeNumberNTestRounds {
-		buffer = [16]byte { }
-		number := uint64(rand.Int())
-		_, err := EncodeGBEU[uint64](buffer[:], number)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeGBEU[uint64](buffer[:])
-		if err != nil { test.Fatal(err) }
-		if decoded != number {
-			test.Error("not equal:")
-			test.Errorf("%d != %d", decoded, number)
-			test.Errorf("%x != %x", decoded, number)
-			test.Fatal(buffer)
-		}
-	}
-}
-
-func TestGBEUSize(test *testing.T) {
-	if correct, got := 3, GBEUSize(uint(0x100000)); correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := 3, GBEUSize(uint(0x123456)); correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := 4, GBEUSize(uint(0x223456)); correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := 1, GBEUSize(uint(0)); correct != got {
-		test.Fatal("not equal:", got)
-	}
-	if correct, got := 1, GBEUSize(uint(127)); correct != got {
-		test.Fatal("not equal:", got)
-	}
-}
-
-func TestString(test *testing.T) {
-	var buffer [16]byte
-	_, err := EncodeString[string](buffer[:], "hello")
-	if !errIs(err, ErrWrongBufferLength, "encoding string: wrong buffer length") { test.Fatal(err) }
-	_, err = EncodeString[string](buffer[:0], "hello")
-	if !errIs(err, ErrWrongBufferLength, "encoding string: wrong buffer length") { test.Fatal(err) }
-	_, _, err = DecodeString[string](buffer[:])
-	if err != nil { test.Fatal(err) }
-	_, _, err = DecodeString[string](buffer[:0])
-	if err != nil { test.Fatal(err) }
-	
-	for _ = range largeNumberNTestRounds {
-		length := rand.Intn(16)
-		str := randString(length)
-		_, err := EncodeString[string](buffer[:length], str)
-		if err != nil { test.Fatal(err) }
-		decoded, _, err := DecodeString[string](buffer[:length])
-		if err != nil { test.Fatal(err) }
-		if decoded != str {
-			test.Fatalf("%s != %s", decoded, str)
-		}
-	}
-}
-
-func TestU16CastSafe(test *testing.T) {
-	number, ok := U16CastSafe(90_000)
-	if ok { test.Fatalf("false positive: %v, %v", number, ok) }
-	number, ok = U16CastSafe(-478)
-	if ok { test.Fatalf("false positive: %v, %v", number, ok) }
-	number, ok = U16CastSafe(3870)
-	if !ok { test.Fatalf("false negative: %v, %v", number, ok) }
-	if got, correct := number, uint16(3870); got != correct {
-		test.Fatalf("not equal: %v %v", got, correct)
-	}
-	number, ok = U16CastSafe(0)
-	if !ok { test.Fatalf("false negative: %v, %v", number, ok) }
-	if got, correct := number, uint16(0); got != correct {
-		test.Fatalf("not equal: %v %v", got, correct)
-	}
-}
-
-func randString(length int) string {
-	buffer := make([]byte, length)
-	for index := range buffer {
-		buffer[index] = randStringBytes[rand.Intn(len(randStringBytes))]
-	}
-	return string(buffer)
-}
-
-func randInts[T interface { ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 }] (length int) []T {
-	buffer := make([]T, length)
-	for index := range buffer {
-		buffer[index] = T(rand.Int())
-	}
-	return buffer
-}
-
-func randStrings[T interface { ~string }] (length, maxItemLength int) []T {
-	buffer := make([]T, length)
-	for index := range buffer {
-		buffer[index] = T(randString(rand.Intn(maxItemLength)))
-	}
-	return buffer
-}
-
-func errIs(err error, wraps error, description string) bool {
-	return err != nil && (wraps == nil || errors.Is(err, wraps)) && err.Error() == description
-}