examples/ping: Add a ping example

examples/ping/client/main.go

@@ -0,0 +1,71 @@
+package main
+
+import "os"
+import "io"
+import "fmt"
+import "log"
+import "net"
+import "time"
+import "errors"
+import "context"
+import "git.tebibyte.media/sashakoshka/hopp"
+import "git.tebibyte.media/sashakoshka/hopp/examples/ping"
+
+func main() {
+	name := os.Args[0]
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s HOST:PORT\n", name)
+		os.Exit(2)
+	}
+	address := os.Args[1]
+	
+	conn, err := dial(address)
+	handleErr(1, err)
+	trans, err := conn.OpenTrans()
+	handleErr(1, err)
+
+	go func() {
+		defer fmt.Fprintf(os.Stdout, "(i) disconnected\n")
+		for {
+			message, _, err := ping.Receive(trans)
+			if err != nil {
+				if !errors.Is(err, io.EOF) {
+					handleErr(1, err)
+				}
+				break
+			}
+			switch message := message.(type) {
+			case *ping.MessagePong:
+				log.Printf("--> pong (%d) from %v", message, address)
+			}
+		}
+	}()
+
+	message := ping.MessagePing(0)
+	for {
+		log.Printf("<-- ping (%d)", message)
+		_, err := ping.Send(trans, &message)
+		handleErr(1, err)
+		message ++
+		time.Sleep(time.Second)
+	}
+}
+
+func dial(address string) (hopp.Conn, error) {
+	// ctx, done := context.WithTimeout(context.Background(), 16 * time.Second)
+	// defer done()
+	// conn, err := hopp.Dial(ctx, "tcp", address, nil)
+	// if err != nil { return nil, err }
+	// return conn, nil
+	underlying, err := net.Dial("tcp", address)
+	if err != nil { return nil, err }
+	conn := hopp.AdaptA(underlying, hopp.PartyClient)
+	return conn, nil
+}
+
+func handleErr(code int, err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], err)
+		os.Exit(code)
+	}
+}

examples/ping/protocol.go

@@ -0,0 +1,143 @@
+package ping
+
+// Code generated by the Holanet PDL compiler. DO NOT EDIT.
+// 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
+
+import "fmt"
+import "git.tebibyte.media/sashakoshka/hopp"
+import "git.tebibyte.media/sashakoshka/hopp/tape"
+
+// 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 {
+	tape.Encodable
+	tape.Decodable
+
+	// Method returns the method code of the message.
+	Method() uint16
+}
+
+// Send encodes a message and sends it along a transaction.
+func Send(trans hopp.Trans, message Message) (n int, err error) {
+	writer, err := trans.SendWriter(message.Method())
+	if err != nil { return n, err }
+	defer writer.Close()
+	encoder := tape.NewEncoder(writer)
+	n, err = message.Encode(encoder)
+	if err != nil { return n, err }
+	return n, encoder.Flush()
+}
+
+// canAssign determines if data from the given source tag can be assigned to
+// a Go type represented by destination. It is designed to receive destination
+// values from [generate.Generator.generateCanAssign]. The eventual Go type and
+// the destination tag must come from the same (or hash-equivalent) PDL type.
+func canAssign(destination, source tape.Tag) bool {
+	if destination.Is(source) { return true }
+	if (destination.Is(tape.SBA) || destination.Is(tape.LBA)) &&
+		(source.Is(tape.SBA) || source.Is(tape.LBA)) {
+		return true
+	}
+	return false
+}
+
+// boolInt converts a bool to an integer.
+func boolInt(input bool) int {
+	if input {
+		return 1
+	} else {
+		return 0
+	}
+}
+
+// ensure ucontainer is always imported
+var _ hopp.Option[int]
+
+// Ping is sent by the client to the server. It may contain any number. This
+// number will be returned to the client via a [Pong] message.
+type MessagePing int32
+
+// Method returns the message's method number.
+func(this *MessagePing) Method() uint16 { return 0x0000 }
+
+// Encode encodes this message's tag and value.
+func(this *MessagePing) Encode(encoder *tape.Encoder) (n int, err error) {
+	tag_1 := tape.LSI.WithCN(3)
+	nn, err := encoder.WriteTag(tag_1)
+	n += nn; if err != nil { return n, err }
+	nn, err = encoder.WriteInt32(int32((*this)))
+	n += nn; if err != nil { return n, err }
+	return n, nil
+}
+
+// Decode decodes this message's tag and value.
+func(this *MessagePing) Decode(decoder *tape.Decoder) (n int, err error) {
+	tag, nn, err := decoder.ReadTag()
+	n += nn; if err != nil { return n, err }
+	if !(canAssign(tape.LSI, tag)) {
+		nn, err = tape.Skim(decoder, tag)
+		n += nn; if err != nil { return n, err }
+		return n, nil
+	}
+	destination_2, nn, err := decoder.ReadInt32()
+	n += nn; if err != nil { return n, err }
+	*this = MessagePing(destination_2)
+	return n, nil
+}
+
+// Pong is sent by the server to the client in response to a [Ping] message, It
+// will contain the same number as that message.
+type MessagePong int32
+
+// Method returns the message's method number.
+func(this *MessagePong) Method() uint16 { return 0x0001 }
+
+// Encode encodes this message's tag and value.
+func(this *MessagePong) Encode(encoder *tape.Encoder) (n int, err error) {
+	tag_3 := tape.LSI.WithCN(3)
+	nn, err := encoder.WriteTag(tag_3)
+	n += nn; if err != nil { return n, err }
+	nn, err = encoder.WriteInt32(int32((*this)))
+	n += nn; if err != nil { return n, err }
+	return n, nil
+}
+
+// Decode decodes this message's tag and value.
+func(this *MessagePong) Decode(decoder *tape.Decoder) (n int, err error) {
+	tag, nn, err := decoder.ReadTag()
+	n += nn; if err != nil { return n, err }
+	if !(canAssign(tape.LSI, tag)) {
+		nn, err = tape.Skim(decoder, tag)
+		n += nn; if err != nil { return n, err }
+		return n, nil
+	}
+	destination_4, nn, err := decoder.ReadInt32()
+	n += nn; if err != nil { return n, err }
+	*this = MessagePong(destination_4)
+	return n, nil
+}
+
+// Receive decodes a message from a transaction and returns it as a value.
+// Use a type switch to determine what type of message it is.
+func Receive(trans hopp.Trans) (message any, n int, err error) {
+	method, reader, err := trans.ReceiveReader()
+	decoder := tape.NewDecoder(reader)
+	if err != nil { return nil, n, err }
+	switch method {
+	case 0x0000:
+		var message MessagePing
+		nn, err := message.Decode(decoder)
+		n += nn; if err != nil { return nil, n, err }
+		return message, n, nil
+	case 0x0001:
+		var message MessagePong
+		nn, err := message.Decode(decoder)
+		n += nn; if err != nil { return nil, n, err }
+		return message, n, nil
+	}
+	return nil, n, fmt.Errorf("%w: M%04X", hopp.ErrUnknownMethod, method)
+}

examples/ping/protocol.pdl

@@ -0,0 +1,7 @@
+// Ping is sent by the client to the server. It may contain any number. This
+// number will be returned to the client via a [Pong] message.
+M0000 Ping I32
+
+// Pong is sent by the server to the client in response to a [Ping] message, It
+// will contain the same number as that message.
+M0001 Pong I32

examples/ping/server/main.go

@@ -0,0 +1,77 @@
+package main
+
+import "os"
+import "io"
+import "fmt"
+import "log"
+import "errors"
+import "git.tebibyte.media/sashakoshka/hopp"
+import "git.tebibyte.media/sashakoshka/hopp/examples/ping"
+
+func main() {
+	name := os.Args[0]
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s HOST:PORT\n", name)
+		os.Exit(2)
+	}
+	address  := os.Args[1]
+	err := listen(address)
+	handleErr(1, err)
+}
+
+func listen(address string) error {
+	listener, err := hopp.Listen("tcp", address, nil)
+	if err != nil { return err }
+	log.Printf("(i) hosting on %s", address)
+	for {
+		conn, err := listener.Accept()
+		if err != nil { return err }
+		go run(conn)
+	}
+}
+
+func run(conn hopp.Conn) {
+	log.Printf("-=E %v connected", conn.RemoteAddr())
+	defer log.Printf("X=- %v disconnected", conn.RemoteAddr())
+	defer conn.Close()
+	
+	for {
+		trans, err := conn.AcceptTrans()
+		if err != nil {
+			if !errors.Is(err, io.EOF) {
+				log.Printf("XXX %v failed: %v", conn.RemoteAddr(), err)
+			}
+			return
+		}
+		go runTrans(conn, trans)
+	}
+}
+
+func runTrans(conn hopp.Conn, trans hopp.Trans) {
+	for {
+		message, _, err := ping.Receive(trans)
+		if err != nil {
+			if !errors.Is(err, io.EOF) {
+				log.Printf("XXX failed to receive message: %v", err)
+			}
+			return
+		}
+		switch message := message.(type) {
+		case *ping.MessagePing:
+			log.Printf("--> ping (%d) from %v", message, conn.RemoteAddr())
+			response := ping.MessagePong(*message)
+			_, err := ping.Send(trans, &response)
+			if err != nil {
+				log.Printf("XXX failed to send message: %v", err)
+				return
+			}
+		}
+	}
+}
+
+func handleErr(code int, err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], err)
+		os.Exit(code)
+	}
+}

generate/generate_test.go

@@ -276,31 +276,32 @@ func TestGenerateRunEncodeDecode(test *testing.T) {
 		}
 		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,
+			snake.O().AddL(0xE0, 14).AddS(
+				snake.L(0x00, 0x00, 0x20, 0x23),
+				snake.L(0x00, 0x01, 0x21, 0x32, 0x47),
+				snake.L(0x00, 0x02, 0x23, 0x87, 0x32, 0x45, 0x23),
+				snake.L(0x00, 0x03, 0x27, 0x32, 0x84, 0x02, 0x90, 0x34, 0x09, 0x82, 0x34),
+				snake.L(0x00, 0x04, 0x40, 0x23),
+				snake.L(0x00, 0x05, 0x41, 0x32, 0x47),
+				snake.L(0x00, 0x06, 0x43, 0x57, 0x32, 0x45, 0x23),
+				snake.L(0x00, 0x07, 0x47, 0x32, 0x84, 0x02, 0x90, 0x34, 0x09, 0x82, 0x34),
+				snake.L(0x00, 0x08, 0x63, 0x45, 0x12, 0x63, 0xCE),
+				snake.L(0x00, 0x09, 0x67, 0x40, 0x74, 0x4E, 0x3D, 0x6F, 0xCD, 0x17, 0x75),
+				snake.L(0x00, 0x0A, 0x87, 'f', 'o', 'x', ' ', 'b', 'e', 'd'),
+				snake.L(0x00, 0x0B, 0xC0, 0x04, 0x41,
 					0x00, 0x07,
 					0x00, 0x06,
 					0x00, 0x05,
-					0x00, 0x04 },
-				[]byte { 0x00, 0x0C, 0xE0, 0x02,
+					0x00, 0x04),
+				snake.L(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 },
-				))
+					0x00, 0x02, 0x67, 0x40, 0x11, 0x99, 0x99, 0x99, 0x99, 0x99, 0x9A),
+				snake.O(snake.L(0x00, 0x0D, 0xE0, 0x03),
+					snake.S(
+						snake.L(0x00, 0x01, 0x63, 0x43, 0xF4, 0xC0, 0x00),
+						snake.L(0x00, 0x02, 0x82, 'h', 'i'),
+						snake.L(0x00, 0x03, 0x21, 0x39, 0x92)),
+				)))
 	`)
 }
 

generate/misc_test.go

@@ -37,6 +37,7 @@ func testGenerateRun(test *testing.T, protocol *Protocol, title, imports, testCa
 		import "reflect"
 		import "git.tebibyte.media/sashakoshka/hopp/tape"
 		import tu "git.tebibyte.media/sashakoshka/hopp/internal/testutil"
+		import "git.tebibyte.media/sashakoshka/hopp/internal/testutil/snake"
 		` + imports
 	setup := `log.Println("*** BEGIN TEST CASE OUTPUT ***")`
 	teardown := `log.Println("--- END TEST CASE OUTPUT ---")`
@@ -63,6 +64,7 @@ func testGenerateRun(test *testing.T, protocol *Protocol, title, imports, testCa
 			switch data := data.(type) {
 			case []byte:      flat = data
 			case tu.Snake:    flat = data.Flatten()
+			case snake.Snake: flat = data.Flatten()
 			}
 			message := reflect.New(reflect.ValueOf(correct).Elem().Type()).Interface().(Message)
 			log.Println("before: ", message)
@@ -79,9 +81,7 @@ func testGenerateRun(test *testing.T, protocol *Protocol, title, imports, testCa
 			}
 		}
 
-		// 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 { }
+		func testEncodeDecode(message Message, data any) {buffer := bytes.Buffer { }
 			log.Println("encoding:")
 			encoder := tape.NewEncoder(&buffer)
 			n, err := message.Encode(encoder)
@@ -93,13 +93,30 @@ func testGenerateRun(test *testing.T, protocol *Protocol, title, imports, testCa
 			if n != len(got) {
 				log.Fatalf("n incorrect: %d != %d\n", n, len(got))
 			}
+			
+			var flat []byte
+			switch data := data.(type) {
+			case []byte:
+				flat = data
+				if ok, n := snake.Check(snake.L(data...), got); !ok {
+					log.Fatalln("not equal at", n)
+				}
+			case tu.Snake:
+				flat = data.Flatten()
 				if ok, n := data.Check(got); !ok {
 					log.Fatalln("not equal at", n)
 				}
+			case snake.Node:
+				flat = data.Flatten()
+				if ok, n := snake.Check(data, got); !ok {
+					log.Fatalln("not equal at", n)
+				}
+			default:
+				panic("AUSIAUGH AAAUUGUHGHGHH OUHGHGJDSGK")
+			}
 		
 			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)

internal/testutil/snake/snake.go

@@ -0,0 +1,214 @@
+// Package 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.
+package snake
+
+import "fmt"
+import "strings"
+import tu "git.tebibyte.media/sashakoshka/hopp/internal/testutil"
+
+var _ Node = Order { }
+var _ Node = Snake { }
+var _ Node = Leaf  { }
+
+// Check checks the data against the specified node. If the data doesn't satisfy
+// the node, or the comparison succeded but didn't consume all the data, this
+// function returns false, and the index of the byte where the inequality is.
+func Check(node Node, data []byte) (ok bool, n int) {
+	ok, n = node.Check(data)
+	if !ok {
+		return false, n
+	}
+	if n != len(data) {
+		return false, n
+	}
+	return true, n
+}
+
+// O returns a new order given a vararg node slice.
+func O(nodes ...Node) Order {
+	return Order(nodes)
+}
+
+// S returns a new snake given a vararg node slice.
+func S(nodes ...Node) Snake {
+	return Snake(nodes)
+}
+
+// L returns a new leaf given a vararg byte slice.
+func L(data ...byte) Leaf {
+	return Leaf([]byte(data))
+}
+
+// Order is satisfied when the data satisfies each of its nodes in the order
+// that they are specified in the slice.
+type Order []Node
+
+// Check determines if the data satisfies the Order.
+func (this Order) Check(data []byte) (ok bool, n int) {
+	left := data
+	for _, node := range this {
+		ok, nn := node.Check(left)
+		n += nn; if !ok { return false, n }
+		left = left[nn:]
+	}
+	return true, n
+}
+
+// Flatten returns the Order flattened to a byte array. The result of this
+// function always satisfies the Order.
+func (this Order) Flatten() []byte {
+	flat := []byte { }
+	for _, node := range this {
+		flat = append(flat, node.Flatten()...)
+	}
+	return flat
+}
+
+func (this Order) String() string {
+	out := strings.Builder { }
+	for index, node := range this {
+		if index > 0 {
+			fmt.Fprint(&out, " :")
+		}
+		fmt.Fprintf(&out, " %v", node)
+	}
+	return out.String()
+}
+
+// Add returns a new order with the given nodes appended to it.
+func (this Order) Add(nodes ...Node) Order {
+	newOrder := make(Order, len(this) + len(nodes))
+	copy(newOrder, this)
+	copy(newOrder[len(this):], Order(nodes))
+	return newOrder
+}
+
+// AddO returns a new order with the given order appended to it.
+func (this Order) AddO(nodes ...Node) Order {
+	return this.Add(O(nodes...))
+}
+
+// AddS returns a new order with the given snake appended to it.
+func (this Order) AddS(nodes ...Node) Order {
+	return this.Add(S(nodes...))
+}
+
+// AddL returns a new order with the given leaf appended to it.
+func (this Order) AddL(data ...byte) Order {
+	return this.Add(L(data...))
+}
+
+// Snake is satisfied when the data satisfies each of its nodes in no particular
+// order.
+type Snake []Node
+
+// Check determines if the data satisfies the snake.
+func (this Snake) Check(data []byte) (ok bool, n int) {
+	fmt.Println("CHECKING SNAKE")
+	left := data
+	nodes := map[int] Node { }
+	for key, node := range this {
+		nodes[key] = node
+	}
+	for len(nodes) > 0 {
+		found := false
+		for key, node := range nodes {
+			fmt.Println(left, key, node)
+			ok, nn := node.Check(left)
+			fmt.Println(ok, nn)
+			if !ok { continue }
+			n += nn
+			left = data[n:]
+			delete(nodes, key)
+			found = true
+			break
+		}
+		if !found { 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 (this Snake) Flatten() []byte {
+	flat := []byte { }
+	for _, node := range this {
+		flat = append(flat, node.Flatten()...)
+	}
+	return flat
+}
+
+func (this Snake) String() string {
+	out := strings.Builder { }
+	out.WriteString("[")
+	for index, node := range this {
+		if index > 0 {
+			fmt.Fprint(&out, " /")
+		}
+		fmt.Fprintf(&out, " %v", node)
+	}
+	out.WriteString(" ]")
+	return out.String()
+}
+
+// Add returns a new snake with the given nodes appended to it.
+func (this Snake) Add(nodes ...Node) Snake {
+	newSnake := make(Snake, len(this) + len(nodes))
+	copy(newSnake, this)
+	copy(newSnake[len(this):], Snake(nodes))
+	return newSnake
+}
+
+// AddO returns a new snake with the given order appended to it.
+func (this Snake) AddO(nodes ...Node) Snake {
+	return this.Add(O(nodes...))
+}
+
+// AddS returns a new snake with the given snake appended to it.
+func (this Snake) AddS(nodes ...Node) Snake {
+	return this.Add(S(nodes...))
+}
+
+// AddL returns a new snake with the given leaf appended to it.
+func (this Snake) AddL(data ... byte) Snake {
+	return this.Add(L(data...))
+}
+
+// Leaf is satisfied when the data matches it exactly.
+type Leaf []byte
+
+// Check determines if the data is equal to the leaf.
+func (this Leaf) Check(data []byte) (ok bool, n int) {
+	if len(data) < len(this) {
+		return false, len(data)
+	}
+	for index, byt := range this {
+		if byt != data[index] {
+			return false, index
+		}
+	}
+	return true, len(this)
+}
+
+// This one's easy.
+func (this Leaf) Flatten() []byte {
+	return []byte(this)
+}
+
+func (this Leaf) String() string {
+	return tu.HexBytes([]byte(this))
+}
+
+// Node represents a snake node.
+type Node interface {
+	// Check determines if the data satisfies the node. If satisfied, the function
+	// will return true, and the index at which it stopped. If not, the
+	// function will return false, and the index of the first byte that
+	// didn't match. As long as the start of the data satisfies the node,
+	// whatever comes after it doesn't matter.
+	Check(data []byte) (ok bool, n int)
+	// Flatten returns the node flattened to a byte array. The result of
+	// this function always satisfies the node.
+	Flatten() []byte
+}

internal/testutil/snake/snake_test.go

@@ -0,0 +1,89 @@
+package snake
+
+import "testing"
+
+func TestSnakeA(test *testing.T) {
+	snake := O().AddL(1, 6).AddS(
+		L(1),
+		L(2),
+		L(3),
+		L(4),
+		L(5),
+	).AddL(9)
+
+	test.Log(snake)
+
+	ok, n := Check(snake, []byte { 1, 6, 1, 2, 3, 4, 5, 9 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 5, 4, 3, 2, 1, 9 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 3, 1, 4, 2, 5, 9 })
+	if !ok { test.Fatal("false negative:", n) }
+	
+	ok, n = Check(snake, []byte { 1, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 1, 2, 3, 4, 5, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 0, 2, 3, 4, 5, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 7, 1, 4, 2, 5, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 7, 3, 1, 4, 2, 5, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 7, 3, 1, 4, 2, 5, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 1, 2, 3, 4, 5, 9, 10})
+	if ok { test.Fatal("false positive:", n) }
+}
+
+func TestSnakeB(test *testing.T) {
+	snake := O().AddO(L(1), L(6)).AddS(
+		L(1),
+		L(2),
+	).AddL(9).AddS(
+		L(3, 2),
+		L(0),
+		L(1, 1, 2, 3),
+	)
+
+	test.Log(snake)
+
+	ok, n := Check(snake, []byte { 1, 6, 1, 2, 9, 3, 2, 0, 1, 1, 2, 3})
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 2, 1, 9, 0, 1, 1, 2, 3, 3, 2})
+	if !ok { test.Fatal("false negative:", n) }
+	
+	ok, n = Check(snake, []byte { 1, 6, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 1, 2, 9 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 9, 3, 2, 0, 1, 1, 2, 3})
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 2, 9, 0, 1, 1, 2, 3, 3, 2})
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 1, 6, 1, 2, 9, 3, 2, 1, 1, 2, 3})
+	if ok { test.Fatal("false positive:", n) }
+}
+
+func TestSnakeC(test *testing.T) {
+	snake := S(
+		L(1, 2, 3),
+		S(L(6), L(7), L(8)),
+	)
+
+	test.Log(snake)
+
+	ok, n := Check(snake, []byte { 1, 2, 3, 6, 7, 8 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = Check(snake, []byte { 6, 7, 8, 1, 2, 3 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = Check(snake, []byte { 7, 8, 6, 1, 2, 3 })
+	if !ok { test.Fatal("false negative:", n) }
+	ok, n = Check(snake, []byte { 1, 2, 3, 8, 6, 7 })
+	if !ok { test.Fatal("false negative:", n) }
+
+	ok, n = Check(snake, []byte { 2, 1, 3, 6, 7, 8 })
+	if ok { test.Fatal("false positive:", n) }
+	ok, n = Check(snake, []byte { 6, 1, 2, 3, 7, 8 })
+	if ok { test.Fatal("false positive:", n) }
+}

metadapta.go

@@ -390,7 +390,7 @@ func (this *readerA) pull() (uint16, error) {
 	// close and return error on failure
 	this.eof = true
 	this.parent.Close()
-	return 0, fmt.Errorf("could not receive message: %w", this.parent.bestErr())
+	return 0, this.parent.bestErr()
 }
 
 func (this *readerA) Read(buffer []byte) (int, error) {