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