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Published: Apr 2, 2021 License: Apache-2.0 Imports: 9 Imported by: 4

README

This code was copied over with many thanks from https://github.com/Joystream/parity-codec-go/tree/develop/withreflect

Chainsafe vs Joystream scale codec

  • Code quality wise Chainsafe codec is better because of proper handling(no panic), use of standard interfaces, more tests and good comments.
  • However Joystream codec has better usability because of the way it handles structs or unknown types by providing two interfaces.
    // Encodeable is an interface that defines a custom encoding rules for a data type.
    // Should be defined for structs (not pointers to them).
    // See OptionBool for an example implementation.
    type Encodeable interface {
        // ParityEncode encodes and write this structure into a stream
        ParityEncode(encoder Encoder)
    }
    
    // Decodeable is an interface that defines a custom encoding rules for a data type.
    // Should be defined for pointers to structs.
    // See OptionBool for an example implementation.
    type Decodeable interface {
        // ParityDecode populates this structure from a stream (overwriting the current contents), return false on failure
        ParityDecode(decoder Decoder)
    }
    

    This helped in debugging issues because structs could be debugged one field at a time when decoding and encoding. It was easy to see the progress of decoding for example by looking at already decoded struct fields and the buffere thats passed in within the decoder struct. This could have been implemented in client code for Chainsafe codec in hindsight, but just dealing with RPC execution issues was of higher priority.

It's better if the good features of both could be integrated together to create a nicer library.

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Reverse

func Reverse(b []byte)

Reverse reverses bytes in place (manipulates the underlying array)

func ToKeyedVec

func ToKeyedVec(value interface{}, prependKey []byte) ([]byte, error)

ToKeyedVec replicates the behaviour of Rust's to_keyed_vec helper.

Types

type Decodeable

type Decodeable interface {
	// ParityDecode populates this structure from a stream (overwriting the current contents), return false on failure
	Decode(decoder Decoder) error
}

Decodeable is an interface that defines a custom encoding rules for a data type. Should be defined for pointers to structs. See OptionBool for an example implementation.

type Decoder

type Decoder struct {
	// contains filtered or unexported fields
}

Decoder is a wraper around a Reader that allows decoding data items from a stream.

func NewDecoder

func NewDecoder(reader io.Reader) *Decoder

func (Decoder) Decode

func (pd Decoder) Decode(target interface{}) error

Decode takes a pointer to a decodable value and populates it from the stream.

func (Decoder) DecodeIntoReflectValue

func (pd Decoder) DecodeIntoReflectValue(target reflect.Value) error

DecodeIntoReflectValue populates a writable reflect.Value from the stream

func (Decoder) DecodeOption

func (pd Decoder) DecodeOption(hasValue *bool, valuePointer interface{}) error

DecodeOption decodes a optionally available value into a boolean presence field and a value.

func (Decoder) DecodeUintCompact

func (pd Decoder) DecodeUintCompact() (*big.Int, error)

DecodeUintCompact decodes a compact-encoded integer. See EncodeUintCompact method.

func (Decoder) Read

func (pd Decoder) Read(bytes []byte) error

Read reads bytes from a stream into a buffer

func (Decoder) ReadOneByte

func (pd Decoder) ReadOneByte() (byte, error)

ReadOneByte reads a next byte from the stream. Named so to avoid a linter warning about a clash with io.ByteReader.ReadByte

type Encodeable

type Encodeable interface {
	// ParityEncode encodes and write this structure into a stream
	Encode(encoder Encoder) error
}

Encodeable is an interface that defines a custom encoding rules for a data type. Should be defined for structs (not pointers to them). See OptionBool for an example implementation.

type Encoder

type Encoder struct {
	// contains filtered or unexported fields
}

Encoder is a wrapper around a Writer that allows encoding data items to a stream. Allows passing encoding options

func NewEncoder

func NewEncoder(writer io.Writer) *Encoder

func (Encoder) Encode

func (pe Encoder) Encode(value interface{}) error

Encode a value to the stream.

func (Encoder) EncodeOption

func (pe Encoder) EncodeOption(hasValue bool, value interface{}) error

EncodeOption stores optionally present value to the stream.

func (Encoder) EncodeUintCompact

func (pe Encoder) EncodeUintCompact(v big.Int) error

EncodeUintCompact writes an unsigned integer to the stream using the compact encoding. A typical usage is storing the length of a collection. Definition of compact encoding: 0b00 00 00 00 / 00 00 00 00 / 00 00 00 00 / 00 00 00 00

xx xx xx 00															(0 ... 2**6 - 1)		(u8)
yL yL yL 01 / yH yH yH yL												(2**6 ... 2**14 - 1)	(u8, u16)  low LH high
zL zL zL 10 / zM zM zM zL / zM zM zM zM / zH zH zH zM					(2**14 ... 2**30 - 1)	(u16, u32)  low LMMH high
nn nn nn 11 [ / zz zz zz zz ]{4 + n}									(2**30 ... 2**536 - 1)	(u32, u64, u128, U256, U512, U520) straight LE-encoded

Rust implementation: see impl<'a> Encode for CompactRef<'a, u64>

func (Encoder) PushByte

func (pe Encoder) PushByte(b byte) error

PushByte writes a single byte to an encoder.

func (Encoder) Write

func (pe Encoder) Write(bytes []byte) error

Write several bytes to the encoder.

type OptionBool

type OptionBool struct {
	// contains filtered or unexported fields
}

OptionBool is a structure that can store a boolean or a missing value. Note that encoding rules are slightly different from other "Option" fields.

func NewOptionBool

func NewOptionBool(value bool) OptionBool

NewOptionBool creates an OptionBool with a value.

func NewOptionBoolEmpty

func NewOptionBoolEmpty() OptionBool

NewOptionBoolEmpty creates an OptionBool without a value.

func (*OptionBool) Decode

func (o *OptionBool) Decode(decoder Decoder) error

ParityDecode implements decoding for OptionBool as per Rust implementation.

func (OptionBool) Encode

func (o OptionBool) Encode(encoder Encoder) error

ParityEncode implements encoding for OptionBool as per Rust implementation.

Source Files

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