hexutil

Documentation

Overview

Package hexutil implements hex encoding with 0x prefix. This encoding is used by the Ethereum RPC API to transport binary data in JSON payloads.

Encoding Rules

All hex data must have prefix "0x".

For byte slices, the hex data must be of even length. An empty byte slice encodes as "0x".

Integers are encoded using the least amount of digits (no leading zero digits). Their encoding may be of uneven length. The number zero encodes as "0x0".

Index

• Variables
• func Decode(input string) ([]byte, error)
• func DecodeBig(input string) (*big.Int, error)
• func DecodeUint64(input string) (uint64, error)
• func Encode(b []byte) string
• func EncodeBig(bigint *big.Int) string
• func EncodeUint64(i uint64) string
• func MustDecode(input string) []byte
• func MustDecodeBig(input string) *big.Int
• func MustDecodeUint64(input string) uint64
• func UnmarshalFixedText(typname string, input, out []byte) error
• func UnmarshalFixedUnprefixedText(typname string, input, out []byte) error
• type Big
  • func (b Big) MarshalText() ([]byte, error)
  • func (b *Big) String() string
  • func (b *Big) ToInt() *big.Int
  • func (b *Big) UnmarshalJSON(input []byte) error
  • func (b *Big) UnmarshalText(input []byte) error
• type Bytes
  • func (b Bytes) MarshalText() ([]byte, error)
  • func (b Bytes) String() string
  • func (b *Bytes) UnmarshalJSON(input []byte) error
  • func (b *Bytes) UnmarshalText(input []byte) error
• type Uint
  • func (b Uint) MarshalText() ([]byte, error)
  • func (b Uint) String() string
  • func (b *Uint) UnmarshalJSON(input []byte) error
  • func (b *Uint) UnmarshalText(input []byte) error
• type Uint64
  • func (b Uint64) MarshalText() ([]byte, error)
  • func (b Uint64) String() string
  • func (b *Uint64) UnmarshalJSON(input []byte) error
  • func (b *Uint64) UnmarshalText(input []byte) error

Examples

• UnmarshalFixedText

Variables

var (
	ErrEmptyString   = errors.New("empty hex string")
	ErrMissingPrefix = errors.New("missing 0x prefix for hex data")
	ErrSyntax        = errors.New("invalid hex")
	ErrEmptyNumber   = errors.New("hex number has no digits after 0x")
	ErrLeadingZero   = errors.New("hex number has leading zero digits after 0x")
	ErrOddLength     = errors.New("hex string has odd length")
	ErrUint64Range   = errors.New("hex number does not fit into 64 bits")
	ErrUintRange     = fmt.Errorf("hex number does not fit into %d bits", uintBits)
	ErrBig256Range   = errors.New("hex number does not fit into 256 bits")
)

Functions

func Decode

func Decode(input string) ([]byte, error)

Decode decodes a hex string with 0x prefix.

func DecodeBig

func DecodeBig(input string) (*big.Int, error)

DecodeBig decodes a hex string with 0x prefix as a quantity. Numbers larger than 256 bits are not accepted.

func DecodeUint64

func DecodeUint64(input string) (uint64, error)

DecodeUint64 decodes a hex string with 0x prefix as a quantity.

func Encode

func Encode(b []byte) string

Encode encodes b as a hex string with 0x prefix.

func EncodeBig

func EncodeBig(bigint *big.Int) string

EncodeBig encodes bigint as a hex string with 0x prefix. The sign of the integer is ignored.

func EncodeUint64

func EncodeUint64(i uint64) string

EncodeUint64 encodes i as a hex string with 0x prefix.

func MustDecode

func MustDecode(input string) []byte

MustDecode decodes a hex string with 0x prefix. It panics for invalid input.

func MustDecodeBig

func MustDecodeBig(input string) *big.Int

MustDecodeBig decodes a hex string with 0x prefix as a quantity. It panics for invalid input.

func MustDecodeUint64

func MustDecodeUint64(input string) uint64

MustDecodeUint64 decodes a hex string with 0x prefix as a quantity. It panics for invalid input.

func UnmarshalFixedText

func UnmarshalFixedText(typname string, input, out []byte) error

UnmarshalFixedText decodes the input as a string with 0x prefix. The length of out determines the required input length. This function is commonly used to implement the UnmarshalText method for fixed-size types.

Example

package main

import (
	"encoding/json"
	"fmt"

	"github.com/ethereum/go-ethereum/common/hexutil"
)

type MyType [5]byte

func (v *MyType) UnmarshalText(input []byte) error {
	return hexutil.UnmarshalFixedText("MyType", input, v[:])
}

func (v MyType) String() string {
	return hexutil.Bytes(v[:]).String()
}

func main() {
	var v1, v2 MyType
	fmt.Println("v1 error:", json.Unmarshal([]byte(`"0x01"`), &v1))
	fmt.Println("v2 error:", json.Unmarshal([]byte(`"0x0101010101"`), &v2))
	fmt.Println("v2:", v2)
}

Output:

v1 error: hex string has length 2, want 10 for MyType
v2 error: <nil>
v2: 0x0101010101

func UnmarshalFixedUnprefixedText

func UnmarshalFixedUnprefixedText(typname string, input, out []byte) error

UnmarshalFixedUnprefixedText decodes the input as a string with optional 0x prefix. The length of out determines the required input length. This function is commonly used to implement the UnmarshalText method for fixed-size types.

Types

type Big

type Big big.Int

Big marshals/unmarshals as a JSON string with 0x prefix. The zero value marshals as "0x0".

Negative integers are not supported at this time. Attempting to marshal them will return an error. Values larger than 256bits are rejected by Unmarshal but will be marshaled without error.

func (Big) MarshalText

func (b Big) MarshalText() ([]byte, error)

MarshalText implements encoding.TextMarshaler

func (*Big) String

func (b *Big) String() string

String returns the hex encoding of b.

func (*Big) ToInt

func (b *Big) ToInt() *big.Int

ToInt converts b to a big.Int.

func (*Big) UnmarshalJSON

func (b *Big) UnmarshalJSON(input []byte) error

UnmarshalJSON implements json.Unmarshaler.

func (*Big) UnmarshalText

func (b *Big) UnmarshalText(input []byte) error

UnmarshalText implements encoding.TextUnmarshaler

type Bytes

type Bytes []byte

Bytes marshals/unmarshals as a JSON string with 0x prefix. The empty slice marshals as "0x".

func (Bytes) MarshalText

func (b Bytes) MarshalText() ([]byte, error)

MarshalText implements encoding.TextMarshaler

func (Bytes) String

func (b Bytes) String() string

String returns the hex encoding of b.

func (*Bytes) UnmarshalJSON

func (b *Bytes) UnmarshalJSON(input []byte) error

UnmarshalJSON implements json.Unmarshaler.

func (*Bytes) UnmarshalText

func (b *Bytes) UnmarshalText(input []byte) error

UnmarshalText implements encoding.TextUnmarshaler.

type Uint

type Uint uint

Uint marshals/unmarshals as a JSON string with 0x prefix. The zero value marshals as "0x0".

func (Uint) MarshalText

func (b Uint) MarshalText() ([]byte, error)

MarshalText implements encoding.TextMarshaler.

func (Uint) String

func (b Uint) String() string

String returns the hex encoding of b.

func (*Uint) UnmarshalJSON

func (b *Uint) UnmarshalJSON(input []byte) error

UnmarshalJSON implements json.Unmarshaler.

func (*Uint) UnmarshalText

func (b *Uint) UnmarshalText(input []byte) error

UnmarshalText implements encoding.TextUnmarshaler.

type Uint64

type Uint64 uint64

Uint64 marshals/unmarshals as a JSON string with 0x prefix. The zero value marshals as "0x0".

func (Uint64) MarshalText

func (b Uint64) MarshalText() ([]byte, error)

MarshalText implements encoding.TextMarshaler.

func (Uint64) String

func (b Uint64) String() string

String returns the hex encoding of b.

func (*Uint64) UnmarshalJSON

func (b *Uint64) UnmarshalJSON(input []byte) error

UnmarshalJSON implements json.Unmarshaler.

func (*Uint64) UnmarshalText

func (b *Uint64) UnmarshalText(input []byte) error

UnmarshalText implements encoding.TextUnmarshaler