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json.go
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json.go
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// Code extracted from vendor/github.com/ethereum/go-ethereum/common/hexutil/json.go
package types
import (
"encoding/hex"
"encoding/json"
"fmt"
"reflect"
"strconv"
)
const (
badNibble = ^uint64(0)
uintBits = 32 << (uint64(^uint(0)) >> 63)
)
// Errors
var (
ErrEmptyString = &decError{"empty hex string"}
ErrSyntax = &decError{"invalid hex string"}
ErrMissingPrefix = &decError{"hex string without 0x prefix"}
ErrOddLength = &decError{"hex string of odd length"}
ErrEmptyNumber = &decError{"hex string \"0x\""}
ErrLeadingZero = &decError{"hex number with leading zero digits"}
ErrUint64Range = &decError{"hex number > 64 bits"}
ErrUintRange = &decError{fmt.Sprintf("hex number > %d bits", uintBits)}
ErrBig256Range = &decError{"hex number > 256 bits"}
)
type decError struct{ msg string }
func (err decError) Error() string { return err.msg }
func decodeNibble(in byte) uint64 {
switch {
case in >= '0' && in <= '9':
return uint64(in - '0')
case in >= 'A' && in <= 'F':
return uint64(in - 'A' + 10)
case in >= 'a' && in <= 'f':
return uint64(in - 'a' + 10)
default:
return badNibble
}
}
// UnmarshalText implements encoding.TextUnmarshaler.
func (b *HexBytes) UnmarshalText(input []byte) error {
raw, err := checkText(input, true)
if err != nil {
return err
}
dec := make([]byte, len(raw)/2)
if _, err = hex.Decode(dec, raw); err != nil {
err = mapError(err)
} else {
*b = dec
}
return err
}
// UnmarshalFixedHexText 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.
func UnmarshalFixedHexText(typname string, input, out []byte) error {
raw, err := checkText(input, true)
if err != nil {
return err
}
if len(raw)/2 != len(out) {
return fmt.Errorf("hex string has length %d, want %d for %s", len(raw), len(out)*2, typname)
}
// Pre-verify syntax before modifying out.
for _, b := range raw {
if decodeNibble(b) == badNibble {
return ErrSyntax
}
}
_, err = hex.Decode(out, raw)
return err
}
// String returns the hex encoding of b.
func (b HexBytes) String() string {
return EncodeHex(b)
}
// EncodeHex encodes b as a hex string with 0x prefix.
func EncodeHex(b []byte) string {
enc := make([]byte, len(b)*2+2)
copy(enc, "0x")
hex.Encode(enc[2:], b)
return string(enc)
}
// DecodeHex decodes a hex string with 0x prefix.
func DecodeHex(input string) ([]byte, error) {
if len(input) == 0 {
return nil, ErrEmptyString
}
if !has0xPrefix(input) {
return nil, ErrMissingPrefix
}
b, err := hex.DecodeString(input[2:])
if err != nil {
err = mapError(err)
}
return b, err
}
// MustDecodeHex decodes a hex string with 0x prefix. It panics for invalid input.
func MustDecodeHex(input string) []byte {
dec, err := DecodeHex(input)
if err != nil {
panic(err)
}
return dec
}
func isString(input []byte) bool {
return len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"'
}
func bytesHave0xPrefix(input []byte) bool {
return len(input) >= 2 && input[0] == '0' && (input[1] == 'x' || input[1] == 'X')
}
func checkText(input []byte, wantPrefix bool) ([]byte, error) {
if len(input) == 0 {
return nil, nil // empty strings are allowed
}
if bytesHave0xPrefix(input) {
input = input[2:]
} else if wantPrefix {
return nil, ErrMissingPrefix
}
if len(input)%2 != 0 {
return nil, ErrOddLength
}
return input, nil
}
func mapError(err error) error {
if err, ok := err.(*strconv.NumError); ok {
switch err.Err {
case strconv.ErrRange:
return ErrUint64Range
case strconv.ErrSyntax:
return ErrSyntax
}
}
if _, ok := err.(hex.InvalidByteError); ok {
return ErrSyntax
}
if err == hex.ErrLength {
return ErrOddLength
}
return err
}
func wrapTypeError(err error, typ reflect.Type) error {
if _, ok := err.(*decError); ok {
return &json.UnmarshalTypeError{Value: err.Error(), Type: typ}
}
return err
}
func errNonString(typ reflect.Type) error {
return &json.UnmarshalTypeError{Value: "non-string", Type: typ}
}