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hash.go
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hash.go
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// Code extracted from vendor/github.com/ethereum/go-ethereum/common/types.go
package types
import (
"encoding/hex"
"fmt"
"reflect"
)
const (
// HashLength is the expected length of the hash
HashLength = 32
)
// Hash represents the 32 byte Keccak256 hash of arbitrary data.
type Hash [HashLength]byte
var hashT = reflect.TypeOf(Hash{})
// Encode encodes b as a hex string with 0x prefix.
func encode(b []byte) string {
enc := make([]byte, len(b)*2+2)
copy(enc, "0x")
hex.Encode(enc[2:], b)
return string(enc)
}
// FromHex returns the bytes represented by the hexadecimal string s.
// s may be prefixed with "0x".
func FromHex(s string) []byte {
if has0xPrefix(s) {
s = s[2:]
}
if len(s)%2 == 1 {
s = "0" + s
}
return Hex2Bytes(s)
}
// HexToHash sets byte representation of s to hash.
// If b is larger than len(h), b will be cropped from the left.
func HexToHash(s string) Hash { return BytesToHash(FromHex(s)) }
// Hex converts a hash to a hex string.
func (h *Hash) Hex() string { return encode(h[:]) }
// Bytes gets the byte representation of the underlying hash.
func (h Hash) Bytes() []byte { return h[:] }
// String implements the stringer interface and is used also by the logger when
// doing full logging into a file.
func (h Hash) String() string {
return h.Hex()
}
// SetBytes sets the hash to the value of b.
// If b is larger than len(h), b will be cropped from the left.
func (h *Hash) SetBytes(b []byte) {
if len(b) > len(h) {
b = b[len(b)-HashLength:]
}
copy(h[HashLength-len(b):], b)
}
// UnmarshalText parses a hash in hex syntax.
func (h *Hash) UnmarshalText(input []byte) error {
return UnmarshalFixedText("Hash", input, h[:])
}
// UnmarshalJSON parses a hash in hex syntax.
func (h *Hash) UnmarshalJSON(input []byte) error {
return UnmarshalFixedJSON(hashT, input, h[:])
}
// MarshalText returns the hex representation of h.
func (h Hash) MarshalText() ([]byte, error) {
return HexBytes(h[:]).MarshalText()
}
// BytesToHash sets b to hash.
// If b is larger than len(h), b will be cropped from the left.
func BytesToHash(b []byte) Hash {
var h Hash
h.SetBytes(b)
return h
}
// UnmarshalFixedJSON 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
// UnmarshalJSON method for fixed-size types.
func UnmarshalFixedJSON(typ reflect.Type, input, out []byte) error {
if !isString(input) {
return errNonString(typ)
}
return wrapTypeError(UnmarshalFixedText(typ.String(), input[1:len(input)-1], out), typ)
}
// 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.
func UnmarshalFixedText(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
}