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id.go
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id.go
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// Copyright (C) 2019-2022, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
package ids
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"github.com/ava-labs/avalanchego/utils"
"github.com/ava-labs/avalanchego/utils/cb58"
"github.com/ava-labs/avalanchego/utils/hashing"
"github.com/ava-labs/avalanchego/utils/wrappers"
)
const nullStr = "null"
var (
// Empty is a useful all zero value
Empty = ID{}
errMissingQuotes = errors.New("first and last characters should be quotes")
_ utils.Sortable[ID] = ID{}
)
// ID wraps a 32 byte hash used as an identifier
type ID [32]byte
// ToID attempt to convert a byte slice into an id
func ToID(bytes []byte) (ID, error) {
return hashing.ToHash256(bytes)
}
// FromString is the inverse of ID.String()
func FromString(idStr string) (ID, error) {
bytes, err := cb58.Decode(idStr)
if err != nil {
return ID{}, err
}
return ToID(bytes)
}
func (id ID) MarshalJSON() ([]byte, error) {
str, err := cb58.Encode(id[:])
if err != nil {
return nil, err
}
return []byte("\"" + str + "\""), nil
}
func (id *ID) UnmarshalJSON(b []byte) error {
str := string(b)
if str == nullStr { // If "null", do nothing
return nil
} else if len(str) < 2 {
return errMissingQuotes
}
lastIndex := len(str) - 1
if str[0] != '"' || str[lastIndex] != '"' {
return errMissingQuotes
}
// Parse CB58 formatted string to bytes
bytes, err := cb58.Decode(str[1:lastIndex])
if err != nil {
return fmt.Errorf("couldn't decode ID to bytes: %w", err)
}
*id, err = ToID(bytes)
return err
}
func (id *ID) UnmarshalText(text []byte) error {
return id.UnmarshalJSON(text)
}
// Prefix this id to create a more selective id. This can be used to store
// multiple values under the same key. For example:
// prefix1(id) -> confidence
// prefix2(id) -> vertex
// This will return a new id and not modify the original id.
func (id ID) Prefix(prefixes ...uint64) ID {
packer := wrappers.Packer{
Bytes: make([]byte, len(prefixes)*wrappers.LongLen+hashing.HashLen),
}
for _, prefix := range prefixes {
packer.PackLong(prefix)
}
packer.PackFixedBytes(id[:])
return hashing.ComputeHash256Array(packer.Bytes)
}
// Bit returns the bit value at the ith index of the byte array. Returns 0 or 1
func (id ID) Bit(i uint) int {
byteIndex := i / BitsPerByte
bitIndex := i % BitsPerByte
b := id[byteIndex]
// b = [7, 6, 5, 4, 3, 2, 1, 0]
b >>= bitIndex
// b = [0, ..., bitIndex + 1, bitIndex]
// 1 = [0, 0, 0, 0, 0, 0, 0, 1]
b &= 1
// b = [0, 0, 0, 0, 0, 0, 0, bitIndex]
return int(b)
}
// Hex returns a hex encoded string of this id.
func (id ID) Hex() string {
return hex.EncodeToString(id[:])
}
func (id ID) String() string {
// We assume that the maximum size of a byte slice that
// can be stringified is at least the length of an ID
s, _ := cb58.Encode(id[:])
return s
}
func (id ID) MarshalText() ([]byte, error) {
return []byte(id.String()), nil
}
func (id ID) Less(other ID) bool {
return bytes.Compare(id[:], other[:]) < 0
}