gotosocial/vendor/git.iim.gay/grufwub/go-hashenc/hashenc.go
kim (grufwub) e43a46e982 add git.iim.gay/grufwub/go-store for storage backend, replacing blob.Storage
Signed-off-by: kim (grufwub) <grufwub@gmail.com>
2021-09-11 20:12:47 +01:00

58 lines
1.3 KiB
Go

package hashenc
import (
"hash"
"git.iim.gay/grufwub/go-bytes"
)
// HashEncoder defines an interface for calculating encoded hash sums of binary data
type HashEncoder interface {
// EncodeSum calculates the hash sum of src and encodes (at most) Size() into dst
EncodeSum(dst []byte, src []byte)
// EncodedSum calculates the encoded hash sum of src and returns data in a newly allocated bytes.Bytes
EncodedSum(src []byte) bytes.Bytes
// Size returns the expected length of encoded hashes
Size() int
}
// New returns a new HashEncoder instance based on supplied hash.Hash and Encoder supplying functions
func New(hash hash.Hash, enc Encoder) HashEncoder {
hashSize := hash.Size()
return &henc{
hash: hash,
hbuf: make([]byte, hashSize),
enc: enc,
size: enc.EncodedLen(hashSize),
}
}
// henc is the HashEncoder implementation
type henc struct {
hash hash.Hash
hbuf []byte
enc Encoder
size int
}
func (henc *henc) EncodeSum(dst []byte, src []byte) {
// Hash supplied bytes
henc.hash.Reset()
henc.hash.Write(src)
henc.hbuf = henc.hash.Sum(henc.hbuf[:0])
// Encode the hashsum and return a copy
henc.enc.Encode(dst, henc.hbuf)
}
func (henc *henc) EncodedSum(src []byte) bytes.Bytes {
dst := make([]byte, henc.size)
henc.EncodeSum(dst, src)
return bytes.ToBytes(dst)
}
func (henc *henc) Size() int {
return henc.size
}