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path: root/plumbing/format/packfile/diff_delta.go
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Diffstat (limited to 'plumbing/format/packfile/diff_delta.go')
-rw-r--r--plumbing/format/packfile/diff_delta.go44
1 files changed, 7 insertions, 37 deletions
diff --git a/plumbing/format/packfile/diff_delta.go b/plumbing/format/packfile/diff_delta.go
index 295b411..7c9360e 100644
--- a/plumbing/format/packfile/diff_delta.go
+++ b/plumbing/format/packfile/diff_delta.go
@@ -25,10 +25,10 @@ const (
// To generate target again, you will need the obtained object and "base" one.
// Error will be returned if base or target object cannot be read.
func GetDelta(base, target plumbing.EncodedObject) (plumbing.EncodedObject, error) {
- return getDelta(make(deltaIndex), base, target)
+ return getDelta(new(deltaIndex), base, target)
}
-func getDelta(index deltaIndex, base, target plumbing.EncodedObject) (plumbing.EncodedObject, error) {
+func getDelta(index *deltaIndex, base, target plumbing.EncodedObject) (plumbing.EncodedObject, error) {
br, err := base.Reader()
if err != nil {
return nil, err
@@ -63,23 +63,23 @@ func getDelta(index deltaIndex, base, target plumbing.EncodedObject) (plumbing.E
// DiffDelta returns the delta that transforms src into tgt.
func DiffDelta(src, tgt []byte) []byte {
- return diffDelta(make(deltaIndex), src, tgt)
+ return diffDelta(new(deltaIndex), src, tgt)
}
-func diffDelta(sindex deltaIndex, src []byte, tgt []byte) []byte {
+func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte {
buf := bufPool.Get().(*bytes.Buffer)
buf.Reset()
buf.Write(deltaEncodeSize(len(src)))
buf.Write(deltaEncodeSize(len(tgt)))
- if len(sindex) == 0 {
- initMatch(sindex, src)
+ if len(index.entries) == 0 {
+ index.init(src)
}
ibuf := bufPool.Get().(*bytes.Buffer)
ibuf.Reset()
for i := 0; i < len(tgt); i++ {
- offset, l := findMatch(src, tgt, sindex, i)
+ offset, l := index.findMatch(src, tgt, i)
if l < s {
ibuf.WriteByte(tgt[i])
@@ -135,19 +135,6 @@ func encodeInsertOperation(ibuf, buf *bytes.Buffer) {
ibuf.Reset()
}
-func initMatch(index deltaIndex, src []byte) {
- i := 0
- for {
- if i+s > len(src) {
- break
- }
-
- ch := hashBuf(src[i : i+s])
- index[ch] = i
- i += s
- }
-}
-
// https://lemire.me/blog/2015/10/22/faster-hashing-without-effort/
func hashBuf(buf []byte) int64 {
var h int64
@@ -168,21 +155,6 @@ func hashBuf(buf []byte) int64 {
return h
}
-func findMatch(src, tgt []byte, sindex deltaIndex, tgtOffset int) (srcOffset, l int) {
- if len(tgt) >= tgtOffset+s {
- ch := hashBuf(tgt[tgtOffset : tgtOffset+s])
- var ok bool
- srcOffset, ok = sindex[ch]
- if !ok {
- return
- }
-
- l = matchLength(src, tgt, tgtOffset, srcOffset)
- }
-
- return
-}
-
func matchLength(src, tgt []byte, otgt, osrc int) int {
l := 0
for {
@@ -239,5 +211,3 @@ func encodeCopyOperation(offset, length int) []byte {
return append([]byte{byte(code)}, opcodes...)
}
-
-type deltaIndex map[int64]int