aboutsummaryrefslogtreecommitdiffstats
path: root/plumbing
diff options
context:
space:
mode:
Diffstat (limited to 'plumbing')
-rw-r--r--plumbing/format/packfile/delta_test.go93
-rw-r--r--plumbing/format/packfile/diff.go397
-rw-r--r--plumbing/format/packfile/diff_delta.go147
-rw-r--r--plumbing/format/packfile/patch_delta.go (renamed from plumbing/format/packfile/delta.go)0
4 files changed, 637 insertions, 0 deletions
diff --git a/plumbing/format/packfile/delta_test.go b/plumbing/format/packfile/delta_test.go
new file mode 100644
index 0000000..4ef9b70
--- /dev/null
+++ b/plumbing/format/packfile/delta_test.go
@@ -0,0 +1,93 @@
+package packfile
+
+import (
+ "fmt"
+
+ . "gopkg.in/check.v1"
+)
+
+type DeltaSuite struct {
+ testCases []deltaTest
+}
+
+var _ = Suite(&DeltaSuite{})
+
+type piece struct {
+ val string
+ times int
+}
+
+type deltaTest struct {
+ description string
+ base []piece
+ target []piece
+}
+
+func (s *DeltaSuite) SetUpSuite(c *C) {
+ s.testCases = []deltaTest{{
+ description: "distinct file",
+ base: []piece{{"0", 300}},
+ target: []piece{{"2", 200}},
+ }, {
+ description: "same file",
+ base: []piece{{"1", 3000}},
+ target: []piece{{"1", 3000}},
+ }, {
+ description: "small file",
+ base: []piece{{"1", 3}},
+ target: []piece{{"1", 3}, {"0", 1}},
+ }, {
+ description: "big file",
+ base: []piece{{"1", 300000}},
+ target: []piece{{"1", 30000}, {"0", 1000000}},
+ }, {
+ description: "add elements before",
+ base: []piece{{"0", 200}},
+ target: []piece{{"1", 300}, {"0", 200}},
+ }, {
+ description: "add 10 times more elements at the end",
+ base: []piece{{"1", 300}, {"0", 200}},
+ target: []piece{{"0", 2000}},
+ }, {
+ description: "add elements between",
+ base: []piece{{"0", 400}},
+ target: []piece{{"0", 200}, {"1", 200}, {"0", 200}},
+ }, {
+ description: "add elements after",
+ base: []piece{{"0", 200}},
+ target: []piece{{"0", 200}, {"1", 200}},
+ }, {
+ description: "modify elements at the end",
+ base: []piece{{"1", 300}, {"0", 200}},
+ target: []piece{{"0", 100}},
+ }, {
+ description: "complex modification",
+ base: []piece{{"0", 3}, {"1", 40}, {"2", 30}, {"3", 2},
+ {"4", 400}, {"5", 23}},
+ target: []piece{{"1", 30}, {"2", 20}, {"7", 40}, {"4", 400},
+ {"5", 10}},
+ }}
+}
+
+func (s *DeltaSuite) TestAddDelta(c *C) {
+ for _, t := range s.testCases {
+ baseBuf := genBytes(t.base)
+ targetBuf := genBytes(t.target)
+ delta := DiffDelta(baseBuf, targetBuf)
+ result := PatchDelta(baseBuf, delta)
+
+ c.Log(fmt.Printf("Executing test case: %s\n", t.description))
+ c.Assert(result, DeepEquals, targetBuf)
+ }
+}
+
+func genBytes(elements []piece) []byte {
+ var result []byte
+ for _, e := range elements {
+ for i := 0; i < e.times; i++ {
+ result = append(result, e.val...)
+ }
+ }
+
+ return result
+}
diff --git a/plumbing/format/packfile/diff.go b/plumbing/format/packfile/diff.go
new file mode 100644
index 0000000..ff34329
--- /dev/null
+++ b/plumbing/format/packfile/diff.go
@@ -0,0 +1,397 @@
+package packfile
+
+/*
+
+Copyright (c) 2013, Patrick Mezard
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+ Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+ Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+ The names of its contributors may not be used to endorse or promote
+products derived from this software without specific prior written
+permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*/
+
+// Code based on https://github.com/pmezard/go-difflib
+// Removed unnecessary code for this use case and changed string inputs to byte
+
+type match struct {
+ A int
+ B int
+ Size int
+}
+
+type opCode struct {
+ Tag byte
+ I1 int
+ I2 int
+ J1 int
+ J2 int
+}
+
+// SequenceMatcher compares sequence of bytes. The basic
+// algorithm predates, and is a little fancier than, an algorithm
+// published in the late 1980's by Ratcliff and Obershelp under the
+// hyperbolic name "gestalt pattern matching". The basic idea is to find
+// the longest contiguous matching subsequence that contains no "junk"
+// elements (R-O doesn't address junk). The same idea is then applied
+// recursively to the pieces of the sequences to the left and to the right
+// of the matching subsequence. This does not yield minimal edit
+// sequences, but does tend to yield matches that "look right" to people.
+//
+// SequenceMatcher tries to compute a "human-friendly diff" between two
+// sequences. Unlike e.g. UNIX(tm) diff, the fundamental notion is the
+// longest *contiguous* & junk-free matching subsequence. That's what
+// catches peoples' eyes. The Windows(tm) windiff has another interesting
+// notion, pairing up elements that appear uniquely in each sequence.
+// That, and the method here, appear to yield more intuitive difference
+// reports than does diff. This method appears to be the least vulnerable
+// to synching up on blocks of "junk lines", though (like blank lines in
+// ordinary text files, or maybe "<P>" lines in HTML files). That may be
+// because this is the only method of the 3 that has a *concept* of
+// "junk" <wink>.
+//
+// Timing: Basic R-O is cubic time worst case and quadratic time expected
+// case. SequenceMatcher is quadratic time for the worst case and has
+// expected-case behavior dependent in a complicated way on how many
+// elements the sequences have in common; best case time is linear.
+type sequenceMatcher struct {
+ a []byte
+ b []byte
+ b2j map[byte][]int
+ IsJunk func(byte) bool
+ autoJunk bool
+ bJunk map[byte]struct{}
+ matchingBlocks []match
+ fullBCount map[byte]int
+ bPopular map[byte]struct{}
+ opCodes []opCode
+}
+
+func newMatcher(a, b []byte) *sequenceMatcher {
+ m := sequenceMatcher{autoJunk: true}
+ m.SetSeqs(a, b)
+ return &m
+}
+
+// Set two sequences to be compared.
+func (m *sequenceMatcher) SetSeqs(a, b []byte) {
+ m.SetSeq1(a)
+ m.SetSeq2(b)
+}
+
+// Set the first sequence to be compared. The second sequence to be compared is
+// not changed.
+//
+// SequenceMatcher computes and caches detailed information about the second
+// sequence, so if you want to compare one sequence S against many sequences,
+// use .SetSeq2(s) once and call .SetSeq1(x) repeatedly for each of the other
+// sequences.
+//
+// See also SetSeqs() and SetSeq2().
+func (m *sequenceMatcher) SetSeq1(a []byte) {
+ if &a == &m.a {
+ return
+ }
+ m.a = a
+ m.matchingBlocks = nil
+ m.opCodes = nil
+}
+
+// Set the second sequence to be compared. The first sequence to be compared is
+// not changed.
+func (m *sequenceMatcher) SetSeq2(b []byte) {
+ if &b == &m.b {
+ return
+ }
+ m.b = b
+ m.matchingBlocks = nil
+ m.opCodes = nil
+ m.fullBCount = nil
+ m.chainB()
+}
+
+func (m *sequenceMatcher) chainB() {
+ // Populate line -> index mapping
+ b2j := map[byte][]int{}
+ for i, s := range m.b {
+ indices := b2j[s]
+ indices = append(indices, i)
+ b2j[s] = indices
+ }
+
+ // Purge junk elements
+ m.bJunk = map[byte]struct{}{}
+ if m.IsJunk != nil {
+ junk := m.bJunk
+ for s := range b2j {
+ if m.IsJunk(s) {
+ junk[s] = struct{}{}
+ }
+ }
+ for s := range junk {
+ delete(b2j, s)
+ }
+ }
+
+ // Purge remaining popular elements
+ popular := map[byte]struct{}{}
+ n := len(m.b)
+ if m.autoJunk && n >= 200 {
+ ntest := n/100 + 1
+ for s, indices := range b2j {
+ if len(indices) > ntest {
+ popular[s] = struct{}{}
+ }
+ }
+ for s := range popular {
+ delete(b2j, s)
+ }
+ }
+ m.bPopular = popular
+ m.b2j = b2j
+}
+
+func (m *sequenceMatcher) isBJunk(s byte) bool {
+ _, ok := m.bJunk[s]
+ return ok
+}
+
+// Find longest matching block in a[alo:ahi] and b[blo:bhi].
+//
+// If IsJunk is not defined:
+//
+// Return (i,j,k) such that a[i:i+k] is equal to b[j:j+k], where
+// alo <= i <= i+k <= ahi
+// blo <= j <= j+k <= bhi
+// and for all (i',j',k') meeting those conditions,
+// k >= k'
+// i <= i'
+// and if i == i', j <= j'
+//
+// In other words, of all maximal matching blocks, return one that
+// starts earliest in a, and of all those maximal matching blocks that
+// start earliest in a, return the one that starts earliest in b.
+//
+// If IsJunk is defined, first the longest matching block is
+// determined as above, but with the additional restriction that no
+// junk element appears in the block. Then that block is extended as
+// far as possible by matching (only) junk elements on both sides. So
+// the resulting block never matches on junk except as identical junk
+// happens to be adjacent to an "interesting" match.
+//
+// If no blocks match, return (alo, blo, 0).
+func (m *sequenceMatcher) findLongestMatch(alo, ahi, blo, bhi int) match {
+ // CAUTION: stripping common prefix or suffix would be incorrect.
+ // E.g.,
+ // ab
+ // acab
+ // Longest matching block is "ab", but if common prefix is
+ // stripped, it's "a" (tied with "b"). UNIX(tm) diff does so
+ // strip, so ends up claiming that ab is changed to acab by
+ // inserting "ca" in the middle. That's minimal but unintuitive:
+ // "it's obvious" that someone inserted "ac" at the front.
+ // Windiff ends up at the same place as diff, but by pairing up
+ // the unique 'b's and then matching the first two 'a's.
+ besti, bestj, bestsize := alo, blo, 0
+
+ // find longest junk-free match
+ // during an iteration of the loop, j2len[j] = length of longest
+ // junk-free match ending with a[i-1] and b[j]
+ j2len := map[int]int{}
+ for i := alo; i != ahi; i++ {
+ // look at all instances of a[i] in b; note that because
+ // b2j has no junk keys, the loop is skipped if a[i] is junk
+ newj2len := map[int]int{}
+ for _, j := range m.b2j[m.a[i]] {
+ // a[i] matches b[j]
+ if j < blo {
+ continue
+ }
+ if j >= bhi {
+ break
+ }
+ k := j2len[j-1] + 1
+ newj2len[j] = k
+ if k > bestsize {
+ besti, bestj, bestsize = i-k+1, j-k+1, k
+ }
+ }
+ j2len = newj2len
+ }
+
+ // Extend the best by non-junk elements on each end. In particular,
+ // "popular" non-junk elements aren't in b2j, which greatly speeds
+ // the inner loop above, but also means "the best" match so far
+ // doesn't contain any junk *or* popular non-junk elements.
+ for besti > alo && bestj > blo && !m.isBJunk(m.b[bestj-1]) &&
+ m.a[besti-1] == m.b[bestj-1] {
+ besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
+ }
+ for besti+bestsize < ahi && bestj+bestsize < bhi &&
+ !m.isBJunk(m.b[bestj+bestsize]) &&
+ m.a[besti+bestsize] == m.b[bestj+bestsize] {
+ bestsize += 1
+ }
+
+ // Now that we have a wholly interesting match (albeit possibly
+ // empty!), we may as well suck up the matching junk on each
+ // side of it too. Can't think of a good reason not to, and it
+ // saves post-processing the (possibly considerable) expense of
+ // figuring out what to do with it. In the case of an empty
+ // interesting match, this is clearly the right thing to do,
+ // because no other kind of match is possible in the regions.
+ for besti > alo && bestj > blo && m.isBJunk(m.b[bestj-1]) &&
+ m.a[besti-1] == m.b[bestj-1] {
+ besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
+ }
+ for besti+bestsize < ahi && bestj+bestsize < bhi &&
+ m.isBJunk(m.b[bestj+bestsize]) &&
+ m.a[besti+bestsize] == m.b[bestj+bestsize] {
+ bestsize += 1
+ }
+
+ return match{A: besti, B: bestj, Size: bestsize}
+}
+
+// Return list of triples describing matching subsequences.
+//
+// Each triple is of the form (i, j, n), and means that
+// a[i:i+n] == b[j:j+n]. The triples are monotonically increasing in
+// i and in j. It's also guaranteed that if (i, j, n) and (i', j', n') are
+// adjacent triples in the list, and the second is not the last triple in the
+// list, then i+n != i' or j+n != j'. IOW, adjacent triples never describe
+// adjacent equal blocks.
+//
+// The last triple is a dummy, (len(a), len(b), 0), and is the only
+// triple with n==0.
+func (m *sequenceMatcher) GetMatchingBlocks() []match {
+ if m.matchingBlocks != nil {
+ return m.matchingBlocks
+ }
+
+ var matchBlocks func(alo, ahi, blo, bhi int, matched []match) []match
+ matchBlocks = func(alo, ahi, blo, bhi int, matched []match) []match {
+ match := m.findLongestMatch(alo, ahi, blo, bhi)
+ i, j, k := match.A, match.B, match.Size
+ if match.Size > 0 {
+ if alo < i && blo < j {
+ matched = matchBlocks(alo, i, blo, j, matched)
+ }
+ matched = append(matched, match)
+ if i+k < ahi && j+k < bhi {
+ matched = matchBlocks(i+k, ahi, j+k, bhi, matched)
+ }
+ }
+ return matched
+ }
+ matched := matchBlocks(0, len(m.a), 0, len(m.b), nil)
+
+ // It's possible that we have adjacent equal blocks in the
+ // matching_blocks list now.
+ nonAdjacent := []match{}
+ i1, j1, k1 := 0, 0, 0
+ for _, b := range matched {
+ // Is this block adjacent to i1, j1, k1?
+ i2, j2, k2 := b.A, b.B, b.Size
+ if i1+k1 == i2 && j1+k1 == j2 {
+ // Yes, so collapse them -- this just increases the length of
+ // the first block by the length of the second, and the first
+ // block so lengthened remains the block to compare against.
+ k1 += k2
+ } else {
+ // Not adjacent. Remember the first block (k1==0 means it's
+ // the dummy we started with), and make the second block the
+ // new block to compare against.
+ if k1 > 0 {
+ nonAdjacent = append(nonAdjacent, match{i1, j1, k1})
+ }
+ i1, j1, k1 = i2, j2, k2
+ }
+ }
+ if k1 > 0 {
+ nonAdjacent = append(nonAdjacent, match{i1, j1, k1})
+ }
+
+ nonAdjacent = append(nonAdjacent, match{len(m.a), len(m.b), 0})
+ m.matchingBlocks = nonAdjacent
+ return m.matchingBlocks
+}
+
+const (
+ tagReplace = 'r'
+ tagDelete = 'd'
+ tagInsert = 'i'
+ tagEqual = 'e'
+)
+
+// Return list of 5-tuples describing how to turn a into b.
+//
+// Each tuple is of the form (tag, i1, i2, j1, j2). The first tuple
+// has i1 == j1 == 0, and remaining tuples have i1 == the i2 from the
+// tuple preceding it, and likewise for j1 == the previous j2.
+//
+// The tags are characters, with these meanings:
+//
+// 'r' (replace): a[i1:i2] should be replaced by b[j1:j2]
+//
+// 'd' (delete): a[i1:i2] should be deleted, j1==j2 in this case.
+//
+// 'i' (insert): b[j1:j2] should be inserted at a[i1:i1], i1==i2 in this case.
+//
+// 'e' (equal): a[i1:i2] == b[j1:j2]
+func (m *sequenceMatcher) GetOpCodes() []opCode {
+ if m.opCodes != nil {
+ return m.opCodes
+ }
+ i, j := 0, 0
+ matching := m.GetMatchingBlocks()
+ opCodes := make([]opCode, 0, len(matching))
+ for _, m := range matching {
+ // invariant: we've pumped out correct diffs to change
+ // a[:i] into b[:j], and the next matching block is
+ // a[ai:ai+size] == b[bj:bj+size]. So we need to pump
+ // out a diff to change a[i:ai] into b[j:bj], pump out
+ // the matching block, and move (i,j) beyond the match
+ ai, bj, size := m.A, m.B, m.Size
+ tag := byte(0)
+ if i < ai && j < bj {
+ tag = tagReplace
+ } else if i < ai {
+ tag = tagDelete
+ } else if j < bj {
+ tag = tagInsert
+ }
+ if tag > 0 {
+ opCodes = append(opCodes, opCode{tag, i, ai, j, bj})
+ }
+ i, j = ai+size, bj+size
+ // the list of matching blocks is terminated by a
+ // sentinel with size 0
+ if size > 0 {
+ opCodes = append(opCodes, opCode{tagEqual, ai, i, bj, j})
+ }
+ }
+ m.opCodes = opCodes
+ return m.opCodes
+}
diff --git a/plumbing/format/packfile/diff_delta.go b/plumbing/format/packfile/diff_delta.go
new file mode 100644
index 0000000..eaed377
--- /dev/null
+++ b/plumbing/format/packfile/diff_delta.go
@@ -0,0 +1,147 @@
+package packfile
+
+import (
+ "io/ioutil"
+
+ "gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+// See https://github.com/jelmer/dulwich/blob/master/dulwich/pack.py and
+// https://github.com/tarruda/node-git-core/blob/master/src/js/delta.js
+// for more info
+
+const (
+ maxCopyLen = 0xffff
+)
+
+// GetDelta returns the way of how to transform base object to target object
+func GetDelta(base, target plumbing.Object) ([]byte, error) {
+ baseReader, err := base.Reader()
+ if err != nil {
+ return nil, err
+ }
+ targetReader, err := target.Reader()
+ if err != nil {
+ return nil, err
+ }
+
+ baseBuf, err := ioutil.ReadAll(baseReader)
+ if err != nil {
+ return nil, err
+ }
+
+ targetBuf, err := ioutil.ReadAll(targetReader)
+ if err != nil {
+ return nil, err
+ }
+
+ return DiffDelta(baseBuf, targetBuf), nil
+}
+
+// DiffDelta returns the way of how to transform baseBuf to targetBuf
+func DiffDelta(baseBuf []byte, targetBuf []byte) []byte {
+ var outBuff []byte
+
+ outBuff = append(outBuff, deltaEncodeSize(len(baseBuf))...)
+ outBuff = append(outBuff, deltaEncodeSize(len(targetBuf))...)
+
+ sm := newMatcher(baseBuf, targetBuf)
+ for _, op := range sm.GetOpCodes() {
+ switch {
+ case op.Tag == tagEqual:
+ copyStart := op.I1
+ copyLen := op.I2 - op.I1
+ for {
+ if copyLen <= 0 {
+ break
+ }
+ var toCopy int
+ if copyLen < maxCopyLen {
+ toCopy = copyLen
+ } else {
+ toCopy = maxCopyLen
+ }
+
+ outBuff = append(outBuff, encodeCopyOperation(copyStart, toCopy)...)
+ copyStart += toCopy
+ copyLen -= toCopy
+ }
+ case op.Tag == tagReplace || op.Tag == tagInsert:
+ s := op.J2 - op.J1
+ o := op.J1
+ for {
+ if s <= 127 {
+ break
+ }
+ outBuff = append(outBuff, byte(127))
+ outBuff = append(outBuff, targetBuf[o:o+127]...)
+ s -= 127
+ o += 127
+ }
+ outBuff = append(outBuff, byte(s))
+ outBuff = append(outBuff, targetBuf[o:o+s]...)
+ }
+ }
+
+ return outBuff
+}
+
+func deltaEncodeSize(size int) []byte {
+ var ret []byte
+ c := size & 0x7f
+ size >>= 7
+ for {
+ if size == 0 {
+ break
+ }
+
+ ret = append(ret, byte(c|0x80))
+ c = size & 0x7f
+ size >>= 7
+ }
+ ret = append(ret, byte(c))
+
+ return ret
+}
+
+func encodeCopyOperation(offset, length int) []byte {
+ code := 0x80
+ var opcodes []byte
+
+ if offset&0xff != 0 {
+ opcodes = append(opcodes, byte(offset&0xff))
+ code |= 0x01
+ }
+
+ if offset&0xff00 != 0 {
+ opcodes = append(opcodes, byte((offset&0xff00)>>8))
+ code |= 0x02
+ }
+
+ if offset&0xff0000 != 0 {
+ opcodes = append(opcodes, byte((offset&0xff0000)>>16))
+ code |= 0x04
+ }
+
+ if offset&0xff000000 != 0 {
+ opcodes = append(opcodes, byte((offset&0xff000000)>>24))
+ code |= 0x08
+ }
+
+ if length&0xff != 0 {
+ opcodes = append(opcodes, byte(length&0xff))
+ code |= 0x10
+ }
+
+ if length&0xff00 != 0 {
+ opcodes = append(opcodes, byte((length&0xff00)>>8))
+ code |= 0x20
+ }
+
+ if length&0xff0000 != 0 {
+ opcodes = append(opcodes, byte((length&0xff0000)>>16))
+ code |= 0x40
+ }
+
+ return append([]byte{byte(code)}, opcodes...)
+}
diff --git a/plumbing/format/packfile/delta.go b/plumbing/format/packfile/patch_delta.go
index 2493a39..2493a39 100644
--- a/plumbing/format/packfile/delta.go
+++ b/plumbing/format/packfile/patch_delta.go
generated by cgit (git 2.34.1) at 2024-11-16 12:58:57 +0000