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@@ -0,0 +1,772 @@
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+// Package difflib is a partial port of Python difflib module.
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+//
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+// It provides tools to compare sequences of strings and generate textual diffs.
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+//
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+// The following class and functions have been ported:
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+//
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+// - SequenceMatcher
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+//
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+// - unified_diff
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+//
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+// - context_diff
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+//
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+// Getting unified diffs was the main goal of the port. Keep in mind this code
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+// is mostly suitable to output text differences in a human friendly way, there
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+// are no guarantees generated diffs are consumable by patch(1).
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+package difflib
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+
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+import (
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+ "bufio"
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+ "bytes"
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+ "fmt"
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+ "io"
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+ "strings"
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+)
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+
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+func min(a, b int) int {
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+ if a < b {
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+ return a
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+ }
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+ return b
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+}
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+
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+func max(a, b int) int {
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+ if a > b {
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+ return a
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+ }
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+ return b
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+}
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+
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+func calculateRatio(matches, length int) float64 {
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+ if length > 0 {
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+ return 2.0 * float64(matches) / float64(length)
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+ }
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+ return 1.0
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+}
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+
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+type Match struct {
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+ A int
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+ B int
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+ Size int
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+}
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+
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+type OpCode struct {
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+ Tag byte
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+ I1 int
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+ I2 int
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+ J1 int
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+ J2 int
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+}
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+
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+// SequenceMatcher compares sequence of strings. The basic
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+// algorithm predates, and is a little fancier than, an algorithm
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+// published in the late 1980's by Ratcliff and Obershelp under the
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+// hyperbolic name "gestalt pattern matching". The basic idea is to find
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+// the longest contiguous matching subsequence that contains no "junk"
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+// elements (R-O doesn't address junk). The same idea is then applied
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+// recursively to the pieces of the sequences to the left and to the right
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+// of the matching subsequence. This does not yield minimal edit
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+// sequences, but does tend to yield matches that "look right" to people.
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+//
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+// SequenceMatcher tries to compute a "human-friendly diff" between two
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+// sequences. Unlike e.g. UNIX(tm) diff, the fundamental notion is the
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+// longest *contiguous* & junk-free matching subsequence. That's what
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+// catches peoples' eyes. The Windows(tm) windiff has another interesting
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+// notion, pairing up elements that appear uniquely in each sequence.
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+// That, and the method here, appear to yield more intuitive difference
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+// reports than does diff. This method appears to be the least vulnerable
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+// to synching up on blocks of "junk lines", though (like blank lines in
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+// ordinary text files, or maybe "<P>" lines in HTML files). That may be
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+// because this is the only method of the 3 that has a *concept* of
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+// "junk" <wink>.
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+//
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+// Timing: Basic R-O is cubic time worst case and quadratic time expected
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+// case. SequenceMatcher is quadratic time for the worst case and has
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+// expected-case behavior dependent in a complicated way on how many
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+// elements the sequences have in common; best case time is linear.
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+type SequenceMatcher struct {
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+ a []string
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+ b []string
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+ b2j map[string][]int
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+ IsJunk func(string) bool
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+ autoJunk bool
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+ bJunk map[string]struct{}
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+ matchingBlocks []Match
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+ fullBCount map[string]int
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+ bPopular map[string]struct{}
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+ opCodes []OpCode
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+}
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+
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+func NewMatcher(a, b []string) *SequenceMatcher {
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+ m := SequenceMatcher{autoJunk: true}
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+ m.SetSeqs(a, b)
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+ return &m
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+}
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+
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+func NewMatcherWithJunk(a, b []string, autoJunk bool,
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+ isJunk func(string) bool) *SequenceMatcher {
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+
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+ m := SequenceMatcher{IsJunk: isJunk, autoJunk: autoJunk}
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+ m.SetSeqs(a, b)
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+ return &m
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+}
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+
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+// Set two sequences to be compared.
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+func (m *SequenceMatcher) SetSeqs(a, b []string) {
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+ m.SetSeq1(a)
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+ m.SetSeq2(b)
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+}
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+
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+// Set the first sequence to be compared. The second sequence to be compared is
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+// not changed.
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+//
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+// SequenceMatcher computes and caches detailed information about the second
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+// sequence, so if you want to compare one sequence S against many sequences,
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+// use .SetSeq2(s) once and call .SetSeq1(x) repeatedly for each of the other
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+// sequences.
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+//
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+// See also SetSeqs() and SetSeq2().
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+func (m *SequenceMatcher) SetSeq1(a []string) {
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+ if &a == &m.a {
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+ return
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+ }
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+ m.a = a
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+ m.matchingBlocks = nil
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+ m.opCodes = nil
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+}
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+
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+// Set the second sequence to be compared. The first sequence to be compared is
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+// not changed.
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+func (m *SequenceMatcher) SetSeq2(b []string) {
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+ if &b == &m.b {
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+ return
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+ }
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+ m.b = b
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+ m.matchingBlocks = nil
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+ m.opCodes = nil
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+ m.fullBCount = nil
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+ m.chainB()
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+}
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+
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+func (m *SequenceMatcher) chainB() {
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+ // Populate line -> index mapping
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+ b2j := map[string][]int{}
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+ for i, s := range m.b {
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+ indices := b2j[s]
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+ indices = append(indices, i)
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+ b2j[s] = indices
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+ }
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+
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+ // Purge junk elements
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+ m.bJunk = map[string]struct{}{}
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+ if m.IsJunk != nil {
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+ junk := m.bJunk
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+ for s, _ := range b2j {
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+ if m.IsJunk(s) {
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+ junk[s] = struct{}{}
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+ }
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+ }
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+ for s, _ := range junk {
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+ delete(b2j, s)
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+ }
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+ }
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+
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+ // Purge remaining popular elements
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+ popular := map[string]struct{}{}
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+ n := len(m.b)
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+ if m.autoJunk && n >= 200 {
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+ ntest := n/100 + 1
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+ for s, indices := range b2j {
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+ if len(indices) > ntest {
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+ popular[s] = struct{}{}
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+ }
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+ }
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+ for s, _ := range popular {
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+ delete(b2j, s)
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+ }
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+ }
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+ m.bPopular = popular
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+ m.b2j = b2j
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+}
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+
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+func (m *SequenceMatcher) isBJunk(s string) bool {
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+ _, ok := m.bJunk[s]
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+ return ok
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+}
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+
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+// Find longest matching block in a[alo:ahi] and b[blo:bhi].
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+//
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+// If IsJunk is not defined:
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+//
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+// Return (i,j,k) such that a[i:i+k] is equal to b[j:j+k], where
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+// alo <= i <= i+k <= ahi
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+// blo <= j <= j+k <= bhi
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+// and for all (i',j',k') meeting those conditions,
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+// k >= k'
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+// i <= i'
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+// and if i == i', j <= j'
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+//
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+// In other words, of all maximal matching blocks, return one that
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+// starts earliest in a, and of all those maximal matching blocks that
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+// start earliest in a, return the one that starts earliest in b.
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+//
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+// If IsJunk is defined, first the longest matching block is
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+// determined as above, but with the additional restriction that no
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+// junk element appears in the block. Then that block is extended as
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+// far as possible by matching (only) junk elements on both sides. So
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+// the resulting block never matches on junk except as identical junk
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+// happens to be adjacent to an "interesting" match.
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+//
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+// If no blocks match, return (alo, blo, 0).
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+func (m *SequenceMatcher) findLongestMatch(alo, ahi, blo, bhi int) Match {
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+ // CAUTION: stripping common prefix or suffix would be incorrect.
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+ // E.g.,
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+ // ab
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+ // acab
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+ // Longest matching block is "ab", but if common prefix is
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+ // stripped, it's "a" (tied with "b"). UNIX(tm) diff does so
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+ // strip, so ends up claiming that ab is changed to acab by
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+ // inserting "ca" in the middle. That's minimal but unintuitive:
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+ // "it's obvious" that someone inserted "ac" at the front.
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+ // Windiff ends up at the same place as diff, but by pairing up
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+ // the unique 'b's and then matching the first two 'a's.
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+ besti, bestj, bestsize := alo, blo, 0
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+
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+ // find longest junk-free match
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+ // during an iteration of the loop, j2len[j] = length of longest
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+ // junk-free match ending with a[i-1] and b[j]
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+ j2len := map[int]int{}
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+ for i := alo; i != ahi; i++ {
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+ // look at all instances of a[i] in b; note that because
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+ // b2j has no junk keys, the loop is skipped if a[i] is junk
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+ newj2len := map[int]int{}
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+ for _, j := range m.b2j[m.a[i]] {
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+ // a[i] matches b[j]
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+ if j < blo {
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+ continue
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+ }
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+ if j >= bhi {
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+ break
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+ }
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+ k := j2len[j-1] + 1
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+ newj2len[j] = k
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+ if k > bestsize {
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+ besti, bestj, bestsize = i-k+1, j-k+1, k
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+ }
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+ }
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+ j2len = newj2len
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+ }
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+
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+ // Extend the best by non-junk elements on each end. In particular,
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+ // "popular" non-junk elements aren't in b2j, which greatly speeds
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+ // the inner loop above, but also means "the best" match so far
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+ // doesn't contain any junk *or* popular non-junk elements.
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+ for besti > alo && bestj > blo && !m.isBJunk(m.b[bestj-1]) &&
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+ m.a[besti-1] == m.b[bestj-1] {
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+ besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
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+ }
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+ for besti+bestsize < ahi && bestj+bestsize < bhi &&
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+ !m.isBJunk(m.b[bestj+bestsize]) &&
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+ m.a[besti+bestsize] == m.b[bestj+bestsize] {
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+ bestsize += 1
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+ }
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+
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+ // Now that we have a wholly interesting match (albeit possibly
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+ // empty!), we may as well suck up the matching junk on each
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+ // side of it too. Can't think of a good reason not to, and it
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+ // saves post-processing the (possibly considerable) expense of
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+ // figuring out what to do with it. In the case of an empty
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+ // interesting match, this is clearly the right thing to do,
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+ // because no other kind of match is possible in the regions.
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+ for besti > alo && bestj > blo && m.isBJunk(m.b[bestj-1]) &&
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+ m.a[besti-1] == m.b[bestj-1] {
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+ besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
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+ }
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+ for besti+bestsize < ahi && bestj+bestsize < bhi &&
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+ m.isBJunk(m.b[bestj+bestsize]) &&
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+ m.a[besti+bestsize] == m.b[bestj+bestsize] {
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+ bestsize += 1
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+ }
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+
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+ return Match{A: besti, B: bestj, Size: bestsize}
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+}
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+
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+// Return list of triples describing matching subsequences.
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+//
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+// Each triple is of the form (i, j, n), and means that
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+// a[i:i+n] == b[j:j+n]. The triples are monotonically increasing in
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+// i and in j. It's also guaranteed that if (i, j, n) and (i', j', n') are
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+// adjacent triples in the list, and the second is not the last triple in the
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+// list, then i+n != i' or j+n != j'. IOW, adjacent triples never describe
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+// adjacent equal blocks.
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+//
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+// The last triple is a dummy, (len(a), len(b), 0), and is the only
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+// triple with n==0.
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+func (m *SequenceMatcher) GetMatchingBlocks() []Match {
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+ if m.matchingBlocks != nil {
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+ return m.matchingBlocks
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+ }
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+
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+ var matchBlocks func(alo, ahi, blo, bhi int, matched []Match) []Match
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+ matchBlocks = func(alo, ahi, blo, bhi int, matched []Match) []Match {
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+ match := m.findLongestMatch(alo, ahi, blo, bhi)
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+ i, j, k := match.A, match.B, match.Size
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+ if match.Size > 0 {
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+ if alo < i && blo < j {
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+ matched = matchBlocks(alo, i, blo, j, matched)
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+ }
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+ matched = append(matched, match)
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+ if i+k < ahi && j+k < bhi {
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+ matched = matchBlocks(i+k, ahi, j+k, bhi, matched)
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+ }
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+ }
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+ return matched
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+ }
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+ matched := matchBlocks(0, len(m.a), 0, len(m.b), nil)
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+
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+ // It's possible that we have adjacent equal blocks in the
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+ // matching_blocks list now.
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+ nonAdjacent := []Match{}
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+ i1, j1, k1 := 0, 0, 0
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+ for _, b := range matched {
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+ // Is this block adjacent to i1, j1, k1?
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+ i2, j2, k2 := b.A, b.B, b.Size
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+ if i1+k1 == i2 && j1+k1 == j2 {
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+ // Yes, so collapse them -- this just increases the length of
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+ // the first block by the length of the second, and the first
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+ // block so lengthened remains the block to compare against.
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+ k1 += k2
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+ } else {
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+ // Not adjacent. Remember the first block (k1==0 means it's
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+ // the dummy we started with), and make the second block the
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+ // new block to compare against.
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+ if k1 > 0 {
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+ nonAdjacent = append(nonAdjacent, Match{i1, j1, k1})
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+ }
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+ i1, j1, k1 = i2, j2, k2
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+ }
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+ }
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+ if k1 > 0 {
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+ nonAdjacent = append(nonAdjacent, Match{i1, j1, k1})
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+ }
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+
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+ nonAdjacent = append(nonAdjacent, Match{len(m.a), len(m.b), 0})
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+ m.matchingBlocks = nonAdjacent
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+ return m.matchingBlocks
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+}
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+
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+// Return list of 5-tuples describing how to turn a into b.
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+//
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+// Each tuple is of the form (tag, i1, i2, j1, j2). The first tuple
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+// has i1 == j1 == 0, and remaining tuples have i1 == the i2 from the
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+// tuple preceding it, and likewise for j1 == the previous j2.
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+//
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+// The tags are characters, with these meanings:
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+//
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+// 'r' (replace): a[i1:i2] should be replaced by b[j1:j2]
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+//
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+// 'd' (delete): a[i1:i2] should be deleted, j1==j2 in this case.
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+//
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+// 'i' (insert): b[j1:j2] should be inserted at a[i1:i1], i1==i2 in this case.
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+//
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+// 'e' (equal): a[i1:i2] == b[j1:j2]
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+func (m *SequenceMatcher) GetOpCodes() []OpCode {
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+ if m.opCodes != nil {
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+ return m.opCodes
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+ }
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+ i, j := 0, 0
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+ matching := m.GetMatchingBlocks()
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+ opCodes := make([]OpCode, 0, len(matching))
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+ for _, m := range matching {
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+ // invariant: we've pumped out correct diffs to change
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+ // a[:i] into b[:j], and the next matching block is
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+ // a[ai:ai+size] == b[bj:bj+size]. So we need to pump
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+ // out a diff to change a[i:ai] into b[j:bj], pump out
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+ // the matching block, and move (i,j) beyond the match
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+ ai, bj, size := m.A, m.B, m.Size
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+ tag := byte(0)
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+ if i < ai && j < bj {
|
|
|
+ tag = 'r'
|
|
|
+ } else if i < ai {
|
|
|
+ tag = 'd'
|
|
|
+ } else if j < bj {
|
|
|
+ tag = 'i'
|
|
|
+ }
|
|
|
+ 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{'e', ai, i, bj, j})
|
|
|
+ }
|
|
|
+ }
|
|
|
+ m.opCodes = opCodes
|
|
|
+ return m.opCodes
|
|
|
+}
|
|
|
+
|
|
|
+// Isolate change clusters by eliminating ranges with no changes.
|
|
|
+//
|
|
|
+// Return a generator of groups with up to n lines of context.
|
|
|
+// Each group is in the same format as returned by GetOpCodes().
|
|
|
+func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode {
|
|
|
+ if n < 0 {
|
|
|
+ n = 3
|
|
|
+ }
|
|
|
+ codes := m.GetOpCodes()
|
|
|
+ if len(codes) == 0 {
|
|
|
+ codes = []OpCode{OpCode{'e', 0, 1, 0, 1}}
|
|
|
+ }
|
|
|
+ // Fixup leading and trailing groups if they show no changes.
|
|
|
+ if codes[0].Tag == 'e' {
|
|
|
+ c := codes[0]
|
|
|
+ i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
|
|
|
+ codes[0] = OpCode{c.Tag, max(i1, i2-n), i2, max(j1, j2-n), j2}
|
|
|
+ }
|
|
|
+ if codes[len(codes)-1].Tag == 'e' {
|
|
|
+ c := codes[len(codes)-1]
|
|
|
+ i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
|
|
|
+ codes[len(codes)-1] = OpCode{c.Tag, i1, min(i2, i1+n), j1, min(j2, j1+n)}
|
|
|
+ }
|
|
|
+ nn := n + n
|
|
|
+ groups := [][]OpCode{}
|
|
|
+ group := []OpCode{}
|
|
|
+ for _, c := range codes {
|
|
|
+ i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
|
|
|
+ // End the current group and start a new one whenever
|
|
|
+ // there is a large range with no changes.
|
|
|
+ if c.Tag == 'e' && i2-i1 > nn {
|
|
|
+ group = append(group, OpCode{c.Tag, i1, min(i2, i1+n),
|
|
|
+ j1, min(j2, j1+n)})
|
|
|
+ groups = append(groups, group)
|
|
|
+ group = []OpCode{}
|
|
|
+ i1, j1 = max(i1, i2-n), max(j1, j2-n)
|
|
|
+ }
|
|
|
+ group = append(group, OpCode{c.Tag, i1, i2, j1, j2})
|
|
|
+ }
|
|
|
+ if len(group) > 0 && !(len(group) == 1 && group[0].Tag == 'e') {
|
|
|
+ groups = append(groups, group)
|
|
|
+ }
|
|
|
+ return groups
|
|
|
+}
|
|
|
+
|
|
|
+// Return a measure of the sequences' similarity (float in [0,1]).
|
|
|
+//
|
|
|
+// Where T is the total number of elements in both sequences, and
|
|
|
+// M is the number of matches, this is 2.0*M / T.
|
|
|
+// Note that this is 1 if the sequences are identical, and 0 if
|
|
|
+// they have nothing in common.
|
|
|
+//
|
|
|
+// .Ratio() is expensive to compute if you haven't already computed
|
|
|
+// .GetMatchingBlocks() or .GetOpCodes(), in which case you may
|
|
|
+// want to try .QuickRatio() or .RealQuickRation() first to get an
|
|
|
+// upper bound.
|
|
|
+func (m *SequenceMatcher) Ratio() float64 {
|
|
|
+ matches := 0
|
|
|
+ for _, m := range m.GetMatchingBlocks() {
|
|
|
+ matches += m.Size
|
|
|
+ }
|
|
|
+ return calculateRatio(matches, len(m.a)+len(m.b))
|
|
|
+}
|
|
|
+
|
|
|
+// Return an upper bound on ratio() relatively quickly.
|
|
|
+//
|
|
|
+// This isn't defined beyond that it is an upper bound on .Ratio(), and
|
|
|
+// is faster to compute.
|
|
|
+func (m *SequenceMatcher) QuickRatio() float64 {
|
|
|
+ // viewing a and b as multisets, set matches to the cardinality
|
|
|
+ // of their intersection; this counts the number of matches
|
|
|
+ // without regard to order, so is clearly an upper bound
|
|
|
+ if m.fullBCount == nil {
|
|
|
+ m.fullBCount = map[string]int{}
|
|
|
+ for _, s := range m.b {
|
|
|
+ m.fullBCount[s] = m.fullBCount[s] + 1
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ // avail[x] is the number of times x appears in 'b' less the
|
|
|
+ // number of times we've seen it in 'a' so far ... kinda
|
|
|
+ avail := map[string]int{}
|
|
|
+ matches := 0
|
|
|
+ for _, s := range m.a {
|
|
|
+ n, ok := avail[s]
|
|
|
+ if !ok {
|
|
|
+ n = m.fullBCount[s]
|
|
|
+ }
|
|
|
+ avail[s] = n - 1
|
|
|
+ if n > 0 {
|
|
|
+ matches += 1
|
|
|
+ }
|
|
|
+ }
|
|
|
+ return calculateRatio(matches, len(m.a)+len(m.b))
|
|
|
+}
|
|
|
+
|
|
|
+// Return an upper bound on ratio() very quickly.
|
|
|
+//
|
|
|
+// This isn't defined beyond that it is an upper bound on .Ratio(), and
|
|
|
+// is faster to compute than either .Ratio() or .QuickRatio().
|
|
|
+func (m *SequenceMatcher) RealQuickRatio() float64 {
|
|
|
+ la, lb := len(m.a), len(m.b)
|
|
|
+ return calculateRatio(min(la, lb), la+lb)
|
|
|
+}
|
|
|
+
|
|
|
+// Convert range to the "ed" format
|
|
|
+func formatRangeUnified(start, stop int) string {
|
|
|
+ // Per the diff spec at http://www.unix.org/single_unix_specification/
|
|
|
+ beginning := start + 1 // lines start numbering with one
|
|
|
+ length := stop - start
|
|
|
+ if length == 1 {
|
|
|
+ return fmt.Sprintf("%d", beginning)
|
|
|
+ }
|
|
|
+ if length == 0 {
|
|
|
+ beginning -= 1 // empty ranges begin at line just before the range
|
|
|
+ }
|
|
|
+ return fmt.Sprintf("%d,%d", beginning, length)
|
|
|
+}
|
|
|
+
|
|
|
+// Unified diff parameters
|
|
|
+type UnifiedDiff struct {
|
|
|
+ A []string // First sequence lines
|
|
|
+ FromFile string // First file name
|
|
|
+ FromDate string // First file time
|
|
|
+ B []string // Second sequence lines
|
|
|
+ ToFile string // Second file name
|
|
|
+ ToDate string // Second file time
|
|
|
+ Eol string // Headers end of line, defaults to LF
|
|
|
+ Context int // Number of context lines
|
|
|
+}
|
|
|
+
|
|
|
+// Compare two sequences of lines; generate the delta as a unified diff.
|
|
|
+//
|
|
|
+// Unified diffs are a compact way of showing line changes and a few
|
|
|
+// lines of context. The number of context lines is set by 'n' which
|
|
|
+// defaults to three.
|
|
|
+//
|
|
|
+// By default, the diff control lines (those with ---, +++, or @@) are
|
|
|
+// created with a trailing newline. This is helpful so that inputs
|
|
|
+// created from file.readlines() result in diffs that are suitable for
|
|
|
+// file.writelines() since both the inputs and outputs have trailing
|
|
|
+// newlines.
|
|
|
+//
|
|
|
+// For inputs that do not have trailing newlines, set the lineterm
|
|
|
+// argument to "" so that the output will be uniformly newline free.
|
|
|
+//
|
|
|
+// The unidiff format normally has a header for filenames and modification
|
|
|
+// times. Any or all of these may be specified using strings for
|
|
|
+// 'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.
|
|
|
+// The modification times are normally expressed in the ISO 8601 format.
|
|
|
+func WriteUnifiedDiff(writer io.Writer, diff UnifiedDiff) error {
|
|
|
+ buf := bufio.NewWriter(writer)
|
|
|
+ defer buf.Flush()
|
|
|
+ wf := func(format string, args ...interface{}) error {
|
|
|
+ _, err := buf.WriteString(fmt.Sprintf(format, args...))
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ ws := func(s string) error {
|
|
|
+ _, err := buf.WriteString(s)
|
|
|
+ return err
|
|
|
+ }
|
|
|
+
|
|
|
+ if len(diff.Eol) == 0 {
|
|
|
+ diff.Eol = "\n"
|
|
|
+ }
|
|
|
+
|
|
|
+ started := false
|
|
|
+ m := NewMatcher(diff.A, diff.B)
|
|
|
+ for _, g := range m.GetGroupedOpCodes(diff.Context) {
|
|
|
+ if !started {
|
|
|
+ started = true
|
|
|
+ fromDate := ""
|
|
|
+ if len(diff.FromDate) > 0 {
|
|
|
+ fromDate = "\t" + diff.FromDate
|
|
|
+ }
|
|
|
+ toDate := ""
|
|
|
+ if len(diff.ToDate) > 0 {
|
|
|
+ toDate = "\t" + diff.ToDate
|
|
|
+ }
|
|
|
+ if diff.FromFile != "" || diff.ToFile != "" {
|
|
|
+ err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol)
|
|
|
+ if err != nil {
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol)
|
|
|
+ if err != nil {
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ }
|
|
|
+ }
|
|
|
+ first, last := g[0], g[len(g)-1]
|
|
|
+ range1 := formatRangeUnified(first.I1, last.I2)
|
|
|
+ range2 := formatRangeUnified(first.J1, last.J2)
|
|
|
+ if err := wf("@@ -%s +%s @@%s", range1, range2, diff.Eol); err != nil {
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ for _, c := range g {
|
|
|
+ i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
|
|
|
+ if c.Tag == 'e' {
|
|
|
+ for _, line := range diff.A[i1:i2] {
|
|
|
+ if err := ws(" " + line); err != nil {
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ }
|
|
|
+ continue
|
|
|
+ }
|
|
|
+ if c.Tag == 'r' || c.Tag == 'd' {
|
|
|
+ for _, line := range diff.A[i1:i2] {
|
|
|
+ if err := ws("-" + line); err != nil {
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ }
|
|
|
+ }
|
|
|
+ if c.Tag == 'r' || c.Tag == 'i' {
|
|
|
+ for _, line := range diff.B[j1:j2] {
|
|
|
+ if err := ws("+" + line); err != nil {
|
|
|
+ return err
|
|
|
+ }
|
|
|
+ }
|
|
|
+ }
|
|
|
+ }
|
|
|
+ }
|
|
|
+ return nil
|
|
|
+}
|
|
|
+
|
|
|
+// Like WriteUnifiedDiff but returns the diff a string.
|
|
|
+func GetUnifiedDiffString(diff UnifiedDiff) (string, error) {
|
|
|
+ w := &bytes.Buffer{}
|
|
|
+ err := WriteUnifiedDiff(w, diff)
|
|
|
+ return string(w.Bytes()), err
|
|
|
+}
|
|
|
+
|
|
|
+// Convert range to the "ed" format.
|
|
|
+func formatRangeContext(start, stop int) string {
|
|
|
+ // Per the diff spec at http://www.unix.org/single_unix_specification/
|
|
|
+ beginning := start + 1 // lines start numbering with one
|
|
|
+ length := stop - start
|
|
|
+ if length == 0 {
|
|
|
+ beginning -= 1 // empty ranges begin at line just before the range
|
|
|
+ }
|
|
|
+ if length <= 1 {
|
|
|
+ return fmt.Sprintf("%d", beginning)
|
|
|
+ }
|
|
|
+ return fmt.Sprintf("%d,%d", beginning, beginning+length-1)
|
|
|
+}
|
|
|
+
|
|
|
+type ContextDiff UnifiedDiff
|
|
|
+
|
|
|
+// Compare two sequences of lines; generate the delta as a context diff.
|
|
|
+//
|
|
|
+// Context diffs are a compact way of showing line changes and a few
|
|
|
+// lines of context. The number of context lines is set by diff.Context
|
|
|
+// which defaults to three.
|
|
|
+//
|
|
|
+// By default, the diff control lines (those with *** or ---) are
|
|
|
+// created with a trailing newline.
|
|
|
+//
|
|
|
+// For inputs that do not have trailing newlines, set the diff.Eol
|
|
|
+// argument to "" so that the output will be uniformly newline free.
|
|
|
+//
|
|
|
+// The context diff format normally has a header for filenames and
|
|
|
+// modification times. Any or all of these may be specified using
|
|
|
+// strings for diff.FromFile, diff.ToFile, diff.FromDate, diff.ToDate.
|
|
|
+// The modification times are normally expressed in the ISO 8601 format.
|
|
|
+// If not specified, the strings default to blanks.
|
|
|
+func WriteContextDiff(writer io.Writer, diff ContextDiff) error {
|
|
|
+ buf := bufio.NewWriter(writer)
|
|
|
+ defer buf.Flush()
|
|
|
+ var diffErr error
|
|
|
+ wf := func(format string, args ...interface{}) {
|
|
|
+ _, err := buf.WriteString(fmt.Sprintf(format, args...))
|
|
|
+ if diffErr == nil && err != nil {
|
|
|
+ diffErr = err
|
|
|
+ }
|
|
|
+ }
|
|
|
+ ws := func(s string) {
|
|
|
+ _, err := buf.WriteString(s)
|
|
|
+ if diffErr == nil && err != nil {
|
|
|
+ diffErr = err
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ if len(diff.Eol) == 0 {
|
|
|
+ diff.Eol = "\n"
|
|
|
+ }
|
|
|
+
|
|
|
+ prefix := map[byte]string{
|
|
|
+ 'i': "+ ",
|
|
|
+ 'd': "- ",
|
|
|
+ 'r': "! ",
|
|
|
+ 'e': " ",
|
|
|
+ }
|
|
|
+
|
|
|
+ started := false
|
|
|
+ m := NewMatcher(diff.A, diff.B)
|
|
|
+ for _, g := range m.GetGroupedOpCodes(diff.Context) {
|
|
|
+ if !started {
|
|
|
+ started = true
|
|
|
+ fromDate := ""
|
|
|
+ if len(diff.FromDate) > 0 {
|
|
|
+ fromDate = "\t" + diff.FromDate
|
|
|
+ }
|
|
|
+ toDate := ""
|
|
|
+ if len(diff.ToDate) > 0 {
|
|
|
+ toDate = "\t" + diff.ToDate
|
|
|
+ }
|
|
|
+ if diff.FromFile != "" || diff.ToFile != "" {
|
|
|
+ wf("*** %s%s%s", diff.FromFile, fromDate, diff.Eol)
|
|
|
+ wf("--- %s%s%s", diff.ToFile, toDate, diff.Eol)
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ first, last := g[0], g[len(g)-1]
|
|
|
+ ws("***************" + diff.Eol)
|
|
|
+
|
|
|
+ range1 := formatRangeContext(first.I1, last.I2)
|
|
|
+ wf("*** %s ****%s", range1, diff.Eol)
|
|
|
+ for _, c := range g {
|
|
|
+ if c.Tag == 'r' || c.Tag == 'd' {
|
|
|
+ for _, cc := range g {
|
|
|
+ if cc.Tag == 'i' {
|
|
|
+ continue
|
|
|
+ }
|
|
|
+ for _, line := range diff.A[cc.I1:cc.I2] {
|
|
|
+ ws(prefix[cc.Tag] + line)
|
|
|
+ }
|
|
|
+ }
|
|
|
+ break
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ range2 := formatRangeContext(first.J1, last.J2)
|
|
|
+ wf("--- %s ----%s", range2, diff.Eol)
|
|
|
+ for _, c := range g {
|
|
|
+ if c.Tag == 'r' || c.Tag == 'i' {
|
|
|
+ for _, cc := range g {
|
|
|
+ if cc.Tag == 'd' {
|
|
|
+ continue
|
|
|
+ }
|
|
|
+ for _, line := range diff.B[cc.J1:cc.J2] {
|
|
|
+ ws(prefix[cc.Tag] + line)
|
|
|
+ }
|
|
|
+ }
|
|
|
+ break
|
|
|
+ }
|
|
|
+ }
|
|
|
+ }
|
|
|
+ return diffErr
|
|
|
+}
|
|
|
+
|
|
|
+// Like WriteContextDiff but returns the diff a string.
|
|
|
+func GetContextDiffString(diff ContextDiff) (string, error) {
|
|
|
+ w := &bytes.Buffer{}
|
|
|
+ err := WriteContextDiff(w, diff)
|
|
|
+ return string(w.Bytes()), err
|
|
|
+}
|
|
|
+
|
|
|
+// Split a string on "\n" while preserving them. The output can be used
|
|
|
+// as input for UnifiedDiff and ContextDiff structures.
|
|
|
+func SplitLines(s string) []string {
|
|
|
+ lines := strings.SplitAfter(s, "\n")
|
|
|
+ lines[len(lines)-1] += "\n"
|
|
|
+ return lines
|
|
|
+}
|
Lucas Servén Marín