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- // Package difflib is a partial port of Python difflib module.
- //
- // It provides tools to compare sequences of strings and generate textual diffs.
- //
- // The following class and functions have been ported:
- //
- // - SequenceMatcher
- //
- // - unified_diff
- //
- // - context_diff
- //
- // Getting unified diffs was the main goal of the port. Keep in mind this code
- // is mostly suitable to output text differences in a human friendly way, there
- // are no guarantees generated diffs are consumable by patch(1).
- package difflib
- import (
- "bufio"
- "bytes"
- "fmt"
- "io"
- "strings"
- )
- func min(a, b int) int {
- if a < b {
- return a
- }
- return b
- }
- func max(a, b int) int {
- if a > b {
- return a
- }
- return b
- }
- func calculateRatio(matches, length int) float64 {
- if length > 0 {
- return 2.0 * float64(matches) / float64(length)
- }
- return 1.0
- }
- 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 strings. 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 []string
- b []string
- b2j map[string][]int
- IsJunk func(string) bool
- autoJunk bool
- bJunk map[string]struct{}
- matchingBlocks []Match
- fullBCount map[string]int
- bPopular map[string]struct{}
- opCodes []OpCode
- }
- func NewMatcher(a, b []string) *SequenceMatcher {
- m := SequenceMatcher{autoJunk: true}
- m.SetSeqs(a, b)
- return &m
- }
- func NewMatcherWithJunk(a, b []string, autoJunk bool,
- isJunk func(string) bool) *SequenceMatcher {
- m := SequenceMatcher{IsJunk: isJunk, autoJunk: autoJunk}
- m.SetSeqs(a, b)
- return &m
- }
- // Set two sequences to be compared.
- func (m *SequenceMatcher) SetSeqs(a, b []string) {
- 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 []string) {
- 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 []string) {
- 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[string][]int{}
- for i, s := range m.b {
- indices := b2j[s]
- indices = append(indices, i)
- b2j[s] = indices
- }
- // Purge junk elements
- m.bJunk = map[string]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[string]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 string) 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
- }
- // 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 = '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
- }
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