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Copyright (c) 2013, Patrick Mezard |
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All rights reserved. |
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions are |
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met: |
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|
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Redistributions of source code must retain the above copyright |
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notice, this list of conditions and the following disclaimer. |
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Redistributions in binary form must reproduce the above copyright |
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notice, this list of conditions and the following disclaimer in the |
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documentation and/or other materials provided with the distribution. |
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The names of its contributors may not be used to endorse or promote |
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products derived from this software without specific prior written |
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permission. |
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|
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A |
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PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED |
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TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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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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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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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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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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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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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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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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// 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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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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func NewMatcherWithJunk(a, b []string, autoJunk bool, |
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isJunk func(string) bool) *SequenceMatcher { |
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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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// 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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// 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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// 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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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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// 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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// 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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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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// 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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// 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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// 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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// 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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return Match{A: besti, B: bestj, Size: bestsize} |
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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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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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// 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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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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// 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 { |
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tag = 'r' |
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} else if i < ai { |
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tag = 'd' |
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} else if j < bj { |
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tag = 'i' |
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} |
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if tag > 0 { |
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opCodes = append(opCodes, OpCode{tag, i, ai, j, bj}) |
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} |
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i, j = ai+size, bj+size |
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// the list of matching blocks is terminated by a
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// sentinel with size 0
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if size > 0 { |
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opCodes = append(opCodes, OpCode{'e', ai, i, bj, j}) |
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} |
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} |
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m.opCodes = opCodes |
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return m.opCodes |
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} |
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// Isolate change clusters by eliminating ranges with no changes.
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//
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// Return a generator of groups with up to n lines of context.
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// Each group is in the same format as returned by GetOpCodes().
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func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode { |
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if n < 0 { |
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n = 3 |
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} |
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codes := m.GetOpCodes() |
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if len(codes) == 0 { |
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codes = []OpCode{OpCode{'e', 0, 1, 0, 1}} |
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} |
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// Fixup leading and trailing groups if they show no changes.
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if codes[0].Tag == 'e' { |
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c := codes[0] |
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i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2 |
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codes[0] = OpCode{c.Tag, max(i1, i2-n), i2, max(j1, j2-n), j2} |
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} |
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if codes[len(codes)-1].Tag == 'e' { |
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c := codes[len(codes)-1] |
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i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2 |
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codes[len(codes)-1] = OpCode{c.Tag, i1, min(i2, i1+n), j1, min(j2, j1+n)} |
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} |
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nn := n + n |
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groups := [][]OpCode{} |
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group := []OpCode{} |
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for _, c := range codes { |
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i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2 |
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// End the current group and start a new one whenever
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// there is a large range with no changes.
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if c.Tag == 'e' && i2-i1 > nn { |
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group = append(group, OpCode{c.Tag, i1, min(i2, i1+n), |
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j1, min(j2, j1+n)}) |
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groups = append(groups, group) |
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group = []OpCode{} |
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i1, j1 = max(i1, i2-n), max(j1, j2-n) |
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} |
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group = append(group, OpCode{c.Tag, i1, i2, j1, j2}) |
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} |
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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 |
||||
} |
||||
Loading…
Reference in new issue