*: revendor
This commit is contained in:
Eric Chiang
133
vendor/github.com/kylelemons/godebug/diff/diff.go
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vendored
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133
vendor/github.com/kylelemons/godebug/diff/diff.go
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// Copyright 2013 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package diff implements a linewise diff algorithm.
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package diff
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import (
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"bytes"
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"fmt"
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"strings"
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)
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// Chunk represents a piece of the diff. A chunk will not have both added and
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// deleted lines. Equal lines are always after any added or deleted lines.
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// A Chunk may or may not have any lines in it, especially for the first or last
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// chunk in a computation.
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type Chunk struct {
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Added []string
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Deleted []string
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Equal []string
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}
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// Diff returns a string containing a line-by-line unified diff of the linewise
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// changes required to make A into B. Each line is prefixed with '+', '-', or
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// ' ' to indicate if it should be added, removed, or is correct respectively.
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func Diff(A, B string) string {
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aLines := strings.Split(A, "\n")
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bLines := strings.Split(B, "\n")
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chunks := DiffChunks(aLines, bLines)
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buf := new(bytes.Buffer)
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for _, c := range chunks {
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for _, line := range c.Added {
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fmt.Fprintf(buf, "+%s\n", line)
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}
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for _, line := range c.Deleted {
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fmt.Fprintf(buf, "-%s\n", line)
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}
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for _, line := range c.Equal {
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fmt.Fprintf(buf, " %s\n", line)
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}
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}
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return strings.TrimRight(buf.String(), "\n")
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}
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// DiffChunks uses an O(D(N+M)) shortest-edit-script algorithm
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// to compute the edits required from A to B and returns the
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// edit chunks.
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func DiffChunks(A, B []string) []Chunk {
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// algorithm: http://www.xmailserver.org/diff2.pdf
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N, M := len(A), len(B)
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MAX := N + M
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V := make([]int, 2*MAX+1)
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Vs := make([][]int, 0, 8)
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var D int
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dLoop:
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for D = 0; D <= MAX; D++ {
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for k := -D; k <= D; k += 2 {
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var x int
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if k == -D || (k != D && V[MAX+k-1] < V[MAX+k+1]) {
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x = V[MAX+k+1]
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} else {
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x = V[MAX+k-1] + 1
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}
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y := x - k
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for x < N && y < M && A[x] == B[y] {
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x++
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y++
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}
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V[MAX+k] = x
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if x >= N && y >= M {
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Vs = append(Vs, append(make([]int, 0, len(V)), V...))
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break dLoop
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}
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}
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Vs = append(Vs, append(make([]int, 0, len(V)), V...))
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}
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if D == 0 {
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return nil
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}
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chunks := make([]Chunk, D+1)
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x, y := N, M
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for d := D; d > 0; d-- {
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V := Vs[d]
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k := x - y
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insert := k == -d || (k != d && V[MAX+k-1] < V[MAX+k+1])
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x1 := V[MAX+k]
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var x0, xM, kk int
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if insert {
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kk = k + 1
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x0 = V[MAX+kk]
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xM = x0
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} else {
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kk = k - 1
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x0 = V[MAX+kk]
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xM = x0 + 1
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}
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y0 := x0 - kk
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var c Chunk
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if insert {
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c.Added = B[y0:][:1]
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} else {
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c.Deleted = A[x0:][:1]
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}
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if xM < x1 {
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c.Equal = A[xM:][:x1-xM]
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}
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x, y = x0, y0
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chunks[d] = c
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}
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if x > 0 {
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chunks[0].Equal = A[:x]
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}
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return chunks
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}
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120
vendor/github.com/kylelemons/godebug/diff/diff_test.go
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120
vendor/github.com/kylelemons/godebug/diff/diff_test.go
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@@ -0,0 +1,120 @@
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// Copyright 2013 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package diff
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import (
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"fmt"
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"reflect"
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"strings"
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"testing"
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)
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func TestDiff(t *testing.T) {
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tests := []struct {
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desc string
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A, B []string
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chunks []Chunk
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}{
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{
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desc: "constitution",
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A: []string{
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"We the People of the United States, in Order to form a more perfect Union,",
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"establish Justice, insure domestic Tranquility, provide for the common defence,",
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"and secure the Blessings of Liberty to ourselves",
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"and our Posterity, do ordain and establish this Constitution for the United",
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"States of America.",
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},
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B: []string{
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"We the People of the United States, in Order to form a more perfect Union,",
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"establish Justice, insure domestic Tranquility, provide for the common defence,",
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"promote the general Welfare, and secure the Blessings of Liberty to ourselves",
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"and our Posterity, do ordain and establish this Constitution for the United",
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"States of America.",
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},
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chunks: []Chunk{
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0: {
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Equal: []string{
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"We the People of the United States, in Order to form a more perfect Union,",
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"establish Justice, insure domestic Tranquility, provide for the common defence,",
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},
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},
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1: {
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Deleted: []string{
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"and secure the Blessings of Liberty to ourselves",
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},
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},
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2: {
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Added: []string{
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"promote the general Welfare, and secure the Blessings of Liberty to ourselves",
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},
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Equal: []string{
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"and our Posterity, do ordain and establish this Constitution for the United",
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"States of America.",
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},
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},
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},
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},
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}
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for _, test := range tests {
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got := DiffChunks(test.A, test.B)
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if got, want := len(got), len(test.chunks); got != want {
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t.Errorf("%s: edit distance = %v, want %v", test.desc, got-1, want-1)
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continue
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}
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for i := range got {
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got, want := got[i], test.chunks[i]
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if got, want := got.Added, want.Added; !reflect.DeepEqual(got, want) {
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t.Errorf("%s[%d]: Added = %v, want %v", test.desc, i, got, want)
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}
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if got, want := got.Deleted, want.Deleted; !reflect.DeepEqual(got, want) {
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t.Errorf("%s[%d]: Deleted = %v, want %v", test.desc, i, got, want)
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}
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if got, want := got.Equal, want.Equal; !reflect.DeepEqual(got, want) {
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t.Errorf("%s[%d]: Equal = %v, want %v", test.desc, i, got, want)
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}
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}
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}
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}
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func ExampleDiff() {
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constitution := strings.TrimSpace(`
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We the People of the United States, in Order to form a more perfect Union,
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establish Justice, insure domestic Tranquility, provide for the common defence,
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promote the general Welfare, and secure the Blessings of Liberty to ourselves
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and our Posterity, do ordain and establish this Constitution for the United
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States of America.
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`)
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got := strings.TrimSpace(`
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:wq
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We the People of the United States, in Order to form a more perfect Union,
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establish Justice, insure domestic Tranquility, provide for the common defence,
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and secure the Blessings of Liberty to ourselves
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and our Posterity, do ordain and establish this Constitution for the United
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States of America.
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`)
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fmt.Println(Diff(got, constitution))
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// Output:
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// -:wq
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// We the People of the United States, in Order to form a more perfect Union,
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// establish Justice, insure domestic Tranquility, provide for the common defence,
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// -and secure the Blessings of Liberty to ourselves
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// +promote the general Welfare, and secure the Blessings of Liberty to ourselves
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// and our Posterity, do ordain and establish this Constitution for the United
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// States of America.
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}
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