/* Copyright 2019 The Kubernetes Authors. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ package diff import ( "bytes" "strings" "github.com/sergi/go-diff/diffmatchpatch" "k8s.io/klog/v2" ) func FormatDiff(lString, rString string) string { results := buildDiffLines(lString, rString) return renderText(results, 2) } func renderText(results []lineRecord, context int) string { keep := make([]bool, len(results)) for i := range results { if results[i].Type == diffmatchpatch.DiffEqual { continue } for j := i - context; j <= i+context; j++ { if j >= 0 && j < len(keep) { keep[j] = true } } } var b bytes.Buffer wroteSkip := false for i := range results { if !keep[i] { if !wroteSkip { b.WriteString("...\n") wroteSkip = true } continue } switch results[i].Type { case diffmatchpatch.DiffDelete: b.WriteString("- ") case diffmatchpatch.DiffInsert: b.WriteString("+ ") case diffmatchpatch.DiffEqual: b.WriteString(" ") } b.WriteString(results[i].Line) b.WriteString("\n") wroteSkip = false } return b.String() } type lineRecord struct { Type diffmatchpatch.Operation Line string } func buildDiffLines(lString, rString string) []lineRecord { dmp := diffmatchpatch.New() diffs := dmp.DiffMain(lString, rString, false) // We do need to cleanup, as otherwise we get some spurious changes on complex diffs diffs = dmp.DiffCleanupSemantic(diffs) var l, r string var results []lineRecord for _, diff := range diffs { lines := strings.Split(diff.Text, "\n") switch diff.Type { case diffmatchpatch.DiffInsert: if len(lines) > 0 { r += lines[0] if len(lines) > 1 { results = append(results, lineRecord{Type: diffmatchpatch.DiffInsert, Line: r}) r = "" } } for i := 1; i < len(lines)-1; i++ { line := lines[i] results = append(results, lineRecord{Type: diffmatchpatch.DiffInsert, Line: line}) } if len(lines) > 1 { r = lines[len(lines)-1] } case diffmatchpatch.DiffDelete: if len(lines) > 0 { l += lines[0] if len(lines) > 1 { results = append(results, lineRecord{Type: diffmatchpatch.DiffDelete, Line: l}) l = "" } } for i := 1; i < len(lines)-1; i++ { line := lines[i] results = append(results, lineRecord{Type: diffmatchpatch.DiffDelete, Line: line}) } if len(lines) > 1 { l = lines[len(lines)-1] } case diffmatchpatch.DiffEqual: if len(lines) == 1 { l += lines[0] r += lines[0] } if len(lines) > 1 { if l != "" || r != "" { l += lines[0] r += lines[0] } else { results = append(results, lineRecord{Type: diffmatchpatch.DiffEqual, Line: lines[0]}) } if r != "" { results = append(results, lineRecord{Type: diffmatchpatch.DiffInsert, Line: r}) r = "" } if l != "" { results = append(results, lineRecord{Type: diffmatchpatch.DiffDelete, Line: l}) l = "" } } for i := 1; i < len(lines)-1; i++ { line := lines[i] results = append(results, lineRecord{Type: diffmatchpatch.DiffEqual, Line: line}) } if len(lines) > 1 { l = lines[len(lines)-1] r = lines[len(lines)-1] } default: klog.Fatalf("unexpected dmp type: %v", diff.Type) } } if l != "" && l == r { results = append(results, lineRecord{Type: diffmatchpatch.DiffEqual, Line: l}) } else { if l != "" { results = append(results, lineRecord{Type: diffmatchpatch.DiffDelete, Line: l}) } if r != "" { results = append(results, lineRecord{Type: diffmatchpatch.DiffInsert, Line: r}) } } return results }