1// Copyright 2017 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Copied from go1.17 tree: //src/cmd/internal/edit/edit.go 6 7// Package edit implements buffered position-based editing of byte slices. 8package main 9 10import ( 11 "fmt" 12 "sort" 13) 14 15// A Buffer is a queue of edits to apply to a given byte slice. 16type Buffer struct { 17 old []byte 18 q edits 19} 20 21// An edit records a single text modification: change the bytes in [start,end) to new. 22type edit struct { 23 start int 24 end int 25 new string 26} 27 28// An edits is a list of edits that is sortable by start offset, breaking ties by end offset. 29type edits []edit 30 31func (x edits) Len() int { return len(x) } 32func (x edits) Swap(i, j int) { x[i], x[j] = x[j], x[i] } 33func (x edits) Less(i, j int) bool { 34 if x[i].start != x[j].start { 35 return x[i].start < x[j].start 36 } 37 return x[i].end < x[j].end 38} 39 40// NewBuffer returns a new buffer to accumulate changes to an initial data slice. 41// The returned buffer maintains a reference to the data, so the caller must ensure 42// the data is not modified until after the Buffer is done being used. 43func NewBuffer(data []byte) *Buffer { 44 return &Buffer{old: data} 45} 46 47func (b *Buffer) Insert(pos int, new string) { 48 if pos < 0 || pos > len(b.old) { 49 panic("invalid edit position") 50 } 51 b.q = append(b.q, edit{pos, pos, new}) 52} 53 54func (b *Buffer) Delete(start, end int) { 55 if end < start || start < 0 || end > len(b.old) { 56 panic("invalid edit position") 57 } 58 b.q = append(b.q, edit{start, end, ""}) 59} 60 61func (b *Buffer) Replace(start, end int, new string) { 62 if end < start || start < 0 || end > len(b.old) { 63 panic("invalid edit position") 64 } 65 b.q = append(b.q, edit{start, end, new}) 66} 67 68// Bytes returns a new byte slice containing the original data 69// with the queued edits applied. 70func (b *Buffer) Bytes() []byte { 71 // Sort edits by starting position and then by ending position. 72 // Breaking ties by ending position allows insertions at point x 73 // to be applied before a replacement of the text at [x, y). 74 sort.Stable(b.q) 75 76 var new []byte 77 offset := 0 78 for i, e := range b.q { 79 if e.start < offset { 80 e0 := b.q[i-1] 81 panic(fmt.Sprintf("overlapping edits: [%d,%d)->%q, [%d,%d)->%q", e0.start, e0.end, e0.new, e.start, e.end, e.new)) 82 } 83 new = append(new, b.old[offset:e.start]...) 84 offset = e.end 85 new = append(new, e.new...) 86 } 87 new = append(new, b.old[offset:]...) 88 return new 89} 90 91// String returns a string containing the original data 92// with the queued edits applied. 93func (b *Buffer) String() string { 94 return string(b.Bytes()) 95} 96