зеркало из https://github.com/golang/tools.git
97 строки
2.6 KiB
Go
97 строки
2.6 KiB
Go
// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package edit implements buffered position-based editing of byte slices.
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package edit
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import (
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"fmt"
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"sort"
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)
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// A Buffer is a queue of edits to apply to a given byte slice.
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type Buffer struct {
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old []byte
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q edits
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}
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// An edit records a single text modification: change the bytes in [start,end) to new.
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type edit struct {
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start int
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end int
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new string
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}
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// An edits is a list of edits that is sortable by start offset, breaking ties by end offset.
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type edits []edit
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func (x edits) Len() int { return len(x) }
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func (x edits) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
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func (x edits) Less(i, j int) bool {
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if x[i].start != x[j].start {
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return x[i].start < x[j].start
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}
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return x[i].end < x[j].end
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}
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// NewBuffer returns a new buffer to accumulate changes to an initial data slice.
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// The returned buffer maintains a reference to the data, so the caller must ensure
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// the data is not modified until after the Buffer is done being used.
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func NewBuffer(old []byte) *Buffer {
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return &Buffer{old: old}
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}
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// Insert inserts the new string at old[pos:pos].
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func (b *Buffer) Insert(pos int, new string) {
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if pos < 0 || pos > len(b.old) {
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panic("invalid edit position")
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}
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b.q = append(b.q, edit{pos, pos, new})
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}
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// Delete deletes the text old[start:end].
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func (b *Buffer) Delete(start, end int) {
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if end < start || start < 0 || end > len(b.old) {
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panic("invalid edit position")
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}
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b.q = append(b.q, edit{start, end, ""})
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}
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// Replace replaces old[start:end] with new.
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func (b *Buffer) Replace(start, end int, new string) {
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if end < start || start < 0 || end > len(b.old) {
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panic("invalid edit position")
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}
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b.q = append(b.q, edit{start, end, new})
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}
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// Bytes returns a new byte slice containing the original data
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// with the queued edits applied.
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func (b *Buffer) Bytes() []byte {
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// Sort edits by starting position and then by ending position.
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// Breaking ties by ending position allows insertions at point x
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// to be applied before a replacement of the text at [x, y).
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sort.Stable(b.q)
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var new []byte
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offset := 0
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for i, e := range b.q {
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if e.start < offset {
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e0 := b.q[i-1]
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panic(fmt.Sprintf("overlapping edits: [%d,%d)->%q, [%d,%d)->%q", e0.start, e0.end, e0.new, e.start, e.end, e.new))
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}
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new = append(new, b.old[offset:e.start]...)
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offset = e.end
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new = append(new, e.new...)
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}
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new = append(new, b.old[offset:]...)
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return new
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}
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// String returns a string containing the original data
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// with the queued edits applied.
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func (b *Buffer) String() string {
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return string(b.Bytes())
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}
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