91 lines
1.6 KiB
Go
91 lines
1.6 KiB
Go
// Copyright 2013 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 collate
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import (
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"bytes"
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"sort"
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)
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const (
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maxSortBuffer = 40960
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maxSortEntries = 4096
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)
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type swapper interface {
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Swap(i, j int)
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}
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type sorter struct {
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buf *Buffer
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keys [][]byte
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src swapper
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}
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func (s *sorter) init(n int) {
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if s.buf == nil {
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s.buf = &Buffer{}
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s.buf.init()
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}
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if cap(s.keys) < n {
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s.keys = make([][]byte, n)
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}
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s.keys = s.keys[0:n]
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}
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func (s *sorter) clean() {
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if len(s.buf.key) > maxSortBuffer {
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s.buf.key = s.buf.buf[:0]
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}
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if len(s.keys) > maxSortEntries {
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s.keys = nil
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}
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}
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func (s *sorter) sort(src swapper) {
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s.src = src
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sort.Sort(s)
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}
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func (s sorter) Len() int {
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return len(s.keys)
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}
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func (s sorter) Less(i, j int) bool {
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return bytes.Compare(s.keys[i], s.keys[j]) == -1
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}
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func (s sorter) Swap(i, j int) {
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s.keys[i], s.keys[j] = s.keys[j], s.keys[i]
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s.src.Swap(i, j)
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}
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// A Lister can be sorted by Collator's Sort method.
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type Lister interface {
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Len() int
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Swap(i, j int)
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// Bytes returns the bytes of the text at index i.
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Bytes(i int) []byte
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}
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// Sort uses sort.Sort to sort the strings represented by x using the rules of c.
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func (c *Collator) Sort(x Lister) {
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n := x.Len()
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c.sorter.init(n)
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for i := 0; i < n; i++ {
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c.sorter.keys[i] = c.Key(c.sorter.buf, x.Bytes(i))
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}
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c.sorter.sort(x)
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}
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// Strings sorts x using the rules of c.
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func (c *Collator) Strings(x []string) {
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c.sorter.init(len(x))
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for i, s := range x {
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c.sorter.keys[i] = c.KeyFromString(c.sorter.buf, s)
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}
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c.sorter.sort(sort.StringSlice(x))
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}
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