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52 lines
1.1 KiB
Go
52 lines
1.1 KiB
Go
// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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package comparer
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import "bytes"
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type bytesComparer struct{}
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func (bytesComparer) Compare(a, b []byte) int {
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return bytes.Compare(a, b)
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}
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func (bytesComparer) Name() string {
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return "leveldb.BytewiseComparator"
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}
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func (bytesComparer) Separator(dst, a, b []byte) []byte {
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i, n := 0, len(a)
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if n > len(b) {
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n = len(b)
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}
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for ; i < n && a[i] == b[i]; i++ {
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}
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if i >= n {
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// Do not shorten if one string is a prefix of the other
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} else if c := a[i]; c < 0xff && c+1 < b[i] {
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dst = append(dst, a[:i+1]...)
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dst[len(dst)-1]++
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return dst
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}
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return nil
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}
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func (bytesComparer) Successor(dst, b []byte) []byte {
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for i, c := range b {
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if c != 0xff {
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dst = append(dst, b[:i+1]...)
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dst[len(dst)-1]++
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return dst
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}
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}
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return nil
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}
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// DefaultComparer are default implementation of the Comparer interface.
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// It uses the natural ordering, consistent with bytes.Compare.
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var DefaultComparer = bytesComparer{}
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