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93 lines
2.5 KiB
93 lines
2.5 KiB
// Copyright (c) 2014 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package analysis
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import (
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"bytes"
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"unicode/utf8"
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)
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func DeleteRune(in []rune, pos int) []rune {
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if pos >= len(in) {
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return in
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}
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copy(in[pos:], in[pos+1:])
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return in[:len(in)-1]
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}
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func InsertRune(in []rune, pos int, r rune) []rune {
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// create a new slice 1 rune larger
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rv := make([]rune, len(in)+1)
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// copy the characters before the insert pos
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copy(rv[0:pos], in[0:pos])
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// set the inserted rune
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rv[pos] = r
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// copy the characters after the insert pos
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copy(rv[pos+1:], in[pos:])
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return rv
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}
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// BuildTermFromRunesOptimistic will build a term from the provided runes
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// AND optimistically attempt to encode into the provided buffer
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// if at any point it appears the buffer is too small, a new buffer is
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// allocated and that is used instead
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// this should be used in cases where frequently the new term is the same
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// length or shorter than the original term (in number of bytes)
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func BuildTermFromRunesOptimistic(buf []byte, runes []rune) []byte {
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rv := buf
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used := 0
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for _, r := range runes {
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nextLen := utf8.RuneLen(r)
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if used+nextLen > len(rv) {
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// alloc new buf
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buf = make([]byte, len(runes)*utf8.UTFMax)
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// copy work we've already done
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copy(buf, rv[:used])
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rv = buf
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}
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written := utf8.EncodeRune(rv[used:], r)
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used += written
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}
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return rv[:used]
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}
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func BuildTermFromRunes(runes []rune) []byte {
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return BuildTermFromRunesOptimistic(make([]byte, len(runes)*utf8.UTFMax), runes)
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}
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func TruncateRunes(input []byte, num int) []byte {
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runes := bytes.Runes(input)
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runes = runes[:len(runes)-num]
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out := BuildTermFromRunes(runes)
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return out
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}
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func RunesEndsWith(input []rune, suffix string) bool {
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inputLen := len(input)
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suffixRunes := []rune(suffix)
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suffixLen := len(suffixRunes)
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if suffixLen > inputLen {
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return false
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}
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for i := suffixLen - 1; i >= 0; i-- {
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if input[inputLen-(suffixLen-i)] != suffixRunes[i] {
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return false
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}
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}
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return true
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}
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