79 lines
1.8 KiB
Go
79 lines
1.8 KiB
Go
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// Copyright (c) 2017 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 levenshtein
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import "unicode/utf8"
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// dynamicLevenshtein is the rune-based automaton, which is used
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// during the building of the ut8-aware byte-based automaton
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type dynamicLevenshtein struct {
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query string
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distance uint
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}
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func (d *dynamicLevenshtein) start() []int {
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runeCount := utf8.RuneCountInString(d.query)
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rv := make([]int, runeCount+1)
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for i := 0; i < runeCount+1; i++ {
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rv[i] = i
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}
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return rv
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}
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func (d *dynamicLevenshtein) isMatch(state []int) bool {
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last := state[len(state)-1]
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if uint(last) <= d.distance {
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return true
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}
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return false
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}
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func (d *dynamicLevenshtein) canMatch(state []int) bool {
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if len(state) > 0 {
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min := state[0]
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for i := 1; i < len(state); i++ {
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if state[i] < min {
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min = state[i]
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}
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}
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if uint(min) <= d.distance {
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return true
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}
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}
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return false
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}
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func (d *dynamicLevenshtein) accept(state []int, r *rune) []int {
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next := []int{state[0] + 1}
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i := 0
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for _, c := range d.query {
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var cost int
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if r == nil || c != *r {
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cost = 1
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}
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v := min(min(next[i]+1, state[i+1]+1), state[i]+cost)
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next = append(next, min(v, int(d.distance)+1))
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i++
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}
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return next
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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