dispatch/vendor/github.com/couchbase/vellum/levenshtein/rune.go
2018-05-04 23:39:27 +02:00

79 lines
1.8 KiB
Go

// Copyright (c) 2017 Couchbase, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package levenshtein
import "unicode/utf8"
// dynamicLevenshtein is the rune-based automaton, which is used
// during the building of the ut8-aware byte-based automaton
type dynamicLevenshtein struct {
query string
distance uint
}
func (d *dynamicLevenshtein) start() []int {
runeCount := utf8.RuneCountInString(d.query)
rv := make([]int, runeCount+1)
for i := 0; i < runeCount+1; i++ {
rv[i] = i
}
return rv
}
func (d *dynamicLevenshtein) isMatch(state []int) bool {
last := state[len(state)-1]
if uint(last) <= d.distance {
return true
}
return false
}
func (d *dynamicLevenshtein) canMatch(state []int) bool {
if len(state) > 0 {
min := state[0]
for i := 1; i < len(state); i++ {
if state[i] < min {
min = state[i]
}
}
if uint(min) <= d.distance {
return true
}
}
return false
}
func (d *dynamicLevenshtein) accept(state []int, r *rune) []int {
next := []int{state[0] + 1}
i := 0
for _, c := range d.query {
var cost int
if r == nil || c != *r {
cost = 1
}
v := min(min(next[i]+1, state[i+1]+1), state[i]+cost)
next = append(next, min(v, int(d.distance)+1))
i++
}
return next
}
func min(a, b int) int {
if a < b {
return a
}
return b
}