gf/text/gstr/gstr_levenshtein.go

// Copyright 2018 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

package gstr

// Levenshtein calculates Levenshtein distance between two strings.
// costIns: Defines the cost of insertion.
// costRep: Defines the cost of replacement.
// costDel: Defines the cost of deletion.
// See http://php.net/manual/en/function.levenshtein.php.
func Levenshtein(str1, str2 string, costIns, costRep, costDel int) int {
	var maxLen = 255
	l1 := len(str1)
	l2 := len(str2)
	if l1 == 0 {
		return l2 * costIns
	}
	if l2 == 0 {
		return l1 * costDel
	}
	if l1 > maxLen || l2 > maxLen {
		return -1
	}

	tmp := make([]int, l2+1)
	p1 := make([]int, l2+1)
	p2 := make([]int, l2+1)
	var c0, c1, c2 int
	var i1, i2 int
	for i2 := 0; i2 <= l2; i2++ {
		p1[i2] = i2 * costIns
	}
	for i1 = 0; i1 < l1; i1++ {
		p2[0] = p1[0] + costDel
		for i2 = 0; i2 < l2; i2++ {
			if str1[i1] == str2[i2] {
				c0 = p1[i2]
			} else {
				c0 = p1[i2] + costRep
			}
			c1 = p1[i2+1] + costDel
			if c1 < c0 {
				c0 = c1
			}
			c2 = p2[i2] + costIns
			if c2 < c0 {
				c0 = c2
			}
			p2[i2+1] = c0
		}
		tmp = p1
		p1 = p2
		p2 = tmp
	}
	c0 = p1[l2]

	return c0
}