gstr_similartext.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

// SimilarText calculates the similarity between two strings.
// See http://php.net/manual/en/function.similar-text.php.
func SimilarText(first, second string, percent *float64) int {
	var similarText func(string, string, int, int) int
	similarText = func(str1, str2 string, len1, len2 int) int {
		var sum, max int
		pos1, pos2 := 0, 0

		// Find the longest segment of the same section in two strings
		for i := 0; i < len1; i++ {
			for j := 0; j < len2; j++ {
				for l := 0; (i+l < len1) && (j+l < len2) && (str1[i+l] == str2[j+l]); l++ {
					if l+1 > max {
						max = l + 1
						pos1 = i
						pos2 = j
					}
				}
			}
		}

		if sum = max; sum > 0 {
			if pos1 > 0 && pos2 > 0 {
				sum += similarText(str1, str2, pos1, pos2)
			}
			if (pos1+max < len1) && (pos2+max < len2) {
				s1 := []byte(str1)
				s2 := []byte(str2)
				sum += similarText(string(s1[pos1+max:]), string(s2[pos2+max:]), len1-pos1-max, len2-pos2-max)
			}
		}

		return sum
	}

	l1, l2 := len(first), len(second)
	if l1+l2 == 0 {
		return 0
	}
	sim := similarText(first, second, l1, l2)
	if percent != nil {
		*percent = float64(sim*200) / float64(l1+l2)
	}
	return sim
}