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WP_Text_Diff_Renderer_Table::compute_string_distance( string $string1, string $string2 )

Computes a number that is intended to reflect the “distance” between two strings.

Parameters

$string1

(string) (Required)

$string2

(string) (Required)

Return

(int)

Source

File: wp-includes/class-wp-text-diff-renderer-table.php 

public function compute_string_distance( $string1, $string2 ) {
		// Use an md5 hash of the strings for a count cache, as it's fast to generate, and collisions aren't a concern.
		$count_key1 = md5( $string1 );
		$count_key2 = md5( $string2 );

		// Cache vectors containing character frequency for all chars in each string.
		if ( ! isset( $this->count_cache[ $count_key1 ] ) ) {
			$this->count_cache[ $count_key1 ] = count_chars( $string1 );
		}
		if ( ! isset( $this->count_cache[ $count_key2 ] ) ) {
			$this->count_cache[ $count_key2 ] = count_chars( $string2 );
		}

		$chars1 = $this->count_cache[ $count_key1 ];
		$chars2 = $this->count_cache[ $count_key2 ];

		$difference_key = md5( implode( ',', $chars1 ) . ':' . implode( ',', $chars2 ) );
		if ( ! isset( $this->difference_cache[ $difference_key ] ) ) {
			// L1-norm of difference vector.
			$this->difference_cache[ $difference_key ] = array_sum( array_map( array( $this, 'difference' ), $chars1, $chars2 ) );
		}

		$difference = $this->difference_cache[ $difference_key ];

		// $string1 has zero length? Odd. Give huge penalty by not dividing.
		if ( ! $string1 ) {
			return $difference;
		}

		// Return distance per character (of string1).
		return $difference / strlen( $string1 );
	}

Changelog

Version Description
2.6.0 Introduced.

© 2003–2019 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/compute_string_distance