relevanssi_add_accent_variations()

relevanssi_add_accent_variations.php

<?php

/**
 * Adds accented variations to letters.
 *
 * In order to have non-accented letters in search terms match the accented terms in
 * full text, this function adds accent variations to the search terms.
 *
 * @param string $word The word to manipulate.
 *
 * @return string The word with accent variations.
 */
function relevanssi_add_accent_variations( $word ) {
	/**
	 * Filters the accent replacement array.
	 *
	 * @param array Array of replacements. 'from' has the source characters, 'to' the replacements.
	 */
	$replacement_arrays = apply_filters('relevanssi_accents_replacement_arrays', array(
		'from' => array( 'a', 'c', 'e', 'i', 'o', 'u', 'n', 'ss' ),
		'to'   => array( '(a|á|à|â)', '(c|ç)', '(e|é|è|ê|ë)', '(i|í|ì|î|ï)', '(o|ó|ò|ô|õ)', '(u|ú|ù|ü|û)', '(n|ñ)', '(ss|ß)' ),
	));

	$len        = mb_strlen( $word );
	$word_array = array();
	for ( $i = 0; $i < $len; $i++ ) {
		$char         = mb_substr( $word, $i, 1 );
		$word_array[] = $char;
	}
	$word = implode( '-?', $word_array );

	$word = str_ireplace( $replacement_arrays['from'], $replacement_arrays['to'], $word );

	$word = preg_replace( '/s$/', "(s|'s|’s)", $word );
	$word = preg_replace( '/^o/', "(o|o'|o’)", $word );

	return $word;
}