PHP Recursive str_replace: replaceTree

1 minute read

Working with trees

When working with tree data structures you often need to craft them in different ways. PHP offers a lot of functions to change the shape of arrays, but often they only go 1 level deep. Trees can count an almost infinite number of levels. Hence we need recursive replacements for our beloved array & string functions.

replaceTree

replaceTree is the tree version of str_replace. It will recursively replace through an array of strings.

<?php
/**
 * Recursive alternative to str_replace that supports replacing keys as well
 *
 * The following code block can be utilized by PEAR's Testing_DocTest
 * <code>
 * // Input //
 * $settings = array(
 *	 "Credits" => "@appname@ created by @author@",
 *	 "Description" => "@appname@ can parse logfiles and store then in mysql",
 *	 "@author@_mail" => "kevin@vanzonneveld.net"
 * );
 * $mapping = array(
 *	 "@author@" => "kevin",
 *	 "@appname@" => "logchopper"
 * );
 *
 * // Execute //
 * $settings = replaceTree(
 *	 array_keys($mapping), array_values($mapping), $settings, true
 * );
 *
 * // Show //
 * print_r($settings);
 *
 * // expects:
 * // Array
 * // (
 * //	 [Credits] => logchopper created by kevin
 * //	 [Description] => logchopper can parse logfiles and store then in mysql
 * //	 [kevin_mail] => kevin@vanzonneveld.net
 * // )
 * </code>
 *
 * @param string  $search
 * @param string  $replace
 * @param array   $array
 * @param boolean $keys_too
 *
 * @return array
 */
function replaceTree($search="", $replace="", $array=false, $keys_too=false)
{
	if (!is_array($array)) {
		// Regular replace
		return str_replace($search, $replace, $array);
	}

	$newArr = array();
	foreach ($array as $k=>$v) {
		// Replace keys as well?
		$add_key = $k;
		if ($keys_too) {
			$add_key = str_replace($search, $replace, $k);
		}

		// Recurse
		$newArr[$add_key] = replaceTree($search, $replace, $v, $keys_too);
	}
	return $newArr;
}
?>

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