Call a function on each combination of the values of multiple arrays. When array_map etc. isn't enough.

do_with_arrays.php

<?php
/**
 * Call a function on each combination of the values of multiple arrays.
 *
 * First parameter should by a callable function name or an array with the
 * following key value pairs:
 *
 *   'callback'    string  A callable function or method name.
 *   'break_early' boolean True if function can quit early.
 *   'break_on'    mixed   Value that if returned by callback will short-circuit iteration.
 *
 * The second and following parameters should be arrays of values to be passed into the
 * callback function.
 *
 * Example:
 * do_with_arrays( 'printf', '%s %s, ', array('red','green','yellow'),array('apples','peppers'));
 *
 * Prints: red apples, red peppers, green apples, green peppers, yellow apples, yellow peppers,
 *
 * @return mixed An nested array of values returned from callback or the break_on value.
 */
function do_with_arrays() {
	// Function accepts multiple arrays to iterate through.
	$arrays = func_get_args();
	$args = array();

	/**
	 * The first argument is either the function we call on each combination of values
	 * requested or an array of additional arguments.
	 */
	$first_arg = array_shift( $arrays );
	if ( is_callable( $first_arg ) ) {
		$args['callback'] = $first_arg;
	} elseif ( isset( $first_arg['callback'] ) && is_callable( $args['callback'] ) ) {
		$args = $first_arg;
	} else {
		return false;
	}

	// Set defaults for breaking early.
	$args = array_merge( array(
		'break_early' => false,
		'break_on' => false,
	), $args );

	// Values are set up, now start doing the real work.
	return _private_do_with_arrays( $args, $arrays );
}

/**
 * Not intended to be called directly. Parameters are set up inside do_with_arrays
 * so that this function can focus on recursion.
 *
 */
function _private_do_with_arrays( $args, $arrays ) {
	$results = array();

	foreach ( $arrays as $position => $array ) {
		if ( is_array( $array ) ) {

			// Replace the first array we find with each of its values and recurse.
			foreach ( $array as $key => $value ) {
				$arrays[ $position ] = $value;

				// Call this function again to loop through the next array.
				$results[ $key ] = _private_do_with_arrays( $args, $arrays );

				// If we allow breaking early and have found break-on value, return.
				if ( $args['break_early'] && $args['break_on'] === $results[ $key ] ) {
					return $results[ $key ];
				}
			}

			return $results;
		}
	}

	/**
	 * If we haven't returned yet, none of the values in $arrays are really arrays and
	 * we can finally do what we were created to do.
	 */
	return call_user_func_array( $args['callback'], $arrays );
}