Flatten array and convert $_POST array into the HTML names that would create it

flatten-array.php

/**
 * post2name
 *
 * Converts a $_POST array to a flat array of the form element `name`s which would have produced it.
 *
 * For example, the PHP array:
 *
 *     'foo' => 'bar',
 *     'baz' => [
 *         'foo' => 'bar',
 *     ],
 *
 * would turn into:
 *
 *     'foo' => 'bar',
 *     'baz[foo]' => 'bar',
 *
 * @param  array $array Array to be converted
 * @return array Flat array of HTML `name`s
 */

function post2name( $array ) {
	$result = array();
	$array = flatten_array( $array );
	foreach ( $array as $key => $value ) {
		$parts = explode( '.', $key );
		$i = 0;
		$new_key = '';
		foreach ( $parts as $part ) {
			if ( $i !== 0 ) $part = '[' . $part . ']';
			$new_key .= $part;
			$i++;
		}
		$i = 0;
		$result[ $new_key ] = $value;
	}
	return $result;
}

/**
 * flatten_array
 *
 * Turns a multi-dimensional array into a flat one separated by dots
 *
 * @param array $array Array to be flattened
 * @param string $prefix Received previous value from recursive call
 *
 * @return array Flat array
 */

function flatten_array( $array, $prefix = '' ) {
	$result = array();
	foreach( $array as $key => $value ) {
		if ( is_array( $value ) ) {
			$result = $result + flatten_array( $value, $prefix . $key . '.' );
		} else {
			$result[ $prefix . $key ] = $value;
		}
	}
	return $result;
}