stephpy

%skip   space     \s
%token  bracket_  \(
%token _bracket   \)
%token  comma     ,
%token  number    (0|[1-9]\d*)(\.\d+)?([eE][\+\-]?\d+)?
%token  plus      \+
%token  minus     \-|−
%token  pow       \*\*
%token  times     \*|×
%token  percent   %

stephpy

<?php
function array_diff_simple($a, $b)
{
    $r = array();

    foreach($a as $key => $val) {
        if(!isset($b[$key])) {
            $r[$key] = $val;
        } else {
            if(is_array($b[$key]) && !is_array($val)) {