使用PHP数组作为索引路径

Question

I have a hierarchical array path in a flat PHP array, e.g.: $path = array('fruit', 'banana', 'fresh');

I define my multidimensional array as $tree. How would you use $path to set/get the appropriate node in $tree? $tree[$path] = 'blablabl'; throws an "Illegal offset error". I'm not sure how I would implode() the path to a string and use eval() to get the index. What's the most straightforward way to do this?

Answer 1

I solved the same problem with references:

function &walk_path(array &$root, array $path)
{
    $cursor = &$root;
    foreach ($path as $e) { $cursor = &$cursor[$e]; }
    return $cursor;
}

$db = [];
$tmp = &walk_path($db, ["users","deanna", "favourite food"]);
$tmp = "chocolate";
print_r($db);

will produce

Array
(
    [users] => Array
        (
            [deanna] => Array
                (
                    [favourite food] => chocolate
                )

        )

)

Note that since PHP autovivicates this will create any non-existent keys either as an array with the only key being the next elemenet in the path or null if it is the leaf node. This is fortunately exactly the behaviour I needed. However, it still strikes me as a bit akward that I have to write this function myself in a lanuage so focused on its arrays. Any suggestions to make this shorter are very welcome.