PHP address array tree node using string or array - php

Question

Say, I have data in a tree structure implemented as an array of arrays to an arbitrary depth, something like
print_r($my_array);
Array
(
[id] => 123
[value] => Hello, World!
[child] => Array
(
[name] => Foo
[bar] => baz
)
[otherchild] => Array
(
[status] => fubar
[list] => Array
(
[one] => 1
[two] => 3
)
)
[sanity] => unchecked
)
Now, using a single string as key I would like to address a node at an arbitrary depth, Let's say I have a key something like this:
$key = 'otherchild|list|two';
Using this key I want to be able to address the value stored in
$my_array['otherchild']['list']['two']
Obviously I can explode('|', $key) to get an array of keys, and shifting values off of this and using those to address sub-arrays makes it easy to obtain the value I'm looking for, something like
$value = $my_array;
$keys = explode('|', $key);
while ($k = array_shift($keys)) {
if (isset($value[$k])) {
$value = $value[$k];
} else {
// handle failure
}
} // Here, if all keys exist, $value holds value of addressed node
But I'm stuck trying to update values in a generic way, ie without having to resort to something like
$keys = explode('|', $key);
if (count($keys) == 1) {
$my_array[$keys[0]] = $new_value;
} else if (count($keys) == 2) {
$my_array[$keys[0]][$keys[1]] = $new_value;
} else if ...
Any ideas?

Answer 1

function setAt(array & $a, $key, $value)
{
$keys = explode('|', $key);
// Start with the root node (the array itself)
$node = & $a;
// Walk the tree, create nodes as needed
foreach ($keys as $k) {
// Create node if it does not exist
if (! isset($node[$k])) {
$node[$k] = array();
}
// Walk to the node
$node = & $node[$k];
}
// Position found; store the value
$node = $value;
}
// Test
$array = array();
// Add new values
setAt($array, 'some|key', 'value1');
setAt($array, 'some|otherkey', 'val2');
setAt($array, 'key3', 'value3');
print_r($array);
// Overwrite existing values
setAt($array, 'some|key', 'new-value');
print_r($array);
setAt($array, 'some', 'thing');
print_r($array);

Answer 2

If you're looking for a short answer, you can also use eval().
$elem = "\$array['" . str_replace("|", "']['", $key) . "']";
$val = eval("return isset($elem) ? $elem : null;");