How to convert implicit nesting from an array - php

Question

Given a PHP array that looks like:
[
'foo' => 1,
'bar[0]' => 6,
'bar[1]' => 7,
'bar[2]' => 8,
'baz' => 'anything',
... and so on
]
I want to convert the "implied" nesting into real arrays, while leaving the rest untouched, to result in:
[
'foo' => 1,
'bar' => [6, 7, 8],
'baz' => 'anything',
]
I've searched the php docs but can't find a utility for this. I'm sure I could write a function to do this, but it feels like reinventing the wheel. Surely such a function already exists?

Answer 1

You can use array_walk() and preg_match to see if the key should be an "array". We can then pass in our final array by reference to allow us to edit it.
For example
<?php
$a = [
'foo' => 1,
'bar[0]' => 6,
'bar[1]' => 7,
'bar[2]' => 8,
'baz' => 'anything',
];
$end = [];
array_walk($a, function($val, $key) use(&$end) {
//See if the key is something like "bar[1]"
if( preg_match("/^([a-z]+)\[[0-9]+\]$/", $key, $match) ) {
//See if "bar" key exists in our final array, if not create it.
if( array_key_exists($match[1], $end) == FALSE ) {
return $end[$match[1]] = array($val);
}
//Add value to array we created above
return $end[$match[1]][] = $val;
}
//It's just a normal key, so just add it to our final array
return $end[$key] = $val;
});
print_r($end);
https://eval.in/315998

Answer 2

just playing around. See comments for explanation of code.
/*
our source array
*/
$a = array(
'foo' => 1,
'bar[0]' => 6,
'bar[1]' => 7,
'bar[2]' => 8,
'baz' => 'anything'
);
// an array declared to hold all variable names present in array.
$vars = array();
/*
http://php.net/manual/en/function.extract.php
extract all values from the array with keys are variable names. Keys like
bar[0] do not make sense to extract function so it ignores them.
*/
extract($a);
/*
Now that we've got all variables we possibly could using extract(), we
traverse the source array to create the $bar array ourselves.
*/
foreach($a as $k => $v) {
/*
if key contains a [
this check could be rigorous, but I leave that to the production code developer
*/
if(strstr($k, '[')) {
/*
replace the [number] part from key to get the array name, i.e., "bar"
*/
$arr_name = preg_replace('/\[\d+\]/', '', $k);
/*
using variable variables feature (http://php.net/manual/en/language.variables.variable.php)
check if we've created the array already. if not, create now. and
record the variable name in $vars array for future reference
*/
if(!is_array($$arr_name)) {
$$arr_name = array();
$vars[] = $arr_name;
}
/*
formulate and eval() (http://php.net/manual/en/function.eval.php)
a statement that inserts current $v into our created array
eval is evil so do some rigorous testing before using it
*/
eval('$' . $k . '=' . $v . ';');
}
else{
//otherwise just record the variable.
$vars[] = $k;
}
}
/* $vars holds names of all variables you got from stream */
var_dump($vars);
/* display the variables */
var_dump($foo, $bar, $baz);
/* almost forgot, http://php.net/manual/en/function.var-dump.php */