array_replace_recursive() without creation of keys - php

Question

In PHP, array_replace_recursive() does two things according to the documentation:
If a key from the first array exists in the second array, its value will be replaced by the value from the second array.
If the key exists in the second array, and not the first, it will be created in the first array.
Is there an alternative that only does the replacement, and doesn't create new keys?
For example:
$array = [
'apple' => TRUE,
'pear' => TRUE,
'basket' => [
'banana' => TRUE,
],
'punnet' => [
'strawberry' => TRUE,
],
];
$replacement = [
'banana' => [
'REPLACEMENT!'
],
];
The result should be:
$array = [
'apple' => TRUE,
'pear' => TRUE,
'basket' => [
'banana' => [
'REPLACEMENT!'
],
],
'punnet' => [
'strawberry' => TRUE,
],
];

Answer 1

You will need to use array_intersect_key() to create an array that contains only the keys that are in the two arrays, then you can merge.
$array1 = [
'a' => 1,
'b' => 2,
'c' => 3,
'd' => 4,
];
$array2 = [
'b' => 14,
'c' => 70,
'f' => 5,
];
// $array2 has to be the first arguments for $inter to have its value instead of the value of $array1
$inter = array_intersect_key($array2, $array1);
$merged = array_replace_recursive($array1, $inter);
// Merged will be:
[
'a' => 1,
'b' => 14,
'c' => 70,
'd' => 4,
];
array_intersect_key
EDIT
For this to work recursively, you can use this function found here
/**
* Recursively computes the intersection of arrays using keys for comparison.
*
* #param array $array1 The array with master keys to check.
* #param array $array2 An array to compare keys against.
* #return array associative array containing all the entries of array1 which have keys that are present in array2.
**/
function array_intersect_key_recursive(array $array1, array $array2) {
$array1 = array_intersect_key($array1, $array2);
foreach ($array1 as $key => &$value) {
if (is_array($value) && is_array($array2[$key])) {
$value = array_intersect_key_recursive($value, $array2[$key]);
}
}
return $array1;
}

Answer 2

If you don't like creation of non existant keys, you can use array_replace_recursive() as is and then you can roll out your own recursive version which would remove all extra keys. You may however roll out your own recursive replace version instead of the below 2 pass solution, but I would prefer the below described to avoid re-inventing the wheel of array_replace_recursive()(since you know what the wheel is about).
function removeNonExistantKeys(&$basket,&$base){
$keys = array_diff_key($basket, $base);
foreach($keys as $unwanted_key => $value){
unset($basket[ $unwanted_key ]);
}
foreach($basket as $key => &$value){
if(is_array($value) && is_array( $base[ $key ] )){
removeNonExistantKeys($value , $base[ $key ]);
}
}
}
We use & references wherever needed to edit the same copy of the array.
The above function uses array_diff_key to find difference between 2 sets of array in terms of keys and unsets all of them in the next foreach.
We then walk recursively to both modified and initial arrays into it's sub children performing the same task.
Driver code:
<?php
$base = array('citrus' => array( "orange") , 'berries' => array("blackberry", "raspberry"),'a' => ['b' => 'f']);
$replacements = array('citrus' => array('pineapple'), 'berries' => array('blueberry'),'a' => ['b' => 'd','e' => 'ab']);
$basket = array_replace_recursive($base, $replacements);
function removeNonExistantKeys(&$basket,&$base){
$keys = array_diff_key($basket, $base);
foreach($keys as $unwanted_key => $value){
unset($basket[ $unwanted_key ]);
}
foreach($basket as $key => &$value){
if(is_array($value) && is_array( $base[ $key ] )){
removeNonExistantKeys($value , $base[ $key ]);
}
}
}
removeNonExistantKeys($basket,$base);
print_r($basket);

Answer 3

This does what I needed:
array_walk_recursive($array, function(&$value, $key, $replacements) {
if (isset($replacements[$key])) {
$value = $replacements[$key];
}
}, ['replace' => 'replacement']);