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CaseInsensitiveArray.php
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Fri, Jun 7, 20:21

CaseInsensitiveArray.php
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<?php
/**
* A case-insensitive associative array.
*
* This class represents an associative array in which the keys are considered
* to be case insensitive. This means that `$array['key']` and `$array['KEY']`
* will refer to the same array element.
*
* ```lang=php
* $array = new CaseInsensitiveArray();
*
* $array['key'] = 'value';
* echo $array['KEY']; // 'value'
*
* $array['kEy'] = 'foobar';
* var_dump($array->toArray()); // array('key' => 'foobar')
* ```
*
* Note that it is not possible to reuse case variants of a key. That is, if
* the array contains key `xyz` then it is not possible to use any of the
* following case variants as an array key: `xyZ`, `xYz`, `xYZ`, `Xyz`, `XyZ`,
* `XYz`, `XYZ`. In order to use a case variant as a key, it is necessary to
* first unset the original case variant.
*
* ```lang=php
* $array = new CaseInsensitiveArray(array('key' => 'foo', 'KEY' => 'bar'));
* var_dump($array->toArray()); // array('key' => 'bar')
*
* $array['KEY'] = 'baz';
* var_dump($array->toArray()); // array('key' => 'baz')
*
* unset($array['key']);
* $array['KEY'] = 'baz';
* var_dump($array->toArray()); // array('KEY' => 'baz')
* ```
*/
final class CaseInsensitiveArray extends PhutilArray {
/**
* Mapping between original and case-invariant keys.
*
* All keys in the parent `PhutilArray` are indexed using the case-invariant
* key rather than the original key.
*
* @var map<string, string>
*/
private $keys = array();
/**
* Construct a new array object.
*
* @param array The input array.
*/
public function __construct(array $data = array()) {
foreach ($data as $key => $value) {
$this->offsetSet($key, $value);
}
}
public function getKeys() {
return array_values($this->keys);
}
public function offsetExists($key) {
$key = $this->transformKey($key);
return array_key_exists($key, $this->keys);
}
public function offsetGet($key) {
$key = $this->transformKey($key);
return parent::offsetGet($this->keys[$key]);
}
public function offsetSet($key, $value) {
$transformed_key = $this->transformKey($key);
if (isset($this->keys[$transformed_key])) {
// If the key already exists, reuse it and override the
// existing value.
$key = $this->keys[$transformed_key];
} else {
// If the key doesn't yet, create a new array element.
$this->keys[$transformed_key] = $key;
}
parent::offsetSet($key, $value);
}
public function offsetUnset($key) {
$key = $this->transformKey($key);
parent::offsetUnset($this->keys[$key]);
unset($this->keys[$key]);
}
/**
* Transform an array key.
*
* This method transforms an array key to be case-invariant. We //could//
* just call [[http://php.net/manual/en/function.strtolower.php |
* `strtolower`]] directly, but this method allows us to contain the key
* transformation logic within a single method, should it ever change.
*
* Theoretically, we should be able to use any of the following functions
* for the purpose of key transformations:
*
* - [[http://php.net/manual/en/function.strtolower.php | `strtolower`]]
* - [[http://php.net/manual/en/function.strtoupper.php | `strtoupper`]]
* - Some creative use of other
* [[http://php.net/manual/en/book.strings.php | string transformation]]
* functions.
*
* @param string The input key.
* @return string The transformed key.
*/
private function transformKey($key) {
return phutil_utf8_strtolower($key);
}
}

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