<?php
/**
* Array-like object with a default value that is populated when nonexistent
* keys are accessed. This is particularly useful to avoid constructs like this:
*
* $counts = array();
* foreach ($fruit as $fruit) {
* if (!isset($counts[$fruit])) {
* $counts[$fruit] = 0;
* }
* $counts[$fruit] += 1;
* }
*
* Instead, you can use PhutilArrayWithDefaultValue:
*
* $counts = new PhutilArrayWithDefaultValue();
* foreach ($fruits as $fruit) {
* $counts[$fruit] += 1;
* }
*
* NOTE: You must use the `+= 1` operator, not `++`, because PHP is the crown
* jewel of programming languages.
*
* Normally, the default value is `0` to allow the object to be used to count
* things or build bitmasks. You can change the default with
* @{method:setDefaultValue}.
*/
final class PhutilArrayWithDefaultValue extends PhutilArray {
private $defaultValue = 0;
public function setDefaultValue($default_value) {
$this->defaultValue = $default_value;
return $this;
}
public function offsetExists($key) {
return true;
}
public function offsetGet($key) {
if (!parent::offsetExists($key)) {
$this->offsetSet($key, $this->defaultValue);
}
return parent::offsetGet($key);
}
}