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- <?php
- namespace Elgg\Cache;
- /**
- * Least Recently Used Cache
- *
- * A fixed sized cache that removes the element used last when it reaches its
- * size limit.
- *
- * Based on https://github.com/cash/LRUCache
- *
- * @access private
- *
- * @package Elgg.Core
- * @subpackage Cache
- */
- class LRUCache implements \ArrayAccess {
- /** @var int */
- protected $maximumSize;
- /**
- * The front of the array contains the LRU element
- *
- * @var array
- */
- protected $data = array();
- /**
- * Create a LRU Cache
- *
- * @param int $size The size of the cache
- * @throws \InvalidArgumentException
- */
- public function __construct($size) {
- if (!is_int($size) || $size <= 0) {
- throw new \InvalidArgumentException();
- }
- $this->maximumSize = $size;
- }
- /**
- * Get the value cached with this key
- *
- * @param int|string $key The key. Strings that are ints are cast to ints.
- * @param mixed $default The value to be returned if key not found. (Optional)
- * @return mixed
- */
- public function get($key, $default = null) {
- if (isset($this->data[$key])) {
- $this->recordAccess($key);
- return $this->data[$key];
- } else {
- return $default;
- }
- }
- /**
- * Add something to the cache
- *
- * @param int|string $key The key. Strings that are ints are cast to ints.
- * @param mixed $value The value to cache
- * @return void
- */
- public function set($key, $value) {
- if (isset($this->data[$key])) {
- $this->data[$key] = $value;
- $this->recordAccess($key);
- } else {
- $this->data[$key] = $value;
- if ($this->size() > $this->maximumSize) {
- // remove least recently used element (front of array)
- reset($this->data);
- unset($this->data[key($this->data)]);
- }
- }
- }
- /**
- * Get the number of elements in the cache
- *
- * @return int
- */
- public function size() {
- return count($this->data);
- }
- /**
- * Does the cache contain an element with this key
- *
- * @param int|string $key The key
- * @return boolean
- */
- public function containsKey($key) {
- return isset($this->data[$key]);
- }
- /**
- * Remove the element with this key.
- *
- * @param int|string $key The key
- * @return mixed Value or null if not set
- */
- public function remove($key) {
- if (isset($this->data[$key])) {
- $value = $this->data[$key];
- unset($this->data[$key]);
- return $value;
- } else {
- return null;
- }
- }
- /**
- * Clear the cache
- *
- * @return void
- */
- public function clear() {
- $this->data = array();
- }
- /**
- * Moves the element from current position to end of array
- *
- * @param int|string $key The key
- * @return void
- */
- protected function recordAccess($key) {
- $value = $this->data[$key];
- unset($this->data[$key]);
- $this->data[$key] = $value;
- }
- /**
- * Assigns a value for the specified key
- *
- * @see \ArrayAccess::offsetSet()
- *
- * @param int|string $key The key to assign the value to.
- * @param mixed $value The value to set.
- * @return void
- */
- public function offsetSet($key, $value) {
- $this->set($key, $value);
- }
- /**
- * Get the value for specified key
- *
- * @see \ArrayAccess::offsetGet()
- *
- * @param int|string $key The key to retrieve.
- * @return mixed
- */
- public function offsetGet($key) {
- return $this->get($key);
- }
- /**
- * Unsets a key.
- *
- * @see \ArrayAccess::offsetUnset()
- *
- * @param int|string $key The key to unset.
- * @return void
- */
- public function offsetUnset($key) {
- $this->remove($key);
- }
- /**
- * Does key exist?
- *
- * @see \ArrayAccess::offsetExists()
- *
- * @param int|string $key A key to check for.
- * @return boolean
- */
- public function offsetExists($key) {
- return $this->containsKey($key);
- }
- }
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