<?php

namespace Psr\Cache;

/**
* CacheItemPoolInterface generates CacheItemInterface objects.
*
* The primary purpose of Cache\CacheItemPoolInterface is to accept a key from
* the Calling Library and return the associated Cache\CacheItemInterface object.
* It is also the primary point of interaction with the entire cache collection.
* All configuration and initialization of the Pool is left up to an
* Implementing Library.
*/
interface CacheItemPoolInterface
{
/**
* Returns a Cache Item representing the specified key.
*
* This method must always return a CacheItemInterface object, even in case of
* a cache miss. It MUST NOT return null.
*
* @param string $key
* The key for which to return the corresponding Cache Item.
*
* @throws InvalidArgumentException
* If the $key string is not a legal value a \Psr\Cache\InvalidArgumentException
* MUST be thrown.
*
* @return CacheItemInterface
* The corresponding Cache Item.
*/
public function getItem($key);

/**
* Returns a traversable set of cache items.
*
* @param string[] $keys
* An indexed array of keys of items to retrieve.
*
* @throws InvalidArgumentException
* If any of the keys in $keys are not a legal value a \Psr\Cache\InvalidArgumentException
* MUST be thrown.
*
* @return array|\Traversable
* A traversable collection of Cache Items keyed by the cache keys of
* each item. A Cache item will be returned for each key, even if that
* key is not found. However, if no keys are specified then an empty
* traversable MUST be returned instead.
*/
public function getItems(array $keys = array());

/**
* Confirms if the cache contains specified cache item.
*
* Note: This method MAY avoid retrieving the cached value for performance reasons.
* This could result in a race condition with CacheItemInterface::get(). To avoid
* such situation use CacheItemInterface::isHit() instead.
*
* @param string $key
* The key for which to check existence.
*
* @throws InvalidArgumentException
* If the $key string is not a legal value a \Psr\Cache\InvalidArgumentException
* MUST be thrown.
*
* @return bool
* True if item exists in the cache, false otherwise.
*/
public function hasItem($key);

/**
* Deletes all items in the pool.
*
* @return bool
* True if the pool was successfully cleared. False if there was an error.
*/
public function clear();

/**
* Removes the item from the pool.
*
* @param string $key
* The key to delete.
*
* @throws InvalidArgumentException
* If the $key string is not a legal value a \Psr\Cache\InvalidArgumentException
* MUST be thrown.
*
* @return bool
* True if the item was successfully removed. False if there was an error.
*/
public function deleteItem($key);

/**
* Removes multiple items from the pool.
*
* @param string[] $keys
* An array of keys that should be removed from the pool.

* @throws InvalidArgumentException
* If any of the keys in $keys are not a legal value a \Psr\Cache\InvalidArgumentException
* MUST be thrown.
*
* @return bool
* True if the items were successfully removed. False if there was an error.
*/
public function deleteItems(array $keys);

/**
* Persists a cache item immediately.
*
* @param CacheItemInterface $item
* The cache item to save.
*
* @return bool
* True if the item was successfully persisted. False if there was an error.
*/
public function save(CacheItemInterface $item);

/**
* Sets a cache item to be persisted later.
*
* @param CacheItemInterface $item
* The cache item to save.
*
* @return bool
* False if the item could not be queued or if a commit was attempted and failed. True otherwise.
*/
public function saveDeferred(CacheItemInterface $item);

/**
* Persists any deferred cache items.
*
* @return bool
* True if all not-yet-saved items were successfully saved or there were none. False otherwise.
*/
public function commit();
}