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Diffstat (limited to 'vendor/ramsey/collection/src/DoubleEndedQueueInterface.php')
| -rw-r--r-- | vendor/ramsey/collection/src/DoubleEndedQueueInterface.php | 309 |
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diff --git a/vendor/ramsey/collection/src/DoubleEndedQueueInterface.php b/vendor/ramsey/collection/src/DoubleEndedQueueInterface.php new file mode 100644 index 000000000..6b23cf553 --- /dev/null +++ b/vendor/ramsey/collection/src/DoubleEndedQueueInterface.php @@ -0,0 +1,309 @@ +<?php + +/** + * This file is part of the ramsey/collection library + * + * For the full copyright and license information, please view the LICENSE + * file that was distributed with this source code. + * + * @copyright Copyright (c) Ben Ramsey <ben@benramsey.com> + * @license http://opensource.org/licenses/MIT MIT + */ + +declare(strict_types=1); + +namespace Ramsey\Collection; + +use Ramsey\Collection\Exception\NoSuchElementException; + +/** + * A linear collection that supports element insertion and removal at both ends. + * + * Most `DoubleEndedQueueInterface` implementations place no fixed limits on the + * number of elements they may contain, but this interface supports + * capacity-restricted double-ended queues as well as those with no fixed size + * limit. + * + * This interface defines methods to access the elements at both ends of the + * double-ended queue. Methods are provided to insert, remove, and examine the + * element. Each of these methods exists in two forms: one throws an exception + * if the operation fails, the other returns a special value (either `null` or + * `false`, depending on the operation). The latter form of the insert operation + * is designed specifically for use with capacity-restricted implementations; in + * most implementations, insert operations cannot fail. + * + * The twelve methods described above are summarized in the following table: + * + * <table> + * <caption>Summary of DoubleEndedQueueInterface methods</caption> + * <thead> + * <tr> + * <th></th> + * <th colspan=2>First Element (Head)</th> + * <th colspan=2>Last Element (Tail)</th> + * </tr> + * <tr> + * <td></td> + * <td><em>Throws exception</em></td> + * <td><em>Special value</em></td> + * <td><em>Throws exception</em></td> + * <td><em>Special value</em></td> + * </tr> + * </thead> + * <tbody> + * <tr> + * <th>Insert</th> + * <td><code>addFirst()</code></td> + * <td><code>offerFirst()</code></td> + * <td><code>addLast()</code></td> + * <td><code>offerLast()</code></td> + * </tr> + * <tr> + * <th>Remove</th> + * <td><code>removeFirst()</code></td> + * <td><code>pollFirst()</code></td> + * <td><code>removeLast()</code></td> + * <td><code>pollLast()</code></td> + * </tr> + * <tr> + * <th>Examine</th> + * <td><code>firstElement()</code></td> + * <td><code>peekFirst()</code></td> + * <td><code>lastElement()</code></td> + * <td><code>peekLast()</code></td> + * </tr> + * </tbody> + * </table> + * + * This interface extends the `QueueInterface`. When a double-ended queue is + * used as a queue, FIFO (first-in-first-out) behavior results. Elements are + * added at the end of the double-ended queue and removed from the beginning. + * The methods inherited from the `QueueInterface` are precisely equivalent to + * `DoubleEndedQueueInterface` methods as indicated in the following table: + * + * <table> + * <caption>Comparison of QueueInterface and DoubleEndedQueueInterface methods</caption> + * <thead> + * <tr> + * <th>QueueInterface Method</th> + * <th>DoubleEndedQueueInterface Method</th> + * </tr> + * </thead> + * <tbody> + * <tr> + * <td><code>add()</code></td> + * <td><code>addLast()</code></td> + * </tr> + * <tr> + * <td><code>offer()</code></td> + * <td><code>offerLast()</code></td> + * </tr> + * <tr> + * <td><code>remove()</code></td> + * <td><code>removeFirst()</code></td> + * </tr> + * <tr> + * <td><code>poll()</code></td> + * <td><code>pollFirst()</code></td> + * </tr> + * <tr> + * <td><code>element()</code></td> + * <td><code>firstElement()</code></td> + * </tr> + * <tr> + * <td><code>peek()</code></td> + * <td><code>peekFirst()</code></td> + * </tr> + * </tbody> + * </table> + * + * Double-ended queues can also be used as LIFO (last-in-first-out) stacks. When + * a double-ended queue is used as a stack, elements are pushed and popped from + * the beginning of the double-ended queue. Stack concepts are precisely + * equivalent to `DoubleEndedQueueInterface` methods as indicated in the table + * below: + * + * <table> + * <caption>Comparison of stack concepts and DoubleEndedQueueInterface methods</caption> + * <thead> + * <tr> + * <th>Stack concept</th> + * <th>DoubleEndedQueueInterface Method</th> + * </tr> + * </thead> + * <tbody> + * <tr> + * <td><em>push</em></td> + * <td><code>addFirst()</code></td> + * </tr> + * <tr> + * <td><em>pop</em></td> + * <td><code>removeFirst()</code></td> + * </tr> + * <tr> + * <td><em>peek</em></td> + * <td><code>peekFirst()</code></td> + * </tr> + * </tbody> + * </table> + * + * Note that the `peek()` method works equally well when a double-ended queue is + * used as a queue or a stack; in either case, elements are drawn from the + * beginning of the double-ended queue. + * + * While `DoubleEndedQueueInterface` implementations are not strictly required + * to prohibit the insertion of `null` elements, they are strongly encouraged to + * do so. Users of any `DoubleEndedQueueInterface` implementations that do allow + * `null` elements are strongly encouraged *not* to take advantage of the + * ability to insert nulls. This is so because `null` is used as a special + * return value by various methods to indicated that the double-ended queue is + * empty. + */ +interface DoubleEndedQueueInterface extends QueueInterface +{ + /** + * Inserts the specified element at the front of this queue if it is + * possible to do so immediately without violating capacity restrictions. + * + * When using a capacity-restricted double-ended queue, it is generally + * preferable to use the `offerFirst()` method. + * + * @param mixed $element The element to add to the front of this queue. + * + * @return bool `true` if this queue changed as a result of the call. + * + * @throws \RuntimeException if a queue refuses to add a particular element + * for any reason other than that it already contains the element. + * Implementations should use a more-specific exception that extends + * `\RuntimeException`. + */ + public function addFirst($element): bool; + + /** + * Inserts the specified element at the end of this queue if it is possible + * to do so immediately without violating capacity restrictions. + * + * When using a capacity-restricted double-ended queue, it is generally + * preferable to use the `offerLast()` method. + * + * This method is equivalent to `add()`. + * + * @param mixed $element The element to add to the end of this queue. + * + * @return bool `true` if this queue changed as a result of the call. + * + * @throws \RuntimeException if a queue refuses to add a particular element + * for any reason other than that it already contains the element. + * Implementations should use a more-specific exception that extends + * `\RuntimeException`. + */ + public function addLast($element): bool; + + /** + * Inserts the specified element at the front of this queue if it is + * possible to do so immediately without violating capacity restrictions. + * + * When using a capacity-restricted queue, this method is generally + * preferable to `addFirst()`, which can fail to insert an element only by + * throwing an exception. + * + * @param mixed $element The element to add to the front of this queue. + * + * @return bool `true` if the element was added to this queue, else `false`. + */ + public function offerFirst($element): bool; + + /** + * Inserts the specified element at the end of this queue if it is possible + * to do so immediately without violating capacity restrictions. + * + * When using a capacity-restricted queue, this method is generally + * preferable to `addLast()` which can fail to insert an element only by + * throwing an exception. + * + * @param mixed $element The element to add to the end of this queue. + * + * @return bool `true` if the element was added to this queue, else `false`. + */ + public function offerLast($element): bool; + + /** + * Retrieves and removes the head of this queue. + * + * This method differs from `pollFirst()` only in that it throws an + * exception if this queue is empty. + * + * @return mixed the first element in this queue. + * + * @throws NoSuchElementException if this queue is empty. + */ + public function removeFirst(); + + /** + * Retrieves and removes the tail of this queue. + * + * This method differs from `pollLast()` only in that it throws an exception + * if this queue is empty. + * + * @return mixed the last element in this queue. + * + * @throws NoSuchElementException if this queue is empty. + */ + public function removeLast(); + + /** + * Retrieves and removes the head of this queue, or returns `null` if this + * queue is empty. + * + * @return mixed|null the head of this queue, or `null` if this queue is empty. + */ + public function pollFirst(); + + /** + * Retrieves and removes the tail of this queue, or returns `null` if this + * queue is empty. + * + * @return mixed|null the tail of this queue, or `null` if this queue is empty. + */ + public function pollLast(); + + /** + * Retrieves, but does not remove, the head of this queue. + * + * This method differs from `peekFirst()` only in that it throws an + * exception if this queue is empty. + * + * @return mixed the head of this queue. + * + * @throws NoSuchElementException if this queue is empty. + */ + public function firstElement(); + + /** + * Retrieves, but does not remove, the tail of this queue. + * + * This method differs from `peekLast()` only in that it throws an exception + * if this queue is empty. + * + * @return mixed the tail of this queue. + * + * @throws NoSuchElementException if this queue is empty. + */ + public function lastElement(); + + /** + * Retrieves, but does not remove, the head of this queue, or returns `null` + * if this queue is empty. + * + * @return mixed|null the head of this queue, or `null` if this queue is empty. + */ + public function peekFirst(); + + /** + * Retrieves, but does not remove, the tail of this queue, or returns `null` + * if this queue is empty. + * + * @return mixed|null the tail of this queue, or `null` if this queue is empty. + */ + public function peekLast(); +} |