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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/external/jsr166/java/util/Deque.java')
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diff --git a/gcc-4.4.3/libjava/classpath/external/jsr166/java/util/Deque.java b/gcc-4.4.3/libjava/classpath/external/jsr166/java/util/Deque.java new file mode 100644 index 000000000..a769561dc --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/external/jsr166/java/util/Deque.java @@ -0,0 +1,547 @@ +/* + * Written by Doug Lea and Josh Bloch with assistance from members of + * JCP JSR-166 Expert Group and released to the public domain, as explained + * at http://creativecommons.org/licenses/publicdomain + */ + +package java.util; + +/** + * A linear collection that supports element insertion and removal at + * both ends. The name <i>deque</i> is short for "double ended queue" + * and is usually pronounced "deck". Most <tt>Deque</tt> + * implementations place no fixed limits on the number of elements + * they may contain, but this interface supports capacity-restricted + * deques as well as those with no fixed size limit. + * + * <p>This interface defines methods to access the elements at both + * ends of the deque. 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 <tt>null</tt> or <tt>false</tt>, depending on + * the operation). The latter form of the insert operation is + * designed specifically for use with capacity-restricted + * <tt>Deque</tt> implementations; in most implementations, insert + * operations cannot fail. + * + * <p>The twelve methods described above are summarized in the + * following table: + * + * <p> + * <table BORDER CELLPADDING=3 CELLSPACING=1> + * <tr> + * <td></td> + * <td ALIGN=CENTER COLSPAN = 2> <b>First Element (Head)</b></td> + * <td ALIGN=CENTER COLSPAN = 2> <b>Last Element (Tail)</b></td> + * </tr> + * <tr> + * <td></td> + * <td ALIGN=CENTER><em>Throws exception</em></td> + * <td ALIGN=CENTER><em>Special value</em></td> + * <td ALIGN=CENTER><em>Throws exception</em></td> + * <td ALIGN=CENTER><em>Special value</em></td> + * </tr> + * <tr> + * <td><b>Insert</b></td> + * <td>{@link #addFirst addFirst(e)}</td> + * <td>{@link #offerFirst offerFirst(e)}</td> + * <td>{@link #addLast addLast(e)}</td> + * <td>{@link #offerLast offerLast(e)}</td> + * </tr> + * <tr> + * <td><b>Remove</b></td> + * <td>{@link #removeFirst removeFirst()}</td> + * <td>{@link #pollFirst pollFirst()}</td> + * <td>{@link #removeLast removeLast()}</td> + * <td>{@link #pollLast pollLast()}</td> + * </tr> + * <tr> + * <td><b>Examine</b></td> + * <td>{@link #getFirst getFirst()}</td> + * <td>{@link #peekFirst peekFirst()}</td> + * <td>{@link #getLast getLast()}</td> + * <td>{@link #peekLast peekLast()}</td> + * </tr> + * </table> + * + * <p>This interface extends the {@link Queue} interface. When a deque is + * used as a queue, FIFO (First-In-First-Out) behavior results. Elements are + * added at the end of the deque and removed from the beginning. The methods + * inherited from the <tt>Queue</tt> interface are precisely equivalent to + * <tt>Deque</tt> methods as indicated in the following table: + * + * <p> + * <table BORDER CELLPADDING=3 CELLSPACING=1> + * <tr> + * <td ALIGN=CENTER> <b><tt>Queue</tt> Method</b></td> + * <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> + * </tr> + * <tr> + * <td>{@link java.util.Queue#add add(e)}</td> + * <td>{@link #addLast addLast(e)}</td> + * </tr> + * <tr> + * <td>{@link java.util.Queue#offer offer(e)}</td> + * <td>{@link #offerLast offerLast(e)}</td> + * </tr> + * <tr> + * <td>{@link java.util.Queue#remove remove()}</td> + * <td>{@link #removeFirst removeFirst()}</td> + * </tr> + * <tr> + * <td>{@link java.util.Queue#poll poll()}</td> + * <td>{@link #pollFirst pollFirst()}</td> + * </tr> + * <tr> + * <td>{@link java.util.Queue#element element()}</td> + * <td>{@link #getFirst getFirst()}</td> + * </tr> + * <tr> + * <td>{@link java.util.Queue#peek peek()}</td> + * <td>{@link #peek peekFirst()}</td> + * </tr> + * </table> + * + * <p>Deques can also be used as LIFO (Last-In-First-Out) stacks. This + * interface should be used in preference to the legacy {@link Stack} class. + * When a deque is used as a stack, elements are pushed and popped from the + * beginning of the deque. Stack methods are precisely equivalent to + * <tt>Deque</tt> methods as indicated in the table below: + * + * <p> + * <table BORDER CELLPADDING=3 CELLSPACING=1> + * <tr> + * <td ALIGN=CENTER> <b>Stack Method</b></td> + * <td ALIGN=CENTER> <b>Equivalent <tt>Deque</tt> Method</b></td> + * </tr> + * <tr> + * <td>{@link #push push(e)}</td> + * <td>{@link #addFirst addFirst(e)}</td> + * </tr> + * <tr> + * <td>{@link #pop pop()}</td> + * <td>{@link #removeFirst removeFirst()}</td> + * </tr> + * <tr> + * <td>{@link #peek peek()}</td> + * <td>{@link #peekFirst peekFirst()}</td> + * </tr> + * </table> + * + * <p>Note that the {@link #peek peek} method works equally well when + * a deque is used as a queue or a stack; in either case, elements are + * drawn from the beginning of the deque. + * + * <p>This interface provides two methods to remove interior + * elements, {@link #removeFirstOccurrence removeFirstOccurrence} and + * {@link #removeLastOccurrence removeLastOccurrence}. + * + * <p>Unlike the {@link List} interface, this interface does not + * provide support for indexed access to elements. + * + * <p>While <tt>Deque</tt> implementations are not strictly required + * to prohibit the insertion of null elements, they are strongly + * encouraged to do so. Users of any <tt>Deque</tt> implementations + * that do allow null elements are strongly encouraged <i>not</i> to + * take advantage of the ability to insert nulls. This is so because + * <tt>null</tt> is used as a special return value by various methods + * to indicated that the deque is empty. + * + * <p><tt>Deque</tt> implementations generally do not define + * element-based versions of the <tt>equals</tt> and <tt>hashCode</tt> + * methods, but instead inherit the identity-based versions from class + * <tt>Object</tt>. + * + * <p>This interface is a member of the <a + * href="{@docRoot}/../technotes/guides/collections/index.html"> Java Collections + * Framework</a>. + * + * @author Doug Lea + * @author Josh Bloch + * @since 1.6 + * @param <E> the type of elements held in this collection + */ + +public interface Deque<E> extends Queue<E> { + /** + * Inserts the specified element at the front of this deque if it is + * possible to do so immediately without violating capacity restrictions. + * When using a capacity-restricted deque, it is generally preferable to + * use method {@link #offerFirst}. + * + * @param e the element to add + * @throws IllegalStateException if the element cannot be added at this + * time due to capacity restrictions + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + void addFirst(E e); + + /** + * Inserts the specified element at the end of this deque if it is + * possible to do so immediately without violating capacity restrictions. + * When using a capacity-restricted deque, it is generally preferable to + * use method {@link #offerLast}. + * + * <p>This method is equivalent to {@link #add}. + * + * @param e the element to add + * @throws IllegalStateException if the element cannot be added at this + * time due to capacity restrictions + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + void addLast(E e); + + /** + * Inserts the specified element at the front of this deque unless it would + * violate capacity restrictions. When using a capacity-restricted deque, + * this method is generally preferable to the {@link #addFirst} method, + * which can fail to insert an element only by throwing an exception. + * + * @param e the element to add + * @return <tt>true</tt> if the element was added to this deque, else + * <tt>false</tt> + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + boolean offerFirst(E e); + + /** + * Inserts the specified element at the end of this deque unless it would + * violate capacity restrictions. When using a capacity-restricted deque, + * this method is generally preferable to the {@link #addLast} method, + * which can fail to insert an element only by throwing an exception. + * + * @param e the element to add + * @return <tt>true</tt> if the element was added to this deque, else + * <tt>false</tt> + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + boolean offerLast(E e); + + /** + * Retrieves and removes the first element of this deque. This method + * differs from {@link #pollFirst pollFirst} only in that it throws an + * exception if this deque is empty. + * + * @return the head of this deque + * @throws NoSuchElementException if this deque is empty + */ + E removeFirst(); + + /** + * Retrieves and removes the last element of this deque. This method + * differs from {@link #pollLast pollLast} only in that it throws an + * exception if this deque is empty. + * + * @return the tail of this deque + * @throws NoSuchElementException if this deque is empty + */ + E removeLast(); + + /** + * Retrieves and removes the first element of this deque, + * or returns <tt>null</tt> if this deque is empty. + * + * @return the head of this deque, or <tt>null</tt> if this deque is empty + */ + E pollFirst(); + + /** + * Retrieves and removes the last element of this deque, + * or returns <tt>null</tt> if this deque is empty. + * + * @return the tail of this deque, or <tt>null</tt> if this deque is empty + */ + E pollLast(); + + /** + * Retrieves, but does not remove, the first element of this deque. + * + * This method differs from {@link #peekFirst peekFirst} only in that it + * throws an exception if this deque is empty. + * + * @return the head of this deque + * @throws NoSuchElementException if this deque is empty + */ + E getFirst(); + + /** + * Retrieves, but does not remove, the last element of this deque. + * This method differs from {@link #peekLast peekLast} only in that it + * throws an exception if this deque is empty. + * + * @return the tail of this deque + * @throws NoSuchElementException if this deque is empty + */ + E getLast(); + + /** + * Retrieves, but does not remove, the first element of this deque, + * or returns <tt>null</tt> if this deque is empty. + * + * @return the head of this deque, or <tt>null</tt> if this deque is empty + */ + E peekFirst(); + + /** + * Retrieves, but does not remove, the last element of this deque, + * or returns <tt>null</tt> if this deque is empty. + * + * @return the tail of this deque, or <tt>null</tt> if this deque is empty + */ + E peekLast(); + + /** + * Removes the first occurrence of the specified element from this deque. + * If the deque does not contain the element, it is unchanged. + * More formally, removes the first element <tt>e</tt> such that + * <tt>(o==null ? e==null : o.equals(e))</tt> + * (if such an element exists). + * Returns <tt>true</tt> if this deque contained the specified element + * (or equivalently, if this deque changed as a result of the call). + * + * @param o element to be removed from this deque, if present + * @return <tt>true</tt> if an element was removed as a result of this call + * @throws ClassCastException if the class of the specified element + * is incompatible with this deque (optional) + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements (optional) + */ + boolean removeFirstOccurrence(Object o); + + /** + * Removes the last occurrence of the specified element from this deque. + * If the deque does not contain the element, it is unchanged. + * More formally, removes the last element <tt>e</tt> such that + * <tt>(o==null ? e==null : o.equals(e))</tt> + * (if such an element exists). + * Returns <tt>true</tt> if this deque contained the specified element + * (or equivalently, if this deque changed as a result of the call). + * + * @param o element to be removed from this deque, if present + * @return <tt>true</tt> if an element was removed as a result of this call + * @throws ClassCastException if the class of the specified element + * is incompatible with this deque (optional) + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements (optional) + */ + boolean removeLastOccurrence(Object o); + + // *** Queue methods *** + + /** + * Inserts the specified element into the queue represented by this deque + * (in other words, at the tail of this deque) if it is possible to do so + * immediately without violating capacity restrictions, returning + * <tt>true</tt> upon success and throwing an + * <tt>IllegalStateException</tt> if no space is currently available. + * When using a capacity-restricted deque, it is generally preferable to + * use {@link #offer(Object) offer}. + * + * <p>This method is equivalent to {@link #addLast}. + * + * @param e the element to add + * @return <tt>true</tt> (as specified by {@link Collection#add}) + * @throws IllegalStateException if the element cannot be added at this + * time due to capacity restrictions + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + boolean add(E e); + + /** + * Inserts the specified element into the queue represented by this deque + * (in other words, at the tail of this deque) if it is possible to do so + * immediately without violating capacity restrictions, returning + * <tt>true</tt> upon success and <tt>false</tt> if no space is currently + * available. When using a capacity-restricted deque, this method is + * generally preferable to the {@link #add} method, which can fail to + * insert an element only by throwing an exception. + * + * <p>This method is equivalent to {@link #offerLast}. + * + * @param e the element to add + * @return <tt>true</tt> if the element was added to this deque, else + * <tt>false</tt> + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + boolean offer(E e); + + /** + * Retrieves and removes the head of the queue represented by this deque + * (in other words, the first element of this deque). + * This method differs from {@link #poll poll} only in that it throws an + * exception if this deque is empty. + * + * <p>This method is equivalent to {@link #removeFirst()}. + * + * @return the head of the queue represented by this deque + * @throws NoSuchElementException if this deque is empty + */ + E remove(); + + /** + * Retrieves and removes the head of the queue represented by this deque + * (in other words, the first element of this deque), or returns + * <tt>null</tt> if this deque is empty. + * + * <p>This method is equivalent to {@link #pollFirst()}. + * + * @return the first element of this deque, or <tt>null</tt> if + * this deque is empty + */ + E poll(); + + /** + * Retrieves, but does not remove, the head of the queue represented by + * this deque (in other words, the first element of this deque). + * This method differs from {@link #peek peek} only in that it throws an + * exception if this deque is empty. + * + * <p>This method is equivalent to {@link #getFirst()}. + * + * @return the head of the queue represented by this deque + * @throws NoSuchElementException if this deque is empty + */ + E element(); + + /** + * Retrieves, but does not remove, the head of the queue represented by + * this deque (in other words, the first element of this deque), or + * returns <tt>null</tt> if this deque is empty. + * + * <p>This method is equivalent to {@link #peekFirst()}. + * + * @return the head of the queue represented by this deque, or + * <tt>null</tt> if this deque is empty + */ + E peek(); + + + // *** Stack methods *** + + /** + * Pushes an element onto the stack represented by this deque (in other + * words, at the head of this deque) if it is possible to do so + * immediately without violating capacity restrictions, returning + * <tt>true</tt> upon success and throwing an + * <tt>IllegalStateException</tt> if no space is currently available. + * + * <p>This method is equivalent to {@link #addFirst}. + * + * @param e the element to push + * @throws IllegalStateException if the element cannot be added at this + * time due to capacity restrictions + * @throws ClassCastException if the class of the specified element + * prevents it from being added to this deque + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements + * @throws IllegalArgumentException if some property of the specified + * element prevents it from being added to this deque + */ + void push(E e); + + /** + * Pops an element from the stack represented by this deque. In other + * words, removes and returns the first element of this deque. + * + * <p>This method is equivalent to {@link #removeFirst()}. + * + * @return the element at the front of this deque (which is the top + * of the stack represented by this deque) + * @throws NoSuchElementException if this deque is empty + */ + E pop(); + + + // *** Collection methods *** + + /** + * Removes the first occurrence of the specified element from this deque. + * If the deque does not contain the element, it is unchanged. + * More formally, removes the first element <tt>e</tt> such that + * <tt>(o==null ? e==null : o.equals(e))</tt> + * (if such an element exists). + * Returns <tt>true</tt> if this deque contained the specified element + * (or equivalently, if this deque changed as a result of the call). + * + * <p>This method is equivalent to {@link #removeFirstOccurrence}. + * + * @param o element to be removed from this deque, if present + * @return <tt>true</tt> if an element was removed as a result of this call + * @throws ClassCastException if the class of the specified element + * is incompatible with this deque (optional) + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements (optional) + */ + boolean remove(Object o); + + /** + * Returns <tt>true</tt> if this deque contains the specified element. + * More formally, returns <tt>true</tt> if and only if this deque contains + * at least one element <tt>e</tt> such that + * <tt>(o==null ? e==null : o.equals(e))</tt>. + * + * @param o element whose presence in this deque is to be tested + * @return <tt>true</tt> if this deque contains the specified element + * @throws ClassCastException if the type of the specified element + * is incompatible with this deque (optional) + * @throws NullPointerException if the specified element is null and this + * deque does not permit null elements (optional) + */ + boolean contains(Object o); + + /** + * Returns the number of elements in this deque. + * + * @return the number of elements in this deque + */ + public int size(); + + /** + * Returns an iterator over the elements in this deque in proper sequence. + * The elements will be returned in order from first (head) to last (tail). + * + * @return an iterator over the elements in this deque in proper sequence + */ + Iterator<E> iterator(); + + /** + * Returns an iterator over the elements in this deque in reverse + * sequential order. The elements will be returned in order from + * last (tail) to first (head). + * + * @return an iterator over the elements in this deque in reverse + * sequence + */ + Iterator<E> descendingIterator(); + +} |