diff options
Diffstat (limited to 'android')
| -rw-r--r-- | android/src/com/artifex/mupdfdemo/ArrayDeque.java | 856 | ||||
| -rw-r--r-- | android/src/com/artifex/mupdfdemo/AsyncTask.java | 1 | ||||
| -rw-r--r-- | android/src/com/artifex/mupdfdemo/Deque.java | 554 |
3 files changed, 1410 insertions, 1 deletions
diff --git a/android/src/com/artifex/mupdfdemo/ArrayDeque.java b/android/src/com/artifex/mupdfdemo/ArrayDeque.java new file mode 100644 index 00000000..a66c63b5 --- /dev/null +++ b/android/src/com/artifex/mupdfdemo/ArrayDeque.java @@ -0,0 +1,856 @@ +/* + * Written by Josh Bloch of Google Inc. and released to the public domain, + * as explained at http://creativecommons.org/publicdomain/zero/1.0/. + */ + +package com.artifex.mupdfdemo; + +import java.util.AbstractCollection; +import java.util.Arrays; +import java.util.Collection; +import java.util.ConcurrentModificationException; +import java.util.Deque; +import java.util.Iterator; +import java.util.LinkedList; +import java.util.List; +import java.util.NoSuchElementException; +import java.util.Queue; +import java.util.Stack; + +// BEGIN android-note +// removed link to collections framework docs +// END android-note + +/** + * Resizable-array implementation of the {@link Deque} interface. Array + * deques have no capacity restrictions; they grow as necessary to support + * usage. They are not thread-safe; in the absence of external + * synchronization, they do not support concurrent access by multiple threads. + * Null elements are prohibited. This class is likely to be faster than + * {@link Stack} when used as a stack, and faster than {@link LinkedList} + * when used as a queue. + * + * <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time. + * Exceptions include {@link #remove(Object) remove}, {@link + * #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence + * removeLastOccurrence}, {@link #contains contains}, {@link #iterator + * iterator.remove()}, and the bulk operations, all of which run in linear + * time. + * + * <p>The iterators returned by this class's <tt>iterator</tt> method are + * <i>fail-fast</i>: If the deque is modified at any time after the iterator + * is created, in any way except through the iterator's own <tt>remove</tt> + * method, the iterator will generally throw a {@link + * ConcurrentModificationException}. Thus, in the face of concurrent + * modification, the iterator fails quickly and cleanly, rather than risking + * arbitrary, non-deterministic behavior at an undetermined time in the + * future. + * + * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed + * as it is, generally speaking, impossible to make any hard guarantees in the + * presence of unsynchronized concurrent modification. Fail-fast iterators + * throw <tt>ConcurrentModificationException</tt> on a best-effort basis. + * Therefore, it would be wrong to write a program that depended on this + * exception for its correctness: <i>the fail-fast behavior of iterators + * should be used only to detect bugs.</i> + * + * <p>This class and its iterator implement all of the + * <em>optional</em> methods of the {@link Collection} and {@link + * Iterator} interfaces. + * + * @author Josh Bloch and Doug Lea + * @since 1.6 + * @param <E> the type of elements held in this collection + */ +public class ArrayDeque<E> extends AbstractCollection<E> + implements Deque<E>, Cloneable, java.io.Serializable +{ + /** + * The array in which the elements of the deque are stored. + * The capacity of the deque is the length of this array, which is + * always a power of two. The array is never allowed to become + * full, except transiently within an addX method where it is + * resized (see doubleCapacity) immediately upon becoming full, + * thus avoiding head and tail wrapping around to equal each + * other. We also guarantee that all array cells not holding + * deque elements are always null. + */ + private transient Object[] elements; + + /** + * The index of the element at the head of the deque (which is the + * element that would be removed by remove() or pop()); or an + * arbitrary number equal to tail if the deque is empty. + */ + private transient int head; + + /** + * The index at which the next element would be added to the tail + * of the deque (via addLast(E), add(E), or push(E)). + */ + private transient int tail; + + /** + * The minimum capacity that we'll use for a newly created deque. + * Must be a power of 2. + */ + private static final int MIN_INITIAL_CAPACITY = 8; + + // ****** Array allocation and resizing utilities ****** + + /** + * Allocate empty array to hold the given number of elements. + * + * @param numElements the number of elements to hold + */ + private void allocateElements(int numElements) { + int initialCapacity = MIN_INITIAL_CAPACITY; + // Find the best power of two to hold elements. + // Tests "<=" because arrays aren't kept full. + if (numElements >= initialCapacity) { + initialCapacity = numElements; + initialCapacity |= (initialCapacity >>> 1); + initialCapacity |= (initialCapacity >>> 2); + initialCapacity |= (initialCapacity >>> 4); + initialCapacity |= (initialCapacity >>> 8); + initialCapacity |= (initialCapacity >>> 16); + initialCapacity++; + + if (initialCapacity < 0) // Too many elements, must back off + initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements + } + elements = new Object[initialCapacity]; + } + + /** + * Double the capacity of this deque. Call only when full, i.e., + * when head and tail have wrapped around to become equal. + */ + private void doubleCapacity() { + // assert head == tail; + int p = head; + int n = elements.length; + int r = n - p; // number of elements to the right of p + int newCapacity = n << 1; + if (newCapacity < 0) + throw new IllegalStateException("Sorry, deque too big"); + Object[] a = new Object[newCapacity]; + System.arraycopy(elements, p, a, 0, r); + System.arraycopy(elements, 0, a, r, p); + elements = a; + head = 0; + tail = n; + } + + /** + * Copies the elements from our element array into the specified array, + * in order (from first to last element in the deque). It is assumed + * that the array is large enough to hold all elements in the deque. + * + * @return its argument + */ + private <T> T[] copyElements(T[] a) { + if (head < tail) { + System.arraycopy(elements, head, a, 0, size()); + } else if (head > tail) { + int headPortionLen = elements.length - head; + System.arraycopy(elements, head, a, 0, headPortionLen); + System.arraycopy(elements, 0, a, headPortionLen, tail); + } + return a; + } + + /** + * Constructs an empty array deque with an initial capacity + * sufficient to hold 16 elements. + */ + public ArrayDeque() { + elements = new Object[16]; + } + + /** + * Constructs an empty array deque with an initial capacity + * sufficient to hold the specified number of elements. + * + * @param numElements lower bound on initial capacity of the deque + */ + public ArrayDeque(int numElements) { + allocateElements(numElements); + } + + /** + * Constructs a deque containing the elements of the specified + * collection, in the order they are returned by the collection's + * iterator. (The first element returned by the collection's + * iterator becomes the first element, or <i>front</i> of the + * deque.) + * + * @param c the collection whose elements are to be placed into the deque + * @throws NullPointerException if the specified collection is null + */ + public ArrayDeque(Collection<? extends E> c) { + allocateElements(c.size()); + addAll(c); + } + + // The main insertion and extraction methods are addFirst, + // addLast, pollFirst, pollLast. The other methods are defined in + // terms of these. + + /** + * Inserts the specified element at the front of this deque. + * + * @param e the element to add + * @throws NullPointerException if the specified element is null + */ + public void addFirst(E e) { + if (e == null) + throw new NullPointerException("e == null"); + elements[head = (head - 1) & (elements.length - 1)] = e; + if (head == tail) + doubleCapacity(); + } + + /** + * Inserts the specified element at the end of this deque. + * + * <p>This method is equivalent to {@link #add}. + * + * @param e the element to add + * @throws NullPointerException if the specified element is null + */ + public void addLast(E e) { + if (e == null) + throw new NullPointerException("e == null"); + elements[tail] = e; + if ( (tail = (tail + 1) & (elements.length - 1)) == head) + doubleCapacity(); + } + + /** + * Inserts the specified element at the front of this deque. + * + * @param e the element to add + * @return <tt>true</tt> (as specified by {@link Deque#offerFirst}) + * @throws NullPointerException if the specified element is null + */ + public boolean offerFirst(E e) { + addFirst(e); + return true; + } + + /** + * Inserts the specified element at the end of this deque. + * + * @param e the element to add + * @return <tt>true</tt> (as specified by {@link Deque#offerLast}) + * @throws NullPointerException if the specified element is null + */ + public boolean offerLast(E e) { + addLast(e); + return true; + } + + /** + * @throws NoSuchElementException {@inheritDoc} + */ + public E removeFirst() { + E x = pollFirst(); + if (x == null) + throw new NoSuchElementException(); + return x; + } + + /** + * @throws NoSuchElementException {@inheritDoc} + */ + public E removeLast() { + E x = pollLast(); + if (x == null) + throw new NoSuchElementException(); + return x; + } + + public E pollFirst() { + int h = head; + @SuppressWarnings("unchecked") E result = (E) elements[h]; + // Element is null if deque empty + if (result == null) + return null; + elements[h] = null; // Must null out slot + head = (h + 1) & (elements.length - 1); + return result; + } + + public E pollLast() { + int t = (tail - 1) & (elements.length - 1); + @SuppressWarnings("unchecked") E result = (E) elements[t]; + if (result == null) + return null; + elements[t] = null; + tail = t; + return result; + } + + /** + * @throws NoSuchElementException {@inheritDoc} + */ + public E getFirst() { + @SuppressWarnings("unchecked") E result = (E) elements[head]; + if (result == null) + throw new NoSuchElementException(); + return result; + } + + /** + * @throws NoSuchElementException {@inheritDoc} + */ + public E getLast() { + @SuppressWarnings("unchecked") + E result = (E) elements[(tail - 1) & (elements.length - 1)]; + if (result == null) + throw new NoSuchElementException(); + return result; + } + + public E peekFirst() { + @SuppressWarnings("unchecked") E result = (E) elements[head]; + // elements[head] is null if deque empty + return result; + } + + public E peekLast() { + @SuppressWarnings("unchecked") + E result = (E) elements[(tail - 1) & (elements.length - 1)]; + return result; + } + + /** + * Removes the first occurrence of the specified element in this + * deque (when traversing the deque from head to tail). + * If the deque does not contain the element, it is unchanged. + * More formally, removes the first element <tt>e</tt> such that + * <tt>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 the deque contained the specified element + */ + public boolean removeFirstOccurrence(Object o) { + if (o == null) + return false; + int mask = elements.length - 1; + int i = head; + Object x; + while ( (x = elements[i]) != null) { + if (o.equals(x)) { + delete(i); + return true; + } + i = (i + 1) & mask; + } + return false; + } + + /** + * Removes the last occurrence of the specified element in this + * deque (when traversing the deque from head to tail). + * If the deque does not contain the element, it is unchanged. + * More formally, removes the last element <tt>e</tt> such that + * <tt>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 the deque contained the specified element + */ + public boolean removeLastOccurrence(Object o) { + if (o == null) + return false; + int mask = elements.length - 1; + int i = (tail - 1) & mask; + Object x; + while ( (x = elements[i]) != null) { + if (o.equals(x)) { + delete(i); + return true; + } + i = (i - 1) & mask; + } + return false; + } + + // *** Queue methods *** + + /** + * Inserts the specified element at the end of this deque. + * + * <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 NullPointerException if the specified element is null + */ + public boolean add(E e) { + addLast(e); + return true; + } + + /** + * Inserts the specified element at the end of this deque. + * + * <p>This method is equivalent to {@link #offerLast}. + * + * @param e the element to add + * @return <tt>true</tt> (as specified by {@link Queue#offer}) + * @throws NullPointerException if the specified element is null + */ + public boolean offer(E e) { + return offerLast(e); + } + + /** + * Retrieves and removes the head of the queue represented by 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 {@inheritDoc} + */ + public E remove() { + return removeFirst(); + } + + /** + * 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 head of the queue represented by this deque, or + * <tt>null</tt> if this deque is empty + */ + public E poll() { + return pollFirst(); + } + + /** + * Retrieves, but does not remove, the head of the queue represented by + * 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 {@inheritDoc} + */ + public E element() { + return getFirst(); + } + + /** + * Retrieves, but does not remove, the head of the queue represented by + * 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 + */ + public E peek() { + return peekFirst(); + } + + // *** Stack methods *** + + /** + * Pushes an element onto the stack represented by this deque. In other + * words, inserts the element at the front of this deque. + * + * <p>This method is equivalent to {@link #addFirst}. + * + * @param e the element to push + * @throws NullPointerException if the specified element is null + */ + public void push(E e) { + addFirst(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 {@inheritDoc} + */ + public E pop() { + return removeFirst(); + } + + private void checkInvariants() { + // assert elements[tail] == null; + // assert head == tail ? elements[head] == null : + // (elements[head] != null && + // elements[(tail - 1) & (elements.length - 1)] != null); + // assert elements[(head - 1) & (elements.length - 1)] == null; + } + + /** + * Removes the element at the specified position in the elements array, + * adjusting head and tail as necessary. This can result in motion of + * elements backwards or forwards in the array. + * + * <p>This method is called delete rather than remove to emphasize + * that its semantics differ from those of {@link List#remove(int)}. + * + * @return true if elements moved backwards + */ + private boolean delete(int i) { + //checkInvariants(); + final Object[] elements = this.elements; + final int mask = elements.length - 1; + final int h = head; + final int t = tail; + final int front = (i - h) & mask; + final int back = (t - i) & mask; + + // Invariant: head <= i < tail mod circularity + if (front >= ((t - h) & mask)) + throw new ConcurrentModificationException(); + + // Optimize for least element motion + if (front < back) { + if (h <= i) { + System.arraycopy(elements, h, elements, h + 1, front); + } else { // Wrap around + System.arraycopy(elements, 0, elements, 1, i); + elements[0] = elements[mask]; + System.arraycopy(elements, h, elements, h + 1, mask - h); + } + elements[h] = null; + head = (h + 1) & mask; + return false; + } else { + if (i < t) { // Copy the null tail as well + System.arraycopy(elements, i + 1, elements, i, back); + tail = t - 1; + } else { // Wrap around + System.arraycopy(elements, i + 1, elements, i, mask - i); + elements[mask] = elements[0]; + System.arraycopy(elements, 1, elements, 0, t); + tail = (t - 1) & mask; + } + return true; + } + } + + // *** Collection Methods *** + + /** + * Returns the number of elements in this deque. + * + * @return the number of elements in this deque + */ + public int size() { + return (tail - head) & (elements.length - 1); + } + + /** + * Returns <tt>true</tt> if this deque contains no elements. + * + * @return <tt>true</tt> if this deque contains no elements + */ + public boolean isEmpty() { + return head == tail; + } + + /** + * Returns an iterator over the elements in this deque. The elements + * will be ordered from first (head) to last (tail). This is the same + * order that elements would be dequeued (via successive calls to + * {@link #remove} or popped (via successive calls to {@link #pop}). + * + * @return an iterator over the elements in this deque + */ + public Iterator<E> iterator() { + return new DeqIterator(); + } + + public Iterator<E> descendingIterator() { + return new DescendingIterator(); + } + + private class DeqIterator implements Iterator<E> { + /** + * Index of element to be returned by subsequent call to next. + */ + private int cursor = head; + + /** + * Tail recorded at construction (also in remove), to stop + * iterator and also to check for comodification. + */ + private int fence = tail; + + /** + * Index of element returned by most recent call to next. + * Reset to -1 if element is deleted by a call to remove. + */ + private int lastRet = -1; + + public boolean hasNext() { + return cursor != fence; + } + + public E next() { + if (cursor == fence) + throw new NoSuchElementException(); + @SuppressWarnings("unchecked") E result = (E) elements[cursor]; + // This check doesn't catch all possible comodifications, + // but does catch the ones that corrupt traversal + if (tail != fence || result == null) + throw new ConcurrentModificationException(); + lastRet = cursor; + cursor = (cursor + 1) & (elements.length - 1); + return result; + } + + public void remove() { + if (lastRet < 0) + throw new IllegalStateException(); + if (delete(lastRet)) { // if left-shifted, undo increment in next() + cursor = (cursor - 1) & (elements.length - 1); + fence = tail; + } + lastRet = -1; + } + } + + private class DescendingIterator implements Iterator<E> { + /* + * This class is nearly a mirror-image of DeqIterator, using + * tail instead of head for initial cursor, and head instead of + * tail for fence. + */ + private int cursor = tail; + private int fence = head; + private int lastRet = -1; + + public boolean hasNext() { + return cursor != fence; + } + + public E next() { + if (cursor == fence) + throw new NoSuchElementException(); + cursor = (cursor - 1) & (elements.length - 1); + @SuppressWarnings("unchecked") E result = (E) elements[cursor]; + if (head != fence || result == null) + throw new ConcurrentModificationException(); + lastRet = cursor; + return result; + } + + public void remove() { + if (lastRet < 0) + throw new IllegalStateException(); + if (!delete(lastRet)) { + cursor = (cursor + 1) & (elements.length - 1); + fence = head; + } + lastRet = -1; + } + } + + /** + * 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.equals(e)</tt>. + * + * @param o object to be checked for containment in this deque + * @return <tt>true</tt> if this deque contains the specified element + */ + public boolean contains(Object o) { + if (o == null) + return false; + int mask = elements.length - 1; + int i = head; + Object x; + while ( (x = elements[i]) != null) { + if (o.equals(x)) + return true; + i = (i + 1) & mask; + } + return false; + } + + /** + * Removes a single instance 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.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 this deque contained the specified element + */ + public boolean remove(Object o) { + return removeFirstOccurrence(o); + } + + /** + * Removes all of the elements from this deque. + * The deque will be empty after this call returns. + */ + public void clear() { + int h = head; + int t = tail; + if (h != t) { // clear all cells + head = tail = 0; + int i = h; + int mask = elements.length - 1; + do { + elements[i] = null; + i = (i + 1) & mask; + } while (i != t); + } + } + + /** + * Returns an array containing all of the elements in this deque + * in proper sequence (from first to last element). + * + * <p>The returned array will be "safe" in that no references to it are + * maintained by this deque. (In other words, this method must allocate + * a new array). The caller is thus free to modify the returned array. + * + * <p>This method acts as bridge between array-based and collection-based + * APIs. + * + * @return an array containing all of the elements in this deque + */ + public Object[] toArray() { + return copyElements(new Object[size()]); + } + + /** + * Returns an array containing all of the elements in this deque in + * proper sequence (from first to last element); the runtime type of the + * returned array is that of the specified array. If the deque fits in + * the specified array, it is returned therein. Otherwise, a new array + * is allocated with the runtime type of the specified array and the + * size of this deque. + * + * <p>If this deque fits in the specified array with room to spare + * (i.e., the array has more elements than this deque), the element in + * the array immediately following the end of the deque is set to + * <tt>null</tt>. + * + * <p>Like the {@link #toArray()} method, this method acts as bridge between + * array-based and collection-based APIs. Further, this method allows + * precise control over the runtime type of the output array, and may, + * under certain circumstances, be used to save allocation costs. + * + * <p>Suppose <tt>x</tt> is a deque known to contain only strings. + * The following code can be used to dump the deque into a newly + * allocated array of <tt>String</tt>: + * + * <pre> {@code String[] y = x.toArray(new String[0]);}</pre> + * + * Note that <tt>toArray(new Object[0])</tt> is identical in function to + * <tt>toArray()</tt>. + * + * @param a the array into which the elements of the deque are to + * be stored, if it is big enough; otherwise, a new array of the + * same runtime type is allocated for this purpose + * @return an array containing all of the elements in this deque + * @throws ArrayStoreException if the runtime type of the specified array + * is not a supertype of the runtime type of every element in + * this deque + * @throws NullPointerException if the specified array is null + */ + @SuppressWarnings("unchecked") + public <T> T[] toArray(T[] a) { + int size = size(); + if (a.length < size) + a = (T[])java.lang.reflect.Array.newInstance( + a.getClass().getComponentType(), size); + copyElements(a); + if (a.length > size) + a[size] = null; + return a; + } + + // *** Object methods *** + + /** + * Returns a copy of this deque. + * + * @return a copy of this deque + */ + public ArrayDeque<E> clone() { + try { + @SuppressWarnings("unchecked") + ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); + result.elements = Arrays.copyOf(elements, elements.length); + return result; + + } catch (CloneNotSupportedException e) { + throw new AssertionError(); + } + } + + /** + * Appease the serialization gods. + */ + private static final long serialVersionUID = 2340985798034038923L; + + /** + * Serialize this deque. + * + * @serialData The current size (<tt>int</tt>) of the deque, + * followed by all of its elements (each an object reference) in + * first-to-last order. + */ + private void writeObject(java.io.ObjectOutputStream s) + throws java.io.IOException { + s.defaultWriteObject(); + + // Write out size + s.writeInt(size()); + + // Write out elements in order. + int mask = elements.length - 1; + for (int i = head; i != tail; i = (i + 1) & mask) + s.writeObject(elements[i]); + } + + /** + * Deserialize this deque. + */ + private void readObject(java.io.ObjectInputStream s) + throws java.io.IOException, ClassNotFoundException { + s.defaultReadObject(); + + // Read in size and allocate array + int size = s.readInt(); + allocateElements(size); + head = 0; + tail = size; + + // Read in all elements in the proper order. + for (int i = 0; i < size; i++) + elements[i] = s.readObject(); + } +} diff --git a/android/src/com/artifex/mupdfdemo/AsyncTask.java b/android/src/com/artifex/mupdfdemo/AsyncTask.java index 67baf62a..b370794c 100644 --- a/android/src/com/artifex/mupdfdemo/AsyncTask.java +++ b/android/src/com/artifex/mupdfdemo/AsyncTask.java @@ -16,7 +16,6 @@ package com.artifex.mupdfdemo; -import java.util.ArrayDeque; import java.util.concurrent.BlockingQueue; import java.util.concurrent.Callable; import java.util.concurrent.CancellationException; diff --git a/android/src/com/artifex/mupdfdemo/Deque.java b/android/src/com/artifex/mupdfdemo/Deque.java new file mode 100644 index 00000000..4bb176b2 --- /dev/null +++ b/android/src/com/artifex/mupdfdemo/Deque.java @@ -0,0 +1,554 @@ +/* + * 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/publicdomain/zero/1.0/ + */ + +package com.artifex.mupdfdemo; + +import java.util.Collection; +import java.util.Iterator; +import java.util.List; +import java.util.NoSuchElementException; +import java.util.Queue; +import java.util.Stack; + +// BEGIN android-note +// removed link to collections framework docs +// END android-note + +/** + * 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>. + * + * @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(); + +} |