Adds the Deque interface, and allows LinkedList to implement that interface.

This also changes ConcurrentLinkedQueue to implement the Queue interface, and just throw exceptions for operations which are not currently implemented.

classpath/java/util/Deque.java

@@ -0,0 +1,31 @@
+/* Copyright (c) 2008-2014, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util;
+
+public interface Deque<T> extends Queue<T> {
+  public boolean offerFirst(T e);
+  public void push(T e);
+  public void addFirst(T element);
+  public boolean offerLast(T e);
+  public void addLast(T element);
+  public T peekFirst();
+  public T getFirst();
+  public T peekLast();
+  public T getLast();
+  public T pollFirst();
+  public T removeFirst();
+  public T pop();
+  public T pollLast();
+  public T removeLast();
+  public Iterator<T> descendingIterator();
+  public boolean removeLastOccurrence(Object o);
+  public boolean removeFirstOccurrence(Object o);
+}

classpath/java/util/LinkedList.java

@@ -10,7 +10,7 @@
 
 package java.util;
 
-public class LinkedList<T> extends AbstractSequentialList<T> {
+public class LinkedList<T> extends AbstractSequentialList<T> implements Deque<T> {
   private Cell<T> front;
   private Cell<T> rear;
   private int size;
@@ -85,14 +85,17 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     }
   }
 
+  @Override
   public int size() {
     return size;
   }
 
+  @Override
   public boolean contains(Object element) {
     return find(element) != null;
   }
 
+  @Override
   public int indexOf(Object element) {
     int i = 0;
     for (Cell<T> c = front; c != null; c = c.next) {
@@ -104,6 +107,7 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     return -1;
   }
 
+  @Override
   public int lastIndexOf(Object element) {
     int i = size;
     for (Cell<T> c = rear; c != null; c = c.prev) {
@@ -115,16 +119,24 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     return -1;
   }
 
+  @Override
+  public boolean offer(T element) {
+    return add(element);
+  }
+
+  @Override
   public boolean add(T element) {
     addLast(element);
     return true;
   }
 
+  @Override
   public boolean addAll(Collection<? extends T> collection) {
     for (T t: collection) add(t);
     return true;
   }
 
+  @Override
   public void add(int index, T element) {
     if (index == 0) {
       addFirst(element);
@@ -135,10 +147,31 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     }
   }
 
+  @Override
+  public boolean offerFirst(T e) {
+    addFirst(e);
+    
+    return true;
+  }
+
+  @Override
+  public void push(T e) {
+    addFirst(e);
+  }
+
+  @Override
   public void addFirst(T element) {
     addFirst(new Cell(element, null, null));
   }
 
+  @Override
+  public boolean offerLast(T e) {
+    addLast(e);
+    
+    return true;
+  }
+
+  @Override
   public void addLast(T element) {
     addLast(new Cell(element, null, null));
   }
@@ -147,6 +180,7 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     return find(index).value;
   }
 
+  @Override
   public T set(int index, T value) {
     Cell<T> c = find(index);
     T old = c.value;
@@ -154,6 +188,21 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     return old;
   }
 
+  @Override
+  public T peek() {
+    return peekFirst();
+  }
+
+  @Override
+  public T peekFirst() {
+    if (front != null) {
+      return front.value;
+    } else {
+      return null;
+    }
+  }
+
+  @Override
   public T getFirst() {
     if (front != null) {
       return front.value;
@@ -161,7 +210,17 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
       throw new NoSuchElementException();
     }
   }
+  
+  @Override
+  public T peekLast() {
+    if (rear != null) {
+      return rear.value;
+    } else {
+      return null;
+    }
+  }
 
+  @Override
   public T getLast() {
     if (rear != null) {
       return rear.value;
@@ -170,27 +229,57 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     }
   }
 
+  @Override
   public T remove(int index) {
     Cell<T> c = find(index);
     remove(c);
     return c.value;
   }
 
+  @Override
   public boolean isEmpty() {
     return size() == 0;
   }
 
-  public T removeFirst() {
+  @Override
+  public T poll() {
+    return pollFirst();
+  }
+
+  @Override
+  public T pollFirst() {
     if (front != null) {
       T v = front.value;
       remove(front);
       return v;
     } else {
-      throw new NoSuchElementException();
+      return null;
     }
   }
 
-  public T removeLast() {
+  @Override
+  public T removeFirst() {
+    T result = pollFirst();
+    
+    if (result == null) {
+      throw new NoSuchElementException();
+    } else {
+      return result;
+    }
+  }
+
+  @Override
+  public T pop() {
+    return removeFirst();
+  }
+
+  @Override
+  public T remove() {
+    return removeFirst();
+  }
+
+  @Override
+  public T pollLast() {
     if (rear != null) {
       T v = rear.value;
       remove(rear);
@@ -200,6 +289,18 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     }
   }
 
+  @Override
+  public T removeLast() {
+    T result = pollLast();
+    
+    if (result == null) {
+      throw new NoSuchElementException();
+    } else {
+      return result;
+    }
+  }
+
+  @Override
   public boolean remove(Object element) {
     Cell<T> c = find(element);
     if (c == null) {
@@ -210,15 +311,23 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     }
   }
 
+  @Override
   public void clear() {
     front = rear = null;
     size = 0;
   }
 
+  @Override
   public Iterator<T> iterator() {
     return listIterator();
   }
 
+  @Override
+  public ListIterator<T> listIterator() {
+    return listIterator(0);
+  }
+
+  @Override
   public ListIterator<T> listIterator(int index) {
     MyIterator it = new MyIterator();
     for (int i = 0; i < index; ++i) {
@@ -227,14 +336,67 @@ public class LinkedList<T> extends AbstractSequentialList<T> {
     return it;
   }
 
-  public ListIterator<T> listIterator() {
+  @Override
-    return listIterator(0);
+  public Iterator<T> descendingIterator() {
+    final ListIterator<T> li = listIterator(size());
+    
+    return new Iterator<T>() {
+      @Override
+      public T next() {
+        return li.previous();
+      }
+
+      @Override
+      public boolean hasNext() {
+        return li.hasPrevious();
+      }
+
+      @Override
+      public void remove() {
+        li.remove();
+      }
+    };
   }
 
+  @Override
   public String toString() {
     return Collections.toString(this);
   }
 
+  @Override
+  public T element() {
+    T result = peek();
+    if (result == null) {
+      throw new NoSuchElementException();
+    } else {
+      return result;
+    }
+  }
+
+  @Override
+  public boolean removeFirstOccurrence(Object o) {
+    int index = indexOf(o);
+    if (index > 0) {
+      remove(index);
+      
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  @Override
+  public boolean removeLastOccurrence(Object o) {
+    int lastIndex = lastIndexOf(o);
+    if (lastIndex > 0) {
+      remove(lastIndex);
+      
+      return true;
+    } else {
+      return false;
+    }
+  }
+  
   private static class Cell<T> {
     public T value;
     public Cell<T> prev;

classpath/java/util/concurrent/ConcurrentLinkedQueue.java

@@ -1,8 +1,13 @@
 package java.util.concurrent;
 
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Queue;
+
 import avian.Atomic;
 
-public class ConcurrentLinkedQueue<T> {
+public class ConcurrentLinkedQueue<T> implements Queue<T> {
   private static final long QueueHead;
   private static final long QueueTail;
   private static final long NodeNext;
@@ -25,11 +30,20 @@ public class ConcurrentLinkedQueue<T> {
   private volatile Node<T> head = new Node<T>(null, null);
   private volatile Node<T> tail = head;
 
+  @Override
   public void clear() {
-    // todo: can we safely make this O(1)?
+    // TODO - can we safely make this O(1)?
     while (poll() != null) { }
   }
 
+  @Override
+  public boolean offer(T element) {
+    add(element);
+    
+    return true;
+  }
+
+  @Override
   public boolean add(T value) {
     Node<T> n = new Node<T>(value, null);
     while (true) {
@@ -48,14 +62,36 @@ public class ConcurrentLinkedQueue<T> {
     return true;
   }
 
+  @Override
   public T peek() {
     return poll(false);
   }
 
+  @Override
+  public T element() {
+    T result = peek();
+    if (result == null) {
+      throw new NoSuchElementException();
+    } else {
+      return result;
+    }
+  }
+
+  @Override
   public T poll() {
     return poll(true);
   }
 
+  @Override
+  public T remove() {
+    T result = poll();
+    if (result == null) {
+      throw new NoSuchElementException();
+    } else {
+      return result;
+    }
+  }
+
   private T poll(boolean remove) {
     while (true) {
       Node<T> h = head;
@@ -90,4 +126,63 @@ public class ConcurrentLinkedQueue<T> {
       this.next = next;
     }
   }
+
+  @Override
+  public int size() {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return size() == 0;
+  }
+
+  @Override
+  public boolean contains(Object element) {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean containsAll(Collection<?> c) {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean addAll(Collection<? extends T> collection) {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean remove(Object element) {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean removeAll(Collection<?> c) {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public Object[] toArray() {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public <S> S[] toArray(S[] array) {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public Iterator<T> iterator() {
+    // TODO - implement
+    throw new UnsupportedOperationException();
+  }
 }