/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.collections.primitives;
  
  import java.util.ConcurrentModificationException;
  import java.util.NoSuchElementException;
  
  /**
   * Abstract base class for {@link ShortList}s backed 
   * by random access structures like arrays.
   * <p />
   * Read-only subclasses must override {@link #get}
   * and {@link #size}.  Mutable subclasses
   * should also override {@link #set}.  Variably-sized
   * subclasses should also override {@link #add(short)} 
   * and {@link #removeElementAt}.  All other methods
   * have at least some base implementation derived from 
   * these.  Subclasses may choose to override these methods
   * to provide a more efficient implementation.
   * 
   * @since Commons Primitives 0.1
   * @version $Revision: 480460 $ $Date: 2006-11-29 03:14:21 -0500 (Wed, 29 Nov 2006) $
   * 
   * @author Rodney Waldhoff 
   */
  public abstract class RandomAccessShortList extends AbstractShortCollection implements ShortList {
  
      // constructors
      //-------------------------------------------------------------------------
  
      /** Constructs an empty list. */
      protected RandomAccessShortList() { 
      }    
  
      // fully abstract methods
      //-------------------------------------------------------------------------
      
      public abstract short get(int index);
      public abstract int size();
  
      // unsupported in base
      //-------------------------------------------------------------------------
      
      /** 
       * Unsupported in this implementation. 
       * @throws UnsupportedOperationException since this method is not supported
       */
      public short removeElementAt(int index) {
          throw new UnsupportedOperationException();
      }
      
      /** 
       * Unsupported in this implementation. 
       * @throws UnsupportedOperationException since this method is not supported
       */
      public short set(int index, short element) {
          throw new UnsupportedOperationException();
      }
          
      /** 
       * Unsupported in this implementation. 
       * @throws UnsupportedOperationException since this method is not supported
       */
      public void add(int index, short element) {
          throw new UnsupportedOperationException();
      }
  
      //-------------------------------------------------------------------------
  
      // javadocs here are inherited
      
      public boolean add(short element) {
          add(size(),element);
          return true;
      }
  
      public boolean addAll(int index, ShortCollection collection) {
          boolean modified = false;
          for(ShortIterator iter = collection.iterator(); iter.hasNext(); ) {
              add(index++,iter.next());
              modified = true;
          }
          return modified;
      }
  
     public int indexOf(short element) {
         int i = 0;
         for(ShortIterator iter = iterator(); iter.hasNext(); ) {
             if(iter.next() == element) { 
                 return i;
             } else {
                 i++;
             }
         }
         return -1;
     }
 
     public int lastIndexOf(short element) {
         for(ShortListIterator iter = listIterator(size()); iter.hasPrevious(); ) {
             if(iter.previous() == element) {
                 return iter.nextIndex();
             }
         }
         return -1;
     }
 
     public ShortIterator iterator() {
         return listIterator();
     }
 
     public ShortListIterator listIterator() {
         return listIterator(0);
     }
 
     public ShortListIterator listIterator(int index) {
         return new RandomAccessShortListIterator(this,index);            
     }
 
     public ShortList subList(int fromIndex, int toIndex) {
         return new RandomAccessShortSubList(this,fromIndex,toIndex);
     }
 
     public boolean equals(Object that) {
         if(this == that) { 
             return true; 
         } else if(that instanceof ShortList) {
             ShortList thatList = (ShortList)that;
             if(size() != thatList.size()) {
                 return false;
             }
             for(ShortIterator thatIter = thatList.iterator(), thisIter = iterator(); thisIter.hasNext();) {
                 if(thisIter.next() != thatIter.next()) { 
                     return false; 
                 }
             }
             return true;
         } else {
             return false;
         }        
     }
     
     public int hashCode() {
         int hash = 1;
         for(ShortIterator iter = iterator(); iter.hasNext(); ) {
             hash = 31*hash + iter.next();
         }
         return hash;
     }
     
     public String toString() {
         StringBuffer buf = new StringBuffer();
         buf.append("[");
         for(ShortIterator iter = iterator(); iter.hasNext();) {
             buf.append(iter.next());
             if(iter.hasNext()) {
                 buf.append(", ");
             }
         }
         buf.append("]");
         return buf.toString();
     }
     
     // protected utilities
     //-------------------------------------------------------------------------
     
     /** Get my count of structural modifications. */
     protected int getModCount() {
         return _modCount;
     }
 
     /** Increment my count of structural modifications. */
     protected void incrModCount() {
         _modCount++;
     }
 
     // attributes
     //-------------------------------------------------------------------------
     
     private int _modCount = 0;
 
     // inner classes
     //-------------------------------------------------------------------------
     
     private static class ComodChecker {
         ComodChecker(RandomAccessShortList source) {
             _source = source;  
             resyncModCount();             
         }
         
         protected RandomAccessShortList getList() {
             return _source;
         }
         
         protected void assertNotComodified() throws ConcurrentModificationException {
             if(_expectedModCount != getList().getModCount()) {
                 throw new ConcurrentModificationException();
             }
         }
             
         protected void resyncModCount() {
             _expectedModCount = getList().getModCount();
         }
         
         private RandomAccessShortList _source = null;
         private int _expectedModCount = -1;
     }
     
     protected static class RandomAccessShortListIterator extends ComodChecker implements ShortListIterator {
         RandomAccessShortListIterator(RandomAccessShortList list, int index) {
             super(list);
             if(index < 0 || index > getList().size()) {
                 throw new IndexOutOfBoundsException("Index " + index + " not in [0," + getList().size() + ")");
             } else {
                 _nextIndex = index;
                 resyncModCount();
             }
         }
             
         public boolean hasNext() {
             assertNotComodified();
             return _nextIndex < getList().size();
         }
         
         public boolean hasPrevious() {
             assertNotComodified();
             return _nextIndex > 0;
         }
         
         public int nextIndex() {
             assertNotComodified();
             return _nextIndex;
         }
         
         public int previousIndex() {
             assertNotComodified();
             return _nextIndex - 1;
         }
         
         public short next() {
             assertNotComodified();
             if(!hasNext()) {
                 throw new NoSuchElementException();
             } else {
                 short val = getList().get(_nextIndex);
                 _lastReturnedIndex = _nextIndex;
                 _nextIndex++;
                 return val;
             }
         }
         
         public short previous() {
             assertNotComodified();
             if(!hasPrevious()) {
                 throw new NoSuchElementException();
             } else {
                 short val = getList().get(_nextIndex-1);
                 _lastReturnedIndex = _nextIndex-1;
                 _nextIndex--;
                 return val;
             }
         }
         
         public void add(short value) {
             assertNotComodified();
             getList().add(_nextIndex,value);
             _nextIndex++;
             _lastReturnedIndex = -1;
             resyncModCount();
         }
     
         public void remove() {
             assertNotComodified();
             if (_lastReturnedIndex == -1) {
                 throw new IllegalStateException();
             }
             if (_lastReturnedIndex == _nextIndex) {
                 // remove() following previous()
                 getList().removeElementAt(_lastReturnedIndex);
             } else {
                 // remove() following next()
                 getList().removeElementAt(_lastReturnedIndex);
                 _nextIndex--;
             }
             _lastReturnedIndex = -1;
             resyncModCount();
         }
         
         public void set(short value) {
             assertNotComodified();
             if(-1 == _lastReturnedIndex) {
                 throw new IllegalStateException();
             } else {
                 getList().set(_lastReturnedIndex,value);
                 resyncModCount();
             }
         }
         
         private int _nextIndex = 0;
         private int _lastReturnedIndex = -1;        
     }   
 
     protected static class RandomAccessShortSubList extends RandomAccessShortList implements ShortList {
         RandomAccessShortSubList(RandomAccessShortList list, int fromIndex, int toIndex) {
             if(fromIndex < 0 || toIndex > list.size()) {
                 throw new IndexOutOfBoundsException();
             } else if(fromIndex > toIndex) {
                 throw new IllegalArgumentException();                
             } else {
                 _list = list;
                 _offset = fromIndex;
                 _limit = toIndex - fromIndex;
                 _comod = new ComodChecker(list);
                 _comod.resyncModCount();
             }            
         }
     
         public short get(int index) {
             checkRange(index);
             _comod.assertNotComodified();
             return _list.get(toUnderlyingIndex(index));
         }
     
         public short removeElementAt(int index) {
             checkRange(index);
             _comod.assertNotComodified();
             short val = _list.removeElementAt(toUnderlyingIndex(index));
             _limit--;
             _comod.resyncModCount();
             incrModCount();
             return val;
         }
     
         public short set(int index, short element) {
             checkRange(index);
             _comod.assertNotComodified();
             short val = _list.set(toUnderlyingIndex(index),element);
             incrModCount();
             _comod.resyncModCount();
             return val;
         }
     
         public void add(int index, short element) {
             checkRangeIncludingEndpoint(index);
             _comod.assertNotComodified();
              _list.add(toUnderlyingIndex(index),element);
             _limit++;
             _comod.resyncModCount();
             incrModCount();
         }
     
         public int size() {
             _comod.assertNotComodified();
             return _limit;
         }
     
         private void checkRange(int index) {
             if(index < 0 || index >= size()) {
                 throw new IndexOutOfBoundsException("index " + index + " not in [0," + size() + ")");
             }
         }
           
         private void checkRangeIncludingEndpoint(int index) {
             if(index < 0 || index > size()) {
                 throw new IndexOutOfBoundsException("index " + index + " not in [0," + size() + "]");
             }
         }
           
         private int toUnderlyingIndex(int index) {
             return (index + _offset);
         }
         
         private int _offset = 0;        
         private int _limit = 0; 
         private RandomAccessShortList _list = null;
         private ComodChecker _comod = null;
     
     }
 }