compositemap.java

JAVA 文章管理系统源码

/*
 *  Copyright 2003-2004 The Apache Software Foundation
 *
 *  Licensed 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.map;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.collection.CompositeCollection;
import org.apache.commons.collections.set.CompositeSet;

/**
 * Decorates a map of other maps to provide a single unified view.
 * <p>
 * Changes made to this map will actually be made on the decorated map.
 * Add and remove operations require the use of a pluggable strategy. If no
 * strategy is provided then add and remove are unsupported.
 *
 * @since Commons Collections 3.0
 * @version $Revision: 1.7 $ $Date: 2004/02/18 01:13:19 $
 *
 * @author Brian McCallister
 */
public class CompositeMap implements Map {

    /** Array of all maps in the composite */
    private Map[] composite;

    /** Handle mutation operations */
    private MapMutator mutator;

    /**
     * Create a new, empty, CompositeMap.
     */
    public CompositeMap() {
        this(new Map[]{}, null);
    }

    /**
     * Create a new CompositeMap with two composited Map instances.
     * 
     * @param one  the first Map to be composited
     * @param two  the second Map to be composited
     * @throws IllegalArgumentException if there is a key collision
     */
    public CompositeMap(Map one, Map two) {
        this(new Map[]{one, two}, null);
    }

    /**
     * Create a new CompositeMap with two composited Map instances.
     * 
     * @param one  the first Map to be composited
     * @param two  the second Map to be composited
     * @param mutator  MapMutator to be used for mutation operations
     */
    public CompositeMap(Map one, Map two, MapMutator mutator) {
        this(new Map[]{one, two}, mutator);
    }

    /**
     * Create a new CompositeMap which composites all of the Map instances in the
     * argument. It copies the argument array, it does not use it directly.
     * 
     * @param composite  the Maps to be composited
     * @throws IllegalArgumentException if there is a key collision
     */
    public CompositeMap(Map[] composite) {
        this(composite, null);
    }

    /**
     * Create a new CompositeMap which composites all of the Map instances in the
     * argument. It copies the argument array, it does not use it directly.
     * 
     * @param composite  Maps to be composited
     * @param mutator  MapMutator to be used for mutation operations
     */
    public CompositeMap(Map[] composite, MapMutator mutator) {
        this.mutator = mutator;
        this.composite = new Map[0];
        for (int i = composite.length - 1; i >= 0; --i) {
            this.addComposited(composite[i]);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Specify the MapMutator to be used by mutation operations.
     * 
     * @param mutator  the MapMutator to be used for mutation delegation
     */
    public void setMutator(MapMutator mutator) {
        this.mutator = mutator;
    }
    
    /**
     * Add an additional Map to the composite.
     *
     * @param map  the Map to be added to the composite
     * @throws IllegalArgumentException if there is a key collision and there is no
     *         MapMutator set to handle it.
     */
    public synchronized void addComposited(Map map) throws IllegalArgumentException {
        for (int i = composite.length - 1; i >= 0; --i) {
            Collection intersect = CollectionUtils.intersection(this.composite[i].keySet(), map.keySet());
            if (intersect.size() != 0) {
                if (this.mutator == null) {
                    throw new IllegalArgumentException("Key collision adding Map to CompositeMap");
                }
                else {
                    this.mutator.resolveCollision(this, this.composite[i], map, intersect);
                }
            }
        }
        Map[] temp = new Map[this.composite.length + 1];
        System.arraycopy(this.composite, 0, temp, 0, this.composite.length);
        temp[temp.length - 1] = map;
        this.composite = temp;
    }
    
    /**
     * Remove a Map from the composite.
     *
     * @param map  the Map to be removed from the composite
     * @return The removed Map or <code>null</code> if map is not in the composite
     */
    public synchronized Map removeComposited(Map map) {
        int size = this.composite.length;
        for (int i = 0; i < size; ++i) {
            if (this.composite[i].equals(map)) {
                Map[] temp = new Map[size - 1];
                System.arraycopy(this.composite, 0, temp, 0, i);
                System.arraycopy(this.composite, i + 1, temp, i, size - i - 1);
                this.composite = temp;
                return map;
            }
        }
        return null;
    }

    //-----------------------------------------------------------------------    
    /**
     * Calls <code>clear()</code> on all composited Maps.
     *
     * @throws UnsupportedOperationException if any of the composited Maps do not support clear()
     */
    public void clear() {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            this.composite[i].clear();
        }
    }
    
    /**
     * Returns <tt>true</tt> if this map contains a mapping for the specified
     * key.  More formally, returns <tt>true</tt> if and only if
     * this map contains at a mapping for a key <tt>k</tt> such that
     * <tt>(key==null ? k==null : key.equals(k))</tt>.  (There can be
     * at most one such mapping.)
     *
     * @param key  key whose presence in this map is to be tested.
     * @return <tt>true</tt> if this map contains a mapping for the specified
     *         key.
     *
     * @throws ClassCastException if the key is of an inappropriate type for
     * 		  this map (optional).
     * @throws NullPointerException if the key is <tt>null</tt> and this map
     *            does not not permit <tt>null</tt> keys (optional).
     */
    public boolean containsKey(Object key) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsKey(key)) {
                return true;
            }
        }
        return false;
    }
    
    /**
     * Returns <tt>true</tt> if this map maps one or more keys to the
     * specified value.  More formally, returns <tt>true</tt> if and only if
     * this map contains at least one mapping to a value <tt>v</tt> such that
     * <tt>(value==null ? v==null : value.equals(v))</tt>.  This operation
     * will probably require time linear in the map size for most
     * implementations of the <tt>Map</tt> interface.
     *
     * @param value value whose presence in this map is to be tested.
     * @return <tt>true</tt> if this map maps one or more keys to the
     *         specified value.
     * @throws ClassCastException if the value is of an inappropriate type for
     * 		  this map (optional).
     * @throws NullPointerException if the value is <tt>null</tt> and this map
     *            does not not permit <tt>null</tt> values (optional).
     */
    public boolean containsValue(Object value) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsValue(value)) {
                return true;
            }
        }
        return false;
    }
    
    /**
     * Returns a set view of the mappings contained in this map.  Each element
     * in the returned set is a <code>Map.Entry</code>.  The set is backed by the
     * map, so changes to the map are reflected in the set, and vice-versa.
     * If the map is modified while an iteration over the set is in progress,
     * the results of the iteration are undefined.  The set supports element
     * removal, which removes the corresponding mapping from the map, via the
     * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, <tt>removeAll</tt>,
     * <tt>retainAll</tt> and <tt>clear</tt> operations.  It does not support
     * the <tt>add</tt> or <tt>addAll</tt> operations.
     * <p>
     * This implementation returns a <code>CompositeSet</code> which
     * composites the entry sets from all of the composited maps.
     *
     * @see CompositeSet
     * @return a set view of the mappings contained in this map.
     */
    public Set entrySet() {
        CompositeSet entries = new CompositeSet();
        for (int i = this.composite.length - 1; i >= 0; --i) {
            entries.addComposited(this.composite[i].entrySet());
        }
        return entries;
    }
    
    /**
     * Returns the value to which this map maps the specified key.  Returns
     * <tt>null</tt> if the map contains no mapping for this key.  A return
     * value of <tt>null</tt> does not <i>necessarily</i> indicate that the
     * map contains no mapping for the key; it's also possible that the map
     * explicitly maps the key to <tt>null</tt>.  The <tt>containsKey</tt>
     * operation may be used to distinguish these two cases.
     *
     * <p>More formally, if this map contains a mapping from a key
     * <tt>k</tt> to a value <tt>v</tt> such that <tt>(key==null ? k==null :
     * key.equals(k))</tt>, then this method returns <tt>v</tt>; otherwise
     * it returns <tt>null</tt>.  (There can be at most one such mapping.)
     *
     * @param key key whose associated value is to be returned.
     * @return the value to which this map maps the specified key, or
     *	       <tt>null</tt> if the map contains no mapping for this key.
     *
     * @throws ClassCastException if the key is of an inappropriate type for
     * 		  this map (optional).
     * @throws NullPointerException key is <tt>null</tt> and this map does not
     *		  not permit <tt>null</tt> keys (optional).
     *
     * @see #containsKey(Object)