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/*
* $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/java/org/apache/commons/collections/CollectionUtils.java,v 1.4 2001/05/22 15:53:06 jstrachan Exp $
* $Revision: 1.4 $
* $Date: 2001/05/22 15:53:06 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
*
* The cardinality of each element in the returned {@link Collection}
* will be equal to the maximum of the cardinality of that element
* in the two given {@link Collection}s.
*
* @see Collection#addAll
*/
public static Collection union(final Collection a, final Collection b) {
ArrayList list = new ArrayList();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Set elts = new HashSet(a);
elts.addAll(b);
Iterator it = elts.iterator();
while(it.hasNext()) {
Object obj = it.next();
for(int i=0,m=Math.max(getFreq(obj,mapa),getFreq(obj,mapb));i
* The cardinality of each element in the returned {@link Collection}
* will be equal to the minimum of the cardinality of that element
* in the two given {@link Collection}s.
*
* @see Collection#retainAll
*/
public static Collection intersection(final Collection a, final Collection b) {
ArrayList list = new ArrayList();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Set elts = new HashSet(a);
elts.addAll(b);
Iterator it = elts.iterator();
while(it.hasNext()) {
Object obj = it.next();
for(int i=0,m=Math.min(getFreq(obj,mapa),getFreq(obj,mapb));i
* The cardinality of each element e in the returned {@link Collection}
* will be equal to
* max(cardinality(e,a),cardinality(e,b)) - min(cardinality(e,a),cardinality(e,b)).
*
* This is equivalent to
* {@link #subtract subtract}({@link #union union(a,b)},{@link #intersection intersection(a,b)})
* or
* {@link #union union}({@link #subtract subtract(a,b)},{@link #subtract subtract(b,a)}).
*/
public static Collection disjunction(final Collection a, final Collection b) {
ArrayList list = new ArrayList();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Set elts = new HashSet(a);
elts.addAll(b);
Iterator it = elts.iterator();
while(it.hasNext()) {
Object obj = it.next();
for(int i=0,m=((Math.max(getFreq(obj,mapa),getFreq(obj,mapb)))-(Math.min(getFreq(obj,mapa),getFreq(obj,mapb))));ia - b.
* The cardinality of each element e in the returned {@link Collection}
* will be the cardinality of e in a minus the cardinality
* of e in b, or zero, whichever is greater.
*
* @see Collection#removeAll
*/
public static Collection subtract(final Collection a, final Collection b) {
ArrayList list = new ArrayList( a );
Iterator it = b.iterator();
while(it.hasNext()) {
list.remove(it.next());
}
return list;
}
/**
* Returns a {@link Map} mapping each unique element in
* the given {@link Collection} to an {@link Integer}
* representing the number of occurances of that element
* in the {@link Collection}.
* An entry that maps to null indicates that the
* element does not appear in the given {@link Collection}.
*/
public static Map getCardinalityMap(final Collection col) {
HashMap count = new HashMap();
Iterator it = col.iterator();
while(it.hasNext()) {
Object obj = it.next();
Integer c = (Integer)(count.get(obj));
if(null == c) {
count.put(obj,new Integer(1));
} else {
count.put(obj,new Integer(c.intValue() + 1));
}
}
return count;
}
/**
* Returns true iff a is a sub-collection of b,
* that is, iff the cardinality of e in a is less
* than or equal to the cardinality of e in b,
* for each element e in a.
*
* @see #isProperSubCollection
* @see Collection#containsAll
*/
public static boolean isSubCollection(final Collection a, final Collection b) {
ArrayList list = new ArrayList();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Iterator it = a.iterator();
while(it.hasNext()) {
Object obj = it.next();
if(getFreq(obj,mapa) > getFreq(obj,mapb)) {
return false;
}
}
return true;
}
/**
* Returns true iff a is a proper sub-collection of b,
* that is, iff the cardinality of e in a is less
* than or equal to the cardinality of e in b,
* for each element e in a, and there is at least one
* element f such that the cardinality of f in b
* is strictly greater than the cardinality of f in a.
*
* @see #isSubCollection
* @see Collection#containsAll
*/
public static boolean isProperSubCollection(final Collection a, final Collection b) {
// XXX optimize me!
return CollectionUtils.isSubCollection(a,b) && (!(CollectionUtils.isEqualCollection(a,b)));
}
/**
* Returns true iff the given {@link Collection}s contain
* exactly the same elements with exactly the same cardinality.
*
* That is, iff the cardinality of e in a is
* equal to the cardinality of e in b,
* for each element e in a or b.
*/
public static boolean isEqualCollection(final Collection a, final Collection b) {
if(a.size() != b.size()) {
return false;
} else {
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
if(mapa.size() != mapb.size()) {
return false;
} else {
Iterator it = mapa.keySet().iterator();
while(it.hasNext()) {
Object obj = it.next();
if(getFreq(obj,mapa) != getFreq(obj,mapb)) {
return false;
}
}
return true;
}
}
}
/**
* Returns the number of occurrences of obj
* in col.
*/
public static int cardinality(Object obj, final Collection col) {
int count = 0;
Iterator it = col.iterator();
while(it.hasNext()) {
Object elt = it.next();
if((null == obj && null == elt) || obj.equals(elt)) {
count++;
}
}
return count;
}
/** Finds the first element in the given collection which matches the given predicate
*
* @return the first element of the collection which matches the predicate or null if none could be found
*/
public static Object find( Collection collection, Predicate predicate ) {
if ( collection != null && predicate != null ) {
for ( Iterator iter = collection.iterator(); iter.hasNext(); ) {
Object item = iter.next();
if ( predicate.evaluate( item ) ) {
return item;
}
}
}
return null;
}
/** Executes the given closure on each element in the colleciton
*/
public static void forAllDo( Collection collection, Closure closure) {
if ( collection != null ) {
for ( Iterator iter = collection.iterator(); iter.hasNext(); ) {
Object element = iter.next();
closure.execute( element );
}
}
}
/** Selects all elements from inputCollection which match the given predicate
* into an output collection
*/
public static Collection select( Collection inputCollection, Predicate predicate ) {
ArrayList answer = new ArrayList( inputCollection.size() );
select( inputCollection, predicate, answer );
return answer;
}
/** Selects all elements from inputCollection which match the given predicate
* and adds them to outputCollection
*/
public static void select( Collection inputCollection, Predicate predicate, Collection outputCollection ) {
if ( inputCollection != null && predicate != null ) {
for ( Iterator iter = inputCollection.iterator(); iter.hasNext(); ) {
Object item = iter.next();
if ( predicate.evaluate( item ) ) {
outputCollection.add( item );
}
}
}
}
/** Transforms all elements from inputCollection with the given transformer
* and adds them to the outputCollection
*/
public static Collection collect( Collection inputCollection, Transformer transformer ) {
ArrayList answer = new ArrayList( inputCollection.size() );
collect( inputCollection, transformer, answer );
return answer;
}
/** Transforms all elements from the inputIterator with the given transformer
* and adds them to the outputCollection
*/
public static Collection collect( Iterator inputIterator, Transformer transformer ) {
ArrayList answer = new ArrayList();
collect( inputIterator, transformer, answer );
return answer;
}
/** Transforms all elements from inputCollection with the given transformer
* and adds them to the outputCollection
*
* @return the outputCollection
*/
public static Collection collect( Collection inputCollection, final Transformer transformer, final Collection outputCollection ) {
if ( inputCollection != null ) {
return collect( inputCollection.iterator(), transformer, outputCollection );
}
return outputCollection;
}
/** Transforms all elements from the inputIterator with the given transformer
* and adds them to the outputCollection
*
* @return the outputCollection
*/
public static Collection collect( Iterator inputIterator, final Transformer transformer, final Collection outputCollection ) {
if ( inputIterator != null && transformer != null ) {
while ( inputIterator.hasNext() ) {
Object item = inputIterator.next();
Object value = transformer.transform( item );
outputCollection.add( value );
}
}
return outputCollection;
}
/** Adds all elements in the iteration to the given collection
*/
public static void addAll( Collection collection, Iterator iterator ) {
while ( iterator.hasNext() ) {
collection.add( iterator.next() );
}
}
/** Adds all elements in the enumeration to the given collection
*/
public static void addAll( Collection collection, Enumeration enumeration ) {
while ( enumeration.hasMoreElements() ) {
collection.add( enumeration.nextElement() );
}
}
/** Adds all elements in the array to the given collection
*/
public static void addAll( Collection collection, Object[] elements ) {
for ( int i = 0, size = elements.length; i < size; i++ ) {
collection.add( elements[i] );
}
}
private static final int getFreq(final Object obj, final Map freqMap) {
try {
return ((Integer)(freqMap.get(obj))).intValue();
} catch(NullPointerException e) {
// ignored
} catch(NoSuchElementException e) {
// ignored
}
return 0;
}
}