001: /*
002: * Primitive Collections for Java.
003: * Copyright (C) 2002, 2003 Søren Bak
004: *
005: * This library is free software; you can redistribute it and/or
006: * modify it under the terms of the GNU Lesser General Public
007: * License as published by the Free Software Foundation; either
008: * version 2.1 of the License, or (at your option) any later version.
009: *
010: * This library is distributed in the hope that it will be useful,
011: * but WITHOUT ANY WARRANTY; without even the implied warranty of
012: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
013: * Lesser General Public License for more details.
014: *
015: * You should have received a copy of the GNU Lesser General Public
016: * License along with this library; if not, write to the Free Software
017: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
018: */
019: package bak.pcj.adapter;
020:
021: import bak.pcj.BooleanIterator;
022: import bak.pcj.util.Exceptions;
023: import java.util.Iterator;
024:
025: /**
026: * This class represents adaptions of Java Collections Framework
027: * iterators to primitive iterators over boolean values.
028: *
029: * <p>
030: * Adapters from JCF collections to primitive collections will
031: * fail if the JCF collection contains <tt>null</tt> values or
032: * values of the wrong class. However, adapters are not fast
033: * failing in the case that the underlying collection should
034: * contain illegal values. To implement fast failure would require
035: * every operation to check every element of the underlying
036: * collection before doing anything. Instead validation methods
037: * are provided. They can be called using the assertion facility
038: * in the client code:
039: * <pre>
040: * CollectionToBooleanCollectionAdapter s;
041: * ...
042: * <b>assert</b> s.validate();
043: * </pre>
044: * or by letting the adapter throw an exception on illegal values:
045: * <pre>
046: * CollectionToBooleanCollectionAdapter s;
047: * ...
048: * s.evalidate(); // Throws an exception on illegal values
049: * </pre>
050: * Either way, validation must be invoked directly by the client
051: * code.
052: *
053: * @author Søren Bak
054: * @version 1.2 20-08-2003 23:18
055: * @since 1.0
056: */
057: public class IteratorToBooleanIteratorAdapter implements
058: BooleanIterator {
059:
060: /** The underlying iterator. */
061: private Iterator iterator;
062:
063: /**
064: * Creates a new adaption to an iterator over boolean
065: * values.
066: *
067: * @param iterator
068: * the underlying iterator. This iterator must
069: * return values of class
070: * {@link Boolean Boolean}. Otherwise a
071: * {@link ClassCastException ClassCastException}
072: * will be thrown by
073: * {@link #next() next()}.
074: *
075: * @throws NullPointerException
076: * if <tt>iterator</tt> is <tt>null</tt>.
077: */
078: public IteratorToBooleanIteratorAdapter(Iterator iterator) {
079: if (iterator == null)
080: Exceptions.nullArgument("iterator");
081: this .iterator = iterator;
082: }
083:
084: public boolean hasNext() {
085: return iterator.hasNext();
086: }
087:
088: /**
089: * @throws ClassCastException
090: * if the underlying iterator returns an object
091: * that is not of class
092: * {@link Boolean Boolean}.
093: */
094: public boolean next() {
095: return ((Boolean) iterator.next()).booleanValue();
096: }
097:
098: public void remove() {
099: iterator.remove();
100: }
101:
102: }
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