001: // ============================================================================
002: // $Id: UnaryNegate.java,v 1.14 2006/08/07 03:56:27 davidahall Exp $
003: // Copyright (c) 2002-2005 David A. Hall
004: // ============================================================================
005: // The contents of this file are subject to the Common Development and
006: // Distribution License (CDDL), Version 1.0 (the License); you may not use this
007: // file except in compliance with the License. You should have received a copy
008: // of the the License along with this file: if not, a copy of the License is
009: // available from Sun Microsystems, Inc.
010: //
011: // http://www.sun.com/cddl/cddl.html
012: //
013: // From time to time, the license steward (initially Sun Microsystems, Inc.) may
014: // publish revised and/or new versions of the License. You may not use,
015: // distribute, or otherwise make this file available under subsequent versions
016: // of the License.
017: //
018: // Alternatively, the contents of this file may be used under the terms of the
019: // GNU Lesser General Public License Version 2.1 or later (the "LGPL"), in which
020: // case the provisions of the LGPL are applicable instead of those above. If you
021: // wish to allow use of your version of this file only under the terms of the
022: // LGPL, and not to allow others to use your version of this file under the
023: // terms of the CDDL, indicate your decision by deleting the provisions above
024: // and replace them with the notice and other provisions required by the LGPL.
025: // If you do not delete the provisions above, a recipient may use your version
026: // of this file under the terms of either the CDDL or the LGPL.
027: //
028: // This library is distributed in the hope that it will be useful,
029: // but WITHOUT ANY WARRANTY; without even the implied warranty of
030: // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
031: // ============================================================================
032:
033: package net.sf.jga.fn.logical;
034:
035: import net.sf.jga.fn.UnaryPredicate;
036: import net.sf.jga.fn.UnaryFunctor;
037:
038: /**
039: * Unary Predicate that logically negates the result of a child predicate.
040: * Returns true when child predicate <b>p</b> returns false given object
041: * argument <b>x</b>.
042: * <p>
043: * Copyright © 2002-2005 David A. Hall
044: *
045: * @author <a href="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
046: **/
047:
048: public class UnaryNegate<T> extends UnaryPredicate<T> {
049:
050: static final long serialVersionUID = -722445812960547108L;
051:
052: private UnaryFunctor<? super T, Boolean> _p;
053:
054: /**
055: * Builds a UnaryNegate predicate wrapping the given Unary Predicate.
056: * @throws IllegalArgumentException when no child predicate is given
057: */
058: public UnaryNegate(UnaryFunctor<? super T, Boolean> p) {
059: if (p == null) {
060: throw new IllegalArgumentException(
061: "Child Predicate may not be null");
062: }
063:
064: _p = p;
065: }
066:
067: /**
068: * Returns the child predicate.
069: * @return the child predicate.
070: */
071: public UnaryFunctor<? super T, Boolean> getPredicate() {
072: return _p;
073: }
074:
075: // UnaryPredicate interface
076:
077: /**
078: * Given argument <b>x</b>, returns true when child
079: * predicate <b>p</b> returns false for x, otherwise returns true.
080: *
081: * @return !(p.p(x))
082: */
083: public Boolean fn(T x) {
084: return !_p.fn(x);
085: }
086:
087: /**
088: * Calls the Visitor's <code>visit(UnaryNegate)</code> method, if it
089: * implements the nested Visitor interface.
090: */
091: public void accept(net.sf.jga.fn.Visitor v) {
092: if (v instanceof UnaryNegate.Visitor)
093: ((UnaryNegate.Visitor) v).visit(this );
094: else
095: v.visit(this );
096: }
097:
098: // Object overrides
099:
100: public String toString() {
101: return "UnaryNegate";
102: }
103:
104: // Acyclic Visitor
105:
106: /**
107: * Interface for classes that may interpret a <b>UnaryNegate</b>
108: * predicate.
109: */
110: public interface Visitor extends net.sf.jga.fn.Visitor {
111: public void visit(UnaryNegate host);
112: }
113: }
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