001: // ============================================================================
002: // $Id: Bind2nd.java,v 1.12 2006/01/08 00:52:25 davidahall Exp $
003: // Copyright (c) 2003-2005 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.adaptor;
034:
035: import net.sf.jga.fn.BinaryFunctor;
036: import net.sf.jga.fn.UnaryFunctor;
037:
038: /**
039: * UnaryFunctor that wraps a given BinaryFunctor, passing a constant value
040: * as the second argument of the child functor. The runtime argument is passed
041: * as the first argument of the child functor.
042: * <p>
043: * Copyright © 2003-2005 David A. Hall
044: *
045: * @author <a href="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
046: **/
047:
048: public class Bind2nd<T1, T2, R> extends UnaryFunctor<T1, R> {
049:
050: static final long serialVersionUID = -5977756270123944716L;
051:
052: // The functor whose second argument is bound
053: private BinaryFunctor<T1, T2, R> _f;
054:
055: // The value bound to the second arg
056: private T2 _c;
057:
058: /**
059: * Builds a Bind2nd Functor with the given contant and child functor.
060: * @throws IllegalArgumentException if the functor is null.
061: */
062: public Bind2nd(T2 constant, BinaryFunctor<T1, T2, R> fn) {
063: if (fn == null) {
064: throw new IllegalArgumentException("Must supply a function");
065: }
066: _f = fn;
067: _c = constant;
068: }
069:
070: /**
071: * Returns the child functor for this functor
072: * @return the child functor for this functor
073: */
074: public BinaryFunctor<T1, T2, R> getFunctor() {
075: return _f;
076: }
077:
078: /**
079: * Returns the constant value
080: * @return the constant value
081: */
082: public T2 getConstant() {
083: return _c;
084: }
085:
086: // UnaryFunctor interface
087:
088: /**
089: * Given one argument, passes the argument and the constant value to the
090: * child functor and returns the result.
091: *
092: * @return f(x,c)
093: */
094: public R fn(T1 x) {
095: return _f.fn(x, _c);
096: }
097:
098: /**
099: * Calls the Visitor's <code>visit(Bind2nd)</code> method, if it
100: * implements the nested Visitor interface.
101: */
102: public void accept(net.sf.jga.fn.Visitor v) {
103: if (v instanceof Bind2nd.Visitor)
104: ((Bind2nd.Visitor) v).visit(this );
105: else
106: v.visit(this );
107: }
108:
109: // Object overrides
110:
111: public String toString() {
112: return _f + ".bind2nd(" + _c + ")";
113: }
114:
115: // AcyclicVisitor
116:
117: /**
118: * Interface for classes that may interpret an <b>Bind2nd</b> functor.
119: */
120: public interface Visitor extends net.sf.jga.fn.Visitor {
121: public void visit(Bind2nd bf);
122: }
123: }
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