001: // ============================================================================
002: // $Id: ChainBinary.java,v 1.9 2006/01/08 00:52:25 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.adaptor;
034:
035: import net.sf.jga.fn.BinaryFunctor;
036: import net.sf.jga.fn.UnaryFunctor;
037:
038: /**
039: * Binary Functor that passes the results of a Binary Functor as the argument
040: * to a Unary Functor. This allows for the construction of compound
041: * functors from the primitives found in the arithmetic, logical, property, and
042: * comparison packages.
043: * <p>
044: * Copyright © 2002-2005 David A. Hall
045: *
046: * @author <a href="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
047: **/
048:
049: public class ChainBinary<T1, T2, F, R> extends BinaryFunctor<T1, T2, R> {
050:
051: static final long serialVersionUID = -8161448545088932320L;
052:
053: private UnaryFunctor<F, R> _f;
054:
055: private BinaryFunctor<T1, T2, F> _g;
056:
057: /**
058: * Builds a ChainBinary functor, given outer functor <b>f</b> and inner
059: * functor <b>g</b>.
060: * @throws IllegalArgumentException if any of the functors is missing
061: */
062: public ChainBinary(UnaryFunctor<F, R> f, BinaryFunctor<T1, T2, F> g) {
063: if (f == null || g == null) {
064: String msg = "Two functors are required";
065: throw new IllegalArgumentException(msg);
066: }
067:
068: _f = f;
069: _g = g;
070: ;
071: }
072:
073: /**
074: * Returns the outer functor
075: * @return the outer functor
076: */
077: public UnaryFunctor<F, R> getOuterFunctor() {
078: return _f;
079: }
080:
081: /**
082: * Returns the inner functor
083: * @return the inner functor
084: */
085: public BinaryFunctor<T1, T2, F> getInnerFunctor() {
086: return _g;
087: }
088:
089: // BinaryFunctor interface
090:
091: /**
092: * Passes arguments <b>x</b> and <b>y</b> to the inner functor, and passes
093: * the result to the outer functor.
094: *
095: * @return f(g(x,y))
096: */
097: public R fn(T1 x, T2 y) {
098: return _f.fn(_g.fn(x, y));
099: }
100:
101: /**
102: * Calls the Visitor's <code>visit(ChainBinary)</code> method, if it
103: * implements the nested Visitor interface.
104: */
105: public void accept(net.sf.jga.fn.Visitor v) {
106: if (v instanceof ChainBinary.Visitor)
107: ((ChainBinary.Visitor) v).visit(this );
108: else
109: v.visit(this );
110: }
111:
112: // Object overrides
113:
114: public String toString() {
115: return _f + ".compose(" + _g + ")";
116: }
117:
118: // Acyclic Visitor
119:
120: /**
121: * Interface for classes that may interpret a <b>ChainBinary</b> functor.
122: */
123: public interface Visitor extends net.sf.jga.fn.Visitor {
124: public void visit(ChainBinary host);
125: }
126: }
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