001: // ============================================================================
002: // $Id: Distribute.java,v 1.8 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 its two arguments to two inner Unary Functors,
040: * and uses the results as arguments to an outer Binary Functor. This allows
041: * for the construction of compound functors from the primitives found in the
042: * arithmetic, logical, property, and comparison packages.
043: * <p>
044: * Copyright © 2003-2005 David A. Hall
045: *
046: * @author <a href="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
047: **/
048:
049: public class Distribute<T1, T2, F1, F2, R> extends
050: BinaryFunctor<T1, T2, R> {
051:
052: static final long serialVersionUID = -8288483375404557210L;
053:
054: // The functor to which the first arg is passed
055: private UnaryFunctor<T1, F1> _f;
056:
057: // The functor to which the second arg is passed
058: private UnaryFunctor<T2, F2> _g;
059:
060: // The functor that evaluates the results of the two inner functors
061: private BinaryFunctor<F1, F2, R> _h;
062:
063: /**
064: * Builds a Distribute functor, given two inner functors <b>f</b> and
065: * <b>g</b>, and outer functor <b>h</b>.
066: * @throws IllegalArgumentException if any of the functors is missing
067: */
068: public Distribute(UnaryFunctor<T1, F1> f, UnaryFunctor<T2, F2> g,
069: BinaryFunctor<F1, F2, R> h) {
070: if (f == null || g == null || h == null) {
071: throw new IllegalArgumentException(
072: "Three functors are required");
073: }
074:
075: _f = f;
076: _g = g;
077: _h = h;
078: }
079:
080: /**
081: * Returns the first of two inner functors
082: * @return the first of two inner functors
083: */
084: public UnaryFunctor<T1, F1> getFirstInnerFunctor() {
085: return _f;
086: }
087:
088: /**
089: * Returns the second of two inner functors
090: * @return the second of two inner functors
091: */
092: public UnaryFunctor<T2, F2> getSecondInnerFunctor() {
093: return _g;
094: }
095:
096: /**
097: * Returns the outer functor
098: * @return the outer functor
099: */
100: public BinaryFunctor<F1, F2, R> getOuterFunctor() {
101: return _h;
102: }
103:
104: // BinaryFunctor interface
105:
106: /**
107: * Passes arguments <b>x</b> and <b>y</b> to the corresponding inner
108: * functors, and passes the results of those functors to the outer functor.
109: *
110: * @return h(f(x), g(y))
111: */
112: public R fn(T1 x, T2 y) {
113: return _h.fn(_f.fn(x), _g.fn(y));
114: }
115:
116: /**
117: * Calls the Visitor's <code>visit(Distribute)</code> method, if it
118: * implements the nested Visitor interface.
119: */
120: public void accept(net.sf.jga.fn.Visitor v) {
121: if (v instanceof Distribute.Visitor)
122: ((Distribute.Visitor) v).visit(this );
123: else
124: v.visit(this );
125: }
126:
127: // Object overrides
128:
129: public String toString() {
130: return _h + ".distribute(" + _f + "," + _g + ")";
131: }
132:
133: // Acyclic Visitor
134:
135: /**
136: * Interface for classes that may interpret a <b>Distribute</b> functor.
137: */
138: public interface Visitor extends net.sf.jga.fn.Visitor {
139: public void visit(Distribute host);
140: }
141: }
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