001: // ============================================================================
002: // $Id: ChainUnary.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.UnaryFunctor;
036: import net.sf.jga.fn.UnaryFunctor;
037:
038: /**
039: * Unary Functor that passes the results of one Unary Functor as the argument
040: * to another 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 ChainUnary<T, F, R> extends UnaryFunctor<T, R> {
050:
051: static final long serialVersionUID = -6690274081307420708L;
052:
053: // the outer fn
054: private UnaryFunctor<F, R> _f;
055:
056: // the inner fn
057: private UnaryFunctor<T, F> _g;
058:
059: /**
060: * Builds a BinaryCompose functor, given the outer functor <b>f</b> the
061: * inner functor <b>g</b>.
062: * @throws IllegalArgumentException if any of the functors is missing
063: */
064: public ChainUnary(UnaryFunctor<F, R> f, UnaryFunctor<T, F> g) {
065: if (f == null || g == null) {
066: throw new IllegalArgumentException(
067: "Two functors are required");
068: }
069:
070: _f = f;
071: _g = g;
072: }
073:
074: /**
075: * Returns the outer functor
076: * @return the outer functor
077: */
078: public UnaryFunctor<F, R> getOuterFunctor() {
079: return _f;
080: }
081:
082: /**
083: * Returns the inner functor
084: * @return the inner functor
085: */
086: public UnaryFunctor<T, F> getInnerFunctor() {
087: return _g;
088: }
089:
090: // UnaryFunctor interface
091:
092: /**
093: * Given argument <b>x</b>, passes x to the inner functor, and passes the
094: * result to the outer functor.
095: *
096: * @return f(g(x))
097: */
098: public R fn(T x) {
099: return _f.fn(_g.fn(x));
100: }
101:
102: // Object overrides
103:
104: public String toString() {
105: return _f + ".compose(" + _g + ")";
106: }
107:
108: /**
109: * Calls the Visitor's <code>visit(BinaryCompose)</code> method, if it
110: * implements the nested Visitor interface.
111: */
112: public void accept(net.sf.jga.fn.Visitor v) {
113: if (v instanceof ChainUnary.Visitor)
114: ((ChainUnary.Visitor) v).visit(this );
115: else
116: v.visit(this );
117: }
118:
119: // AcyclicVisitor
120:
121: /**
122: * Interface for classes that may interpret a <b>ChainUnary</b> functor.
123: */
124: public interface Visitor extends net.sf.jga.fn.Visitor {
125: public void visit(ChainUnary bf);
126: }
127: }
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