001: // ============================================================================
002: // $Id: CompoundGenerator.java,v 1.4 2006/01/08 00:52:25 davidahall Exp $
003: // Copyright (c) 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.Generator;
036:
037: /**
038: * Executes two generators, returning the results of the second.
039: * <p>
040: * Copyright © 2005 David A. Hall
041: */
042:
043: public class CompoundGenerator<R> extends Generator<R> {
044:
045: static final long serialVersionUID = -2654287117664423223L;
046:
047: // the first generator. Results of this generator are dropped
048: private Generator<?> _gen1;
049:
050: // the second generator. Results of this generator are returned.
051: private Generator<R> _gen2;
052:
053: public CompoundGenerator(Generator<?> gen1, Generator<R> gen2) {
054: if (gen1 == null || gen2 == null)
055: throw new IllegalArgumentException(
056: "Two generators are required");
057:
058: _gen1 = gen1;
059: _gen2 = gen2;
060: }
061:
062: /**
063: * @return the first of the two nested functors
064: */
065: public Generator<?> getFirstFunctor() {
066: return _gen1;
067: }
068:
069: /**
070: * @return the second of the two nested functors
071: */
072: public Generator<R> getSecondFunctor() {
073: return _gen2;
074: }
075:
076: /**
077: * Executes both generators, returning the results of the second.
078: */
079: public R gen() {
080: _gen1.gen();
081: return _gen2.gen();
082: }
083:
084: /**
085: * Calls the Visitor's <code>visit(Constant)</code> method, if it
086: * implements the nested Visitor interface.
087: */
088: public void accept(net.sf.jga.fn.Visitor v) {
089: if (v instanceof CompoundGenerator.Visitor)
090: ((CompoundGenerator.Visitor) v).visit(this );
091: else
092: v.visit(this );
093: }
094:
095: // Object overrides
096:
097: public String toString() {
098: return _gen1 + "," + _gen2;
099: }
100:
101: // AcyclicVisitor
102:
103: /**
104: * Interface for classes that may interpret a <b>Constant</b> generator.
105: */
106: public interface Visitor extends net.sf.jga.fn.Visitor {
107: public void visit(CompoundGenerator host);
108: }
109: }
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