SchemePairValueImpl.java

/**
 * Copyright 2004-2016 Riccardo Solmi. All rights reserved.
 * This file is part of the Whole Platform.
 *
 * The Whole Platform is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The Whole Platform is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the Whole Platform. If not, see <http://www.gnu.org/licenses/>.
 */
package scheme.old;

class SchemePairValueImpl extends SchemeValueImpl implements SchemePairValue {
    private SchemePairValueImpl(SchemeValue a1, SchemeValue b1) {
	a = a1;
	b = b1;
    }

    public String toString() {
	return "(" + listToString() + ")";
    }

    public String listToString() {
	if (b == null)
	    return SchemeValueImpl.toString(a);
	else if (b instanceof SchemePairValueImpl)
	    return SchemeValueImpl.toString(a) + " " + ((SchemePairValueImpl) b).listToString();
	else
	    return SchemeValueImpl.toString(a) + " . " + b.toString(); 
    }

    public boolean isPair() {
	return true;
    }

    public SchemePairValue asPair() {
	return this;
    }

    public SchemeValue car() {
	return a;
    }

    public SchemeValue cdr() {
	return b;
    }

    public static SchemePairValueImpl valueOf(SchemeValue a1, SchemeValue b1) {
	return new SchemePairValueImpl(a1, b1);
    }

    private final SchemeValue a;
    private final SchemeValue b;
}