VitryTree.java

/*
 * Vitry, copyright (C) Hans Hoglund 2011
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * See COPYING.txt for details.
 */
package vitry.runtime.parse;

import java.util.Iterator;

import org.antlr.runtime.*;
import org.antlr.runtime.tree.*;
import vitry.runtime.*;
import vitry.runtime.error.*;
import vitry.runtime.struct.*;
import vitry.runtime.StandardFunction.Unary;


/**
 * Reflects antlr syntax trees into Vitry. Each node is a Product containing
 * its children. The head token is the first child.
 *
 * @author Hans Hoglund
 */
class VitryTree extends CommonTree implements Product
{

    private final Product delegee = VitryRuntime.productFrom(this);
    private Seq<Pattern> seq = null;
    private boolean generated = false;

    public VitryTree(Token payload) {
        super(payload);
    }

    public Pattern head()
    {
        if (!generated)
        {
            generate();
        }
        if (hasPayload())
        {
            return wrap(token);
        }
        else
        {
            return (seq == null) ? null : seq.head();
        }
    }

    public Seq<Pattern> tail()
    {
        if (!generated)
        {
            generate();
        }
        if (hasPayload())
        {
            return seq;
        }
        else
        {
            return (seq == null) ? null : seq.tail();
        }
    }

    public boolean hasTail()
    {
        if (hasPayload())
        {
            return seq != null;
        }
        else
        {
            return seq != null && seq.tail() != null;
        }
    }

    public boolean hasPayload()
    {
        return token != null;
    }

    public Iterator<Pattern> iterator()
    {
        return new SeqIterator<Pattern>(this);
    }

    /**
     * Converts the child list to a sequence.
     * Replaces singleton with the token they contain.
     */
    private void generate()
    {
        Iterable<Pattern> children = (Iterable<Pattern>) this.children;
        if (children == null)
        {
            this.seq = null;
        }
        else
        {
            this.seq = Seqs.from(children).map(new Unary()
                {
                    public Object apply(Object o) throws InvocationError
                    {

                        CommonTree t = (CommonTree) o;

                        if (t.getChildCount() == 0 && t.getToken() != null)
                        {
                            return wrap(t.getToken());
                        }
                        else
                        {
                            return t;
                        }
                    }
                });
        }
        this.generated = true;
    }

    private static VitryToken wrap(Token t)
    {
        return new VitryToken(t);
    }


    // Delegate rest of interface

    public boolean eq(Object o)
    {
        return delegee.eq(o);
    }

    public Product mapProduct(Function fn)
    {
        return delegee.mapProduct(fn);
    }

    public boolean eq(Atom o)
    {
        return delegee.eq(o);
    }

    public Product prepend(Pattern p)
    {
        return delegee.prepend(p);
    }

    public boolean eq(Tagged o)
    {
        return delegee.eq(o);
    }

    public boolean eq(Product o)
    {
        return delegee.eq(o);
    }

    public <U> Seq<U> map(Function fn)
    {
        return delegee.map(fn);
    }

    public boolean eq(Function p)
    {
        return delegee.eq(p);
    }

    public boolean eq(List p)
    {
        return delegee.eq(p);
    }

    public SeqIterator<Pattern> seqIterator()
    {
        return delegee.seqIterator();
    }

    public boolean eq(Set o)
    {
        return delegee.eq(o);
    }

    public boolean eq(Union o)
    {
        return delegee.eq(o);
    }

    public boolean eq(Intersection o)
    {
        return delegee.eq(o);
    }

    public boolean eq(Type o)
    {
        return delegee.eq(o);
    }

    public boolean match(Object o)
    {
        return delegee.match(o);
    }

    public boolean match(Atom o)
    {
        return delegee.match(o);
    }

    public boolean match(Tagged o)
    {
        return delegee.match(o);
    }

    public boolean match(Product p)
    {
        return delegee.match(p);
    }

    public boolean match(Function p)
    {
        return delegee.match(p);
    }

    public boolean match(List p)
    {
        return delegee.match(p);
    }

    public boolean match(Set p)
    {
        return delegee.match(p);
    }

    public boolean match(Union p)
    {
        return delegee.match(p);
    }

    public boolean match(Intersection p)
    {
        return delegee.match(p);
    }

    public boolean match(Type p)
    {
        return delegee.match(p);
    }

    public boolean eqFor(Pattern o)
    {
        return delegee.eqFor(o);
    }

    public boolean matchFor(Pattern p)
    {
        return delegee.matchFor(p);
    }

    public String toString()
    {
        return delegee.toString();
    }

    public boolean canDestruct()
    {
        return delegee.canDestruct();
    }

    public Seq<Pattern> destruct()
    {
        return delegee.destruct();
    }
}