DCGLibrary.java

/*
 * tuProlog - Copyright (C) 2001-2002  aliCE team at deis.unibo.it
 *
 * This library 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package alice.tuprolog.lib;

import alice.tuprolog.Library;

/**
 * Library for managing DCGs.
 * 
 * Library/Theory dependency: BasicLibrary
 */
public class DCGLibrary extends Library {
	
	public DCGLibrary() {
	}
	
	@Override
	public String getTheory() {
		return
		":- op(1200, xfx, '-->'). \n" +
		":- op(200, xfx, '\\'). \n" +
		"dcg_nonterminal(X) :- list(X), !, fail. \n" +
		"dcg_nonterminal(_). \n" +
		"dcg_terminals(Xs) :- list(Xs). \n" +
		"phrase(Category, String, Left) :- dcg_parse(Category, String \\ Left). \n" +
		"phrase(Category, [H | T]) :- dcg_parse(Category, [H | T] \\ []). \n" +
		"phrase(Category,[]) :- dcg_parse(Category, [] \\ []). \n" +
		"dcg_parse(A, Tokens) :- dcg_nonterminal(A), (A --> B), dcg_parse(B, Tokens). \n" +
		"dcg_parse((A, B), Tokens \\ Xs) :- dcg_parse(A, Tokens \\ Tokens1), dcg_parse(B, Tokens1 \\ Xs). \n" +
		"dcg_parse(A, Tokens) :- dcg_terminals(A), dcg_connect(A, Tokens). \n" +
		"dcg_parse({A}, Xs \\ Xs) :- call(A). \n" +
		"dcg_connect([], Xs \\ Xs). \n" +
		"dcg_connect([W | Ws], [W | Xs] \\ Ys) :- dcg_connect(Ws, Xs \\ Ys). \n";
	}

}