DLVResultParser.cpp

/***************************************************************************
 *   Copyright (C) 2009 by Mushthofa   								*
 *   unintendedchoice@gmail.com  									*
 *                                                                         *
 *   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 2 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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

/**
 * @file DLVResultParser.cpp
 * @author Mushthofa
 * @date Tue 24 03 2009
 *
 * @brief DLV's result parser implemented using Boost Spirit parser framework
 *
 *
 */


#include "DLVResultParser.h"
#include <boost/algorithm/string/trim.hpp>


DLVResultParser::DLVResultParser()
{
}

void DLVResultParser::parseLine(std::string& line)
{
	boost::trim(line);
	answers.clear();
	if(line.size()>0)
	{
		DLVresult_grammar dg;
		tree_parse_info<> parse_tree = ast_parse(line.c_str(), dg, space_p);
		if(parse_tree.full)
		{
			tree_it tree_begin = parse_tree.trees.begin();
			boost::spirit::parser_id node_id = tree_begin->value.id();
			if(node_id == DLVresult_grammar::answerID
						|| node_id == DLVresult_grammar::atomID
						|| node_id == DLVresult_grammar::predicateID)
			{
				AtomPtr answer (new Atom(parseAtom(tree_begin)));
				answers.insert(answer);
			}
			else if(tree_begin->children.size()>0)
			{
				tree_it atoms_it;
				for(atoms_it=tree_begin->children.begin(); 
								atoms_it!=tree_begin->children.end(); 
								++atoms_it)
				{
					AtomPtr answer (new Atom(parseAtom(atoms_it)));
					answers.insert(answer);
				}
			}
			
			/*
			std::map<parser_id, std::string> rule_names;
			rule_names[DLVresult_grammar::constantID] = "constant";
			rule_names[DLVresult_grammar::stringconstID] = "stringconst";
			rule_names[DLVresult_grammar::integerID] = "integer";
			rule_names[DLVresult_grammar::termID] = "term";
			rule_names[DLVresult_grammar::predicateID] = "predicate";
			rule_names[DLVresult_grammar::atomID] = "atom";
			rule_names[DLVresult_grammar::answerID] = "answer";
			rule_names[DLVresult_grammar::answersetID] = "answerset";
			tree_to_xml(std::cout, parse_tree.trees, line.c_str(), rule_names);
			*/
		}
		else
		{
			// Error in parsing DLV's output...
			
			throw FatalError("Failed parsing results from DLV: " + line);
		}
	}
}

Term DLVResultParser::parseTerm(const tree_it& node)
{
	boost::spirit::parser_id node_id = node->value.id();
	std::string termstr (node->value.begin(), node->value.end());
	boost::trim(termstr);
	if(node_id==DLVresult_grammar::symbolID)
	{
		return Term(termstr, Term::SYMBOL);
	}
	if(node_id==DLVresult_grammar::stringconstID)
	{
		return Term(termstr, Term::STRING);
	}
	if(node_id==DLVresult_grammar::integerID)
	{
		return Term(termstr, Term::INTEGER);
	}
	/* Not reachable */
}

Atom DLVResultParser::parseAtom(const tree_it& node)
{
	boost::spirit::parser_id node_id = node->value.id();
	bool strongneg = false;
	tree_it args_node, args_it;
	if(node_id==DLVresult_grammar::answerID)
	{
		strongneg = true;
		args_node = node->children.begin();
	}
	else
		args_node = node;
	std::string predname (args_node->value.begin(), args_node->value.end());
	boost::trim(predname);
	
	/* TODO: ugly hack for encoding classic negation */
	
	if(predname.substr(0, 6) == "m_NEG_")
	{
		predname = predname.substr(6);
		strongneg = true;
	}
	
	Tuple args;
	
	/* Predicate name must be a symbol */
	args.push_back(Term(predname, Term::SYMBOL));
	
	/* Go through all argument nodes */
	
	for(args_it = args_node->children.begin(); 
		   args_it!=args_node->children.end(); 
		   ++args_it)
	{
		args.push_back(parseTerm(args_it));
	}
	
	return Atom(args, strongneg);
}