/* $Id: DefaultOclEvaluator.java 17836 2010-01-12 19:06:55Z linus $
 *****************************************************************************
 * Copyright (c) 2009 Contributors - see below
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    lepekhine
 *****************************************************************************
 *
 * Some portions of this file was previously release using the BSD License:
 */

// Copyright (c) 2008 The Regents of the University of California. All
// Rights Reserved. Permission to use, copy, modify, and distribute this
// software and its documentation without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph appear in all copies. This software program and
// documentation are copyrighted by The Regents of the University of
// California. The software program and documentation are supplied "AS
// IS", without any accompanying services from The Regents. The Regents
// does not warrant that the operation of the program will be
// uninterrupted or error-free. The end-user understands that the program
// was developed for research purposes and is advised not to rely
// exclusively on the program for any reason. IN NO EVENT SHALL THE
// UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
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package org.argouml.profile.internal.ocl;

import java.io.PushbackReader;
import java.io.StringReader;
import java.util.Map;

import org.apache.log4j.Logger;

import tudresden.ocl.parser.OclParser;
import tudresden.ocl.parser.lexer.Lexer;
import tudresden.ocl.parser.node.Start;

/**
 * Evaluates ocl expressions
 *
 * @author maurelio1234
 */
public class DefaultOclEvaluator implements OclExpressionEvaluator {

    /**
     * Logger.
     */
    private static final Logger LOG = Logger
            .getLogger(DefaultOclEvaluator.class);
    
    private static OclExpressionEvaluator instance = null;
    
    /**
     * @return unique instance
     */
    public static OclExpressionEvaluator getInstance() {
        if (instance == null) {
            instance = new DefaultOclEvaluator();
        }
        return instance;
    }
    
    /*
     * @see org.argouml.profile.internal.ocl.OclExpressionEvaluator#evaluate(java.util.HashMap, org.argouml.profile.internal.ocl.ModelInterpreter, java.lang.String)
     */
    public Object evaluate(Map<String, Object> vt, ModelInterpreter mi,
            String ocl) throws InvalidOclException {
        // XXX this seems to be a bug of the parser, 
        // it always requires a context
        
        //LOG.debug("OCL: " + ocl);
        if (ocl.contains("ore")) {
            // TODO: Convert this to some sensible logging
            System.out.println("VOILA!");
        }
        Lexer lexer = new Lexer(new PushbackReader(new StringReader(
                "context X inv: " + ocl), 2));
        OclParser parser = new OclParser(lexer);
        Start tree = null;
        
        try {
            tree = parser.parse();
        } catch (Exception e) {
            throw new InvalidOclException(ocl);
        }
        
        EvaluateExpression ee = new EvaluateExpression(vt, mi);
        tree.apply(ee);
        return ee.getValue();
    }

}