expranalyzer.java

rule engine drools-2.0-beta-18

package org.drools.semantics.java;

/*
 * $Id: ExprAnalyzer.java,v 1.10 2004/11/28 02:22:18 simon Exp $
 *
 * Copyright 2002 (C) The Werken Company. All Rights Reserved.
 *
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. The name "drools" must not be used to endorse or promote products derived
 * from this Software without prior written permission of The Werken Company.
 * For written permission, please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "drools" nor may
 * "drools" appear in their names without prior written permission of The Werken
 * Company. "drools" is a registered trademark of The Werken Company.
 *
 * 5. Due credit should be given to The Werken Company.
 * (http://drools.werken.com/).
 *
 * THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE WERKEN COMPANY OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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import antlr.RecognitionException;
import antlr.TokenStreamException;
import antlr.collections.AST;
import org.drools.rule.Declaration;
import org.drools.semantics.java.parser.JavaLexer;
import org.drools.semantics.java.parser.JavaRecognizer;
import org.drools.semantics.java.parser.JavaTreeParser;

import java.io.StringReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
 * Expression analyzer.
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 *
 * @version $Id: ExprAnalyzer.java,v 1.10 2004/11/28 02:22:18 simon Exp $
 */
public class ExprAnalyzer
{
    // ------------------------------------------------------------
    //     Constructors
    // ------------------------------------------------------------

    /**
     * Construct.
     */
    public ExprAnalyzer()
    {
        // intentionally left blank.
    }

    // ------------------------------------------------------------
    //     Instance methods
    // ------------------------------------------------------------

    /**
     * Analyze an expression.
     *
     * @param expr The expression to analyze.
     * @param availDecls Total set of declarations available.
     *
     * @return The <code>Set</code> of declarations used by the expression.
     *
     * @throws TokenStreamException If an error occurs in the lexer.
     * @throws RecognitionException If an error occurs in the parser.
     * @throws MissingDeclarationException If the expression requires a
     *         declaration not present in the available declarations.
     */
    public List analyze(String expr, List availDecls) throws TokenStreamException,
                                                             RecognitionException,
                                                             MissingDeclarationException
    {
        JavaLexer lexer = new JavaLexer( new StringReader( expr ) );
        JavaRecognizer parser = new JavaRecognizer( lexer );

        parser.ruleCondition( );

        AST ast = parser.getAST( );

        return analyze( availDecls, ast );
    }

    /**
     * Analyze an expression.
     *
     * @param availDecls Total set of declarations available.
     * @param ast The AST for the expression.
     *
     * @return The <code>Set</code> of declarations used by the expression.
     *
     * @throws RecognitionException If an error occurs in the parser.
     */
    private List analyze( List availDecls, AST ast ) throws RecognitionException
    {
        JavaTreeParser treeParser = new JavaTreeParser( );

        treeParser.init( );

        treeParser.exprCondition( ast );

        Set refs = new HashSet( treeParser.getVariableReferences( ) );

        List decls = new ArrayList( );

        Iterator declIter = availDecls.iterator( );
        Declaration eachDecl;

        while ( declIter.hasNext( ) )
        {
            eachDecl = ( Declaration ) declIter.next( );

            if ( refs.contains( eachDecl.getIdentifier( ) ) )
            {
                decls.add( eachDecl );
                refs.remove( eachDecl.getIdentifier( ) );
            }
        }

        /*
         * if ( ! refs.isEmpty() ) { throw new MissingDeclarationException(
         * expr, (String) refs.iterator().next() ); }
         */
        return decls;
    }
}