expranalyzer.java

rule engine drools-2.0-beta-18

package org.drools.semantics.groovy;

/*
 * $Id: ExprAnalyzer.java,v 1.6 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
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import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.MethodNode;
import org.codehaus.groovy.ast.ModuleNode;
import org.codehaus.groovy.control.SourceUnit;
import org.drools.rule.Declaration;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

/**
 * Analyzes python expressions for all mentioned variables.
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 * @author <a href="mailto:[e-mail]">Christiaan ten Klooster </a>
 *
 * @version $Id: ExprAnalyzer.java,v 1.6 2004/11/28 02:22:18 simon Exp $
 */
public class ExprAnalyzer
{

    public ExprAnalyzer()
    {
    }

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

    /**
     * Analyze an expression.
     *
     * @param text The expression to analyze.
     * @param availDecls Total set of declarations available.
     *
     * @return The array of declarations used by the expression.
     *
     * @throws Exception If an error occurs while attempting to analyze the
     *         expression.
     */
    public Declaration[] analyze(String text, List availDecls) throws Exception
    {
        SourceUnit unit = SourceUnit.create( "groovy.script", text );
        unit.parse( );
        unit.convert( );
        ModuleNode module = unit.getAST( );

        ClassNode classNode = ( ClassNode ) module.getClasses( ).get( 0 );
        List methods = classNode.getDeclaredMethods( "run" );
        MethodNode method = ( MethodNode ) methods.get( 0 );
        ASTNode expr = method.getCode( );

        ExprVisitor visitor = new ExprVisitor( );
        expr.visit( visitor );
        Set refs = visitor.getVariables( );

        List decls = new LinkedList( );
        for ( Iterator declIter = availDecls.iterator( ); declIter.hasNext( ); )
        {
            Declaration eachDecl = ( Declaration ) declIter.next( );

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

        return ( Declaration[] ) decls.toArray( new Declaration[ decls.size( ) ] );
    }
}