pythonexpranalyzer.java

drools 一个开放源码的规则引擎

package org.drools.semantics.python;

/*
 * $Id: PythonExprAnalyzer.java,v 1.2 2005/02/04 02:13:38 mproctor 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
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

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

import org.drools.rule.Declaration;
import org.python.parser.ast.modType;

/**
 * Analyzes python expressions for all mentioned variables.
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
public class PythonExprAnalyzer
{
    // ------------------------------------------------------------
    //     Constructors
    // ------------------------------------------------------------

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

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

    /**
     * Analyze an expression.
     *
     * @param expr 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( modType expr,
                                  List availDecls ) throws Exception
    {
        PythonExprVisitor visitor = new PythonExprVisitor( );

        List decls = new ArrayList( );

        Set refs = ( Set ) visitor.eval_input( expr );

        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( ) );
            }
        }

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