interp.java

rule engine drools-2.0-beta-18

package org.drools.semantics.python;

/*
 * $Id: Interp.java,v 1.24 2004/11/29 12:35:52 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
 * 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 org.drools.WorkingMemory;
import org.drools.rule.Declaration;
import org.drools.rule.Rule;
import org.drools.semantics.base.ClassObjectType;
import org.drools.spi.ImportEntry;
import org.drools.spi.KnowledgeHelper;
import org.drools.spi.ObjectType;
import org.drools.spi.Tuple;
import org.python.core.Py;
import org.python.core.PyCode;
import org.python.core.PyDictionary;
import org.python.core.PyModule;
import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.core.PySystemState;
import org.python.core.parser;
import org.python.parser.ast.modType;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Iterator;
import java.util.Map;

/**
 * Base class for Jython interpreter-based Python semantic components.
 *
 * @see Eval
 * @see Exec
 *
 * @author <a href="mailto:[e-mail]">bob mcwhirter </a>
 */
public class Interp
{
    /** The line separator system property ("\n" on UNIX). */
    private static final String LINE_SEPARATOR = System.getProperty( "line.separator" );

    // ------------------------------------------------------------
    //     Class Initialization
    // ------------------------------------------------------------

    // ------------------------------------------------------------
    //     Instance members
    // ------------------------------------------------------------

    /** The rule. */
    private final Rule      rule;

    /** Text. */
    private final String    text;

    /** Original Text */
    private final String    origininalText;

    /** The code. */
    private final PyCode    code;

    /** The AST node. */
    private final modType   node;

    private PyDictionary    globals;

    /**
     * Initialise Jython's PySystemState
     */
    static {
        PySystemState.initialize();

        PySystemState systemState = Py.getSystemState();
        if (systemState == null)
        {
            systemState = new PySystemState();
        }
        Py.setSystemState(systemState);
    }

    // ------------------------------------------------------------
    //     Constructors
    // ------------------------------------------------------------

    /**
     * Construct.
     */
    protected Interp(String text,
                     Rule rule,
                     String type)
    {
        this.rule = rule;
        this.origininalText = text;
        StringBuffer globalText = new StringBuffer();

        Iterator it = rule.getImports( ).iterator();

        while ( it.hasNext( ) )
        {
            ImportEntry importEntry = (ImportEntry) it.next();
            if (importEntry instanceof PythonImportEntry)
            {
                globalText.append(importEntry.getImportEntry());
                globalText.append(";");
                globalText.append(LINE_SEPARATOR);
            }
        }

        globalText.append("def q(cond,on_true,on_false):\n");
        globalText.append("  if cond:\n");
        globalText.append("    return on_true\n");
        globalText.append("  else:\n");
        globalText.append("    return on_false\n");

        if (this.globals == null)
        {
            this.globals = getGlobals(globalText.toString());
        }

        this.text = stripOuterIndention( text );

        try
        {
            this.node = ( modType ) parser.parse( this.text, type );
            this.code = Py.compile( this.node, "<jython>" );
        } catch (Exception e)
        {
            e.printStackTrace();
            throw new RuntimeException( e.getLocalizedMessage( ) );
        }
    }

    /**
     * Parses a python script and returns the globals
     * It is used to be able to inject imports and functions
     * into code when being executed by Py.runCode(...)
     * @param text
     * @return PyDictionary globals
     */
    public PyDictionary getGlobals(String text)
    {
          PyModule module = new PyModule("main", new PyDictionary());

          PyObject locals = module.__dict__;

          Py.exec(Py.compile_flags(text, "<string>", "exec", null), locals, locals);

          return (PyDictionary) locals;
    }

    /**
     * Trims leading indention from the block of text. Since Python relies on
     * indention as part of its syntax, any XML indention introduced needs to be
     * stripped out. For example, this:
     *
     * <pre>
     *
     *  |   &lt;python:consequence&gt;
     *  |       if hello == 'Hello':
     *  |           print &quot;Hi&quot;
     *  |       else:
     *  |           print &quot;Bye&quot;
     *  |   &lt;/python:consequence&gt;
     *
     * </pre>
     *
     * is transformed into:
     *
     * <pre>
     *
     *  |   &lt;python:consequence&gt;
     *  |if hello == 'Hello':
     *  |    print &quot;Hi&quot;
     *  |else:
     *  |    print &quot;Bye&quot;
     *  |   &lt;/python:consequence&gt;
     *
     * </pre>
     *
     * @param text the block of text to be stripped
     * @return the block of text stripped of its leading indention
     */
    private static String stripOuterIndention(String text)
    {
        try
        {
            if ( null == text )
            {
                return null;
            }

            BufferedReader br = new BufferedReader(
                                                    new InputStreamReader(
                                                                           new ByteArrayInputStream(
                                                                                                     text
                                                                                                         .getBytes( ) ) ) );

            StringBuffer unindentedText = new StringBuffer( text.length( ) );

            int lineNo = 0;
            try
            {
                String indent = null;
                for ( String line = br.readLine( ); null != line; line = br
                                                                           .readLine( ) )
                {