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package org.apache.velocity.runtime.parser.node;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */

import java.lang.reflect.InvocationTargetException;

import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.velocity.app.event.EventHandlerUtil;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.exception.VelocityException;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.parser.Parser;
import org.apache.velocity.util.introspection.Info;
import org.apache.velocity.util.introspection.IntrospectionCacheData;
import org.apache.velocity.util.introspection.VelMethod;

/**
 *  ASTMethod.java
 *
 *  Method support for references :  $foo.method()
 *
 *  NOTE :
 *
 *  introspection is now done at render time.
 *
 *  Please look at the Parser.jjt file which is
 *  what controls the generation of this class.
 *
 * @author Jason van Zyl
 * @author Geir Magnusson Jr.
 * @version $Id: ASTMethod.java 720228 2008-11-24 16:58:33Z nbubna $
 */
public class ASTMethod extends SimpleNode
{
    private String methodName = "";
    private int paramCount = 0;

    protected Info uberInfo;

    /**
     * Indicates if we are running in strict reference mode.
     */
    protected boolean strictRef = false;

    /**
     * @param id
     */
    public ASTMethod(int id)
    {
        super(id);
    }

    /**
     * @param p
     * @param id
     */
    public ASTMethod(Parser p, int id)
    {
        super(p, id);
    }

    /**
     * @see org.apache.velocity.runtime.parser.node.SimpleNode#jjtAccept(org.apache.velocity.runtime.parser.node.ParserVisitor, java.lang.Object)
     */
    public Object jjtAccept(ParserVisitor visitor, Object data)
    {
        return visitor.visit(this, data);
    }

    /**
     *  simple init - init our subtree and get what we can from
     *  the AST
     * @param context
     * @param data
     * @return The init result
     * @throws TemplateInitException
     */
    public Object init(  InternalContextAdapter context, Object data)
        throws TemplateInitException
    {
        super.init(  context, data );

        /*
         * make an uberinfo - saves new's later on
         */

        uberInfo = new Info(getTemplateName(),
                getLine(),getColumn());
        /*
         *  this is about all we can do
         */

        methodName = getFirstToken().image;
        paramCount = jjtGetNumChildren() - 1;

        strictRef = rsvc.getBoolean(RuntimeConstants.RUNTIME_REFERENCES_STRICT, false);
        
        return data;
    }

    /**
     *  invokes the method.  Returns null if a problem, the
     *  actual return if the method returns something, or
     *  an empty string "" if the method returns void
     * @param o
     * @param context
     * @return Result or null.
     * @throws MethodInvocationException
     */
    public Object execute(Object o, InternalContextAdapter context)
        throws MethodInvocationException
    {
        /*
         *  new strategy (strategery!) for introspection. Since we want
         *  to be thread- as well as context-safe, we *must* do it now,
         *  at execution time.  There can be no in-node caching,
         *  but if we are careful, we can do it in the context.
         */

        VelMethod method = null;

        Object [] params = new Object[paramCount];

        try
        {
            /*
             * sadly, we do need recalc the values of the args, as this can
             * change from visit to visit
             */

            final Class[] paramClasses = paramCount > 0 ? new Class[paramCount] : ArrayUtils.EMPTY_CLASS_ARRAY;

            for (int j = 0; j < paramCount; j++)
            {
                params[j] = jjtGetChild(j + 1).value(context);

                if (params[j] != null)
                {
                    paramClasses[j] = params[j].getClass();
                }
            }

            /*
             *   check the cache
             */

            MethodCacheKey mck = new MethodCacheKey(methodName, paramClasses);
            IntrospectionCacheData icd =  context.icacheGet( mck );

            /*
             *  like ASTIdentifier, if we have cache information, and the
             *  Class of Object o is the same as that in the cache, we are
             *  safe.
             */

            if ( icd != null && (o != null && icd.contextData == o.getClass()) )
            {

                /*
                 * get the method from the cache
                 */

                method = (VelMethod) icd.thingy;
            }
            else
            {
                /*
                 *  otherwise, do the introspection, and then
                 *  cache it
                 */

                method = rsvc.getUberspect().getMethod(o, methodName, params, new Info(getTemplateName(), getLine(), getColumn()));

                if ((method != null) && (o != null))
                {
                    icd = new IntrospectionCacheData();
                    icd.contextData = o.getClass();
                    icd.thingy = method;

                    context.icachePut( mck, icd );
                }
            }

            /*
             *  if we still haven't gotten the method, either we are calling
             *  a method that doesn't exist (which is fine...)  or I screwed
             *  it up.
             */

            if (method == null)
            {
                if (strictRef)                  
                {
                    // Create a parameter list for the exception error message
                    StringBuffer plist = new StringBuffer();
                    for (int i=0; i