velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/ASTSetDirective.java

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 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.runtime.RuntimeConstants;
import org.apache.velocity.runtime.RuntimeConstants.SpaceGobbling;
import org.apache.velocity.runtime.parser.LogContext;
import org.apache.velocity.runtime.parser.Parser;
import org.apache.velocity.runtime.parser.Token;
import org.apache.velocity.util.introspection.Info;

import java.io.IOException;
import java.io.Writer;

/**
 * Node for the #set directive
 *
 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @version $Id$
 */
public class ASTSetDirective extends SimpleNode
{
    private String leftReference = "";
    private Node right = null;
    private ASTReference left = null;
    private boolean isInitialized;
    private String prefix = "";
    private String postfix = "";

    /*
     * '#' and '$' prefix characters eaten by javacc MORE mode
     */
    private String morePrefix = "";


    /**
     *  This is really immutable after the init, so keep one for this node
     */
    protected Info uberInfo;

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

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

    /**
     * @param p
     * @param id
     */
    public ASTSetDirective(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.  We can get the RHS and LHS as the the tree structure is static
     * @param context
     * @param data
     * @return Init result.
     * @throws TemplateInitException
     */
    public synchronized Object init(InternalContextAdapter context, Object data)
    throws TemplateInitException
    {
        /** This method is synchronized to prevent double initialization or initialization while rendering **/

        if (!isInitialized)
        {
            /*
             *  init the tree correctly
             */

            super.init( context, data );

            /*
             * handle '$' and '#' chars prefix
             */
            Token t = getFirstToken();
            int pos = -1;
            while (t != null && (pos = t.image.lastIndexOf('#')) == -1)
            {
                t = t.next;
            }
            if (t != null && pos > 0)
            {
                morePrefix = t.image.substring(0, pos);
            }


            uberInfo = new Info(getTemplateName(),
                    getLine(), getColumn());

            right = getRightHandSide();
            left = getLeftHandSide();

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

            /*
             *  grab this now.  No need to redo each time
             */
            leftReference = left.firstImage.substring(1);

            /* handle backward compatible space gobbling if asked so */
            if (rsvc.getSpaceGobbling() == SpaceGobbling.BC)
            {
                Node previousNode = null;
                for (int brother = 0; brother < parent.jjtGetNumChildren(); ++brother)
                {
                    Node node = parent.jjtGetChild(brother);
                    if (node == this) break;
                    previousNode = node;
                }
                if (previousNode == null) prefix = "";
                else if (previousNode instanceof ASTText)
                {
                    ASTText text = (ASTText)previousNode;
                    if (text.getCtext().matches("[ \t]*"))
                    {
                        text.setCtext("");
                    }
                }
                else prefix = "";
            }

            isInitialized = true;

            cleanupParserAndTokens();
        }

        return data;
    }

    /**
     * set indentation prefix
     * @param prefix
     */
    public void setPrefix(String prefix)
    {
        this.prefix = prefix;
    }

    /**
     * get indentation prefix
     * @return indentation prefix
     */
    public String getPrefix()
    {
        return prefix;
    }

    /**
     * set indentation postfix
     * @param postfix
     */
    public void setPostfix(String postfix)
    {
        this.postfix = postfix;
    }

    /**
     * get indentation postfix
     * @return indentation prefix
     */
    public String getPostfix()
    {
        return postfix;
    }

    /**
     *   puts the value of the RHS into the context under the key of the LHS
     * @param context
     * @param writer
     * @return True if rendering was sucessful.
     * @throws IOException
     * @throws MethodInvocationException
     */
    public boolean render( InternalContextAdapter context, Writer writer)
        throws IOException, MethodInvocationException
    {
        try
        {
            rsvc.getLogContext().pushLogContext(this, uberInfo);

            SpaceGobbling spaceGobbling = rsvc.getSpaceGobbling();

            /* Velocity 1.x space gobbling for #set is rather wacky:
               prefix is eaten *only* if previous token is not a text node.
               We handle this by appropriately emptying the prefix in BC mode.
             */

            if (morePrefix.length() > 0 || spaceGobbling.compareTo(SpaceGobbling.LINES) < 0)
            {
                writer.write(prefix);
            }

            writer.write(morePrefix);

            /*
             *  get the RHS node, and its value
             */

            Object value = right.value(context);

            if ( value == null && !strictRef)
            {
                String rightReference = null;
                if (right instanceof ASTExpression)
                {
                    rightReference = ((ASTExpression) right).lastImage;
                }
                EventHandlerUtil.invalidSetMethod(rsvc, context, leftReference, rightReference, uberInfo);
            }

            if (morePrefix.length() > 0 || spaceGobbling == SpaceGobbling.NONE)
            {
                writer.write(postfix);
            }

            return left.setValue(context, value);
        }
        finally
        {
            rsvc.getLogContext().popLogContext();
            StringBuilder builder;
        }
    }

    /**
     *  returns the ASTReference that is the LHS of the set statement
     *
     *  @return left hand side of #set statement
     */
    private ASTReference getLeftHandSide()
    {
        return (ASTReference) jjtGetChild(0);
    }

    /**
     *  returns the RHS Node of the set statement
     *
     *  @return right hand side of #set statement
     */
    private Node getRightHandSide()
    {
        return jjtGetChild(1);
    }
}