foreach.java

velocity官方工具包 包括各种JAR包 示例 文档等

package org.apache.velocity.runtime.directive;

/*
 * 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.io.IOException;
import java.io.Writer;
import java.util.Iterator;

import org.apache.velocity.app.event.EventCartridge;
import org.apache.velocity.context.Context;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.parser.node.ASTReference;
import org.apache.velocity.runtime.parser.node.Node;
import org.apache.velocity.runtime.parser.node.SimpleNode;
import org.apache.velocity.runtime.resource.Resource;
import org.apache.velocity.util.introspection.Info;
import org.apache.velocity.util.introspection.IntrospectionCacheData;

/**
 * Foreach directive used for moving through arrays,
 * or objects that provide an Iterator.
 *
 * @author <a href="mailto:[e-mail]">Jason van Zyl</a>
 * @author <a href="mailto:[e-mail]">Geir Magnusson Jr.</a>
 * @author Daniel Rall
 * @version $Id: Foreach.java 479060 2006-11-25 00:30:19Z henning $
 */
public class Foreach extends Directive
{
    /**
     * A special context to use when the foreach iterator returns a null.  This
     * is required since the standard context may not support nulls.
     * All puts and gets are passed through, except for the foreach iterator key.
     */
    protected static class NullHolderContext implements InternalContextAdapter
    {
        private InternalContextAdapter  innerContext = null;
        private String   loopVariableKey = "";
        private boolean  active = true;

        /**
         * Create the context as a wrapper to be used within the foreach
         * @param key the reference used in the foreach
         * @param context the parent context
         */
        private NullHolderContext( String key, InternalContextAdapter context )
        {
           innerContext = context;
           if( key != null )
               loopVariableKey = key;
        }

        /**
         * Get an object from the context, or null if the key is equal to the loop variable
         * @see org.apache.velocity.context.InternalContextAdapter#get(java.lang.String)
         * @exception MethodInvocationException passes on potential exception from reference method call
         */
        public Object get( String key ) throws MethodInvocationException
        {
            return ( active && loopVariableKey.equals(key) )
                ? null
                : innerContext.get(key);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#put(java.lang.String key, java.lang.Object value)
         */
        public Object put( String key, Object value )
        {
            if( loopVariableKey.equals(key) && (value == null) )
            {
                active = true;
            }

            return innerContext.put( key, value );
        }

        /**
         * Allows callers to explicitly put objects in the local context.
         * Objects added to the context through this method always end up
         * in the top-level context of possible wrapped contexts.
         *
         * @param key name of item to set.
         * @param value object to set to key.
         * @see org.apache.velocity.context.InternalWrapperContext#localPut(String, Object)
         */        
        public Object localPut(final String key, final Object value)
        {
            return put(key, value);
        }

       /**
         * Does the context contain the key
         * @see org.apache.velocity.context.InternalContextAdapter#containsKey(java.lang.Object key)
         */
        public boolean containsKey( Object key )
        {
            return innerContext.containsKey(key);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getKeys()
         */
        public Object[] getKeys()
        {
           return innerContext.getKeys();
        }

        /**
         * Remove an object from the context
         * @see org.apache.velocity.context.InternalContextAdapter#remove(java.lang.Object key)
         */
        public Object remove(Object key)
        {
           if( loopVariableKey.equals(key) )
           {
             active = false;
           }
           return innerContext.remove(key);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#pushCurrentTemplateName(java.lang.String s)
         */
        public void pushCurrentTemplateName(String s)
        {
            innerContext.pushCurrentTemplateName(s);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#popCurrentTemplateName()
         */
        public void popCurrentTemplateName()
        {
            innerContext.popCurrentTemplateName();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getCurrentTemplateName()
         */
        public String getCurrentTemplateName()
        {
            return innerContext.getCurrentTemplateName();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getTemplateNameStack()
         */
        public Object[] getTemplateNameStack()
        {
            return innerContext.getTemplateNameStack();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#icacheGet(java.lang.Object key)
         */
        public IntrospectionCacheData icacheGet(Object key)
        {
            return innerContext.icacheGet(key);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#icachePut(java.lang.Object key, org.apache.velocity.util.introspection.IntrospectionCacheData o)
         */
        public void icachePut(Object key, IntrospectionCacheData o)
        {
            innerContext.icachePut(key,o);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#setCurrentResource(org.apache.velocity.runtime.resource.Resource r)
         */
        public void setCurrentResource( Resource r )
        {
            innerContext.setCurrentResource(r);
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getCurrentResource()
         */
        public Resource getCurrentResource()
        {
            return innerContext.getCurrentResource();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getBaseContext()
         */
        public InternalContextAdapter getBaseContext()
        {
            return innerContext.getBaseContext();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getInternalUserContext()
         */
        public Context getInternalUserContext()
        {
            return innerContext.getInternalUserContext();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#attachEventCartridge(org.apache.velocity.app.event.EventCartridge ec)
         */
        public EventCartridge attachEventCartridge(EventCartridge ec)
        {
            EventCartridge cartridge = innerContext.attachEventCartridge( ec );

            return cartridge;
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getEventCartridge()
         */
        public EventCartridge getEventCartridge()
        {
            return innerContext.getEventCartridge();
        }

        /**
         * @see org.apache.velocity.context.InternalContextAdapter#getAllowRendering()
         */