001    // Copyright 2007, 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.services;
016    
017    import org.apache.tapestry5.MarkupWriter;
018    
019    /**
020     * Filter interface for {@link org.apache.tapestry5.services.MarkupRenderer}, which allows for code to execute before
021     * and/or after the main rendering process. Typically, this is to allow for the placement of
022     * {@linkplain org.apache.tapestry5.services.Environment environmental services}.
023     * 
024     * @see org.apache.tapestry5.services.TapestryModule#contributeMarkupRenderer
025     */
026    public interface MarkupRendererFilter
027    {
028        /**
029         * Implementations should perform work before or after passing the writer to the renderer.
030         * 
031         * @param writer
032         *            to which markup should be written
033         * @param renderer
034         *            delegate to which the writer should be passed.
035         */
036        void renderMarkup(MarkupWriter writer, MarkupRenderer renderer);
037    }