    001    // Copyright 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.assets;
    016
    017    import org.apache.tapestry5.ioc.Resource;
    018
    019    import java.io.IOException;
    020    import java.io.InputStream;
    021
    022    /**
    023     * A transformer is used to read a {@link Resource} and pass it through a transformation stage, to get a
    024     * stream that can be used on the client side. Examples of this are languages that "compile" to
    025     * JavaScript, or any of a few higher-level versions of CSS that are compiled to standard CSS.
    026     *
    027     * @since 5.3
    028     */
    029    public interface ResourceTransformer
    030    {
    031        /**
    032         * Read the source input stream and provide a new input stream of the transformed content.
    033         *
    034         * @param source       input content
    035         * @param dependencies allows additional dependencies of the source to be tracked
    036         * @return stream of output content
    037         * @throws IOException
    038         */
    039        InputStream transform(Resource source, ResourceDependencies dependencies) throws IOException;
    040    }