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
015package org.apache.tapestry5.services.pageload;
016
017import java.util.List;
018
019import org.apache.tapestry5.ioc.Resource;
020import org.apache.tapestry5.ioc.util.LocalizedNameGenerator;
021import org.apache.tapestry5.model.ComponentModel;
022
023/**
024 * A central service that encapsulates the rules for locating resources for components. The service can be
025 * overridden, or simply decorated, to implement customized rules for locating templates across
026 * one or more {@linkplain ComponentResourceSelector#getAxis(Class) axes}; this is the approach used to skin
027 * Tapestry applications.
028 * 
029 * @since 5.3
030 */
031public interface ComponentResourceLocator
032{
033    /**
034     * Locates the template for a component (including pages and base classes). The implementation takes into
035     * account the locale and other axes specified by the selector. If the method returns null, then the component
036     * will have no template (which is common for components, but rare for pages).
037     * 
038     * @param model
039     *            defines the component, including its {@linkplain ComponentModel#getBaseResource() base resource}.
040     * @param selector
041     *            used to identify locale, etc., for the template
042     * @return Resource for component template, or null if not found
043     */
044    Resource locateTemplate(ComponentModel model, ComponentResourceSelector selector);
045
046    /**
047     * Locates the properties files that make up the message catalog for a specific component. The properties
048     * files are returned in order of specificity: the properties provided by the first resource override
049     * properties in later resources. Only resources specific to the class associated with the model
050     * should be concerned (message inheritance from base classes is handled by Tapestry).
051     * 
052     * @param baseResource
053     *            the resource for the base component properties file (i.e., with the ".properties" file extension)
054     * @param selector
055     *            defined the locale and other axes used to locate individual properties files
056     * @return list of properties file Resources
057     * @see LocalizedNameGenerator
058     */
059    List<Resource> locateMessageCatalog(Resource baseResource, ComponentResourceSelector selector);
060}