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 org.apache.tapestry5.commons.Resource;
018import org.apache.tapestry5.ioc.util.LocalizedNameGenerator;
019import org.apache.tapestry5.model.ComponentModel;
020
021import java.util.List;
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 * @see org.apache.tapestry5.services.templates.ComponentTemplateLocator
030 * @since 5.3
031 */
032public interface ComponentResourceLocator
033{
034    /**
035     * Locates the template for a component (including pages and base classes). The implementation takes into
036     * account the locale and other axes specified by the selector. If the method returns null, then the component
037     * will have no template (which is common for components, but rare for pages).
038     *
039     * @param model
040     *         defines the component, including its {@linkplain ComponentModel#getBaseResource() base resource}.
041     * @param selector
042     *         used to identify locale, etc., for the template
043     * @return Resource for component template, or null if not found
044     */
045    Resource locateTemplate(ComponentModel model, ComponentResourceSelector selector);
046
047    /**
048     * Locates the properties files that make up the message catalog for a specific component. The properties
049     * files are returned in order of specificity: the properties provided by the first resource override
050     * properties in later resources. Only resources specific to the class associated with the model
051     * should be concerned (message inheritance from base classes is handled by Tapestry).
052     *
053     * @param baseResource
054     *         the resource for the base component properties file (i.e., with the ".properties" file extension)
055     * @param selector
056     *         defined the locale and other axes used to locate individual properties files
057     * @return list of properties file Resources
058     * @see LocalizedNameGenerator
059     */
060    List<Resource> locateMessageCatalog(Resource baseResource, ComponentResourceSelector selector);
061}