| // Copyright 2007, 2008 The Apache Software Foundation |
| // |
| // Licensed 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. |
| |
| package org.apache.tapestry5.services; |
| |
| import org.apache.tapestry5.ComponentResources; |
| |
| /** |
| * Used to lookup meta data concerning a particular component. The primary source of meta data is the meta data defined |
| * for the component, accessed via {@link org.apache.tapestry5.model.ComponentModel#getMeta(String)}. This includes meta |
| * data defined by base classes. When meta-data for a particular component can not be found, a search works up the |
| * containment hierarchy (to the component's container, and the container's container, and so on). If <em>that</em> |
| * proves unfruitful, a system of defaults is provided by configuration and matched against the containing page's |
| * logical name. |
| * <p/> |
| * Finally, if no metadata is available, then {@link org.apache.tapestry5.ioc.services.SymbolSource#valueForSymbol(String)} |
| * is used to obtain a value. |
| */ |
| public interface MetaDataLocator |
| { |
| /** |
| * Searches for the value for the corresponding key. The value, if located, will have symbols expanded, and will be |
| * type coerced to the desired type. |
| * |
| * @param key the key used to locate the meta data (case insensitive) |
| * @param resources the resources of the initial component used in the search |
| * @return the value if found (in the component, the component's container, etc. or via a folder default) or null if |
| * not found anywhere |
| * @throws RuntimeException if the value for the key is not present as meta data of the component, as an override, |
| * or as a symbol |
| */ |
| <T> T findMeta(String key, ComponentResources resources, Class<T> expectedType); |
| } |
