| // Copyright 2006, 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.ioc.services; |
| |
| /** |
| * Makes use of {@link Coercion}s (via {@link CoercionTuple}s) to convert between an input value (of some specific type) |
| * and a desired output type. Smart about coercing, even if it requires multiple coercing steps (i.e., via an |
| * intermediate type, such as String). |
| */ |
| public interface TypeCoercer |
| { |
| /** |
| * Performs a coercion from an input type to a desired output type. When the target type is a primitive, the actual |
| * conversion will be to the equivalent wrapper type. In some cases, the TypeCoercer will need to search for an |
| * appropriate coercion, and may even combine existing coercions to form new ones; in those cases, the results of |
| * the search are cached. |
| * <p/> |
| * <p/> |
| * The TypeCoercer also caches the results of a coercion search. |
| * |
| * @param <S> source type (input) |
| * @param <T> target type (output) |
| * @param input |
| * @param targetType defines the target type |
| * @return the coerced value |
| */ |
| <S, T> T coerce(S input, Class<T> targetType); |
| |
| /** |
| * Used primarily inside test suites, this method performs the same steps as {@link #coerce(Object, Class)}, but |
| * returns a string describing the series of coercision, such as "Object --> String --> Long --> Integer". |
| * |
| * @param <S> source type (input) |
| * @param <T> target type (output) |
| * @param inputType the source coercion type (use void.class for coercions from null) |
| * @param targetType defines the target type |
| * @return a string identifying the series of coercions, or the empty string if no coercion is necessary |
| */ |
| <S, T> String explain(Class<S> inputType, Class<T> targetType); |
| |
| /** |
| * Clears cached information stored by the TypeCoercer. |
| */ |
| void clearCache(); |
| } |