| /* |
| * Copyright (c) OSGi Alliance (2017). All Rights Reserved. |
| * |
| * 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.osgi.util.converter; |
| |
| import java.lang.reflect.Type; |
| |
| import org.osgi.util.function.Function; |
| |
| /** |
| * Rule implementation that works by passing in type arguments rather than |
| * subclassing. The rule supports specifying both <em>from</em> and <em>to</em> |
| * types. Filtering on the <em>from</em> by the {@code Rule} implementation. |
| * Filtering on the <em>to</em> is done by the converter customization |
| * mechanism. |
| * |
| * @author $Id$ |
| * @param <F> The type to convert from. |
| * @param <T> The type to convert to. |
| */ |
| public class TypeRule<F, T> implements TargetRule { |
| private final ConverterFunction function; |
| private final Type toType; |
| |
| /** |
| * Create an instance based on source, target types and a conversion |
| * function. |
| * |
| * @param from The type to convert from. |
| * @param to The type to convert to. |
| * @param func The conversion function to use. |
| */ |
| public TypeRule(Type from, Type to, Function<F,T> func) { |
| function = getFunction(from, func); |
| toType = to; |
| } |
| |
| private static <F, T> ConverterFunction getFunction(final Type from, |
| final Function<F,T> func) { |
| return new ConverterFunction() { |
| @Override |
| @SuppressWarnings("unchecked") |
| public Object apply(Object obj, Type targetType) throws Exception { |
| if (from instanceof Class) { |
| Class< ? > cls = (Class< ? >) from; |
| if (cls.isInstance(obj)) { |
| T res = func.apply((F) obj); |
| if (res != null) |
| return res; |
| else |
| return ConverterFunction.CANNOT_HANDLE; |
| } |
| } |
| return ConverterFunction.CANNOT_HANDLE; |
| } |
| }; |
| } |
| |
| @Override |
| public ConverterFunction getFunction() { |
| return function; |
| } |
| |
| @Override |
| public Type getTargetType() { |
| return toType; |
| } |
| } |