| /* |
| * 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.ParameterizedType; |
| import java.lang.reflect.Type; |
| |
| import org.osgi.util.function.Function; |
| |
| /** |
| * A rule implementation that works by capturing the type arguments via |
| * 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 abstract class Rule<F, T> implements TargetRule { |
| private final ConverterFunction function; |
| |
| /** |
| * Create an instance with a conversion function. |
| * |
| * @param func The conversion function to use. |
| */ |
| public Rule(Function<F,T> func) { |
| function = getGenericFunction(func); |
| } |
| |
| private ConverterFunction getGenericFunction(final Function<F,T> func) { |
| return new ConverterFunction() { |
| @Override |
| @SuppressWarnings("unchecked") |
| public Object apply(Object obj, Type targetType) throws Exception { |
| Rule< ? , ? > r = Rule.this; |
| Type type = ((ParameterizedType) r.getClass() |
| .getGenericSuperclass()).getActualTypeArguments()[0]; |
| |
| if (type instanceof ParameterizedType) { |
| type = ((ParameterizedType) type).getRawType(); |
| } |
| |
| Class< ? > cls = null; |
| if (type instanceof Class) { |
| cls = ((Class< ? >) type); |
| } else { |
| return ConverterFunction.CANNOT_HANDLE; |
| } |
| |
| if (cls.isInstance(obj)) { |
| return func.apply((F) obj); |
| } |
| return ConverterFunction.CANNOT_HANDLE; |
| } |
| }; |
| } |
| |
| @Override |
| public ConverterFunction getFunction() { |
| return function; |
| } |
| |
| @Override |
| public Type getTargetType() { |
| Type type = ((ParameterizedType) getClass().getGenericSuperclass()) |
| .getActualTypeArguments()[1]; |
| return type; |
| } |
| } |