| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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.commons.functor.adapter; |
| |
| import org.apache.commons.functor.NullaryFunction; |
| import org.apache.commons.functor.Function; |
| import org.apache.commons.lang3.Validate; |
| |
| /** |
| * Adapts a |
| * {@link Function Function} |
| * to the |
| * {@link NullaryFunction NullaryFunction} interface |
| * using a constant unary argument. |
| * |
| * @param <T> the returned value type. |
| * @version $Revision: 1345136 $ $Date: 2012-06-01 09:47:06 -0300 (Fri, 01 Jun 2012) $ |
| */ |
| public final class BoundNullaryFunction<T> implements NullaryFunction<T> { |
| /** The {@link Function Function} I'm wrapping. */ |
| private final Function<Object, ? extends T> function; |
| /** The argument to pass to {@code function}. */ |
| private final Object arg; |
| |
| /** |
| * Create a new BoundNullaryFunction instance. |
| * @param <A> the argument value type |
| * @param function the function to adapt |
| * @param arg the constant argument to use |
| */ |
| @SuppressWarnings("unchecked") |
| public <A> BoundNullaryFunction(Function<? super A, ? extends T> function, A arg) { |
| this.function = |
| (Function<Object, ? extends T>) Validate.notNull(function, |
| "Function argument was null"); |
| this.arg = arg; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public T evaluate() { |
| return function.evaluate(arg); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (!(obj instanceof BoundNullaryFunction<?>)) { |
| return false; |
| } |
| BoundNullaryFunction<?> that = (BoundNullaryFunction<?>) obj; |
| if (!(that.function.equals(this.function))) { |
| return false; |
| } |
| return that.arg == this.arg || that.arg != null && that.arg.equals(this.arg); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int hashCode() { |
| int result = "BoundNullaryFunction".hashCode(); |
| result <<= 2; |
| result |= function.hashCode(); |
| result <<= 2; |
| return arg == null ? result : result | arg.hashCode(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "BoundNullaryFunction<" + function.toString() + "(" + arg + ")>"; |
| } |
| |
| /** |
| * Adapt the given, possibly-<code>null</code>, |
| * {@link Function Function} to the |
| * {@link NullaryFunction NullaryFunction} interface by binding |
| * the specified <code>Object</code> as a constant |
| * argument. |
| * When the given <code>Function</code> is <code>null</code>, |
| * returns <code>null</code>. |
| * @param <A> input type |
| * @param <T> result type |
| * @param function the possibly-<code>null</code> |
| * {@link Function Function} to adapt |
| * @param arg the object to bind as a constant argument |
| * @return a <code>BoundNullaryFunction</code> wrapping the given |
| * {@link Function Function}, or <code>null</code> |
| * if the given <code>Function</code> is <code>null</code> |
| */ |
| public static <A, T> BoundNullaryFunction<T> bind(Function<? super A, ? extends T> function, A arg) { |
| return null == function ? null : new BoundNullaryFunction<T>(function, arg); |
| } |
| |
| } |