001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.functor.adapter;
018
019import org.apache.commons.functor.NullaryProcedure;
020import org.apache.commons.functor.Procedure;
021import org.apache.commons.lang3.Validate;
022
023/**
024 * Adapts a
025 * {@link Procedure Procedure}
026 * to the
027 * {@link NullaryProcedure NullaryProcedure} interface
028 * using a constant unary argument.
029 *
030 * @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
031 */
032public final class BoundNullaryProcedure implements NullaryProcedure {
033    /** The {@link Procedure Procedure} I'm wrapping. */
034    private final Procedure<Object> procedure;
035    /** The parameter to pass to {@code procedure}. */
036    private final Object param;
037
038    /**
039     * Create a new BoundNullaryProcedure instance.
040     * @param <A> arg type
041     * @param procedure the procedure to adapt
042     * @param arg the constant argument to use
043     */
044    @SuppressWarnings("unchecked")
045    public <A> BoundNullaryProcedure(Procedure<? super A> procedure, A arg) {
046        this.procedure =
047            (Procedure<Object>) Validate.notNull(procedure,
048                "Procedure argument was null");
049        this.param = arg;
050    }
051
052    /**
053     * {@inheritDoc}
054     */
055    public void run() {
056        procedure.run(param);
057    }
058
059    /**
060     * {@inheritDoc}
061     */
062    @Override
063    public boolean equals(Object obj) {
064        if (obj == this) {
065            return true;
066        }
067        if (!(obj instanceof BoundNullaryProcedure)) {
068            return false;
069        }
070        BoundNullaryProcedure that = (BoundNullaryProcedure) obj;
071        return procedure.equals(that.procedure)
072                && (null == param ? null == that.param : param.equals(that.param));
073    }
074
075    /**
076     * {@inheritDoc}
077     */
078    @Override
079    public int hashCode() {
080        int hash = "BoundNullaryProcedure".hashCode();
081        hash <<= 2;
082        hash ^= procedure.hashCode();
083        if (null != param) {
084            hash <<= 2;
085            hash ^= param.hashCode();
086        }
087        return hash;
088    }
089
090    /**
091     * {@inheritDoc}
092     */
093    @Override
094    public String toString() {
095        return "BoundNullaryProcedure<" + procedure + "(" + param + ")>";
096    }
097
098    /**
099     * Adapt the given, possibly-<code>null</code>,
100     * {@link Procedure Procedure} to the
101     * {@link NullaryProcedure NullaryProcedure} interface by binding
102     * the specified <code>Object</code> as a constant
103     * argument.
104     * When the given <code>Procedure</code> is <code>null</code>,
105     * returns <code>null</code>.
106     *
107     * @param <A> arg type
108     * @param procedure the possibly-<code>null</code>
109     *        {@link Procedure Procedure} to adapt
110     * @param arg the object to bind as a constant argument
111     * @return a <code>BoundNullaryProcedure</code> wrapping the given
112     *         {@link Procedure Procedure}, or <code>null</code>
113     *         if the given <code>Procedure</code> is <code>null</code>
114     */
115    public static <A> BoundNullaryProcedure bind(Procedure<? super A> procedure, A arg) {
116        return null == procedure ? null : new BoundNullaryProcedure(procedure, arg);
117    }
118
119}