| /* |
| * 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.core.algorithm; |
| |
| import java.io.Serializable; |
| import java.util.NoSuchElementException; |
| |
| import org.apache.commons.functor.BinaryFunction; |
| import org.apache.commons.functor.UnaryPredicate; |
| import org.apache.commons.functor.UnaryProcedure; |
| import org.apache.commons.functor.generator.Generator; |
| |
| /** |
| * Return the first Object in a {@link Generator} matching a {@link UnaryPredicate}. |
| * |
| * @param <E> the arguments type. |
| * @version $Revision$ $Date$ |
| */ |
| public final class FindWithinGenerator<E> |
| implements BinaryFunction<Generator<? extends E>, UnaryPredicate<? super E>, E>, Serializable { |
| |
| /** |
| * Basic instance. |
| */ |
| public static final FindWithinGenerator<Object> INSTANCE = new FindWithinGenerator<Object>(); |
| |
| /** |
| * serialVersionUID declaration. |
| */ |
| private static final long serialVersionUID = -2824239991638326134L; |
| |
| /** |
| * Helper procedure. |
| * |
| * @param <T> the argument type. |
| */ |
| private static class FindProcedure<T> implements UnaryProcedure<T> { |
| /** |
| * The object found, if any. |
| */ |
| private T found; |
| /** |
| * Flag to mark an object has been found. |
| */ |
| private boolean wasFound; |
| /** |
| * The adapted predicate. |
| */ |
| private UnaryPredicate<? super T> pred; |
| |
| /** |
| * Create a new FindProcedure. |
| * @param pred the adapted predicate. |
| */ |
| public FindProcedure(UnaryPredicate<? super T> pred) { |
| this.pred = pred; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void run(T obj) { |
| if (!wasFound && pred.test(obj)) { |
| wasFound = true; |
| found = obj; |
| } |
| } |
| } |
| |
| /** |
| * Flag to mark the {@link FindWithinGenerator#evaluate(Generator, UnaryPredicate)} method must return a user |
| * defined object when the adapted procedure does not find any object. |
| */ |
| private final boolean useIfNone; |
| /** |
| * Object to be returned in the case the adapted procedure does not find any object. |
| */ |
| private final E ifNone; |
| |
| /** |
| * Create a new FindWithinGenerator. |
| */ |
| public FindWithinGenerator() { |
| super(); |
| ifNone = null; |
| useIfNone = false; |
| } |
| |
| /** |
| * Create a new FindWithinGenerator. |
| * @param ifNone object to return if the Generator contains no matches. |
| */ |
| public FindWithinGenerator(E ifNone) { |
| super(); |
| this.ifNone = ifNone; |
| useIfNone = true; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * @param left Generator |
| * @param right UnaryPredicate |
| */ |
| public E evaluate(Generator<? extends E> left, UnaryPredicate<? super E> right) { |
| FindProcedure<E> findProcedure = new FindProcedure<E>(right); |
| left.run(findProcedure); |
| if (!findProcedure.wasFound) { |
| if (useIfNone) { |
| return ifNone; |
| } |
| throw new NoSuchElementException("No element matching " + right + " was found."); |
| } |
| return findProcedure.found; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (!(obj instanceof FindWithinGenerator<?>)) { |
| return false; |
| } |
| FindWithinGenerator<?> other = (FindWithinGenerator<?>) obj; |
| return other.useIfNone == useIfNone && !useIfNone |
| || (other.ifNone == this.ifNone || other.ifNone != null && other.ifNone.equals(this.ifNone)); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int hashCode() { |
| if (!this.useIfNone) { |
| return System.identityHashCode(INSTANCE); |
| } |
| int result = "FindWithinGenerator".hashCode(); |
| result ^= this.ifNone == null ? 0 : this.ifNone.hashCode(); |
| return result; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "FindWithinGenerator<" + ifNone + "," + useIfNone + ">"; |
| } |
| |
| /** |
| * Get a static {@link FindWithinGenerator} instance. |
| * @return {@link FindWithinGenerator} |
| */ |
| public static FindWithinGenerator<Object> instance() { |
| return INSTANCE; |
| } |
| } |