- /*
- * Copyright 2001-2004 The Apache Software Foundation
- *
- * 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.apache.commons.collections.functors;
-
- import java.io.Serializable;
- import java.util.Iterator;
- import java.util.Map;
-
- import org.apache.commons.collections.Closure;
- import org.apache.commons.collections.Predicate;
-
- /**
- * Closure implementation calls the closure whose predicate returns true,
- * like a switch statement.
- *
- * @since Commons Collections 3.0
- * @version $Revision: 1.5 $ $Date: 2004/05/16 11:47:38 $
- *
- * @author Stephen Colebourne
- */
- public class SwitchClosure implements Closure, Serializable {
-
- /** Serial version UID */
- static final long serialVersionUID = 3518477308466486130L;
-
- /** The tests to consider */
- private final Predicate[] iPredicates;
- /** The matching closures to call */
- private final Closure[] iClosures;
- /** The default closure to call if no tests match */
- private final Closure iDefault;
-
- /**
- * Factory method that performs validation and copies the parameter arrays.
- *
- * @param predicates array of predicates, cloned, no nulls
- * @param closures matching array of closures, cloned, no nulls
- * @param defaultClosure the closure to use if no match, null means nop
- * @return the <code>chained</code> closure
- * @throws IllegalArgumentException if array is null
- * @throws IllegalArgumentException if any element in the array is null
- */
- public static Closure getInstance(Predicate[] predicates, Closure[] closures, Closure defaultClosure) {
- FunctorUtils.validate(predicates);
- FunctorUtils.validate(closures);
- if (predicates.length != closures.length) {
- throw new IllegalArgumentException("The predicate and closure arrays must be the same size");
- }
- if (predicates.length == 0) {
- return (defaultClosure == null ? NOPClosure.INSTANCE : defaultClosure);
- }
- predicates = FunctorUtils.copy(predicates);
- closures = FunctorUtils.copy(closures);
- return new SwitchClosure(predicates, closures, defaultClosure);
- }
-
- /**
- * Create a new Closure that calls one of the closures depending
- * on the predicates.
- * <p>
- * The Map consists of Predicate keys and Closure values. A closure
- * is called if its matching predicate returns true. Each predicate is evaluated
- * until one returns true. If no predicates evaluate to true, the default
- * closure is called. The default closure is set in the map with a
- * null key. The ordering is that of the iterator() method on the entryset
- * collection of the map.
- *
- * @param predicatesAndClosures a map of predicates to closures
- * @return the <code>switch</code> closure
- * @throws IllegalArgumentException if the map is null
- * @throws IllegalArgumentException if any closure in the map is null
- * @throws ClassCastException if the map elements are of the wrong type
- */
- public static Closure getInstance(Map predicatesAndClosures) {
- Closure[] closures = null;
- Predicate[] preds = null;
- if (predicatesAndClosures == null) {
- throw new IllegalArgumentException("The predicate and closure map must not be null");
- }
- if (predicatesAndClosures.size() == 0) {
- return NOPClosure.INSTANCE;
- }
- // convert to array like this to guarantee iterator() ordering
- Closure defaultClosure = (Closure) predicatesAndClosures.remove(null);
- int size = predicatesAndClosures.size();
- if (size == 0) {
- return (defaultClosure == null ? NOPClosure.INSTANCE : defaultClosure);
- }
- closures = new Closure[size];
- preds = new Predicate[size];
- int i = 0;
- for (Iterator it = predicatesAndClosures.entrySet().iterator(); it.hasNext();) {
- Map.Entry entry = (Map.Entry) it.next();
- preds[i] = (Predicate) entry.getKey();
- closures[i] = (Closure) entry.getValue();
- i++;
- }
- return new SwitchClosure(preds, closures, defaultClosure);
- }
-
- /**
- * Constructor that performs no validation.
- * Use <code>getInstance</code> if you want that.
- *
- * @param predicates array of predicates, not cloned, no nulls
- * @param closures matching array of closures, not cloned, no nulls
- * @param defaultClosure the closure to use if no match, null means nop
- */
- public SwitchClosure(Predicate[] predicates, Closure[] closures, Closure defaultClosure) {
- super();
- iPredicates = predicates;
- iClosures = closures;
- iDefault = (defaultClosure == null ? NOPClosure.INSTANCE : defaultClosure);
- }
-
- /**
- * Executes the closure whose matching predicate returns true
- *
- * @param input the input object
- */
- public void execute(Object input) {
- for (int i = 0; i < iPredicates.length; i++) {
- if (iPredicates[i].evaluate(input) == true) {
- iClosures[i].execute(input);
- return;
- }
- }
- iDefault.execute(input);
- }
-
- /**
- * Gets the predicates, do not modify the array.
- *
- * @return the predicates
- * @since Commons Collections 3.1
- */
- public Predicate[] getPredicates() {
- return iPredicates;
- }
-
- /**
- * Gets the closures, do not modify the array.
- *
- * @return the closures
- * @since Commons Collections 3.1
- */
- public Closure[] getClosures() {
- return iClosures;
- }
-
- /**
- * Gets the default closure.
- *
- * @return the default closure
- * @since Commons Collections 3.1
- */
- public Closure getDefaultClosure() {
- return iDefault;
- }
-
- }