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     */
017    package org.apache.commons.scxml.model;
018    
019    import java.util.ArrayList;
020    import java.util.Collection;
021    import java.util.Iterator;
022    import java.util.List;
023    
024    import org.apache.commons.logging.Log;
025    import org.apache.commons.scxml.Context;
026    import org.apache.commons.scxml.ErrorReporter;
027    import org.apache.commons.scxml.Evaluator;
028    import org.apache.commons.scxml.EventDispatcher;
029    import org.apache.commons.scxml.SCInstance;
030    import org.apache.commons.scxml.SCXMLExpressionException;
031    
032    /**
033     * The class in this SCXML object model that corresponds to the
034     * <if> SCXML element, which serves as a container for conditionally
035     * executed elements. <else> and <elseif> can optionally
036     * appear within an <if> as immediate children, and serve to partition
037     * the elements within an <if>.
038     *
039     */
040    public class If extends Action {
041    
042        /**
043         * Serial version UID.
044         */
045        private static final long serialVersionUID = 1L;
046    
047        /**
048         * An conditional expression which can be evaluated to true or false.
049         */
050        private String cond;
051    
052        /**
053         * The set of executable elements (those that inheriting from
054         * Action) that are contained in this <if> element.
055         */
056        private List actions;
057    
058        /**
059         * The boolean value that dictates whether the particular child action
060         * should be executed.
061         */
062        private boolean execute;
063    
064        /**
065         * Constructor.
066         */
067        public If() {
068            super();
069            this.actions = new ArrayList();
070            this.execute = false;
071        }
072    
073        /**
074         * Get the executable actions contained in this <if>.
075         *
076         * @return Returns the actions.
077         */
078        public final List getActions() {
079            return actions;
080        }
081    
082        /**
083         * Add an Action to the list of executable actions contained in
084         * this <if>.
085         *
086         * @param action The action to add.
087         */
088        public final void addAction(final Action action) {
089            if (action != null) {
090                this.actions.add(action);
091            }
092        }
093    
094        /**
095         * Get the conditional expression.
096         *
097         * @return Returns the cond.
098         */
099        public final String getCond() {
100            return cond;
101        }
102    
103        /**
104         * Set the conditional expression.
105         *
106         * @param cond The cond to set.
107         */
108        public final void setCond(final String cond) {
109            this.cond = cond;
110        }
111    
112        /**
113         * {@inheritDoc}
114         */
115        public void execute(final EventDispatcher evtDispatcher,
116                final ErrorReporter errRep, final SCInstance scInstance,
117                final Log appLog, final Collection derivedEvents)
118        throws ModelException, SCXMLExpressionException {
119            TransitionTarget parentTarget = getParentTransitionTarget();
120            Context ctx = scInstance.getContext(parentTarget);
121            Evaluator eval = scInstance.getEvaluator();
122            ctx.setLocal(getNamespacesKey(), getNamespaces());
123            execute = eval.evalCond(ctx, cond).booleanValue();
124            ctx.setLocal(getNamespacesKey(), null);
125            // The "if" statement is a "container"
126            for (Iterator ifiter = actions.iterator(); ifiter.hasNext();) {
127                Action aa = (Action) ifiter.next();
128                if (execute && !(aa instanceof ElseIf)
129                        && !(aa instanceof Else)) {
130                    aa.execute(evtDispatcher, errRep, scInstance, appLog,
131                        derivedEvents);
132                } else if (execute
133                        && (aa instanceof ElseIf || aa instanceof Else)) {
134                    break;
135                } else if (aa instanceof Else) {
136                    execute = true;
137                } else if (aa instanceof ElseIf) {
138                    ctx.setLocal(getNamespacesKey(), getNamespaces());
139                    execute = eval.evalCond(ctx, ((ElseIf) aa).getCond())
140                            .booleanValue();
141                    ctx.setLocal(getNamespacesKey(), null);
142                }
143            }
144        }
145    
146    }
147