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;
018    
019    import java.io.Serializable;
020    import java.util.Collections;
021    import java.util.HashMap;
022    import java.util.HashSet;
023    import java.util.Map;
024    import java.util.Set;
025    
026    import org.apache.commons.scxml.invoke.Invoker;
027    import org.apache.commons.scxml.invoke.InvokerException;
028    import org.apache.commons.scxml.model.Datamodel;
029    import org.apache.commons.scxml.model.History;
030    import org.apache.commons.scxml.model.TransitionTarget;
031    
032    /**
033     * The <code>SCInstance</code> performs book-keeping functions for
034     * a particular execution of a state chart represented by a
035     * <code>SCXML</code> object.
036     */
037    public class SCInstance implements Serializable {
038    
039        /**
040         * Serial version UID.
041         */
042        private static final long serialVersionUID = 2L;
043    
044        /**
045         * The notification registry.
046         */
047        private NotificationRegistry notificationRegistry;
048    
049        /**
050         * The <code>Map</code> of <code>Context</code>s per
051         * <code>TransitionTarget</code>.
052         */
053        private Map contexts;
054    
055        /**
056         * The <code>Map</code> of last known configurations per
057         * <code>History</code>.
058         */
059        private Map histories;
060    
061        /**
062         * <code>Map</code> for recording the run to completion status of
063         * composite states.
064         */
065        private Map completions;
066    
067        /**
068         * The <code>Invoker</code> classes <code>Map</code>, keyed by
069         * <invoke> target types (specified using "targettype" attribute).
070         */
071        private Map invokerClasses;
072    
073        /**
074         * The <code>Map</code> of active <code>Invoker</code>s, keyed by
075         * (leaf) <code>State</code>s.
076         */
077        private Map invokers;
078    
079        /**
080         * The evaluator for expressions.
081         */
082        private Evaluator evaluator;
083    
084        /**
085         * The root context.
086         */
087        private Context rootContext;
088    
089        /**
090         * The owning state machine executor.
091         */
092        private SCXMLExecutor executor;
093    
094        /**
095         * Constructor.
096         *
097         * @param executor The executor that this instance is attached to.
098         */
099        SCInstance(final SCXMLExecutor executor) {
100            this.notificationRegistry = new NotificationRegistry();
101            this.contexts = Collections.synchronizedMap(new HashMap());
102            this.histories = Collections.synchronizedMap(new HashMap());
103            this.invokerClasses = Collections.synchronizedMap(new HashMap());
104            this.invokers = Collections.synchronizedMap(new HashMap());
105            this.completions = Collections.synchronizedMap(new HashMap());
106            this.evaluator = null;
107            this.rootContext = null;
108            this.executor = executor;
109        }
110    
111        /**
112         * Get the <code>Evaluator</code>.
113         *
114         * @return The evaluator.
115         */
116        public Evaluator getEvaluator() {
117            return evaluator;
118        }
119    
120        /**
121         * Set the <code>Evaluator</code>.
122         *
123         * @param evaluator The evaluator.
124         */
125        void setEvaluator(final Evaluator evaluator) {
126            this.evaluator = evaluator;
127        }
128    
129        /**
130         * Get the root context.
131         *
132         * @return The root context.
133         */
134        public Context getRootContext() {
135            if (rootContext == null && evaluator != null) {
136                rootContext = evaluator.newContext(null);
137            }
138            return rootContext;
139        }
140    
141        /**
142         * Set the root context.
143         *
144         * @param context The root context.
145         */
146        void setRootContext(final Context context) {
147            this.rootContext = context;
148        }
149    
150        /**
151         * Get the notification registry.
152         *
153         * @return The notification registry.
154         */
155        public NotificationRegistry getNotificationRegistry() {
156            return notificationRegistry;
157        }
158    
159        /**
160         * Set the notification registry.
161         *
162         * @param notifRegistry The notification registry.
163         */
164        void setNotificationRegistry(final NotificationRegistry notifRegistry) {
165            this.notificationRegistry = notifRegistry;
166        }
167    
168        /**
169         * Get the <code>Context</code> for this <code>TransitionTarget</code>.
170         * If one is not available it is created.
171         *
172         * @param transitionTarget The TransitionTarget.
173         * @return The Context.
174         */
175        public Context getContext(final TransitionTarget transitionTarget) {
176            Context context = (Context) contexts.get(transitionTarget);
177            if (context == null) {
178                TransitionTarget parent = transitionTarget.getParent();
179                if (parent == null) {
180                    // docroot
181                    context = evaluator.newContext(getRootContext());
182                } else {
183                    context = evaluator.newContext(getContext(parent));
184                }
185                Datamodel datamodel = transitionTarget.getDatamodel();
186                SCXMLHelper.cloneDatamodel(datamodel, context, evaluator, null);
187                contexts.put(transitionTarget, context);
188            }
189            return context;
190        }
191    
192        /**
193         * Get the <code>Context</code> for this <code>TransitionTarget</code>.
194         * May return <code>null</code>.
195         *
196         * @param transitionTarget The <code>TransitionTarget</code>.
197         * @return The Context.
198         */
199        Context lookupContext(final TransitionTarget transitionTarget) {
200            return (Context) contexts.get(transitionTarget);
201        }
202    
203        /**
204         * Set the <code>Context</code> for this <code>TransitionTarget</code>.
205         *
206         * @param transitionTarget The TransitionTarget.
207         * @param context The Context.
208         */
209        void setContext(final TransitionTarget transitionTarget,
210                final Context context) {
211            contexts.put(transitionTarget, context);
212        }
213    
214        /**
215         * Get the last configuration for this history.
216         *
217         * @param history The history.
218         * @return Returns the lastConfiguration.
219         */
220        public Set getLastConfiguration(final History history) {
221            Set lastConfiguration = (Set) histories.get(history);
222            if (lastConfiguration == null) {
223                lastConfiguration = new HashSet();
224                histories.put(history, lastConfiguration);
225            }
226            return lastConfiguration;
227        }
228    
229        /**
230         * Set the last configuration for this history.
231         *
232         * @param history The history.
233         * @param lc The lastConfiguration to set.
234         */
235        public void setLastConfiguration(final History history,
236                final Set lc) {
237            Set lastConfiguration = getLastConfiguration(history);
238            lastConfiguration.clear();
239            lastConfiguration.addAll(lc);
240        }
241    
242        /**
243         * Check whether we have prior history.
244         *
245         * @param history The history.
246         * @return Whether we have a non-empty last configuration
247         */
248        public boolean isEmpty(final History history) {
249            Set lastConfiguration = (Set) histories.get(history);
250            if (lastConfiguration == null || lastConfiguration.isEmpty()) {
251                return true;
252            }
253            return false;
254        }
255    
256        /**
257         * Resets the history state.
258         *
259         * @param history The history.
260         * @see org.apache.commons.scxml.SCXMLExecutor#reset()
261         */
262        public void reset(final History history) {
263            Set lastConfiguration = (Set) histories.get(history);
264            if (lastConfiguration != null) {
265                lastConfiguration.clear();
266            }
267        }
268    
269        /**
270         * Get the {@link SCXMLExecutor} this instance is attached to.
271         *
272         * @return The SCXMLExecutor this instance is attached to.
273         * @see org.apache.commons.scxml.SCXMLExecutor
274         */
275        public SCXMLExecutor getExecutor() {
276            return executor;
277        }
278    
279        /**
280         * Register an {@link Invoker} class for this target type.
281         *
282         * @param targettype The target type (specified by "targettype"
283         *                   attribute of <invoke> tag).
284         * @param invokerClass The <code>Invoker</code> <code>Class</code>.
285         */
286        void registerInvokerClass(final String targettype,
287                final Class invokerClass) {
288            invokerClasses.put(targettype, invokerClass);
289        }
290    
291        /**
292         * Remove the {@link Invoker} class registered for this target
293         * type (if there is one registered).
294         *
295         * @param targettype The target type (specified by "targettype"
296         *                   attribute of <invoke> tag).
297         */
298        void unregisterInvokerClass(final String targettype) {
299            invokerClasses.remove(targettype);
300        }
301    
302        /**
303         * Get the {@link Invoker} for this {@link TransitionTarget}.
304         * May return <code>null</code>. A non-null <code>Invoker</code> will be
305         * returned if and only if the <code>TransitionTarget</code> is
306         * currently active and contains an <invoke> child.
307         *
308         * @param targettype The type of the target being invoked.
309         * @return An {@link Invoker} for the specified type, if an
310         *         invoker class is registered against that type,
311         *         <code>null</code> otherwise.
312         * @throws InvokerException When a suitable {@link Invoker} cannot
313         *                          be instantiated.
314         */
315        public Invoker newInvoker(final String targettype)
316        throws InvokerException {
317            Class invokerClass = (Class) invokerClasses.get(targettype);
318            if (invokerClass == null) {
319                throw new InvokerException("No Invoker registered for "
320                    + "targettype \"" + targettype + "\"");
321            }
322            Invoker invoker = null;
323            try {
324                invoker = (Invoker) invokerClass.newInstance();
325            } catch (InstantiationException ie) {
326                throw new InvokerException(ie.getMessage(), ie.getCause());
327            } catch (IllegalAccessException iae) {
328                throw new InvokerException(iae.getMessage(), iae.getCause());
329            }
330            return invoker;
331        }
332    
333        /**
334        * Get the {@link Invoker} for this {@link TransitionTarget}.
335         * May return <code>null</code>. A non-null {@link Invoker} will be
336         * returned if and only if the {@link TransitionTarget} is
337         * currently active and contains an <invoke> child.
338         *
339         * @param transitionTarget The <code>TransitionTarget</code>.
340         * @return The Invoker.
341         */
342        public Invoker getInvoker(final TransitionTarget transitionTarget) {
343            return (Invoker) invokers.get(transitionTarget);
344        }
345    
346        /**
347         * Set the {@link Invoker} for this {@link TransitionTarget}.
348         *
349         * @param transitionTarget The TransitionTarget.
350         * @param invoker The Invoker.
351         */
352        public void setInvoker(final TransitionTarget transitionTarget,
353                final Invoker invoker) {
354            invokers.put(transitionTarget, invoker);
355        }
356    
357        /**
358         * Return the Map of {@link Invoker}s currently "active".
359         *
360         * @return The map of invokers.
361         */
362        public Map getInvokers() {
363            return invokers;
364        }
365    
366        /**
367         * Get the completion status for this composite
368         * {@link TransitionTarget}.
369         *
370         * @param transitionTarget The <code>TransitionTarget</code>.
371         * @return The completion status.
372         *
373         * @since 0.7
374         */
375        public boolean isDone(final TransitionTarget transitionTarget) {
376            Boolean done = (Boolean) completions.get(transitionTarget);
377            if (done == null) {
378                return false;
379            } else {
380                return done.booleanValue();
381            }
382        }
383    
384        /**
385         * Set the completion status for this composite
386         * {@link TransitionTarget}.
387         *
388         * @param transitionTarget The TransitionTarget.
389         * @param done The completion status.
390         *
391         * @since 0.7
392         */
393        public void setDone(final TransitionTarget transitionTarget,
394                final boolean done) {
395            completions.put(transitionTarget, done ? Boolean.TRUE : Boolean.FALSE);
396        }
397    
398    }
399