    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.io.Serializable;
    020    import java.util.Collection;
    021    import java.util.Map;
    022
    023    import org.apache.commons.logging.Log;
    024    import org.apache.commons.scxml.ErrorReporter;
    025    import org.apache.commons.scxml.EventDispatcher;
    026    import org.apache.commons.scxml.SCInstance;
    027    import org.apache.commons.scxml.SCXMLExpressionException;
    028
    029    /**
    030     * An abstract base class for executable elements in SCXML,
    031     * such as <assign>, <log> etc.
    032     *
    033     */
    034    public abstract class Action implements NamespacePrefixesHolder,
    035            Serializable {
    036
    037        /**
    038         * Link to its parent or container.
    039         */
    040        private Executable parent;
    041
    042        /**
    043         * The current XML namespaces in the SCXML document for this action node,
    044         * preserved for deferred XPath evaluation.
    045         */
    046        private Map namespaces;
    047
    048        /**
    049         * Current document namespaces are saved under this key in the parent
    050         * state's context.
    051         */
    052        private static final String NAMESPACES_KEY = "_ALL_NAMESPACES";
    053
    054        /**
    055         * Constructor.
    056         */
    057        public Action() {
    058            super();
    059            this.parent = null;
    060            this.namespaces = null;
    061        }
    062
    063        /**
    064         * Get the Executable parent.
    065         *
    066         * @return Returns the parent.
    067         */
    068        public final Executable getParent() {
    069            return parent;
    070        }
    071
    072        /**
    073         * Set the Executable parent.
    074         *
    075         * @param parent The parent to set.
    076         */
    077        public final void setParent(final Executable parent) {
    078            this.parent = parent;
    079        }
    080
    081        /**
    082         * Get the XML namespaces at this action node in the SCXML document.
    083         *
    084         * @return Returns the map of namespaces.
    085         */
    086        public final Map getNamespaces() {
    087            return namespaces;
    088        }
    089
    090        /**
    091         * Set the XML namespaces at this action node in the SCXML document.
    092         *
    093         * @param namespaces The document namespaces.
    094         */
    095        public final void setNamespaces(final Map namespaces) {
    096            this.namespaces = namespaces;
    097        }
    098
    099        /**
    100         * Return the parent state.
    101         *
    102         * @return The parent State
    103         * @throws ModelException For an unknown TransitionTarget subclass
    104         *
    105         * @deprecated Use {@link #getParentTransitionTarget()} instead.
    106         */
    107        public final State getParentState() throws ModelException {
    108            TransitionTarget tt = parent.getParent();
    109            if (tt instanceof State) {
    110                State st = (State) tt;
    111                return st;
    112            } else if (tt instanceof Parallel || tt instanceof History) {
    113                State st = (State) tt.getParent();
    114                return st;
    115            } else {
    116                throw new ModelException("Unknown TransitionTarget subclass:"
    117                        + tt.getClass().getName());
    118            }
    119        }
    120
    121        /**
    122         * Return the {@link TransitionTarget} whose {@link Context} this action
    123         * executes in.
    124         *
    125         * @return The parent {@link TransitionTarget}
    126         * @throws ModelException For an unknown TransitionTarget subclass
    127         *
    128         * @since 0.9
    129         */
    130        public final TransitionTarget getParentTransitionTarget()
    131        throws ModelException {
    132            TransitionTarget tt = parent.getParent();
    133            if (tt instanceof State || tt instanceof Parallel) {
    134                return tt;
    135            } else if (tt instanceof History || tt instanceof Initial) {
    136                return tt.getParent();
    137            } else {
    138                throw new ModelException("Unknown TransitionTarget subclass:"
    139                        + tt.getClass().getName());
    140            }
    141        }
    142
    143        /**
    144         * Execute this action instance.
    145         *
    146         * @param evtDispatcher The EventDispatcher for this execution instance
    147         * @param errRep        The ErrorReporter to broadcast any errors
    148         *                      during execution.
    149         * @param scInstance    The state machine execution instance information.
    150         * @param appLog        The application Log.
    151         * @param derivedEvents The collection to which any internal events
    152         *                      arising from the execution of this action
    153         *                      must be added.
    154         *
    155         * @throws ModelException If the execution causes the model to enter
    156         *                        a non-deterministic state.
    157         * @throws SCXMLExpressionException If the execution involves trying
    158         *                        to evaluate an expression which is malformed.
    159         */
    160        public abstract void execute(final EventDispatcher evtDispatcher,
    161            final ErrorReporter errRep, final SCInstance scInstance,
    162            final Log appLog, final Collection derivedEvents)
    163        throws ModelException, SCXMLExpressionException;
    164
    165        /**
    166         * Return the key under which the current document namespaces are saved
    167         * in the parent state's context.
    168         *
    169         * @return The namespaces key
    170         */
    171        protected static String getNamespacesKey() {
    172            return NAMESPACES_KEY;
    173        }
    174
    175    }
    176