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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.scxml;
    18
    19  import java.util.HashSet;
    20  import java.util.IdentityHashMap;
    21  import java.util.Iterator;
    22  import java.util.List;
    23  import java.util.Map;
    24  import java.util.Set;
    25
    26  import org.apache.commons.logging.Log;
    27  import org.apache.commons.logging.LogFactory;
    28  import org.apache.commons.scxml.model.Data;
    29  import org.apache.commons.scxml.model.Datamodel;
    30  import org.apache.commons.scxml.model.Parallel;
    31  import org.apache.commons.scxml.model.Path;
    32  import org.apache.commons.scxml.model.State;
    33  import org.apache.commons.scxml.model.Transition;
    34  import org.apache.commons.scxml.model.TransitionTarget;
    35  import org.apache.commons.scxml.semantics.ErrorConstants;
    36  import org.w3c.dom.CharacterData;
    37  import org.w3c.dom.Node;
    38  import org.w3c.dom.Text;
    39
    40  /***
    41   * Helper class, all methods static final.
    42   *
    43   */
    44  public final class SCXMLHelper {
    45
    46      /***
    47       * Return true if the string is empty.
    48       *
    49       * @param attr The String to test
    50       * @return Is string empty
    51       */
    52      public static boolean isStringEmpty(final String attr) {
    53          if (attr == null || attr.trim().length() == 0) {
    54              return true;
    55          }
    56          return false;
    57      }
    58
    59      /***
    60       * Checks whether a transition target tt (State or Parallel) is a
    61       * descendant of the transition target context.
    62       *
    63       * @param tt
    64       *            TransitionTarget to check - a potential descendant
    65       * @param ctx
    66       *            TransitionTarget context - a potential ancestor
    67       * @return true iff tt is a descendant of ctx, false otherwise
    68       */
    69      public static boolean isDescendant(final TransitionTarget tt,
    70              final TransitionTarget ctx) {
    71          TransitionTarget parent = tt.getParent();
    72          while (parent != null) {
    73              if (parent == ctx) {
    74                  return true;
    75              }
    76              parent = parent.getParent();
    77          }
    78          return false;
    79      }
    80
    81      /***
    82       * Creates a set which contains given states and all their ancestors
    83       * recursively up to the upper bound. Null upperBound means root
    84       * of the state machine.
    85       *
    86       * @param states The Set of States
    87       * @param upperBounds The Set of upper bound States
    88       * @return transitive closure of a given state set
    89       */
    90      public static Set getAncestorClosure(final Set states,
    91              final Set upperBounds) {
    92          Set closure = new HashSet(states.size() * 2);
    93          for (Iterator i = states.iterator(); i.hasNext();) {
    94              TransitionTarget tt = (TransitionTarget) i.next();
    95              while (tt != null) {
    96                  if (!closure.add(tt)) {
    97                      //tt is already a part of the closure
    98                      break;
    99                  }
    100                 if (upperBounds != null && upperBounds.contains(tt)) {
    101                     break;
    102                 }
    103                 tt = tt.getParent();
    104             }
    105         }
    106         return closure;
    107     }
    108
    109     /***
    110      * Checks whether a given set of states is a legal Harel State Table
    111      * configuration (with the respect to the definition of the OR and AND
    112      * states).
    113      *
    114      * @param states
    115      *            a set of states
    116      * @param errRep
    117      *            ErrorReporter to report detailed error info if needed
    118      * @return true if a given state configuration is legal, false otherwise
    119      */
    120     public static boolean isLegalConfig(final Set states,
    121             final ErrorReporter errRep) {
    122         /*
    123          * For every active state we add 1 to the count of its parent. Each
    124          * Parallel should reach count equal to the number of its children and
    125          * contribute by 1 to its parent. Each State should reach count exactly
    126          * 1. SCXML elemnt (top) should reach count exactly 1. We essentially
    127          * summarize up the hierarchy tree starting with a given set of
    128          * states = active configuration.
    129          */
    130         boolean legalConfig = true; // let's be optimists
    131         Map counts = new IdentityHashMap();
    132         Set scxmlCount = new HashSet();
    133         for (Iterator i = states.iterator(); i.hasNext();) {
    134             TransitionTarget tt = (TransitionTarget) i.next();
    135             TransitionTarget parent = null;
    136             while ((parent = tt.getParent()) != null) {
    137                 HashSet cnt = (HashSet) counts.get(parent);
    138                 if (cnt == null) {
    139                     cnt = new HashSet();
    140                     counts.put(parent, cnt);
    141                 }
    142                 cnt.add(tt);
    143                 tt = parent;
    144             }
    145             //top-level contribution
    146             scxmlCount.add(tt);
    147         }
    148         //Validate counts:
    149         for (Iterator i = counts.entrySet().iterator(); i.hasNext();) {
    150             Map.Entry entry = (Map.Entry) i.next();
    151             TransitionTarget tt = (TransitionTarget) entry.getKey();
    152             Set count = (Set) entry.getValue();
    153             if (tt instanceof Parallel) {
    154                 Parallel p = (Parallel) tt;
    155                 if (count.size() < p.getStates().size()) {
    156                     errRep.onError(ErrorConstants.ILLEGAL_CONFIG,
    157                         "Not all AND states active for parallel "
    158                         + p.getId(), entry);
    159                     legalConfig = false;
    160                 }
    161             } else {
    162                 if (count.size() > 1) {
    163                     errRep.onError(ErrorConstants.ILLEGAL_CONFIG,
    164                         "Multiple OR states active for state "
    165                         + tt.getId(), entry);
    166                     legalConfig = false;
    167                 }
    168             }
    169             count.clear(); //cleanup
    170         }
    171         if (scxmlCount.size() > 1) {
    172             errRep.onError(ErrorConstants.ILLEGAL_CONFIG,
    173                     "Multiple top-level OR states active!", scxmlCount);
    174         }
    175         //cleanup
    176         scxmlCount.clear();
    177         counts.clear();
    178         return legalConfig;
    179     }
    180
    181     /***
    182      * Finds the least common ancestor of transition targets tt1 and tt2 if
    183      * one exists.
    184      *
    185      * @param tt1 First TransitionTarget
    186      * @param tt2 Second TransitionTarget
    187      * @return closest common ancestor of tt1 and tt2 or null
    188      */
    189     public static TransitionTarget getLCA(final TransitionTarget tt1,
    190             final TransitionTarget tt2) {
    191         if (tt1 == tt2) {
    192             return tt1; //self-transition
    193         } else if (isDescendant(tt1, tt2)) {
    194             return tt2;
    195         } else if (isDescendant(tt2, tt1)) {
    196             return tt1;
    197         }
    198         Set parents = new HashSet();
    199         TransitionTarget tmp = tt1;
    200         while ((tmp = tmp.getParent()) != null) {
    201             if (tmp instanceof State) {
    202                 parents.add(tmp);
    203             }
    204         }
    205         tmp = tt2;
    206         while ((tmp = tmp.getParent()) != null) {
    207             if (tmp instanceof State) {
    208                 //test redundant add = common ancestor
    209                 if (!parents.add(tmp)) {
    210                     parents.clear();
    211                     return tmp;
    212                 }
    213             }
    214         }
    215         return null;
    216     }
    217
    218     /***
    219      * Returns the set of all states (and parallels) which are exited if a
    220      * given transition t is going to be taken.
    221      * Current states are necessary to be taken into account
    222      * due to orthogonal states and cross-region transitions -
    223      * see UML specs for more details.
    224      *
    225      * @param t
    226      *            transition to be taken
    227      * @param currentStates
    228      *            the set of current states (simple states only)
    229      * @return a set of all states (including composite) which are exited if a
    230      *         given transition is taken
    231      */
    232     public static Set getStatesExited(final Transition t,
    233             final Set currentStates) {
    234         Set allStates = new HashSet();
    235         Path p = t.getPath();
    236         //the easy part
    237         allStates.addAll(p.getUpwardSegment());
    238         TransitionTarget source = t.getParent();
    239         for (Iterator act = currentStates.iterator(); act.hasNext();) {
    240             TransitionTarget a = (TransitionTarget) act.next();
    241             if (isDescendant(a, source)) {
    242                 boolean added = false;
    243                 added = allStates.add(a);
    244                 while (added && a != source) {
    245                     a = a.getParent();
    246                     added = allStates.add(a);
    247                 }
    248             }
    249         }
    250         if (p.isCrossRegion()) {
    251             for (Iterator regions = p.getRegionsExited().iterator();
    252                     regions.hasNext();) {
    253                 Parallel par = ((Parallel) ((State) regions.next()).
    254                     getParent());
    255                 //let's find affected states in sibling regions
    256                 for (Iterator siblings = par.getStates().iterator();
    257                         siblings.hasNext();) {
    258                     State s = (State) siblings.next();
    259                     for (Iterator act = currentStates.iterator();
    260                             act.hasNext();) {
    261                         TransitionTarget a = (TransitionTarget) act.next();
    262                         if (isDescendant(a, s)) {
    263                             //a is affected
    264                             boolean added = false;
    265                             added = allStates.add(a);
    266                             while (added && a != s) {
    267                                 a = a.getParent();
    268                                 added = allStates.add(a);
    269                             }
    270                         }
    271                     }
    272                 }
    273             }
    274         }
    275         return allStates;
    276     }
    277
    278     /***
    279      * According to the UML definition, two transitions
    280      * are conflicting if the sets of states they exit overlap.
    281      *
    282      * @param t1 a transition to check against t2
    283      * @param t2 a transition to check against t1
    284      * @param currentStates the set of current states (simple states only)
    285      * @return true if the t1 and t2 are conflicting transitions
    286      * @see #getStatesExited(Transition, Set)
    287      */
    288     public static boolean inConflict(final Transition t1,
    289             final Transition t2, final Set currentStates) {
    290         Set ts1 = getStatesExited(t1, currentStates);
    291         Set ts2 = getStatesExited(t2, currentStates);
    292         ts1.retainAll(ts2);
    293         if (ts1.isEmpty()) {
    294             return false;
    295         }
    296         return true;
    297     }
    298
    299     /***
    300      * Whether the first argument is a subtype of the second.
    301      *
    302      * @param child The candidate subtype
    303      * @param parent The supertype
    304      * @return true if child is subtype of parent, otherwise false
    305      */
    306     public static boolean subtypeOf(final Class child, final Class parent) {
    307         if (child == null || parent == null) {
    308             return false;
    309         }
    310         for (Class current = child; current != Object.class;
    311                 current = current.getSuperclass()) {
    312             if (current == parent) {
    313                 return true;
    314             }
    315         }
    316         return false;
    317     }
    318
    319     /***
    320      * Whether the class implements the interface.
    321      *
    322      * @param clas The candidate class
    323      * @param interfayce The interface
    324      * @return true if clas implements interfayce, otherwise false
    325      */
    326     public static boolean implementationOf(final Class clas,
    327             final Class interfayce) {
    328         if (clas == null || interfayce == null || !interfayce.isInterface()) {
    329             return false;
    330         }
    331         for (Class current = clas; current != Object.class;
    332                 current = current.getSuperclass()) {
    333             Class[] implementedInterfaces = current.getInterfaces();
    334             for (int i = 0; i < implementedInterfaces.length; i++) {
    335                 if (implementedInterfaces[i] == interfayce) {
    336                     return true;
    337                 }
    338             }
    339         }
    340         return false;
    341     }
    342
    343     /***
    344      * Set node value, depending on its type, from a String.
    345      *
    346      * @param node A Node whose value is to be set
    347      * @param value The new value
    348      */
    349     public static void setNodeValue(final Node node, final String value) {
    350         switch(node.getNodeType()) {
    351             case Node.ATTRIBUTE_NODE:
    352                 node.setNodeValue(value);
    353                 break;
    354             case Node.ELEMENT_NODE:
    355                 //remove all text children
    356                 if (node.hasChildNodes()) {
    357                     Node child = node.getFirstChild();
    358                     while (child != null) {
    359                         if (child.getNodeType() == Node.TEXT_NODE) {
    360                             node.removeChild(child);
    361                         }
    362                         child = child.getNextSibling();
    363                     }
    364                 }
    365                 //create a new text node and append
    366                 Text txt = node.getOwnerDocument().createTextNode(value);
    367                 node.appendChild(txt);
    368                 break;
    369             case Node.TEXT_NODE:
    370             case Node.CDATA_SECTION_NODE:
    371                 ((CharacterData) node).setData(value);
    372                 break;
    373             default:
    374                 String err = "Trying to set value of a strange Node type: "
    375                     + node.getNodeType();
    376                 //Logger.logln(Logger.E, err);
    377                 throw new IllegalArgumentException(err);
    378         }
    379     }
    380
    381     /***
    382      * Retrieve a DOM node value as a string depending on its type.
    383      *
    384      * @param node A node to be retreived
    385      * @return The value as a string
    386      */
    387     public static String getNodeValue(final Node node) {
    388         String result = "";
    389         if (node == null) {
    390             return result;
    391         }
    392         switch(node.getNodeType()) {
    393             case Node.ATTRIBUTE_NODE:
    394                 result = node.getNodeValue();
    395                 break;
    396             case Node.ELEMENT_NODE:
    397                 if (node.hasChildNodes()) {
    398                     Node child = node.getFirstChild();
    399                     StringBuffer buf = new StringBuffer();
    400                     while (child != null) {
    401                         if (child.getNodeType() == Node.TEXT_NODE) {
    402                             buf.append(((CharacterData) child).getData());
    403                         }
    404                         child = child.getNextSibling();
    405                     }
    406                     result = buf.toString();
    407                 }
    408                 break;
    409             case Node.TEXT_NODE:
    410             case Node.CDATA_SECTION_NODE:
    411                 result = ((CharacterData) node).getData();
    412                 break;
    413             default:
    414                 String err = "Trying to get value of a strange Node type: "
    415                     + node.getNodeType();
    416                 //Logger.logln(Logger.W, err );
    417                 throw new IllegalArgumentException(err);
    418         }
    419         return result.trim();
    420     }
    421
    422     /***
    423      * Clone data model.
    424      *
    425      * @param ctx The context to clone to.
    426      * @param datamodel The datamodel to clone.
    427      * @param evaluator The expression evaluator.
    428      * @param log The error log.
    429      */
    430     public static void cloneDatamodel(final Datamodel datamodel,
    431             final Context ctx, final Evaluator evaluator,
    432             final Log log) {
    433         if (datamodel == null) {
    434             return;
    435         }
    436         List data = datamodel.getData();
    437         if (data == null) {
    438             return;
    439         }
    440         for (Iterator iter = data.iterator(); iter.hasNext();) {
    441             Data datum = (Data) iter.next();
    442             Node datumNode = datum.getNode();
    443             Node valueNode = null;
    444             if (datumNode != null) {
    445                 valueNode = datumNode.cloneNode(true);
    446             }
    447             // prefer "src" over "expr" over "inline"
    448             if (!SCXMLHelper.isStringEmpty(datum.getSrc())) {
    449                 ctx.setLocal(datum.getName(), valueNode);
    450             } else if (!SCXMLHelper.isStringEmpty(datum.
    451                     getExpr())) {
    452                 Object value = null;
    453                 try {
    454                     ctx.setLocal(NAMESPACES_KEY, datum.getNamespaces());
    455                     value = evaluator.eval(ctx, datum.getExpr());
    456                     ctx.setLocal(NAMESPACES_KEY, null);
    457                 } catch (SCXMLExpressionException see) {
    458                     if (log != null) {
    459                         log.error(see.getMessage(), see);
    460                     } else {
    461                         Log defaultLog = LogFactory.getLog(SCXMLHelper.class);
    462                         defaultLog.error(see.getMessage(), see);
    463                     }
    464                 }
    465                 ctx.setLocal(datum.getName(), value);
    466             } else {
    467                 ctx.setLocal(datum.getName(), valueNode);
    468             }
    469         }
    470     }
    471
    472     /***
    473      * Discourage instantiation since this is a utility class.
    474      */
    475     private SCXMLHelper() {
    476         super();
    477     }
    478
    479     /***
    480      * Current document namespaces are saved under this key in the parent
    481      * state's context.
    482      */
    483     private static final String NAMESPACES_KEY = "_ALL_NAMESPACES";
    484
    485 }
    486