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1   /*
2    *   Copyright 2005 The Apache Software Foundation
3    *
4    *   Licensed under the Apache License, Version 2.0 (the "License");
5    *   you may not use this file except in compliance with the License.
6    *   You may obtain a copy of the License at
7    *
8    *       http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *   Unless required by applicable law or agreed to in writing, software
11   *   distributed under the License is distributed on an "AS IS" BASIS,
12   *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *   See the License for the specific language governing permissions and
14   *   limitations under the License.
15   *
16   */
17  package org.apache.asn1new.ber.grammar;
18  
19  /***
20   * Define a transition between two states of a grammar. It stores the 
21   * next state, and the action to execute while transiting.  
22   * 
23   *
24   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
25   */
26  public class GrammarTransition
27  {
28      //~ Instance fields ----------------------------------------------------------------------------
29  
30      /*** The next state in the grammar */
31      private int           nextState;
32  
33      /*** The action associated to the transition */
34      private GrammarAction action;
35  
36      /*** The current state */
37      private int        currentState;
38  
39      //~ Constructors -------------------------------------------------------------------------------
40  
41      /***
42       * Creates a new GrammarTransition object.
43       *
44       * @param currentState The current transition 
45       * @param nextState The target state
46       * @param action The action to execute. It could be null.
47       */
48      public GrammarTransition(  int currentState, int nextState, GrammarAction action )
49      {
50          this.currentState      = currentState;
51          this.nextState = nextState;
52          this.action    = action;
53      }
54  
55      //~ Methods ------------------------------------------------------------------------------------
56  
57      /***
58       * @return Returns the target state.
59       */
60      public int getNextState()
61      {
62          return nextState;
63      }
64  
65      /***
66       * Tells if the transition has an associated action.
67       *
68       * @return <code>true</code> if an action has been asociated to the transition
69       */
70      public boolean hasAction()
71      {
72          return action != null;
73      }
74  
75      /***
76       * @return Returns the action associated with the transition
77       */
78      public GrammarAction getAction()
79      {
80          return action;
81      }
82  
83      /***
84       * @param grammar The grammar which state we want a String from
85       * @return A representation of the transition as a string.
86       */
87      public String toString(int grammar, IStates statesEnum)
88      {
89  
90          StringBuffer sb = new StringBuffer();
91  
92          sb.append( "Transition from <" ).append( statesEnum.getState( grammar, currentState ) ).append( "> to <" )
93            .append( statesEnum.getState( grammar, nextState ) ).append( ">, action : " )
94            .append( ( ( action == null ) ? "no action" : action.toString() ) ).append( ">" );
95  
96          return sb.toString();
97      }
98  }