LexerReflectSemantic


1   package fri.patterns.interpreter.parsergenerator.lexer.semantics;
2   
3   import java.util.*;
4   import java.lang.reflect.Method  ;
5   import fri.patterns.interpreter.parsergenerator.lexer.LexerSemantic;
6   import fri.patterns.interpreter.parsergenerator.lexer.ResultTree;
7   import fri.patterns.interpreter.parsergenerator.syntax.Rule;
8   
9   /**
10   * A LexerSemantic that provides the Set of wanted String nonterminals
11   * by method reflection. Callback methods must be of the form
12   * <pre>
13   *  public void EncodingDecl(ResultTree resultTree) {
14   *      this.encodingDecl = resultTree.toString();
15   *  }
16   * </pre>
17   * 
18   * Created on 21.09.2005
19   * @author Fritz Ritzberger
20   */
21  public abstract class LexerReflectSemantic implements LexerSemantic
22  {
23      /**
24       * As expected, this method delegates to the method that is named like the
25       * nonterminal of the passed Rule, with <i>resultTree</i> as the only argument.
26       */
27      public void ruleEvaluated(Rule rule, ResultTree resultTree) {
28          try {
29              Method   m = getClass().getMethod(rule.getNonterminal(), new Class  [] { ResultTree.class });
30              m.setAccessible(true);
31              m.invoke(this, new Object  [] { resultTree });
32          }
33          catch (Exception   e) {
34              e.printStackTrace();
35          }
36      }
37  
38      /**
39       * Provides the Set of wanted nonterminal Strings by searching for
40       * public void methods with (String, Token.Range) arguments.
41       */
42      public Set getWantedNonterminals() {
43          Method   [] methods = getClass().getMethods();
44          Set set = new HashSet(methods.length);
45  
46          for (int i = 0; i < methods.length; i++)    {
47              Method   m = methods[i];
48              Class   [] argClasses = m.getParameterTypes();
49  
50              if (m.getReturnType().equals(void.class) && argClasses.length == 1 && argClasses[0].equals(ResultTree.class))   {
51                  String   name = m.getName();
52                  set.add(name);
53              }
54          }
55          return set;
56      }
57  
58      /**
59       * Returns null as getWantedNonterminals() is provided.
60       */
61      public Set getIgnoredNonterminals() {
62          return null;
63      }
64  
65  }
66
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