KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > antlr > GrammarAnalyzer


1 package antlr;
2
3 /* ANTLR Translator Generator
4  * Project led by Terence Parr at http://www.jGuru.com
5  * Software rights: http://www.antlr.org/RIGHTS.html
6  *
7  * $Id: //depot/code/org.antlr/main/main/antlr/GrammarAnalyzer.java#4 $
8  */
9
10 /**A GrammarAnalyzer computes lookahead from Grammar (which contains
11  * a grammar symbol table) and can then answer questions about the
12  * grammar.
13  *
14  * To access the RuleBlock for a rule name, the grammar symbol table
15  * is consulted.
16  *
17  * There should be no distinction between static & dynamic analysis.
18  * In other words, some of the easy analysis can be done statically
19  * and then the part that is hard statically can be deferred to
20  * parse-time. Interestingly, computing LL(k) for k>1 lookahead
21  * statically is O(|T|^k) where T is the grammar vocabulary, but,
22  * is O(k) at run-time (ignoring the large constant associated with
23  * the size of the grammar). In English, the difference can be
24  * described as "find the set of all possible k-sequences of input"
25  * versus "does this specific k-sequence match?".
26  */
27 public interface GrammarAnalyzer {
28     /**The epsilon token type is an imaginary type used
29      * during analysis. It indicates an incomplete look() computation.
30      * Must be kept consistent with Token constants to be between
31      * MIN_USER_TYPE and INVALID_TYPE.
32      */
33     // public static final int EPSILON_TYPE = 2;
34 public static final int NONDETERMINISTIC = Integer.MAX_VALUE; // lookahead depth
35 public static final int LOOKAHEAD_DEPTH_INIT = -1;
36 }
37
Popular Tags