persistence.antlr.GrammarAnalyzer Maven / Gradle / Ivy
package persistence.antlr;
/* ANTLR Translator Generator
* Project led by Terence Parr at http://www.jGuru.com
* Software rights: http://www.antlr.org/license.html
*
*/
/**A GrammarAnalyzer computes lookahead from Grammar (which contains
* a grammar symbol table) and can then answer questions about the
* grammar.
*
* To access the RuleBlock for a rule name, the grammar symbol table
* is consulted.
*
* There should be no distinction between static & dynamic analysis.
* In other words, some of the easy analysis can be done statically
* and then the part that is hard statically can be deferred to
* parse-time. Interestingly, computing LL(k) for k>1 lookahead
* statically is O(|T|^k) where T is the grammar vocabulary, but,
* is O(k) at run-time (ignoring the large constant associated with
* the size of the grammar). In English, the difference can be
* described as "find the set of all possible k-sequences of input"
* versus "does this specific k-sequence match?".
*/
public interface GrammarAnalyzer {
/**The epsilon token type is an imaginary type used
* during analysis. It indicates an incomplete look() computation.
* Must be kept consistent with Token constants to be between
* MIN_USER_TYPE and INVALID_TYPE.
*/
// public static final int EPSILON_TYPE = 2;
public static final int NONDETERMINISTIC = Integer.MAX_VALUE; // lookahead depth
public static final int LOOKAHEAD_DEPTH_INIT = -1;
}