package antlr;

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.cs.usfca.edu
 * Software rights: http://www.antlr.org/license.html
 *
 * $Id: //depot/code/org.antlr/release/antlr-2.7.7/antlr/GrammarAnalyzer.java#2 $
 */

/**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;
}
