/*******************************************************************************
* Copyright (c) 2008 Scott Stanchfield.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Based on the ANTLR parser generator by Terence Parr, http://antlr.org
* Ric Klaren <klaren@cs.utwente.nl>
* Scott Stanchfield - Modifications for XML Parsing
*******************************************************************************/
package com.javadude.antxr;
/**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;
}