nfa.java

antlr最新版本V3源代码

/*
 [The "BSD licence"]
 Copyright (c) 2005-2006 Terence Parr
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
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 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
    derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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*/
package org.antlr.analysis;

import org.antlr.tool.Grammar;
import org.antlr.tool.NFAFactory;

import java.util.Vector;

/** An NFA (collection of NFAStates) constructed from a grammar.  This
 *  NFA is one big machine for entire grammar.  Decision points are recorded
 *  by the Grammar object so we can, for example, convert to DFA or simulate
 *  the NFA (interpret a decision).
 */
public class NFA {
    public static final int INVALID_ALT_NUMBER = -1;

    /** This NFA represents which grammar? */
    public Grammar grammar;

    /** The NFA states in this NFA.  Maps state number to NFAState object.
     *  This is a Vector instead of a List because I need to be able to grow
     *  this properly.  After talking to Josh Bloch, Collections guy at Sun,
     *  I decided this was easiest solution.
     */
    protected Vector numberToStateList = new Vector(1000);

    /** Which factory created this NFA? */
    protected NFAFactory factory = null;

    public NFA(Grammar g) {
        this.grammar = g;
    }

    public void addState(NFAState state) {
        numberToStateList.setSize(state.stateNumber+1); // make sure we have room
        numberToStateList.set(state.stateNumber, state);
    }

    public NFAState getState(int s) {
        return (NFAState)numberToStateList.get(s);
    }

    public NFAFactory getFactory() {
        return factory;
    }

    public void setFactory(NFAFactory factory) {
        this.factory = factory;
    }
}