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The ANTLR 4 Runtime
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/*
 * [The "BSD license"]
 *  Copyright (c) 2012 Terence Parr
 *  Copyright (c) 2012 Sam Harwell
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  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
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.v4.runtime.dfa;

import org.antlr.v4.runtime.atn.ATNState;
import org.antlr.v4.runtime.atn.ParserATNSimulator;
import org.antlr.v4.runtime.misc.NotNull;
import org.antlr.v4.runtime.misc.Nullable;

import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

public class DFA {
	/** A set of all DFA states. Use {@link Map} so we can get old state back
	 *  ({@link Set} only allows you to see if it's there).
     */
    @NotNull
	public final ConcurrentMap states = new ConcurrentHashMap();

	@Nullable
	public final AtomicReference s0 = new AtomicReference();

	@Nullable
	public final AtomicReference s0full = new AtomicReference();

	public final int decision;

	/** From which ATN state did we create this DFA? */
	@NotNull
	public final ATNState atnStartState;

	private final AtomicInteger nextStateNumber = new AtomicInteger();

	/** Set of configs for a DFA state with at least one conflict? Mainly used as "return value"
	 *  from {@link ParserATNSimulator#predictATN} for retry.
	 */
//	public OrderedHashSet conflictSet;

	public DFA(@NotNull ATNState atnStartState) {
		this(atnStartState, 0);
	}

	public DFA(@NotNull ATNState atnStartState, int decision) {
		this.atnStartState = atnStartState;
		this.decision = decision;
	}

	public boolean isEmpty() {
		return s0.get() == null && s0full.get() == null;
	}

	public boolean isContextSensitive() {
		return s0full.get() != null;
	}

	public DFAState addState(DFAState state) {
		state.stateNumber = nextStateNumber.getAndIncrement();
		DFAState existing = states.putIfAbsent(state, state);
		if (existing != null) {
			return existing;
		}

		return state;
	}

	@Override
	public String toString() { return toString(null); }

	public String toString(@Nullable String[] tokenNames) {
		if ( s0.get()==null ) return "";
		DFASerializer serializer = new DFASerializer(this,tokenNames);
		return serializer.toString();
	}

	public String toString(@Nullable String[] tokenNames, @Nullable String[] ruleNames) {
		if ( s0.get()==null ) return "";
		DFASerializer serializer = new DFASerializer(this,tokenNames,ruleNames,atnStartState.atn);
		return serializer.toString();
	}

	public String toLexerString() {
		if ( s0.get()==null ) return "";
		DFASerializer serializer = new LexerDFASerializer(this);
		return serializer.toString();
	}

}