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The ANTLR 4 Runtime (Optimized)

There is a newer version: 4.9.0

/*
 * Copyright (c) 2012 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD-3-Clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

package org.antlr.v4.runtime.atn;

import org.antlr.v4.runtime.Recognizer;

public final class EmptyPredictionContext extends PredictionContext {
	public static final EmptyPredictionContext LOCAL_CONTEXT = new EmptyPredictionContext(false);
	public static final EmptyPredictionContext FULL_CONTEXT = new EmptyPredictionContext(true);

	private final boolean fullContext;

	private EmptyPredictionContext(boolean fullContext) {
		super(calculateEmptyHashCode());
		this.fullContext = fullContext;
	}

	public boolean isFullContext() {
		return fullContext;
	}

	@Override
	protected PredictionContext addEmptyContext() {
		return this;
	}

	@Override
	protected PredictionContext removeEmptyContext() {
		throw new UnsupportedOperationException("Cannot remove the empty context from itself.");
	}

	@Override
	public PredictionContext getParent(int index) {
		throw new IndexOutOfBoundsException();
	}

	@Override
	public int getReturnState(int index) {
		throw new IndexOutOfBoundsException();
	}

	@Override
	public int findReturnState(int returnState) {
		return -1;
	}

	@Override
	public int size() {
		return 0;
	}

	@Override
	public PredictionContext appendContext(int returnContext, PredictionContextCache contextCache) {
		return contextCache.getChild(this, returnContext);
	}

	@Override
	public PredictionContext appendContext(PredictionContext suffix, PredictionContextCache contextCache) {
		return suffix;
	}

	@Override
	public boolean isEmpty() {
		return true;
	}

	@Override
	public boolean hasEmpty() {
		return true;
	}

	@Override
	public boolean equals(Object o) {
		return this == o;
	}

	@Override
	public String[] toStrings(Recognizer recognizer, int currentState) {
		return new String[] { "[]" };
	}

	@Override
	public String[] toStrings(Recognizer recognizer, PredictionContext stop, int currentState) {
		return new String[] { "[]" };
	}

}