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The ANTLR 4 Runtime
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/*
 * [The "BSD license"]
 *  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 java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;

/**
 *
 * @author sam
 */
public class ArrayEdgeMap extends AbstractEdgeMap {

	private final T[] arrayData;
	private int size;

	@SuppressWarnings("unchecked")
	public ArrayEdgeMap(int minIndex, int maxIndex) {
		super(minIndex, maxIndex);
		arrayData = (T[])new Object[maxIndex - minIndex + 1];
	}

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

	@Override
	public boolean isEmpty() {
		return size == 0;
	}

	@Override
	public boolean containsKey(int key) {
		return get(key) != null;
	}

	@Override
	public T get(int key) {
		if (key < minIndex || key > maxIndex) {
			return null;
		}

		return arrayData[key - minIndex];
	}

	@Override
	public ArrayEdgeMap put(int key, T value) {
		if (key >= minIndex && key <= maxIndex) {
			T existing = arrayData[key - minIndex];
			arrayData[key - minIndex] = value;
			if (existing == null && value != null) {
				size++;
			} else if (existing != null && value == null) {
				size--;
			}
		}

		return this;
	}

	@Override
	public ArrayEdgeMap remove(int key) {
		return put(key, null);
	}

	@Override
	public ArrayEdgeMap putAll(EdgeMap m) {
		if (m.isEmpty()) {
			return this;
		}

		if (m instanceof ArrayEdgeMap) {
			ArrayEdgeMap other = (ArrayEdgeMap)m;
			int minOverlap = Math.max(minIndex, other.minIndex);
			int maxOverlap = Math.min(maxIndex, other.maxIndex);
			for (int i = minOverlap; i <= maxOverlap; i++) {
				T target = other.arrayData[i - other.minIndex];
				if (target != null) {
					T current = this.arrayData[i - this.minIndex];
					this.arrayData[i - this.minIndex] = target;
					size += (current != null ? 0 : 1);
				}
			}

			return this;
		} else if (m instanceof SingletonEdgeMap) {
			SingletonEdgeMap other = (SingletonEdgeMap)m;
			assert !other.isEmpty();
			return put(other.getKey(), other.getValue());
		} else if (m instanceof SparseEdgeMap) {
			SparseEdgeMap other = (SparseEdgeMap)m;
			int[] keys = other.getKeys();
			List values = other.getValues();
			ArrayEdgeMap result = this;
			for (int i = 0; i < values.size(); i++) {
				result = result.put(keys[i], values.get(i));
			}
			return result;
		} else {
			throw new UnsupportedOperationException(String.format("EdgeMap of type %s is supported yet.", m.getClass().getName()));
		}
	}

	@Override
	public ArrayEdgeMap clear() {
		Arrays.fill(arrayData, null);
		return this;
	}

	@Override
	public Map toMap() {
		if (isEmpty()) {
			return Collections.emptyMap();
		}

		Map result = new LinkedHashMap();
		for (int i = 0; i < arrayData.length; i++) {
			if (arrayData[i] == null) {
				continue;
			}

			result.put(i + minIndex, arrayData[i]);
		}

		return result;
	}

	@Override
	public Set> entrySet() {
		return new EntrySet();
	}

	private class EntrySet extends AbstractEntrySet {
		@Override
		public Iterator> iterator() {
			return new EntryIterator();
		}
	}

	private class EntryIterator implements Iterator> {
		private int current;
		private int currentIndex;

		@Override
		public boolean hasNext() {
			return current < size();
		}

		@Override
		public Map.Entry next() {
			if (current >= size()) {
				throw new NoSuchElementException();
			}

			while (arrayData[currentIndex] == null) {
				currentIndex++;
			}

			current++;
			currentIndex++;
			return new Map.Entry() {
				private final int key = minIndex + currentIndex - 1;
				private final T value = arrayData[currentIndex - 1];

				@Override
				public Integer getKey() {
					return key;
				}

				@Override
				public T getValue() {
					return value;
				}

				@Override
				public T setValue(T value) {
					throw new UnsupportedOperationException("Not supported yet.");
				}
			};
		}

		@Override
		public void remove() {
			throw new UnsupportedOperationException("Not supported yet.");
		}
	}
}