/*
 * Copyright (C) 2009 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.Map;

import com.google.common.annotations.GwtCompatible;

/**
 * An implementation of {@link ImmutableTable} that holds a single cell.
 *
 * @author Gregory Kick
 */
@GwtCompatible
class SingletonImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
	final R singleRowKey;
	final C singleColumnKey;
	final V singleValue;

	SingletonImmutableTable(R rowKey, C columnKey, V value) {
		this.singleRowKey = checkNotNull(rowKey);
		this.singleColumnKey = checkNotNull(columnKey);
		this.singleValue = checkNotNull(value);
	}

	SingletonImmutableTable(Cell<R, C, V> cell) {
		this(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
	}

	@Override
	public ImmutableMap<R, V> column(C columnKey) {
		checkNotNull(columnKey);
		return containsColumn(columnKey) ? ImmutableMap.of(singleRowKey, singleValue) : ImmutableMap.<R, V>of();
	}

	@Override
	public ImmutableMap<C, Map<R, V>> columnMap() {
		return ImmutableMap.of(singleColumnKey, (Map<R, V>) ImmutableMap.of(singleRowKey, singleValue));
	}

	@Override
	public ImmutableMap<R, Map<C, V>> rowMap() {
		return ImmutableMap.of(singleRowKey, (Map<C, V>) ImmutableMap.of(singleColumnKey, singleValue));
	}

	@Override
	public int size() {
		return 1;
	}

	@Override
	ImmutableSet<Cell<R, C, V>> createCellSet() {
		return ImmutableSet.of(cellOf(singleRowKey, singleColumnKey, singleValue));
	}

	@Override
	ImmutableCollection<V> createValues() {
		return ImmutableSet.of(singleValue);
	}
}
