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/*
 * Copyright (C) 2008 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.collect.CollectPreconditions.checkNonnegative;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Supplier;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.util.LinkedHashMap;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Table} using linked hash tables. This guarantees predictable iteration
 * order of the various views.
 *
 * 

The views returned by {@link #column}, {@link #columnKeySet()}, and {@link #columnMap()} have * iterators that don't support {@code remove()}. Otherwise, all optional operations are supported. * Null row keys, columns keys, and values are not supported. * *

Lookups by row key are often faster than lookups by column key, because the data is stored in * a {@code Map>}. A method call like {@code column(columnKey).get(rowKey)} still runs * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer, * since an iteration across all row keys occurs. * *

Note that this implementation is not synchronized. If multiple threads access this table * concurrently and one of the threads modifies the table, it must be synchronized externally. * *

See the Guava User Guide article on {@code Table}. * * @author Jared Levy * @since 7.0 */ @GwtCompatible(serializable = true) public class HashBasedTable extends StandardTable { private static class Factory implements Supplier>, Serializable { final int expectedSize; Factory(int expectedSize) { this.expectedSize = expectedSize; } @Override public Map get() { return Maps.newLinkedHashMapWithExpectedSize(expectedSize); } private static final long serialVersionUID = 0; } /** Creates an empty {@code HashBasedTable}. */ public static HashBasedTable create() { return new HashBasedTable<>(new LinkedHashMap>(), new Factory(0)); } /** * Creates an empty {@code HashBasedTable} with the specified map sizes. * * @param expectedRows the expected number of distinct row keys * @param expectedCellsPerRow the expected number of column key / value mappings in each row * @throws IllegalArgumentException if {@code expectedRows} or {@code expectedCellsPerRow} is * negative */ public static HashBasedTable create( int expectedRows, int expectedCellsPerRow) { checkNonnegative(expectedCellsPerRow, "expectedCellsPerRow"); Map> backingMap = Maps.newLinkedHashMapWithExpectedSize(expectedRows); return new HashBasedTable<>(backingMap, new Factory(expectedCellsPerRow)); } /** * Creates a {@code HashBasedTable} with the same mappings as the specified table. * * @param table the table to copy * @throws NullPointerException if any of the row keys, column keys, or values in {@code table} is * null */ public static HashBasedTable create( Table table) { HashBasedTable result = create(); result.putAll(table); return result; } HashBasedTable(Map> backingMap, Factory factory) { super(backingMap, factory); } // Overriding so NullPointerTester test passes. @Override public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) { return super.contains(rowKey, columnKey); } @Override public boolean containsColumn(@Nullable Object columnKey) { return super.containsColumn(columnKey); } @Override public boolean containsRow(@Nullable Object rowKey) { return super.containsRow(rowKey); } @Override public boolean containsValue(@Nullable Object value) { return super.containsValue(value); } @Override public V get(@Nullable Object rowKey, @Nullable Object columnKey) { return super.get(rowKey, columnKey); } @Override public boolean equals(@Nullable Object obj) { return super.equals(obj); } @CanIgnoreReturnValue @Override public V remove(@Nullable Object rowKey, @Nullable Object columnKey) { return super.remove(rowKey, columnKey); } private static final long serialVersionUID = 0; }





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