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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 com.google.common.annotations.GwtCompatible;
import com.google.common.base.Objects;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CompatibleWith;
import java.util.Collection;
import java.util.Map;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A collection that associates an ordered pair of keys, called a row key and a column key, with a
* single value. A table may be sparse, with only a small fraction of row key / column key pairs
* possessing a corresponding value.
*
* The mappings corresponding to a given row key may be viewed as a {@link Map} whose keys are
* the columns. The reverse is also available, associating a column with a row key / value map. Note
* that, in some implementations, data access by column key may have fewer supported operations or
* worse performance than data access by row key.
*
*
The methods returning collections or maps always return views of the underlying table.
* Updating the table can change the contents of those collections, and updating the collections
* will change the table.
*
*
All methods that modify the table are optional, and the views returned by the table may or may
* not be modifiable. When modification isn't supported, those methods will throw an {@link
* UnsupportedOperationException}.
*
*
See the Guava User Guide article on {@code Table}.
*
* @author Jared Levy
* @param the type of the table row keys
* @param the type of the table column keys
* @param the type of the mapped values
* @since 7.0
*/
@GwtCompatible
public interface Table {
// TODO(jlevy): Consider adding methods similar to ConcurrentMap methods.
// Accessors
/**
* Returns {@code true} if the table contains a mapping with the specified row and column keys.
*
* @param rowKey key of row to search for
* @param columnKey key of column to search for
*/
boolean contains(
@Nullable @CompatibleWith("R") Object rowKey,
@Nullable @CompatibleWith("C") Object columnKey);
/**
* Returns {@code true} if the table contains a mapping with the specified row key.
*
* @param rowKey key of row to search for
*/
boolean containsRow(@Nullable @CompatibleWith("R") Object rowKey);
/**
* Returns {@code true} if the table contains a mapping with the specified column.
*
* @param columnKey key of column to search for
*/
boolean containsColumn(@Nullable @CompatibleWith("C") Object columnKey);
/**
* Returns {@code true} if the table contains a mapping with the specified value.
*
* @param value value to search for
*/
boolean containsValue(@Nullable @CompatibleWith("V") Object value);
/**
* Returns the value corresponding to the given row and column keys, or {@code null} if no such
* mapping exists.
*
* @param rowKey key of row to search for
* @param columnKey key of column to search for
*/
V get(
@Nullable @CompatibleWith("R") Object rowKey,
@Nullable @CompatibleWith("C") Object columnKey);
/** Returns {@code true} if the table contains no mappings. */
boolean isEmpty();
/** Returns the number of row key / column key / value mappings in the table. */
int size();
/**
* Compares the specified object with this table for equality. Two tables are equal when their
* cell views, as returned by {@link #cellSet}, are equal.
*/
@Override
boolean equals(@Nullable Object obj);
/**
* Returns the hash code for this table. The hash code of a table is defined as the hash code of
* its cell view, as returned by {@link #cellSet}.
*/
@Override
int hashCode();
// Mutators
/** Removes all mappings from the table. */
void clear();
/**
* Associates the specified value with the specified keys. If the table already contained a
* mapping for those keys, the old value is replaced with the specified value.
*
* @param rowKey row key that the value should be associated with
* @param columnKey column key that the value should be associated with
* @param value value to be associated with the specified keys
* @return the value previously associated with the keys, or {@code null} if no mapping existed
* for the keys
*/
@CanIgnoreReturnValue
@Nullable
V put(R rowKey, C columnKey, V value);
/**
* Copies all mappings from the specified table to this table. The effect is equivalent to calling
* {@link #put} with each row key / column key / value mapping in {@code table}.
*
* @param table the table to add to this table
*/
void putAll(Table table);
/**
* Removes the mapping, if any, associated with the given keys.
*
* @param rowKey row key of mapping to be removed
* @param columnKey column key of mapping to be removed
* @return the value previously associated with the keys, or {@code null} if no such value existed
*/
@CanIgnoreReturnValue
@Nullable
V remove(
@Nullable @CompatibleWith("R") Object rowKey,
@Nullable @CompatibleWith("C") Object columnKey);
// Views
/**
* Returns a view of all mappings that have the given row key. For each row key / column key /
* value mapping in the table with that row key, the returned map associates the column key with
* the value. If no mappings in the table have the provided row key, an empty map is returned.
*
* Changes to the returned map will update the underlying table, and vice versa.
*
* @param rowKey key of row to search for in the table
* @return the corresponding map from column keys to values
*/
Map row(R rowKey);
/**
* Returns a view of all mappings that have the given column key. For each row key / column key /
* value mapping in the table with that column key, the returned map associates the row key with
* the value. If no mappings in the table have the provided column key, an empty map is returned.
*
* Changes to the returned map will update the underlying table, and vice versa.
*
* @param columnKey key of column to search for in the table
* @return the corresponding map from row keys to values
*/
Map column(C columnKey);
/**
* Returns a set of all row key / column key / value triplets. Changes to the returned set will
* update the underlying table, and vice versa. The cell set does not support the {@code add} or
* {@code addAll} methods.
*
* @return set of table cells consisting of row key / column key / value triplets
*/
Set> cellSet();
/**
* Returns a set of row keys that have one or more values in the table. Changes to the set will
* update the underlying table, and vice versa.
*
* @return set of row keys
*/
Set rowKeySet();
/**
* Returns a set of column keys that have one or more values in the table. Changes to the set will
* update the underlying table, and vice versa.
*
* @return set of column keys
*/
Set columnKeySet();
/**
* Returns a collection of all values, which may contain duplicates. Changes to the returned
* collection will update the underlying table, and vice versa.
*
* @return collection of values
*/
Collection values();
/**
* Returns a view that associates each row key with the corresponding map from column keys to
* values. Changes to the returned map will update this table. The returned map does not support
* {@code put()} or {@code putAll()}, or {@code setValue()} on its entries.
*
* In contrast, the maps returned by {@code rowMap().get()} have the same behavior as those
* returned by {@link #row}. Those maps may support {@code setValue()}, {@code put()}, and {@code
* putAll()}.
*
* @return a map view from each row key to a secondary map from column keys to values
*/
Map> rowMap();
/**
* Returns a view that associates each column key with the corresponding map from row keys to
* values. Changes to the returned map will update this table. The returned map does not support
* {@code put()} or {@code putAll()}, or {@code setValue()} on its entries.
*
* In contrast, the maps returned by {@code columnMap().get()} have the same behavior as those
* returned by {@link #column}. Those maps may support {@code setValue()}, {@code put()}, and
* {@code putAll()}.
*
* @return a map view from each column key to a secondary map from row keys to values
*/
Map> columnMap();
/**
* Row key / column key / value triplet corresponding to a mapping in a table.
*
* @since 7.0
*/
interface Cell {
/** Returns the row key of this cell. */
@Nullable
R getRowKey();
/** Returns the column key of this cell. */
@Nullable
C getColumnKey();
/** Returns the value of this cell. */
@Nullable
V getValue();
/**
* Compares the specified object with this cell for equality. Two cells are equal when they have
* equal row keys, column keys, and values.
*/
@Override
boolean equals(@Nullable Object obj);
/**
* Returns the hash code of this cell.
*
* The hash code of a table cell is equal to {@link Objects#hashCode}{@code (e.getRowKey(),
* e.getColumnKey(), e.getValue())}.
*/
@Override
int hashCode();
}
}