/*
* 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 java.util.Collection;
import java.util.Map;
import java.util.Set;
import javax.annotation.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.
*
* <p>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.
*
* <p>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.
*
* <p>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}.
*
* <p>See the Guava User Guide article on <a href=
* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Table">
* {@code Table}</a>.
*
* @author Jared Levy
* @param <R> the type of the table row keys
* @param <C> the type of the table column keys
* @param <V> the type of the mapped values
* @since 7.0
*/
@GwtCompatible
public interface Table<R, C, V> {
// 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 Object rowKey, @Nullable 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 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 Object columnKey);
/**
* Returns {@code true} if the table contains a mapping with the specified
* value.
*
* @param value value to search for
*/
boolean containsValue(@Nullable 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 Object rowKey, @Nullable 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
*/
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<? extends R, ? extends C, ? extends V> 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
*/
V remove(@Nullable Object rowKey, @Nullable 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.
*
* <p>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<C, V> 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.
*
* <p>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<R, V> 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<Cell<R, C, V>> 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<R> 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<C> 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<V> 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.
*
* <p>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<R, Map<C, V>> 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.
*
* <p>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<C, Map<R, V>> columnMap();
/**
* Row key / column key / value triplet corresponding to a mapping in a table.
*
* @since 7.0
*/
interface Cell<R, C, V> {
/**
* Returns the row key of this cell.
*/
R getRowKey();
/**
* Returns the column key of this cell.
*/
C getColumnKey();
/**
* Returns the value of this cell.
*/
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.
*
* <p>The hash code of a table cell is equal to {@link
* Objects#hashCode}{@code (e.getRowKey(), e.getColumnKey(), e.getValue())}.
*/
@Override
int hashCode();
}
}