com.google.common.collect.ArrayTable Maven / Gradle / Ivy
/*
* 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.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Objects;
import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.Nullable;
/**
* Fixed-size {@link Table} implementation backed by a two-dimensional array.
*
* The allowed row and column keys must be supplied when the table is
* created. The table always contains a mapping for every row key / column pair.
* The value corresponding to a given row and column is null unless another
* value is provided.
*
*
The table's size is constant: the product of the number of supplied row
* keys and the number of supplied column keys. The {@code remove} and {@code
* clear} methods are not supported by the table or its views. The {@link
* #erase} and {@link #eraseAll} methods may be used instead.
*
*
The ordering of the row and column keys provided when the table is
* constructed determines the iteration ordering across rows and columns in the
* table's views. None of the view iterators support {@link Iterator#remove}.
* If the table is modified after an iterator is created, the iterator remains
* valid.
*
*
This class requires less memory than the {@link HashBasedTable} and {@link
* TreeBasedTable} implementations, except when the table is sparse.
*
*
Null row keys or column keys are not permitted.
*
*
This class provides methods involving the underlying array structure,
* where the array indices correspond to the position of a row or column in the
* lists of allowed keys and values. See the {@link #at}, {@link #set}, {@link
* #toArray}, {@link #rowKeyList}, and {@link #columnKeyList} methods for more
* details.
*
*
Note that this implementation is not synchronized. If multiple threads
* access the same cell of an {@code ArrayTable} concurrently and one of the
* threads modifies its value, there is no guarantee that the new value will be
* fully visible to the other threads. To guarantee that modifications are
* visible, synchronize access to the table. Unlike other {@code Table}
* implementations, synchronization is unnecessary between a thread that writes
* to one cell and a thread that reads from another.
*
*
See the Guava User Guide article on
* {@code Table}.
*
* @author Jared Levy
* @since 10.0
*/
@Beta
@GwtCompatible(emulated = true)
public final class ArrayTable extends AbstractTable implements Serializable {
/**
* Creates an empty {@code ArrayTable}.
*
* @param rowKeys row keys that may be stored in the generated table
* @param columnKeys column keys that may be stored in the generated table
* @throws NullPointerException if any of the provided keys is null
* @throws IllegalArgumentException if {@code rowKeys} or {@code columnKeys}
* contains duplicates or is empty
*/
public static ArrayTable create(
Iterable rowKeys, Iterable columnKeys) {
return new ArrayTable(rowKeys, columnKeys);
}
/*
* TODO(jlevy): Add factory methods taking an Enum class, instead of an
* iterable, to specify the allowed row keys and/or column keys. Note that
* custom serialization logic is needed to support different enum sizes during
* serialization and deserialization.
*/
/**
* Creates an {@code ArrayTable} with the mappings in the provided table.
*
* If {@code table} includes a mapping with row key {@code r} and a
* separate mapping with column key {@code c}, the returned table contains a
* mapping with row key {@code r} and column key {@code c}. If that row key /
* column key pair in not in {@code table}, the pair maps to {@code null} in
* the generated table.
*
*
The returned table allows subsequent {@code put} calls with the row keys
* in {@code table.rowKeySet()} and the column keys in {@code
* table.columnKeySet()}. Calling {@link #put} with other keys leads to an
* {@code IllegalArgumentException}.
*
*
The ordering of {@code table.rowKeySet()} and {@code
* table.columnKeySet()} determines the row and column iteration ordering of
* the returned table.
*
* @throws NullPointerException if {@code table} has a null key
* @throws IllegalArgumentException if the provided table is empty
*/
public static ArrayTable create(Table table) {
return (table instanceof ArrayTable)
? new ArrayTable((ArrayTable) table)
: new ArrayTable(table);
}
private final ImmutableList rowList;
private final ImmutableList columnList;
// TODO(jlevy): Add getters returning rowKeyToIndex and columnKeyToIndex?
private final ImmutableMap rowKeyToIndex;
private final ImmutableMap columnKeyToIndex;
private final V[][] array;
private ArrayTable(Iterable rowKeys,
Iterable columnKeys) {
this.rowList = ImmutableList.copyOf(rowKeys);
this.columnList = ImmutableList.copyOf(columnKeys);
checkArgument(!rowList.isEmpty());
checkArgument(!columnList.isEmpty());
/*
* TODO(jlevy): Support empty rowKeys or columnKeys? If we do, when
* columnKeys is empty but rowKeys isn't, the table is empty but
* containsRow() can return true and rowKeySet() isn't empty.
*/
rowKeyToIndex = index(rowList);
columnKeyToIndex = index(columnList);
@SuppressWarnings("unchecked")
V[][] tmpArray
= (V[][]) new Object[rowList.size()][columnList.size()];
array = tmpArray;
// Necessary because in GWT the arrays are initialized with "undefined" instead of null.
eraseAll();
}
private static ImmutableMap index(List list) {
ImmutableMap.Builder columnBuilder = ImmutableMap.builder();
for (int i = 0; i < list.size(); i++) {
columnBuilder.put(list.get(i), i);
}
return columnBuilder.build();
}
private ArrayTable(Table table) {
this(table.rowKeySet(), table.columnKeySet());
putAll(table);
}
private ArrayTable(ArrayTable table) {
rowList = table.rowList;
columnList = table.columnList;
rowKeyToIndex = table.rowKeyToIndex;
columnKeyToIndex = table.columnKeyToIndex;
@SuppressWarnings("unchecked")
V[][] copy = (V[][]) new Object[rowList.size()][columnList.size()];
array = copy;
// Necessary because in GWT the arrays are initialized with "undefined" instead of null.
eraseAll();
for (int i = 0; i < rowList.size(); i++) {
System.arraycopy(table.array[i], 0, copy[i], 0, table.array[i].length);
}
}
private abstract static class ArrayMap extends Maps.ImprovedAbstractMap {
private final ImmutableMap keyIndex;
private ArrayMap(ImmutableMap keyIndex) {
this.keyIndex = keyIndex;
}
@Override
public Set keySet() {
return keyIndex.keySet();
}
K getKey(int index) {
return keyIndex.keySet().asList().get(index);
}
abstract String getKeyRole();
@Nullable abstract V getValue(int index);
@Nullable abstract V setValue(int index, V newValue);
@Override
public int size() {
return keyIndex.size();
}
@Override
public boolean isEmpty() {
return keyIndex.isEmpty();
}
@Override
protected Set> createEntrySet() {
return new Maps.EntrySet() {
@Override
Map map() {
return ArrayMap.this;
}
@Override
public Iterator> iterator() {
return new AbstractIndexedListIterator>(size()) {
@Override
protected Entry get(final int index) {
return new AbstractMapEntry() {
@Override
public K getKey() {
return ArrayMap.this.getKey(index);
}
@Override
public V getValue() {
return ArrayMap.this.getValue(index);
}
@Override
public V setValue(V value) {
return ArrayMap.this.setValue(index, value);
}
};
}
};
}
};
}
// TODO(user): consider an optimized values() implementation
@Override
public boolean containsKey(@Nullable Object key) {
return keyIndex.containsKey(key);
}
@Override
public V get(@Nullable Object key) {
Integer index = keyIndex.get(key);
if (index == null) {
return null;
} else {
return getValue(index);
}
}
@Override
public V put(K key, V value) {
Integer index = keyIndex.get(key);
if (index == null) {
throw new IllegalArgumentException(
getKeyRole() + " " + key + " not in " + keyIndex.keySet());
}
return setValue(index, value);
}
@Override
public V remove(Object key) {
throw new UnsupportedOperationException();
}
@Override
public void clear() {
throw new UnsupportedOperationException();
}
}
/**
* Returns, as an immutable list, the row keys provided when the table was
* constructed, including those that are mapped to null values only.
*/
public ImmutableList rowKeyList() {
return rowList;
}
/**
* Returns, as an immutable list, the column keys provided when the table was
* constructed, including those that are mapped to null values only.
*/
public ImmutableList columnKeyList() {
return columnList;
}
/**
* Returns the value corresponding to the specified row and column indices.
* The same value is returned by {@code
* get(rowKeyList().get(rowIndex), columnKeyList().get(columnIndex))}, but
* this method runs more quickly.
*
* @param rowIndex position of the row key in {@link #rowKeyList()}
* @param columnIndex position of the row key in {@link #columnKeyList()}
* @return the value with the specified row and column
* @throws IndexOutOfBoundsException if either index is negative, {@code
* rowIndex} is greater then or equal to the number of allowed row keys,
* or {@code columnIndex} is greater then or equal to the number of
* allowed column keys
*/
public V at(int rowIndex, int columnIndex) {
// In GWT array access never throws IndexOutOfBoundsException.
checkElementIndex(rowIndex, rowList.size());
checkElementIndex(columnIndex, columnList.size());
return array[rowIndex][columnIndex];
}
/**
* Associates {@code value} with the specified row and column indices. The
* logic {@code
* put(rowKeyList().get(rowIndex), columnKeyList().get(columnIndex), value)}
* has the same behavior, but this method runs more quickly.
*
* @param rowIndex position of the row key in {@link #rowKeyList()}
* @param columnIndex position of the row key in {@link #columnKeyList()}
* @param value value to store in the table
* @return the previous value with the specified row and column
* @throws IndexOutOfBoundsException if either index is negative, {@code
* rowIndex} is greater then or equal to the number of allowed row keys,
* or {@code columnIndex} is greater then or equal to the number of
* allowed column keys
*/
public V set(int rowIndex, int columnIndex, @Nullable V value) {
// In GWT array access never throws IndexOutOfBoundsException.
checkElementIndex(rowIndex, rowList.size());
checkElementIndex(columnIndex, columnList.size());
V oldValue = array[rowIndex][columnIndex];
array[rowIndex][columnIndex] = value;
return oldValue;
}
/**
* Returns a two-dimensional array with the table contents. The row and column
* indices correspond to the positions of the row and column in the iterables
* provided during table construction. If the table lacks a mapping for a
* given row and column, the corresponding array element is null.
*
* Subsequent table changes will not modify the array, and vice versa.
*
* @param valueClass class of values stored in the returned array
*/
@GwtIncompatible("reflection")
public V[][] toArray(Class valueClass) {
// Can change to use varargs in JDK 1.6 if we want
@SuppressWarnings("unchecked") // TODO: safe?
V[][] copy = (V[][]) Array.newInstance(
valueClass, new int[] { rowList.size(), columnList.size() });
for (int i = 0; i < rowList.size(); i++) {
System.arraycopy(array[i], 0, copy[i], 0, array[i].length);
}
return copy;
}
/**
* Not supported. Use {@link #eraseAll} instead.
*
* @throws UnsupportedOperationException always
* @deprecated Use {@link #eraseAll}
*/
@Override
@Deprecated public void clear() {
throw new UnsupportedOperationException();
}
/**
* Associates the value {@code null} with every pair of allowed row and column
* keys.
*/
public void eraseAll() {
for (V[] row : array) {
Arrays.fill(row, null);
}
}
/**
* Returns {@code true} if the provided keys are among the keys provided when
* the table was constructed.
*/
@Override
public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
return containsRow(rowKey) && containsColumn(columnKey);
}
/**
* Returns {@code true} if the provided column key is among the column keys
* provided when the table was constructed.
*/
@Override
public boolean containsColumn(@Nullable Object columnKey) {
return columnKeyToIndex.containsKey(columnKey);
}
/**
* Returns {@code true} if the provided row key is among the row keys
* provided when the table was constructed.
*/
@Override
public boolean containsRow(@Nullable Object rowKey) {
return rowKeyToIndex.containsKey(rowKey);
}
@Override
public boolean containsValue(@Nullable Object value) {
for (V[] row : array) {
for (V element : row) {
if (Objects.equal(value, element)) {
return true;
}
}
}
return false;
}
@Override
public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
Integer rowIndex = rowKeyToIndex.get(rowKey);
Integer columnIndex = columnKeyToIndex.get(columnKey);
return (rowIndex == null || columnIndex == null)
? null : at(rowIndex, columnIndex);
}
/**
* Always returns {@code false}.
*/
@Override
public boolean isEmpty() {
return false;
}
/**
* {@inheritDoc}
*
* @throws IllegalArgumentException if {@code rowKey} is not in {@link
* #rowKeySet()} or {@code columnKey} is not in {@link #columnKeySet()}.
*/
@Override
public V put(R rowKey, C columnKey, @Nullable V value) {
checkNotNull(rowKey);
checkNotNull(columnKey);
Integer rowIndex = rowKeyToIndex.get(rowKey);
checkArgument(rowIndex != null, "Row %s not in %s", rowKey, rowList);
Integer columnIndex = columnKeyToIndex.get(columnKey);
checkArgument(columnIndex != null,
"Column %s not in %s", columnKey, columnList);
return set(rowIndex, columnIndex, value);
}
/*
* TODO(jlevy): Consider creating a merge() method, similar to putAll() but
* copying non-null values only.
*/
/**
* {@inheritDoc}
*
* If {@code table} is an {@code ArrayTable}, its null values will be
* stored in this table, possibly replacing values that were previously
* non-null.
*
* @throws NullPointerException if {@code table} has a null key
* @throws IllegalArgumentException if any of the provided table's row keys or
* column keys is not in {@link #rowKeySet()} or {@link #columnKeySet()}
*/
@Override
public void putAll(Table table) {
super.putAll(table);
}
/**
* Not supported. Use {@link #erase} instead.
*
* @throws UnsupportedOperationException always
* @deprecated Use {@link #erase}
*/
@Override
@Deprecated public V remove(Object rowKey, Object columnKey) {
throw new UnsupportedOperationException();
}
/**
* Associates the value {@code null} with the specified keys, assuming both
* keys are valid. If either key is null or isn't among the keys provided
* during construction, this method has no effect.
*
*
This method is equivalent to {@code put(rowKey, columnKey, null)} when
* both provided keys are valid.
*
* @param rowKey row key of mapping to be erased
* @param columnKey column key of mapping to be erased
* @return the value previously associated with the keys, or {@code null} if
* no mapping existed for the keys
*/
public V erase(@Nullable Object rowKey, @Nullable Object columnKey) {
Integer rowIndex = rowKeyToIndex.get(rowKey);
Integer columnIndex = columnKeyToIndex.get(columnKey);
if (rowIndex == null || columnIndex == null) {
return null;
}
return set(rowIndex, columnIndex, null);
}
// TODO(jlevy): Add eraseRow and eraseColumn methods?
@Override
public int size() {
return rowList.size() * columnList.size();
}
/**
* Returns an unmodifiable set of all row key / column key / value
* triplets. Changes to the table will update the returned set.
*
*
The returned set's iterator traverses the mappings with the first row
* key, the mappings with the second row key, and so on.
*
*
The value in the returned cells may change if the table subsequently
* changes.
*
* @return set of table cells consisting of row key / column key / value
* triplets
*/
@Override
public Set> cellSet() {
return super.cellSet();
}
@Override
Iterator> cellIterator() {
return new AbstractIndexedListIterator>(size()) {
@Override protected Cell get(final int index) {
return new Tables.AbstractCell() {
final int rowIndex = index / columnList.size();
final int columnIndex = index % columnList.size();
@Override
public R getRowKey() {
return rowList.get(rowIndex);
}
@Override
public C getColumnKey() {
return columnList.get(columnIndex);
}
@Override
public V getValue() {
return at(rowIndex, columnIndex);
}
};
}
};
}
/**
* Returns a view of all mappings that have the given column key. If the
* column key isn't in {@link #columnKeySet()}, an empty immutable map is
* returned.
*
* Otherwise, for each row key in {@link #rowKeySet()}, the returned map
* associates the row key with the corresponding value in the table. 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
*/
@Override
public Map column(C columnKey) {
checkNotNull(columnKey);
Integer columnIndex = columnKeyToIndex.get(columnKey);
return (columnIndex == null)
? ImmutableMap.of() : new Column(columnIndex);
}
private class Column extends ArrayMap {
final int columnIndex;
Column(int columnIndex) {
super(rowKeyToIndex);
this.columnIndex = columnIndex;
}
@Override
String getKeyRole() {
return "Row";
}
@Override
V getValue(int index) {
return at(index, columnIndex);
}
@Override
V setValue(int index, V newValue) {
return set(index, columnIndex, newValue);
}
}
/**
* Returns an immutable set of the valid column keys, including those that
* are associated with null values only.
*
* @return immutable set of column keys
*/
@Override
public ImmutableSet columnKeySet() {
return columnKeyToIndex.keySet();
}
private transient ColumnMap columnMap;
@Override
public Map> columnMap() {
ColumnMap map = columnMap;
return (map == null) ? columnMap = new ColumnMap() : map;
}
private class ColumnMap extends ArrayMap> {
private ColumnMap() {
super(columnKeyToIndex);
}
@Override
String getKeyRole() {
return "Column";
}
@Override
Map getValue(int index) {
return new Column(index);
}
@Override
Map setValue(int index, Map newValue) {
throw new UnsupportedOperationException();
}
@Override
public Map put(C key, Map value) {
throw new UnsupportedOperationException();
}
}
/**
* Returns a view of all mappings that have the given row key. If the
* row key isn't in {@link #rowKeySet()}, an empty immutable map is
* returned.
*
* Otherwise, for each column key in {@link #columnKeySet()}, the returned
* map associates the column key with the corresponding value in the
* table. 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
*/
@Override
public Map row(R rowKey) {
checkNotNull(rowKey);
Integer rowIndex = rowKeyToIndex.get(rowKey);
return (rowIndex == null) ? ImmutableMap.of() : new Row(rowIndex);
}
private class Row extends ArrayMap {
final int rowIndex;
Row(int rowIndex) {
super(columnKeyToIndex);
this.rowIndex = rowIndex;
}
@Override
String getKeyRole() {
return "Column";
}
@Override
V getValue(int index) {
return at(rowIndex, index);
}
@Override
V setValue(int index, V newValue) {
return set(rowIndex, index, newValue);
}
}
/**
* Returns an immutable set of the valid row keys, including those that are
* associated with null values only.
*
* @return immutable set of row keys
*/
@Override
public ImmutableSet rowKeySet() {
return rowKeyToIndex.keySet();
}
private transient RowMap rowMap;
@Override
public Map> rowMap() {
RowMap map = rowMap;
return (map == null) ? rowMap = new RowMap() : map;
}
private class RowMap extends ArrayMap> {
private RowMap() {
super(rowKeyToIndex);
}
@Override
String getKeyRole() {
return "Row";
}
@Override
Map getValue(int index) {
return new Row(index);
}
@Override
Map setValue(int index, Map newValue) {
throw new UnsupportedOperationException();
}
@Override
public Map put(R key, Map value) {
throw new UnsupportedOperationException();
}
}
/**
* Returns an unmodifiable collection of all values, which may contain
* duplicates. Changes to the table will update the returned collection.
*
* The returned collection's iterator traverses the values of the first row
* key, the values of the second row key, and so on.
*
* @return collection of values
*/
@Override
public Collection values() {
return super.values();
}
private static final long serialVersionUID = 0;
}