com.google.common.collect.StandardTable Maven / Gradle / Ivy
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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.base.Preconditions.checkNotNull;
import static com.google.common.base.Predicates.alwaysTrue;
import static com.google.common.base.Predicates.equalTo;
import static com.google.common.base.Predicates.in;
import static com.google.common.base.Predicates.not;
import static com.google.common.collect.Maps.safeContainsKey;
import static com.google.common.collect.Maps.safeGet;
import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
import static java.util.Objects.requireNonNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Supplier;
import com.google.common.collect.Maps.IteratorBasedAbstractMap;
import com.google.common.collect.Maps.ViewCachingAbstractMap;
import com.google.common.collect.Sets.ImprovedAbstractSet;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.WeakOuter;
import java.io.Serializable;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.CheckForNull;
/**
* {@link Table} implementation backed by a map that associates row keys with column key / value
* secondary maps. This class provides rapid access to records by the row key alone or by both keys,
* but not by just the column key.
*
* 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.
*
* @author Jared Levy
*/
@GwtCompatible
@ElementTypesAreNonnullByDefault
class StandardTable extends AbstractTable implements Serializable {
@GwtTransient final Map> backingMap;
@GwtTransient final Supplier> factory;
StandardTable(Map> backingMap, Supplier> factory) {
this.backingMap = backingMap;
this.factory = factory;
}
// Accessors
@Override
public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
return rowKey != null && columnKey != null && super.contains(rowKey, columnKey);
}
@Override
public boolean containsColumn(@CheckForNull Object columnKey) {
if (columnKey == null) {
return false;
}
for (Map map : backingMap.values()) {
if (safeContainsKey(map, columnKey)) {
return true;
}
}
return false;
}
@Override
public boolean containsRow(@CheckForNull Object rowKey) {
return rowKey != null && safeContainsKey(backingMap, rowKey);
}
@Override
public boolean containsValue(@CheckForNull Object value) {
return value != null && super.containsValue(value);
}
@Override
@CheckForNull
public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
return (rowKey == null || columnKey == null) ? null : super.get(rowKey, columnKey);
}
@Override
public boolean isEmpty() {
return backingMap.isEmpty();
}
@Override
public int size() {
int size = 0;
for (Map map : backingMap.values()) {
size += map.size();
}
return size;
}
// Mutators
@Override
public void clear() {
backingMap.clear();
}
private Map getOrCreate(R rowKey) {
Map map = backingMap.get(rowKey);
if (map == null) {
map = factory.get();
backingMap.put(rowKey, map);
}
return map;
}
@CanIgnoreReturnValue
@Override
@CheckForNull
public V put(R rowKey, C columnKey, V value) {
checkNotNull(rowKey);
checkNotNull(columnKey);
checkNotNull(value);
return getOrCreate(rowKey).put(columnKey, value);
}
@CanIgnoreReturnValue
@Override
@CheckForNull
public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
if ((rowKey == null) || (columnKey == null)) {
return null;
}
Map map = safeGet(backingMap, rowKey);
if (map == null) {
return null;
}
V value = map.remove(columnKey);
if (map.isEmpty()) {
backingMap.remove(rowKey);
}
return value;
}
@CanIgnoreReturnValue
private Map removeColumn(@CheckForNull Object column) {
Map output = new LinkedHashMap<>();
Iterator>> iterator = backingMap.entrySet().iterator();
while (iterator.hasNext()) {
Entry> entry = iterator.next();
V value = entry.getValue().remove(column);
if (value != null) {
output.put(entry.getKey(), value);
if (entry.getValue().isEmpty()) {
iterator.remove();
}
}
}
return output;
}
private boolean containsMapping(
@CheckForNull Object rowKey, @CheckForNull Object columnKey, @CheckForNull Object value) {
return value != null && value.equals(get(rowKey, columnKey));
}
/** Remove a row key / column key / value mapping, if present. */
private boolean removeMapping(
@CheckForNull Object rowKey, @CheckForNull Object columnKey, @CheckForNull Object value) {
if (containsMapping(rowKey, columnKey, value)) {
remove(rowKey, columnKey);
return true;
}
return false;
}
// Views
/**
* Abstract set whose {@code isEmpty()} returns whether the table is empty and whose {@code
* clear()} clears all table mappings.
*/
@WeakOuter
private abstract class TableSet extends ImprovedAbstractSet {
@Override
public boolean isEmpty() {
return backingMap.isEmpty();
}
@Override
public void clear() {
backingMap.clear();
}
}
/**
* {@inheritDoc}
*
* The set's iterator traverses the mappings for the first row, the mappings for the second
* row, and so on.
*
*
Each cell is an immutable snapshot of a row key / column key / value mapping, taken at the
* time the cell is returned by a method call to the set or its iterator.
*/
@Override
public Set> cellSet() {
return super.cellSet();
}
@Override
Iterator> cellIterator() {
return new CellIterator();
}
private class CellIterator implements Iterator> {
final Iterator>> rowIterator = backingMap.entrySet().iterator();
@CheckForNull Entry> rowEntry;
Iterator> columnIterator = Iterators.emptyModifiableIterator();
@Override
public boolean hasNext() {
return rowIterator.hasNext() || columnIterator.hasNext();
}
@Override
public Cell next() {
if (!columnIterator.hasNext()) {
rowEntry = rowIterator.next();
columnIterator = rowEntry.getValue().entrySet().iterator();
}
/*
* requireNonNull is safe because:
*
* - columnIterator started off pointing to an empty iterator, so we must have entered the
* `if` body above at least once. Thus, if we got this far, that `if` body initialized
* rowEntry at least once.
*
* - The only case in which rowEntry is cleared (during remove() below) happens only if the
* caller removed every element from columnIterator. During that process, we would have had
* to iterate it to exhaustion. Then we can apply the logic above about an empty
* columnIterator. (This assumes no concurrent modification, but behavior under concurrent
* modification is undefined, anyway.)
*/
requireNonNull(rowEntry);
Entry columnEntry = columnIterator.next();
return Tables.immutableCell(rowEntry.getKey(), columnEntry.getKey(), columnEntry.getValue());
}
@Override
public void remove() {
columnIterator.remove();
/*
* requireNonNull is safe because:
*
* - columnIterator.remove() succeeded, so it must have returned a value, so it must have been
* initialized by next() -- which initializes rowEntry, too.
*
* - rowEntry isn't cleared except below. If it was cleared below, then either
* columnIterator.remove() would have failed above (if the user hasn't called next() since
* then) or rowEntry would have been initialized by next() (as discussed above).
*/
if (requireNonNull(rowEntry).getValue().isEmpty()) {
rowIterator.remove();
rowEntry = null;
}
}
}
@Override
public Map row(R rowKey) {
return new Row(rowKey);
}
class Row extends IteratorBasedAbstractMap {
final R rowKey;
Row(R rowKey) {
this.rowKey = checkNotNull(rowKey);
}
@CheckForNull Map backingRowMap;
final void updateBackingRowMapField() {
if (backingRowMap == null || (backingRowMap.isEmpty() && backingMap.containsKey(rowKey))) {
backingRowMap = computeBackingRowMap();
}
}
@CheckForNull
Map computeBackingRowMap() {
return backingMap.get(rowKey);
}
// Call this every time we perform a removal.
void maintainEmptyInvariant() {
updateBackingRowMapField();
if (backingRowMap != null && backingRowMap.isEmpty()) {
backingMap.remove(rowKey);
backingRowMap = null;
}
}
@Override
public boolean containsKey(@CheckForNull Object key) {
updateBackingRowMapField();
return (key != null && backingRowMap != null) && Maps.safeContainsKey(backingRowMap, key);
}
@Override
@CheckForNull
public V get(@CheckForNull Object key) {
updateBackingRowMapField();
return (key != null && backingRowMap != null) ? Maps.safeGet(backingRowMap, key) : null;
}
@Override
@CheckForNull
public V put(C key, V value) {
checkNotNull(key);
checkNotNull(value);
if (backingRowMap != null && !backingRowMap.isEmpty()) {
return backingRowMap.put(key, value);
}
return StandardTable.this.put(rowKey, key, value);
}
@Override
@CheckForNull
public V remove(@CheckForNull Object key) {
updateBackingRowMapField();
if (backingRowMap == null) {
return null;
}
V result = Maps.safeRemove(backingRowMap, key);
maintainEmptyInvariant();
return result;
}
@Override
public void clear() {
updateBackingRowMapField();
if (backingRowMap != null) {
backingRowMap.clear();
}
maintainEmptyInvariant();
}
@Override
public int size() {
updateBackingRowMapField();
return (backingRowMap == null) ? 0 : backingRowMap.size();
}
@Override
Iterator> entryIterator() {
updateBackingRowMapField();
if (backingRowMap == null) {
return Iterators.emptyModifiableIterator();
}
final Iterator> iterator = backingRowMap.entrySet().iterator();
return new Iterator>() {
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public Entry next() {
return wrapEntry(iterator.next());
}
@Override
public void remove() {
iterator.remove();
maintainEmptyInvariant();
}
};
}
Entry wrapEntry(final Entry entry) {
return new ForwardingMapEntry() {
@Override
protected Entry delegate() {
return entry;
}
@Override
public V setValue(V value) {
return super.setValue(checkNotNull(value));
}
@Override
public boolean equals(@CheckForNull Object object) {
// TODO(lowasser): identify why this affects GWT tests
return standardEquals(object);
}
};
}
}
/**
* {@inheritDoc}
*
* The returned map's views have iterators that don't support {@code remove()}.
*/
@Override
public Map column(C columnKey) {
return new Column(columnKey);
}
private class Column extends ViewCachingAbstractMap {
final C columnKey;
Column(C columnKey) {
this.columnKey = checkNotNull(columnKey);
}
@Override
@CheckForNull
public V put(R key, V value) {
return StandardTable.this.put(key, columnKey, value);
}
@Override
@CheckForNull
public V get(@CheckForNull Object key) {
return StandardTable.this.get(key, columnKey);
}
@Override
public boolean containsKey(@CheckForNull Object key) {
return StandardTable.this.contains(key, columnKey);
}
@Override
@CheckForNull
public V remove(@CheckForNull Object key) {
return StandardTable.this.remove(key, columnKey);
}
/** Removes all {@code Column} mappings whose row key and value satisfy the given predicate. */
@CanIgnoreReturnValue
boolean removeFromColumnIf(Predicate> predicate) {
boolean changed = false;
Iterator>> iterator = backingMap.entrySet().iterator();
while (iterator.hasNext()) {
Entry> entry = iterator.next();
Map map = entry.getValue();
V value = map.get(columnKey);
if (value != null && predicate.apply(Maps.immutableEntry(entry.getKey(), value))) {
map.remove(columnKey);
changed = true;
if (map.isEmpty()) {
iterator.remove();
}
}
}
return changed;
}
@Override
Set> createEntrySet() {
return new EntrySet();
}
@WeakOuter
private class EntrySet extends ImprovedAbstractSet> {
@Override
public Iterator> iterator() {
return new EntrySetIterator();
}
@Override
public int size() {
int size = 0;
for (Map map : backingMap.values()) {
if (map.containsKey(columnKey)) {
size++;
}
}
return size;
}
@Override
public boolean isEmpty() {
return !containsColumn(columnKey);
}
@Override
public void clear() {
removeFromColumnIf(alwaysTrue());
}
@Override
public boolean contains(@CheckForNull Object o) {
if (o instanceof Entry) {
Entry entry = (Entry) o;
return containsMapping(entry.getKey(), columnKey, entry.getValue());
}
return false;
}
@Override
public boolean remove(@CheckForNull Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
return removeMapping(entry.getKey(), columnKey, entry.getValue());
}
return false;
}
@Override
public boolean retainAll(Collection c) {
return removeFromColumnIf(not(in(c)));
}
}
private class EntrySetIterator extends AbstractIterator> {
final Iterator>> iterator = backingMap.entrySet().iterator();
@Override
@CheckForNull
protected Entry computeNext() {
while (iterator.hasNext()) {
final Entry> entry = iterator.next();
if (entry.getValue().containsKey(columnKey)) {
@WeakOuter
class EntryImpl extends AbstractMapEntry {
@Override
public R getKey() {
return entry.getKey();
}
@Override
public V getValue() {
return entry.getValue().get(columnKey);
}
@Override
public V setValue(V value) {
/*
* The cast is safe because of the containsKey check above. (Well, it's possible for
* the map to change between that call and this one. But if that happens, the
* behavior is undefined because of the concurrent mutation.)
*
* (Our prototype checker happens to be "smart" enough to understand this for the
* *get* call in getValue but not for the *put* call here.)
*
* (Arguably we should use requireNonNull rather than uncheckedCastNullableTToT: We
* know that V is a non-null type because that's the only kind of value type that
* StandardTable supports. Thus, requireNonNull is safe as long as the cell is still
* present. (And if it's not present, behavior is undefined.) However, that's a
* behavior change relative to the old code, so it didn't seem worth risking.)
*/
return uncheckedCastNullableTToT(
entry.getValue().put(columnKey, checkNotNull(value)));
}
}
return new EntryImpl();
}
}
return endOfData();
}
}
@Override
Set createKeySet() {
return new KeySet();
}
@WeakOuter
private class KeySet extends Maps.KeySet {
KeySet() {
super(Column.this);
}
@Override
public boolean contains(@CheckForNull Object obj) {
return StandardTable.this.contains(obj, columnKey);
}
@Override
public boolean remove(@CheckForNull Object obj) {
return StandardTable.this.remove(obj, columnKey) != null;
}
@Override
public boolean retainAll(final Collection c) {
return removeFromColumnIf(Maps.keyPredicateOnEntries(not(in(c))));
}
}
@Override
Collection createValues() {
return new Values();
}
@WeakOuter
private class Values extends Maps.Values {
Values() {
super(Column.this);
}
@Override
public boolean remove(@CheckForNull Object obj) {
return obj != null && removeFromColumnIf(Maps.valuePredicateOnEntries(equalTo(obj)));
}
@Override
public boolean removeAll(final Collection c) {
return removeFromColumnIf(Maps.valuePredicateOnEntries(in(c)));
}
@Override
public boolean retainAll(final Collection c) {
return removeFromColumnIf(Maps.valuePredicateOnEntries(not(in(c))));
}
}
}
@Override
public Set rowKeySet() {
return rowMap().keySet();
}
@LazyInit @CheckForNull private transient Set columnKeySet;
/**
* {@inheritDoc}
*
* The returned set has an iterator that does not support {@code remove()}.
*
*
The set's iterator traverses the columns of the first row, the columns of the second row,
* etc., skipping any columns that have appeared previously.
*/
@Override
public Set columnKeySet() {
Set result = columnKeySet;
return (result == null) ? columnKeySet = new ColumnKeySet() : result;
}
@WeakOuter
private class ColumnKeySet extends TableSet {
@Override
public Iterator iterator() {
return createColumnKeyIterator();
}
@Override
public int size() {
return Iterators.size(iterator());
}
@Override
public boolean remove(@CheckForNull Object obj) {
if (obj == null) {
return false;
}
boolean changed = false;
Iterator> iterator = backingMap.values().iterator();
while (iterator.hasNext()) {
Map map = iterator.next();
if (map.keySet().remove(obj)) {
changed = true;
if (map.isEmpty()) {
iterator.remove();
}
}
}
return changed;
}
@Override
public boolean removeAll(Collection c) {
checkNotNull(c);
boolean changed = false;
Iterator> iterator = backingMap.values().iterator();
while (iterator.hasNext()) {
Map map = iterator.next();
// map.keySet().removeAll(c) can throw a NPE when map is a TreeMap with
// natural ordering and c contains a null.
if (Iterators.removeAll(map.keySet().iterator(), c)) {
changed = true;
if (map.isEmpty()) {
iterator.remove();
}
}
}
return changed;
}
@Override
public boolean retainAll(Collection c) {
checkNotNull(c);
boolean changed = false;
Iterator> iterator = backingMap.values().iterator();
while (iterator.hasNext()) {
Map map = iterator.next();
if (map.keySet().retainAll(c)) {
changed = true;
if (map.isEmpty()) {
iterator.remove();
}
}
}
return changed;
}
@Override
public boolean contains(@CheckForNull Object obj) {
return containsColumn(obj);
}
}
/** Creates an iterator that returns each column value with duplicates omitted. */
Iterator createColumnKeyIterator() {
return new ColumnKeyIterator();
}
private class ColumnKeyIterator extends AbstractIterator {
// Use the same map type to support TreeMaps with comparators that aren't
// consistent with equals().
final Map seen = factory.get();
final Iterator> mapIterator = backingMap.values().iterator();
Iterator> entryIterator = Iterators.emptyIterator();
@Override
@CheckForNull
protected C computeNext() {
while (true) {
if (entryIterator.hasNext()) {
Entry entry = entryIterator.next();
if (!seen.containsKey(entry.getKey())) {
seen.put(entry.getKey(), entry.getValue());
return entry.getKey();
}
} else if (mapIterator.hasNext()) {
entryIterator = mapIterator.next().entrySet().iterator();
} else {
return endOfData();
}
}
}
}
/**
* {@inheritDoc}
*
* The collection's iterator traverses the values for the first row, the values for the second
* row, and so on.
*/
@Override
public Collection values() {
return super.values();
}
@LazyInit @CheckForNull private transient Map> rowMap;
@Override
public Map> rowMap() {
Map> result = rowMap;
return (result == null) ? rowMap = createRowMap() : result;
}
Map> createRowMap() {
return new RowMap();
}
@WeakOuter
class RowMap extends ViewCachingAbstractMap> {
@Override
public boolean containsKey(@CheckForNull Object key) {
return containsRow(key);
}
// performing cast only when key is in backing map and has the correct type
@SuppressWarnings("unchecked")
@Override
@CheckForNull
public Map get(@CheckForNull Object key) {
// requireNonNull is safe because of the containsRow check.
return containsRow(key) ? row((R) requireNonNull(key)) : null;
}
@Override
@CheckForNull
public Map remove(@CheckForNull Object key) {
return (key == null) ? null : backingMap.remove(key);
}
@Override
protected Set>> createEntrySet() {
return new EntrySet();
}
@WeakOuter
class EntrySet extends TableSet>> {
@Override
public Iterator>> iterator() {
return Maps.asMapEntryIterator(
backingMap.keySet(),
new Function>() {
@Override
public Map apply(R rowKey) {
return row(rowKey);
}
});
}
@Override
public int size() {
return backingMap.size();
}
@Override
public boolean contains(@CheckForNull Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
return entry.getKey() != null
&& entry.getValue() instanceof Map
&& Collections2.safeContains(backingMap.entrySet(), entry);
}
return false;
}
@Override
public boolean remove(@CheckForNull Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
return entry.getKey() != null
&& entry.getValue() instanceof Map
&& backingMap.entrySet().remove(entry);
}
return false;
}
}
}
@LazyInit @CheckForNull private transient ColumnMap columnMap;
@Override
public Map> columnMap() {
ColumnMap result = columnMap;
return (result == null) ? columnMap = new ColumnMap() : result;
}
@WeakOuter
private class ColumnMap extends ViewCachingAbstractMap> {
// The cast to C occurs only when the key is in the map, implying that it
// has the correct type.
@SuppressWarnings("unchecked")
@Override
@CheckForNull
public Map get(@CheckForNull Object key) {
// requireNonNull is safe because of the containsColumn check.
return containsColumn(key) ? column((C) requireNonNull(key)) : null;
}
@Override
public boolean containsKey(@CheckForNull Object key) {
return containsColumn(key);
}
@Override
@CheckForNull
public Map remove(@CheckForNull Object key) {
return containsColumn(key) ? removeColumn(key) : null;
}
@Override
public Set>> createEntrySet() {
return new ColumnMapEntrySet();
}
@Override
public Set keySet() {
return columnKeySet();
}
@Override
Collection> createValues() {
return new ColumnMapValues();
}
@WeakOuter
class ColumnMapEntrySet extends TableSet>> {
@Override
public Iterator>> iterator() {
return Maps.asMapEntryIterator(
columnKeySet(),
new Function>() {
@Override
public Map apply(C columnKey) {
return column(columnKey);
}
});
}
@Override
public int size() {
return columnKeySet().size();
}
@Override
public boolean contains(@CheckForNull Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
if (containsColumn(entry.getKey())) {
// requireNonNull is safe because of the containsColumn check.
return requireNonNull(get(entry.getKey())).equals(entry.getValue());
}
}
return false;
}
@Override
public boolean remove(@CheckForNull Object obj) {
/*
* `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
* nullness checker.
*/
if (contains(obj) && obj instanceof Entry) {
Entry entry = (Entry) obj;
removeColumn(entry.getKey());
return true;
}
return false;
}
@Override
public boolean removeAll(Collection c) {
/*
* We can't inherit the normal implementation (which calls
* Sets.removeAllImpl(Set, *Collection*)) because, under some
* circumstances, it attempts to call columnKeySet().iterator().remove,
* which is unsupported.
*/
checkNotNull(c);
return Sets.removeAllImpl(this, c.iterator());
}
@Override
public boolean retainAll(Collection c) {
checkNotNull(c);
boolean changed = false;
for (C columnKey : Lists.newArrayList(columnKeySet().iterator())) {
if (!c.contains(Maps.immutableEntry(columnKey, column(columnKey)))) {
removeColumn(columnKey);
changed = true;
}
}
return changed;
}
}
@WeakOuter
private class ColumnMapValues extends Maps.Values> {
ColumnMapValues() {
super(ColumnMap.this);
}
@Override
public boolean remove(@CheckForNull Object obj) {
for (Entry> entry : ColumnMap.this.entrySet()) {
if (entry.getValue().equals(obj)) {
removeColumn(entry.getKey());
return true;
}
}
return false;
}
@Override
public boolean removeAll(Collection c) {
checkNotNull(c);
boolean changed = false;
for (C columnKey : Lists.newArrayList(columnKeySet().iterator())) {
if (c.contains(column(columnKey))) {
removeColumn(columnKey);
changed = true;
}
}
return changed;
}
@Override
public boolean retainAll(Collection c) {
checkNotNull(c);
boolean changed = false;
for (C columnKey : Lists.newArrayList(columnKeySet().iterator())) {
if (!c.contains(column(columnKey))) {
removeColumn(columnKey);
changed = true;
}
}
return changed;
}
}
}
private static final long serialVersionUID = 0;
}