com.google.common.collect.StandardTable Maven / Gradle / Ivy
/*
* 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.collect.Maps.safeContainsKey;
import static com.google.common.collect.Maps.safeGet;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.base.Supplier;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.AbstractSet;
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.Nullable;
/**
* {@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
class StandardTable implements Table, 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(
@Nullable Object rowKey, @Nullable Object columnKey) {
if ((rowKey == null) || (columnKey == null)) {
return false;
}
Map map = safeGet(backingMap, rowKey);
return map != null && safeContainsKey(map, columnKey);
}
@Override public boolean containsColumn(@Nullable Object columnKey) {
if (columnKey == null) {
return false;
}
for (Map map : backingMap.values()) {
if (safeContainsKey(map, columnKey)) {
return true;
}
}
return false;
}
@Override public boolean containsRow(@Nullable Object rowKey) {
return rowKey != null && safeContainsKey(backingMap, rowKey);
}
@Override public boolean containsValue(@Nullable Object value) {
if (value == null) {
return false;
}
for (Map map : backingMap.values()) {
if (map.containsValue(value)) {
return true;
}
}
return false;
}
@Override public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
if ((rowKey == null) || (columnKey == null)) {
return null;
}
Map map = safeGet(backingMap, rowKey);
return map == null ? null : safeGet(map, 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;
}
@Override public boolean equals(@Nullable Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof Table) {
Table other = (Table) obj;
return cellSet().equals(other.cellSet());
}
return false;
}
@Override public int hashCode() {
return cellSet().hashCode();
}
/**
* Returns the string representation {@code rowMap().toString()}.
*/
@Override public String toString() {
return rowMap().toString();
}
// 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;
}
@Override public V put(R rowKey, C columnKey, V value) {
checkNotNull(rowKey);
checkNotNull(columnKey);
checkNotNull(value);
return getOrCreate(rowKey).put(columnKey, value);
}
@Override public void putAll(
Table table) {
for (Cell cell : table.cellSet()) {
put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
}
}
@Override public V remove(
@Nullable Object rowKey, @Nullable 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;
}
private Map removeColumn(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(
Object rowKey, Object columnKey, Object value) {
return value != null && value.equals(get(rowKey, columnKey));
}
/** Remove a row key / column key / value mapping, if present. */
private boolean removeMapping(Object rowKey, Object columnKey, Object value) {
if (containsMapping(rowKey, columnKey, value)) {
remove(rowKey, columnKey);
return true;
}
return false;
}
// Views
/**
* Abstract collection whose {@code isEmpty()} returns whether the table is
* empty and whose {@code clear()} clears all table mappings.
*/
private abstract class TableCollection extends AbstractCollection {
@Override public boolean isEmpty() {
return backingMap.isEmpty();
}
@Override public void clear() {
backingMap.clear();
}
}
/**
* Abstract set whose {@code isEmpty()} returns whether the table is empty and
* whose {@code clear()} clears all table mappings.
*/
private abstract class TableSet extends AbstractSet {
@Override public boolean isEmpty() {
return backingMap.isEmpty();
}
@Override public void clear() {
backingMap.clear();
}
}
private transient CellSet cellSet;
/**
* {@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() {
CellSet result = cellSet;
return (result == null) ? cellSet = new CellSet() : result;
}
private class CellSet extends TableSet> {
@Override public Iterator> iterator() {
return new CellIterator();
}
@Override public int size() {
return StandardTable.this.size();
}
@Override public boolean contains(Object obj) {
if (obj instanceof Cell) {
Cell cell = (Cell) obj;
return containsMapping(
cell.getRowKey(), cell.getColumnKey(), cell.getValue());
}
return false;
}
@Override public boolean remove(Object obj) {
if (obj instanceof Cell) {
Cell cell = (Cell) obj;
return removeMapping(
cell.getRowKey(), cell.getColumnKey(), cell.getValue());
}
return false;
}
}
private class CellIterator implements Iterator> {
final Iterator>> rowIterator
= backingMap.entrySet().iterator();
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();
}
Entry columnEntry = columnIterator.next();
return Tables.immutableCell(
rowEntry.getKey(), columnEntry.getKey(), columnEntry.getValue());
}
@Override public void remove() {
columnIterator.remove();
if (rowEntry.getValue().isEmpty()) {
rowIterator.remove();
}
}
}
@Override public Map row(R rowKey) {
return new Row(rowKey);
}
class Row extends AbstractMap {
final R rowKey;
Row(R rowKey) {
this.rowKey = checkNotNull(rowKey);
}
Map backingRowMap;
Map backingRowMap() {
return (backingRowMap == null
|| (backingRowMap.isEmpty() && backingMap.containsKey(rowKey)))
? backingRowMap = computeBackingRowMap()
: backingRowMap;
}
Map computeBackingRowMap() {
return backingMap.get(rowKey);
}
// Call this every time we perform a removal.
void maintainEmptyInvariant() {
if (backingRowMap() != null && backingRowMap.isEmpty()) {
backingMap.remove(rowKey);
backingRowMap = null;
}
}
@Override
public boolean containsKey(Object key) {
Map backingRowMap = backingRowMap();
return (key != null && backingRowMap != null)
&& Maps.safeContainsKey(backingRowMap, key);
}
@Override
public V get(Object key) {
Map backingRowMap = backingRowMap();
return (key != null && backingRowMap != null)
? Maps.safeGet(backingRowMap, key)
: null;
}
@Override
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
public V remove(Object key) {
try {
Map backingRowMap = backingRowMap();
if (backingRowMap == null) {
return null;
}
V result = backingRowMap.remove(key);
maintainEmptyInvariant();
return result;
} catch (ClassCastException e) {
return null;
}
}
@Override
public void clear() {
Map backingRowMap = backingRowMap();
if (backingRowMap != null) {
backingRowMap.clear();
}
maintainEmptyInvariant();
}
Set keySet;
@Override
public Set keySet() {
Set result = keySet;
if (result == null) {
return keySet = new Maps.KeySet() {
@Override
Map map() {
return Row.this;
}
};
}
return result;
}
Set> entrySet;
@Override
public Set> entrySet() {
Set> result = entrySet;
if (result == null) {
return entrySet = new RowEntrySet();
}
return result;
}
private class RowEntrySet extends Maps.EntrySet {
@Override
Map map() {
return Row.this;
}
@Override
public int size() {
Map map = backingRowMap();
return (map == null) ? 0 : map.size();
}
@Override
public Iterator> iterator() {
final Map map = backingRowMap();
if (map == null) {
return Iterators.emptyModifiableIterator();
}
final Iterator> iterator = map.entrySet().iterator();
return new Iterator>() {
@Override public boolean hasNext() {
return iterator.hasNext();
}
@Override public Entry next() {
final Entry entry = iterator.next();
return new ForwardingMapEntry() {
@Override protected Entry delegate() {
return entry;
}
@Override public V setValue(V value) {
return super.setValue(checkNotNull(value));
}
@Override
public boolean equals(Object object) {
// TODO(user): identify why this affects GWT tests
return standardEquals(object);
}
};
}
@Override
public void remove() {
iterator.remove();
maintainEmptyInvariant();
}
};
}
}
}
/**
* {@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 Maps.ImprovedAbstractMap {
final C columnKey;
Column(C columnKey) {
this.columnKey = checkNotNull(columnKey);
}
@Override public V put(R key, V value) {
return StandardTable.this.put(key, columnKey, value);
}
@Override public V get(Object key) {
return StandardTable.this.get(key, columnKey);
}
@Override public boolean containsKey(Object key) {
return StandardTable.this.contains(key, columnKey);
}
@Override public V remove(Object key) {
return StandardTable.this.remove(key, columnKey);
}
@Override public Set> createEntrySet() {
return new EntrySet();
}
Values columnValues;
@Override public Collection values() {
Values result = columnValues;
return (result == null) ? columnValues = new Values() : result;
}
/**
* Removes all {@code Column} mappings whose row key and value satisfy the
* given predicate.
*/
boolean removePredicate(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(
new ImmutableEntry(entry.getKey(), value))) {
map.remove(columnKey);
changed = true;
if (map.isEmpty()) {
iterator.remove();
}
}
}
return changed;
}
class EntrySet extends AbstractSet> {
@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() {
Predicate> predicate = Predicates.alwaysTrue();
removePredicate(predicate);
}
@Override public boolean contains(Object o) {
if (o instanceof Entry) {
Entry entry = (Entry) o;
return containsMapping(entry.getKey(), columnKey, entry.getValue());
}
return false;
}
@Override public boolean remove(Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
return removeMapping(entry.getKey(), columnKey, entry.getValue());
}
return false;
}
@Override public boolean removeAll(Collection c) {
boolean changed = false;
for (Object obj : c) {
changed |= remove(obj);
}
return changed;
}
@Override public boolean retainAll(Collection c) {
return removePredicate(Predicates.not(Predicates.in(c)));
}
}
class EntrySetIterator extends AbstractIterator> {
final Iterator>> iterator
= backingMap.entrySet().iterator();
@Override protected Entry computeNext() {
while (iterator.hasNext()) {
final Entry> entry = iterator.next();
if (entry.getValue().containsKey(columnKey)) {
return new AbstractMapEntry() {
@Override public R getKey() {
return entry.getKey();
}
@Override public V getValue() {
return entry.getValue().get(columnKey);
}
@Override public V setValue(V value) {
return entry.getValue().put(columnKey, checkNotNull(value));
}
};
}
}
return endOfData();
}
}
KeySet keySet;
@Override public Set keySet() {
KeySet result = keySet;
return result == null ? keySet = new KeySet() : result;
}
class KeySet extends AbstractSet {
@Override public Iterator iterator() {
return Maps.keyIterator(Column.this.entrySet().iterator());
}
@Override public int size() {
return entrySet().size();
}
@Override public boolean isEmpty() {
return !containsColumn(columnKey);
}
@Override public boolean contains(Object obj) {
return StandardTable.this.contains(obj, columnKey);
}
@Override public boolean remove(Object obj) {
return StandardTable.this.remove(obj, columnKey) != null;
}
@Override public void clear() {
entrySet().clear();
}
@Override public boolean removeAll(final Collection c) {
boolean changed = false;
for (Object obj : c) {
changed |= remove(obj);
}
return changed;
}
@Override public boolean retainAll(final Collection c) {
checkNotNull(c);
Predicate> predicate = new Predicate>() {
@Override
public boolean apply(Entry entry) {
return !c.contains(entry.getKey());
}
};
return removePredicate(predicate);
}
}
class Values extends AbstractCollection {
@Override public Iterator iterator() {
return Maps.valueIterator(Column.this.entrySet().iterator());
}
@Override public int size() {
return entrySet().size();
}
@Override public boolean isEmpty() {
return !containsColumn(columnKey);
}
@Override public void clear() {
entrySet().clear();
}
@Override public boolean remove(Object obj) {
if (obj == null) {
return false;
}
Iterator> iterator = backingMap.values().iterator();
while (iterator.hasNext()) {
Map map = iterator.next();
if (map.entrySet().remove(
new ImmutableEntry(columnKey, obj))) {
if (map.isEmpty()) {
iterator.remove();
}
return true;
}
}
return false;
}
@Override public boolean removeAll(final Collection c) {
checkNotNull(c);
Predicate> predicate = new Predicate>() {
@Override
public boolean apply(Entry entry) {
return c.contains(entry.getValue());
}
};
return removePredicate(predicate);
}
@Override public boolean retainAll(final Collection c) {
checkNotNull(c);
Predicate> predicate = new Predicate>() {
@Override
public boolean apply(Entry entry) {
return !c.contains(entry.getValue());
}
};
return removePredicate(predicate);
}
}
}
private transient RowKeySet rowKeySet;
@Override public Set rowKeySet() {
Set result = rowKeySet;
return (result == null) ? rowKeySet = new RowKeySet() : result;
}
class RowKeySet extends TableSet {
@Override public Iterator iterator() {
return Maps.keyIterator(rowMap().entrySet().iterator());
}
@Override public int size() {
return backingMap.size();
}
@Override public boolean contains(Object obj) {
return containsRow(obj);
}
@Override public boolean remove(Object obj) {
return (obj != null) && backingMap.remove(obj) != null;
}
}
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;
}
private class ColumnKeySet extends TableSet {
@Override public Iterator iterator() {
return createColumnKeyIterator();
}
@Override public int size() {
return Iterators.size(iterator());
}
@Override public boolean remove(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(Object obj) {
if (obj == null) {
return false;
}
for (Map map : backingMap.values()) {
if (map.containsKey(obj)) {
return true;
}
}
return false;
}
}
/**
* 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 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();
}
}
}
}
private transient Values values;
/**
* {@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() {
Values result = values;
return (result == null) ? values = new Values() : result;
}
private class Values extends TableCollection {
@Override public Iterator iterator() {
return new TransformedIterator, V>(cellSet().iterator()) {
@Override
V transform(Cell cell) {
return cell.getValue();
}
};
}
@Override public int size() {
return StandardTable.this.size();
}
}
private transient RowMap rowMap;
@Override public Map> rowMap() {
RowMap result = rowMap;
return (result == null) ? rowMap = new RowMap() : result;
}
class RowMap extends Maps.ImprovedAbstractMap> {
@Override public boolean containsKey(Object key) {
return containsRow(key);
}
// performing cast only when key is in backing map and has the correct type
@SuppressWarnings("unchecked")
@Override public Map get(Object key) {
return containsRow(key) ? row((R) key) : null;
}
@Override public Set keySet() {
return rowKeySet();
}
@Override public Map remove(Object key) {
return (key == null) ? null : backingMap.remove(key);
}
@Override protected Set>> createEntrySet() {
return new EntrySet();
}
class EntrySet extends TableSet>> {
@Override public Iterator>> iterator() {
return new TransformedIterator>>(backingMap.keySet().iterator()) {
@Override
Entry> transform(R rowKey) {
return new ImmutableEntry>(rowKey, row(rowKey));
}
};
}
@Override public int size() {
return backingMap.size();
}
@Override public boolean contains(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(Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
return entry.getKey() != null
&& entry.getValue() instanceof Map
&& backingMap.entrySet().remove(entry);
}
return false;
}
}
}
private transient ColumnMap columnMap;
@Override public Map> columnMap() {
ColumnMap result = columnMap;
return (result == null) ? columnMap = new ColumnMap() : result;
}
private class ColumnMap extends Maps.ImprovedAbstractMap> {
// The cast to C occurs only when the key is in the map, implying that it
// has the correct type.
@SuppressWarnings("unchecked")
@Override public Map get(Object key) {
return containsColumn(key) ? column((C) key) : null;
}
@Override public boolean containsKey(Object key) {
return containsColumn(key);
}
@Override public Map remove(Object key) {
return containsColumn(key) ? removeColumn(key) : null;
}
@Override public Set>> createEntrySet() {
return new ColumnMapEntrySet();
}
@Override public Set keySet() {
return columnKeySet();
}
ColumnMapValues columnMapValues;
@Override public Collection> values() {
ColumnMapValues result = columnMapValues;
return
(result == null) ? columnMapValues = new ColumnMapValues() : result;
}
class ColumnMapEntrySet extends TableSet>> {
@Override public Iterator>> iterator() {
return new TransformedIterator>>(columnKeySet().iterator()) {
@Override
Entry> transform(C columnKey) {
return new ImmutableEntry>(
columnKey, column(columnKey));
}
};
}
@Override public int size() {
return columnKeySet().size();
}
@Override public boolean contains(Object obj) {
if (obj instanceof Entry) {
Entry entry = (Entry) obj;
if (containsColumn(entry.getKey())) {
// The cast to C occurs only when the key is in the map, implying
// that it has the correct type.
@SuppressWarnings("unchecked")
C columnKey = (C) entry.getKey();
return get(columnKey).equals(entry.getValue());
}
}
return false;
}
@Override public boolean remove(Object obj) {
if (contains(obj)) {
Entry entry = (Entry) obj;
removeColumn(entry.getKey());
return true;
}
return false;
}
@Override public boolean removeAll(Collection c) {
boolean changed = false;
for (Object obj : c) {
changed |= remove(obj);
}
return changed;
}
@Override public boolean retainAll(Collection c) {
boolean changed = false;
for (C columnKey : Lists.newArrayList(columnKeySet().iterator())) {
if (!c.contains(new ImmutableEntry>(
columnKey, column(columnKey)))) {
removeColumn(columnKey);
changed = true;
}
}
return changed;
}
}
private class ColumnMapValues extends TableCollection> {
@Override public Iterator> iterator() {
return Maps.valueIterator(ColumnMap.this.entrySet().iterator());
}
@Override public boolean remove(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;
}
@Override public int size() {
return columnKeySet().size();
}
}
}
private static final long serialVersionUID = 0;
}