com.google.common.collect.TableCollectors Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of guava Show documentation
Show all versions of guava Show documentation
Guava is a suite of core and expanded libraries that include
utility classes, google's collections, io classes, and much
much more.
/*
* 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.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Tables.AbstractCell;
import java.util.ArrayList;
import java.util.List;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;
/** Collectors utilities for {@code common.collect.Table} internals. */
@GwtCompatible
final class TableCollectors {
static Collector> toImmutableTable(
Function rowFunction,
Function columnFunction,
Function valueFunction) {
checkNotNull(rowFunction, "rowFunction");
checkNotNull(columnFunction, "columnFunction");
checkNotNull(valueFunction, "valueFunction");
return Collector.of(
(Supplier>) ImmutableTable.Builder::new,
(builder, t) ->
builder.put(rowFunction.apply(t), columnFunction.apply(t), valueFunction.apply(t)),
ImmutableTable.Builder::combine,
ImmutableTable.Builder::build);
}
static Collector> toImmutableTable(
Function rowFunction,
Function columnFunction,
Function valueFunction,
BinaryOperator mergeFunction) {
checkNotNull(rowFunction, "rowFunction");
checkNotNull(columnFunction, "columnFunction");
checkNotNull(valueFunction, "valueFunction");
checkNotNull(mergeFunction, "mergeFunction");
/*
* No mutable Table exactly matches the insertion order behavior of ImmutableTable.Builder, but
* the Builder can't efficiently support merging of duplicate values. Getting around this
* requires some work.
*/
return Collector.of(
() -> new ImmutableTableCollectorState()
/* GWT isn't currently playing nicely with constructor references? */ ,
(state, input) ->
state.put(
rowFunction.apply(input),
columnFunction.apply(input),
valueFunction.apply(input),
mergeFunction),
(s1, s2) -> s1.combine(s2, mergeFunction),
state -> state.toTable());
}
static > Collector toTable(
java.util.function.Function rowFunction,
java.util.function.Function columnFunction,
java.util.function.Function valueFunction,
java.util.function.Supplier tableSupplier) {
return toTable(
rowFunction,
columnFunction,
valueFunction,
(v1, v2) -> {
throw new IllegalStateException("Conflicting values " + v1 + " and " + v2);
},
tableSupplier);
}
static > Collector toTable(
java.util.function.Function rowFunction,
java.util.function.Function columnFunction,
java.util.function.Function valueFunction,
BinaryOperator mergeFunction,
java.util.function.Supplier tableSupplier) {
checkNotNull(rowFunction);
checkNotNull(columnFunction);
checkNotNull(valueFunction);
checkNotNull(mergeFunction);
checkNotNull(tableSupplier);
return Collector.of(
tableSupplier,
(table, input) ->
mergeTables(
table,
rowFunction.apply(input),
columnFunction.apply(input),
valueFunction.apply(input),
mergeFunction),
(table1, table2) -> {
for (Table.Cell cell2 : table2.cellSet()) {
mergeTables(
table1, cell2.getRowKey(), cell2.getColumnKey(), cell2.getValue(), mergeFunction);
}
return table1;
});
}
private static final class ImmutableTableCollectorState {
final List> insertionOrder = new ArrayList<>();
final Table> table = HashBasedTable.create();
void put(R row, C column, V value, BinaryOperator merger) {
MutableCell oldCell = table.get(row, column);
if (oldCell == null) {
MutableCell cell = new MutableCell<>(row, column, value);
insertionOrder.add(cell);
table.put(row, column, cell);
} else {
oldCell.merge(value, merger);
}
}
ImmutableTableCollectorState combine(
ImmutableTableCollectorState other, BinaryOperator merger) {
for (MutableCell cell : other.insertionOrder) {
put(cell.getRowKey(), cell.getColumnKey(), cell.getValue(), merger);
}
return this;
}
ImmutableTable toTable() {
return ImmutableTable.copyOf(insertionOrder);
}
}
private static final class MutableCell extends AbstractCell {
private final R row;
private final C column;
private V value;
MutableCell(R row, C column, V value) {
this.row = checkNotNull(row, "row");
this.column = checkNotNull(column, "column");
this.value = checkNotNull(value, "value");
}
@Override
public R getRowKey() {
return row;
}
@Override
public C getColumnKey() {
return column;
}
@Override
public V getValue() {
return value;
}
void merge(V value, BinaryOperator mergeFunction) {
checkNotNull(value, "value");
this.value = checkNotNull(mergeFunction.apply(this.value, value), "mergeFunction.apply");
}
}
private static void mergeTables(
Table table, R row, C column, V value, BinaryOperator mergeFunction) {
checkNotNull(value);
V oldValue = table.get(row, column);
if (oldValue == null) {
table.put(row, column, value);
} else {
V newValue = mergeFunction.apply(oldValue, value);
if (newValue == null) {
table.remove(row, column);
} else {
table.put(row, column, newValue);
}
}
}
private TableCollectors() {}
}