org.eclipse.collections.api.bag.Bag Maven / Gradle / Ivy
/*
* Copyright (c) 2018 Goldman Sachs and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v. 1.0 which accompany this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.eclipse.collections.api.bag;
import java.util.Collection;
import java.util.DoubleSummaryStatistics;
import java.util.IntSummaryStatistics;
import java.util.LongSummaryStatistics;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.Supplier;
import java.util.stream.Collector;
import java.util.stream.Stream;
import org.eclipse.collections.api.RichIterable;
import org.eclipse.collections.api.block.function.Function;
import org.eclipse.collections.api.block.function.primitive.DoubleFunction;
import org.eclipse.collections.api.block.function.primitive.FloatFunction;
import org.eclipse.collections.api.block.function.primitive.IntFunction;
import org.eclipse.collections.api.block.function.primitive.LongFunction;
import org.eclipse.collections.api.block.function.primitive.ObjectIntToObjectFunction;
import org.eclipse.collections.api.block.predicate.Predicate;
import org.eclipse.collections.api.block.predicate.Predicate2;
import org.eclipse.collections.api.block.predicate.primitive.IntPredicate;
import org.eclipse.collections.api.block.procedure.Procedure;
import org.eclipse.collections.api.block.procedure.primitive.ObjectIntProcedure;
import org.eclipse.collections.api.list.ListIterable;
import org.eclipse.collections.api.map.MapIterable;
import org.eclipse.collections.api.multimap.bag.BagMultimap;
import org.eclipse.collections.api.partition.bag.PartitionBag;
import org.eclipse.collections.api.set.SetIterable;
import org.eclipse.collections.api.tuple.Pair;
import org.eclipse.collections.api.tuple.primitive.ObjectIntPair;
/**
* A Bag is a Collection whose elements are unordered and may contain duplicate entries. It varies from
* MutableCollection in that it adds a protocol for determining, adding, and removing the number of occurrences for an
* item.
*
* @since 1.0
*/
public interface Bag
extends RichIterable
{
/**
* Two bags {@code b1} and {@code b2} are equal if {@code m1.toMapOfItemToCount().equals(m2.toMapOfItemToCount())}.
*
* @see Map#equals(Object)
*/
@Override
boolean equals(Object object);
/**
* Returns the hash code for this Bag, defined as this.{@link #toMapOfItemToCount()}.hashCode().
*
* @see Map#hashCode()
*/
@Override
int hashCode();
@Override
Bag tap(Procedure procedure);
@Override
Bag select(Predicate predicate);
@Override
Bag selectWith(Predicate2 predicate, P parameter);
@Override
Bag reject(Predicate predicate);
@Override
Bag rejectWith(Predicate2 predicate, P parameter);
@Override
PartitionBag partition(Predicate predicate);
@Override
PartitionBag partitionWith(Predicate2 predicate, P parameter);
@Override
Bag selectInstancesOf(Class clazz);
@Override
BagMultimap groupBy(Function function);
@Override
BagMultimap groupByEach(Function> function);
@Override
SetIterable> zipWithIndex();
/**
* For each distinct item, with the number of occurrences, execute the specified procedure.
*/
void forEachWithOccurrences(ObjectIntProcedure procedure);
/**
* The occurrences of a distinct item in the bag.
*/
int occurrencesOf(Object item);
/**
* Returns all elements of the bag that have a number of occurrences that satisfy the predicate.
*
* @since 3.0
*/
Bag selectByOccurrences(IntPredicate predicate);
/**
* Returns all elements of the bag that have more than one occurrence.
*
* @since 9.2
*/
default Bag selectDuplicates()
{
return this.selectByOccurrences(occurrences -> occurrences > 1);
}
/**
* Returns a set containing all elements of the bag that have exactly one occurrence.
*
* @since 9.2
*/
SetIterable selectUnique();
/**
* Returns the {@code count} most frequently occurring items.
*
* In the event of a tie, all of the items with the number of occurrences that match the occurrences of the last
* item will be returned.
*
* @since 6.0
*/
ListIterable> topOccurrences(int count);
/**
* Returns the {@code count} least frequently occurring items.
*
* In the event of a tie, all of the items with the number of occurrences that match the occurrences of the last
* item will be returned.
*
* @since 6.0
*/
ListIterable> bottomOccurrences(int count);
/**
* The size of the Bag when counting only distinct elements.
*/
int sizeDistinct();
/**
* Converts the Bag to a Map of the Item type to its count as an Integer.
*/
MapIterable toMapOfItemToCount();
/**
* Returns a string representation of this bag. The string representation consists of a list of element-count mappings.
*
*
* Assert.assertEquals("{1=1, 2=2, 3=3}", Bags.mutable.with(1, 2, 2, 3, 3, 3).toStringOfItemToCount());
*
* This string representation is similar to {@link java.util.AbstractMap#toString()}, not {@link RichIterable#toString()},
* whereas the {@code toString()} implementation for a Bag is consistent with {@link RichIterable#toString()}.
*
* @return a string representation of this bag
* @since 3.0
*/
String toStringOfItemToCount();
ImmutableBagIterable toImmutable();
/**
* @since 8.0
*/
@Override
default IntSummaryStatistics summarizeInt(IntFunction function)
{
IntSummaryStatistics stats = new IntSummaryStatistics();
this.forEachWithOccurrences((each, occurrences) ->
{
int result = function.intValueOf(each);
for (int i = 0; i < occurrences; i++)
{
stats.accept(result);
}
});
return stats;
}
/**
* @since 8.0
*/
@Override
default DoubleSummaryStatistics summarizeFloat(FloatFunction function)
{
DoubleSummaryStatistics stats = new DoubleSummaryStatistics();
this.forEachWithOccurrences((each, occurrences) ->
{
float result = function.floatValueOf(each);
for (int i = 0; i < occurrences; i++)
{
stats.accept(result);
}
});
return stats;
}
/**
* @since 8.0
*/
@Override
default LongSummaryStatistics summarizeLong(LongFunction function)
{
LongSummaryStatistics stats = new LongSummaryStatistics();
this.forEachWithOccurrences((each, occurrences) ->
{
long result = function.longValueOf(each);
for (int i = 0; i < occurrences; i++)
{
stats.accept(result);
}
});
return stats;
}
/**
* @since 8.0
*/
@Override
default DoubleSummaryStatistics summarizeDouble(DoubleFunction function)
{
DoubleSummaryStatistics stats = new DoubleSummaryStatistics();
this.forEachWithOccurrences((each, occurrences) ->
{
double result = function.doubleValueOf(each);
for (int i = 0; i < occurrences; i++)
{
stats.accept(result);
}
});
return stats;
}
/**
* This method produces the equivalent result as {@link Stream#collect(Collector)}.
*
* @since 8.0
*/
@Override
default R reduceInPlace(Collector collector)
{
A mutableResult = collector.supplier().get();
BiConsumer accumulator = collector.accumulator();
this.forEachWithOccurrences((each, occurrences) ->
{
for (int i = 0; i < occurrences; i++)
{
accumulator.accept(mutableResult, each);
}
});
return collector.finisher().apply(mutableResult);
}
/**
* This method produces the equivalent result as {@link Stream#collect(Supplier, BiConsumer, BiConsumer)}.
*
* @since 8.0
*/
@Override
default R reduceInPlace(Supplier supplier, BiConsumer accumulator)
{
R mutableResult = supplier.get();
this.forEachWithOccurrences((each, occurrences) ->
{
for (int i = 0; i < occurrences; i++)
{
accumulator.accept(mutableResult, each);
}
});
return mutableResult;
}
/**
* Iterates over the unique elements and their occurrences and collects the results of applying the specified function.
*
* @since 10.0
*/
RichIterable collectWithOccurrences(ObjectIntToObjectFunction function);
/**
* Iterates over the unique elements and their occurrences and collects the results of applying the
* specified function into the target collection.
*
* @since 9.1.
*/
default > R collectWithOccurrences(
ObjectIntToObjectFunction function,
R target)
{
this.forEachWithOccurrences((each, occurrences) -> target.add(function.valueOf(each, occurrences)));
return target;
}
}