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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util;
import com.tangosol.util.aggregator.AsynchronousAggregator;
import com.tangosol.util.aggregator.BigDecimalAverage;
import com.tangosol.util.aggregator.BigDecimalMax;
import com.tangosol.util.aggregator.BigDecimalMin;
import com.tangosol.util.aggregator.BigDecimalSum;
import com.tangosol.util.aggregator.ComparableMax;
import com.tangosol.util.aggregator.ComparableMin;
import com.tangosol.util.aggregator.CompositeAggregator;
import com.tangosol.util.aggregator.Count;
import com.tangosol.util.aggregator.DistinctValues;
import com.tangosol.util.aggregator.DoubleAverage;
import com.tangosol.util.aggregator.DoubleMax;
import com.tangosol.util.aggregator.DoubleMin;
import com.tangosol.util.aggregator.DoubleSum;
import com.tangosol.util.aggregator.GroupAggregator;
import com.tangosol.util.aggregator.LongMax;
import com.tangosol.util.aggregator.LongMin;
import com.tangosol.util.aggregator.LongSum;
import com.tangosol.util.aggregator.ReducerAggregator;
import com.tangosol.util.aggregator.ScriptAggregator;
import com.tangosol.util.aggregator.TopNAggregator;
import java.math.BigDecimal;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
/**
* Simple Aggregator DSL.
*
* The methods in this class are for the most part simple factory methods for
* various {@link InvocableMap.EntryAggregator} classes, but in some cases provide additional type
* safety. They also tend to make the code more readable, especially if imported
* statically, so their use is strongly encouraged in lieu of direct construction
* of {@code InvocableMap.EntryAggregator} classes.
*
* @author lh, hr 2018.06.12
*/
@SuppressWarnings("unchecked")
public class Aggregators
{
/**
* Return an AsynchronousAggregator for a given streaming aggregator.
*
* @param aggregator the underlying streaming aggregator
*
* @param the type of the Map entry keys
* @param the type of the Map entry values
* @param the type of the intermediate result during the parallel stage
* @param the type of the value returned by the StreamingAggregator
*/
public static AsynchronousAggregator
asynchronous(InvocableMap.StreamingAggregator aggregator)
{
return new AsynchronousAggregator(aggregator);
}
/**
* Return an AsynchronousAggregator for a given streaming aggregator.
*
* @param aggregator the underlying streaming aggregator
* @param iUnitOrderId the unit-of-order id for this aggregator
*/
public static InvocableMap.EntryAggregator
asynchronous(InvocableMap.StreamingAggregator aggregator, int iUnitOrderId)
{
return new AsynchronousAggregator(aggregator, iUnitOrderId);
}
/**
* Return an aggregator that calculates a average of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
average(ValueExtractor extractor)
{
return new DoubleAverage(extractor);
}
/**
* Return an aggregator that calculates a average of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator average(String sMethod)
{
return new DoubleAverage(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a maximum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
doubleMax(ValueExtractor extractor)
{
return new DoubleMax(extractor);
}
/**
* Return an aggregator that calculates a maximum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator doubleMax(String sMethod)
{
return new DoubleMax(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a minimum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
doubleMin(ValueExtractor extractor)
{
return new DoubleMin(extractor);
}
/**
* Return an aggregator that calculates a minimum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator doubleMin(String sMethod)
{
return new DoubleMin(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a sum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
doubleSum(ValueExtractor extractor)
{
return new DoubleSum(extractor);
}
/**
* Return an aggregator that calculates a sum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java double values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator doubleSum(String sMethod)
{
return new DoubleSum(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a maximum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java long values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
longMax(ValueExtractor extractor)
{
return new LongMax(extractor);
}
/**
* Return an aggregator that calculates a maximum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java long values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator longMax(String sMethod)
{
return new LongMax(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a minimum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java long values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
longMin(ValueExtractor extractor)
{
return new LongMin(extractor);
}
/**
* Return an aggregator that calculates a minimum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java long values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator longMin(String sMethod)
{
return new LongMin(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a sum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java long values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
longSum(ValueExtractor extractor)
{
return new LongSum(extractor);
}
/**
* Return an aggregator that calculates a sum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as Java long values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator longSum(String sMethod)
{
return new LongSum(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a average of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
bigDecimalAverage(ValueExtractor extractor)
{
return new BigDecimalAverage(extractor);
}
/**
* Return an aggregator that calculates a average of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator bigDecimalAverage(String sMethod)
{
return bigDecimalAverage(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a maximum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
bigDecimalMax(ValueExtractor extractor)
{
return new BigDecimalMax(extractor);
}
/**
* Return an aggregator that calculates a maximum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator bigDecimalMax(String sMethod)
{
return bigDecimalMax(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a minimum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
bigDecimalMin(ValueExtractor extractor)
{
return new BigDecimalMin(extractor);
}
/**
* Return an aggregator that calculates a minimum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator bigDecimalMin(String sMethod)
{
return bigDecimalMin(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a sum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param extractor the extractor that provides a value in the form of
* any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
*/
public static InvocableMap.StreamingAggregator
bigDecimalSum(ValueExtractor extractor)
{
return new BigDecimalSum(extractor);
}
/**
* Return an aggregator that calculates a sum of the numeric values extracted
* from a set of entries in a Map. All the extracted Number objects will be treated
* as {@link BigDecimal} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object that is a {@link Number}
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator bigDecimalSum(String sMethod)
{
return bigDecimalSum(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a maximum of the {@link Comparable} values
* extracted from a set of entries in a Map. All the extracted objects will be
* treated as {@link Comparable} values.
*
* @param extractor the extractor that provides a value in the form of
* any object that implements {@link Comparable}
* interface
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMax(ValueExtractor extractor)
{
return new ComparableMax(extractor);
}
/**
* Return an aggregator that calculates a maximum of the values extracted from a set
* of entries in a Map. All the extracted objects will ordered using the specified
* {@link Comparator}.
*
* @param extractor the extractor that provides an object to be compared
* @param comparator the comparator used to compare the extracted object
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMax(ValueExtractor extractor, Comparator comparator)
{
return new ComparableMax(extractor, comparator);
}
/**
* Return an aggregator that calculates a maximum of the {@link Comparable} values
* extracted from a set of entries in a Map. All the extracted objects will be
* treated as {@link Comparable} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any object that implements {@link Comparable}
* interface
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMax(String sMethod)
{
return comparableMax(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a maximum of the values extracted from a set
* of entries in a Map. All the extracted objects will ordered using the specified
* {@link Comparator}.
*
* @param sMethod the name of the method that returns the value to be compared
* @param comparator the comparator used to compare the extracted object
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMax(String sMethod, Comparator comparator)
{
return new ComparableMax(Extractors.extract(sMethod), comparator);
}
/**
* Return an aggregator that calculates a minimum of the {@link Comparable} values
* extracted from a set of entries in a Map. All the extracted objects will be
* treated as {@link Comparable} values.
*
* @param extractor the extractor that provides a value in the form of
* any object that implements {@link Comparable}
* interface
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMin(ValueExtractor extractor)
{
return new ComparableMin(extractor);
}
/**
* Return an aggregator that calculates a minimum of the values extracted from a set
* of entries in a Map. All the extracted objects will ordered using the specified
* {@link Comparator}.
*
* @param extractor the extractor that provides an object to be compared
* @param comparator the comparator used to compare the extracted object
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMin(ValueExtractor extractor, Comparator comparator)
{
return new ComparableMin(extractor, comparator);
}
/**
* Return an aggregator that calculates a minimum of the {@link Comparable} values
* extracted from a set of entries in a Map. All the extracted objects will be
* treated as {@link Comparable} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any object that implements {@link Comparable}
* interface
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMin(String sMethod)
{
return comparableMin(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates a minimum of the values extracted from a set
* of entries in a Map. All the extracted objects will ordered using the specified
* {@link Comparator}.
*
* @param sMethod the name of the method that returns a value in the form
* of any object that implements {@link Comparable}
* interface
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
comparableMin(String sMethod, Comparator comparator)
{
return new ComparableMin(Extractors.extract(sMethod), comparator);
}
/**
* Return an aggregator that calculates the count of the entries in a Map.
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator count()
{
return new Count();
}
/**
* Return an aggregator that calculates the set of distinct values from the entries in a Map.
*
* @param the type of the entry's key
* @param the type of the entry's value
*/
public static InvocableMap.StreamingAggregator> distinctValues()
{
return new DistinctValues(Extractors.identity());
}
/**
* Return an aggregator that calculates the set of distinct values extracted from the entries in a Map.
*
* @param extractor the extractor that provides a value in the form of
* any Java object
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static InvocableMap.StreamingAggregator>
distinctValues(ValueExtractor extractor)
{
return new DistinctValues(extractor);
}
/**
* Return an aggregator that calculates the set of distinct values extracted from the entries in a Map.
*
* @param sMethod the name of the method that returns a value in the form
* of any Java object
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the aggregation result
*/
public static InvocableMap.StreamingAggregator> distinctValues(String sMethod)
{
return distinctValues(Extractors.extract(sMethod));
}
/**
* Return an aggregator that calculates the the combined set of results from a number of aggregators.
*
* @param aAggregator an array of EntryAggregator objects; may not be null
*
* @param the type of the entry's key
* @param the type of the entry's value
*
* @throws NullPointerException if the aggregator array is null
*/
public static InvocableMap.StreamingAggregator>
composite(InvocableMap.EntryAggregator... aAggregator)
{
return new CompositeAggregator(aAggregator);
}
/**
* Create an instance of group aggregator based on a specified property or method
* name(s) and an {@link InvocableMap.EntryAggregator}.
*
* @param aggregator an underlying EntryAggregator
* @param asNames the property or method name(s) to extract values from. The resulting
* {@link ValueExtractor} is used to split InvocableMap entries into distinct
* groups.
*
* @param the type of the Map entry keys
* @param the type of the Map entry values
* @param the type of the extracted value
* @param the type of the group aggregator result
*/
public static InvocableMap.StreamingAggregator, Map>
grouping(InvocableMap.EntryAggregator aggregator, String... asNames)
{
return grouping(aggregator, null, asNames);
}
/**
* Create an instance of group aggregator based on a specified property or method
* name(s) and an {@link InvocableMap.EntryAggregator}.
*
* @param aggregator an underlying EntryAggregator
* @param filter an optional Filter object that will be used to evaluate
* results of each individual group aggregation
* @param asNames the property or method name(s) to extract values from. The resulting
* {@link ValueExtractor} is used to split InvocableMap entries into distinct
* groups.
*
* @param the type of the Map entry keys
* @param the type of the Map entry values
* @param the type of the extracted value
* @param the type of the group aggregator result
*/
public static InvocableMap.StreamingAggregator, Map>
grouping(InvocableMap.EntryAggregator aggregator,
Filter filter,
String... asNames)
{
if (asNames == null || asNames.length == 0)
{
throw new IllegalArgumentException("Names parameter cannot be null or empty");
}
ValueExtractor extractor;
if (asNames.length == 1)
{
extractor = Extractors.extract(asNames[0]);
}
else
{
extractor = (ValueExtractor) Extractors.multi(asNames);
}
return grouping(extractor, aggregator, filter);
}
/**
* Create an instance of group aggregator based on a specified property or method
* name(s) and an {@link InvocableMap.EntryAggregator}.
*
* @param extractor a ValueExtractor that will be used to split a set of
* InvocableMap entries into distinct groups
* @param aggregator an underlying EntryAggregator
*
* @param the type of the Map entry keys
* @param the type of the Map entry values
* @param the type of the value to extract from
* @param the type of the extracted value
* @param the type of the group aggregator result
*/
public static InvocableMap.StreamingAggregator, Map>
grouping(ValueExtractor extractor, InvocableMap.EntryAggregator aggregator)
{
return grouping(extractor, aggregator, null);
}
/**
* Create an instance of group aggregator based on a specified property or method
* name(s) and an {@link InvocableMap.EntryAggregator}.
*
* @param extractor a ValueExtractor that will be used to split a set of
* InvocableMap entries into distinct groups
* @param aggregator an underlying EntryAggregator
* @param filter an optional Filter object used to filter out results
* of individual group aggregation results
*
* @param the type of the Map entry keys
* @param the type of the Map entry values
* @param the type of the value to extract from
* @param the type of the extracted value
* @param the type of the group aggregator result
*/
public static InvocableMap.StreamingAggregator, Map>
grouping(ValueExtractor extractor,
InvocableMap.EntryAggregator aggregator,
Filter filter)
{
return GroupAggregator.createInstance(extractor, aggregator, filter);
}
/**
* Return an aggregator that calculates the top n of the {@link Comparable} values
* extracted from a set of entries in a Map. All the extracted objects will be
* treated as {@link Comparable} values.
*
* @param extractor the extractor that provides a value in the form of
* any object that implements {@link Comparable}
* interface
* @param cResults the maximum number of results to return
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
topN(ValueExtractor extractor, int cResults)
{
return new TopNAggregator(extractor, null, cResults);
}
/**
* Return an aggregator that calculates the top n of the values extracted from a set
* of entries in a Map. All the extracted objects will ordered using the specified
* {@link Comparator}.
*
* @param extractor the extractor that provides an object to be compared
* @param comparator the comparator used to compare the extracted object
* @param cResults the maximum number of results to return
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
topN(ValueExtractor extractor, Comparator comparator, int cResults)
{
return new TopNAggregator(extractor, comparator, cResults);
}
/**
* Return an aggregator that calculates the top n of the {@link Comparable} values
* extracted from a set of entries in a Map. All the extracted objects will be
* treated as {@link Comparable} values.
*
* @param sMethod the name of the method that returns a value in the form
* of any object that implements {@link Comparable}
* interface
* @param cResults the maximum number of results to return
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
topN(String sMethod, int cResults)
{
return new TopNAggregator(Extractors.extract(sMethod), null, cResults);
}
/**
* Return an aggregator that calculates the top n of the values extracted from a set
* of entries in a Map. All the extracted objects will ordered using the specified
* {@link Comparator}.
*
* @param sMethod the name of the method that returns the value to be compared
* @param comparator the comparator used to compare the extracted object
* @param cResults the maximum number of results to return
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator
topN(String sMethod, Comparator comparator, int cResults)
{
return new TopNAggregator(Extractors.extract(sMethod), comparator, cResults);
}
/**
* Return an aggregator that will return the extracted value for each entry in the map.
*
* @param extractor the extractor that provides an value(s) to be returned
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the value to extract from
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator>
reduce(ValueExtractor extractor)
{
return new ReducerAggregator(extractor);
}
/**
* Return an aggregator that will return the extracted value for each entry in the map.
*
* @param sMethod the name of the method to use to obtain the value
*
* @param the type of the entry's key
* @param the type of the entry's value
* @param the type of the aggregation result
*/
public static > InvocableMap.StreamingAggregator>
reduce(String sMethod)
{
return new ReducerAggregator(Extractors.extract(sMethod));
}
/**
* Return an aggregator that is implemented in a script using the specified
* language.
*
* @param sLanguage the string specifying one of the supported languages
* @param sName the name of the {@link InvocableMap.StreamingAggregator}
* that needs to be evaluated
* @param aoArgs the arguments to be passed to the
* {@link InvocableMap.StreamingAggregator}
* @param the type of key that the
* {@link InvocableMap.StreamingAggregator} will receive
* @param the type of value that the
* {@link InvocableMap.StreamingAggregator} will receive
* @param the type of partial result this
* {@link InvocableMap.StreamingAggregator} will return
* @param