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The module for FunctionalJ Core.
There is a newer version: 1.0.17
// ============================================================================
// Copyright (c) 2017-2021 Nawapunth Manusitthipol (NawaMan - http://nawaman.net).
// ----------------------------------------------------------------------------
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
// ============================================================================
package functionalj.stream.doublestream;

import static functionalj.function.Func.f;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.DoubleFunction;
import java.util.function.Function;
import java.util.function.Supplier;

import functionalj.function.aggregator.DoubleAggregation;
import functionalj.list.doublelist.DoubleFuncList;
import functionalj.map.FuncMap;
import functionalj.map.ImmutableFuncMap;
import functionalj.stream.doublestream.collect.DoubleCollectorPlus;
import lombok.val;


public interface AsDoubleStreamPlusWithGroupingBy {
    
    public DoubleStreamPlus doubleStreamPlus();
    
    /** Group the elements by determining the grouping keys */
    public default  FuncMap groupingBy(DoubleFunction keyMapper) {
        val toFuncList = f((GrowOnlyDoubleArray array) -> array.toFuncList());
        val newArray   = f(() -> new GrowOnlyDoubleArray());
        val streamPlus = this.doubleStreamPlus();
        
        Supplier  >                                 supplier;
        BiConsumer, Double>                         accumulator;
        BiConsumer, Map>  combiner;
        
        supplier = LinkedHashMap::new;
        accumulator = (map, each) -> {
            val key = keyMapper.apply(each);
            map.compute(key, (k, a)->{
                if (a == null) {
                    a = newArray.get();
                }
                a.add(each);
                return a;
            });
        };
        combiner = (map1, map2) -> map1.putAll(map2);
        
        val theMap = streamPlus.boxed().collect(supplier, accumulator, combiner);
        return ImmutableFuncMap
                    .from    (theMap)
                    .mapValue(toFuncList);
    }
    
    /** Group the elements by determining the grouping keys */
    public default  FuncMap groupingBy(DoubleAggregation keyAggregation) {
        val keyMapper = keyAggregation.newAggregator();
        return groupingBy(keyMapper);
    }
    
    /** Group the elements by determining the grouping keys and aggregate the result */
    public default  FuncMap groupingBy(
            DoubleFunction             keyMapper,
            Function aggregate) {
        return groupingBy(keyMapper)
                .mapValue(aggregate);
    }
    
    /** Group the elements by determining the grouping keys and aggregate the result */
    public default  FuncMap groupingBy(
            DoubleAggregation          keyAggregation,
            Function aggregate) {
        val keyMapper = keyAggregation.newAggregator();
        return groupingBy(keyMapper, aggregate);
    }
    
    /** Group the elements by determining the grouping keys and aggregate the result */
    public default  FuncMap groupingBy(
            DoubleFunction      keyMapper,
            DoubleAggregation aggregate) {
        val valueMapper = f((DoubleFuncList list) -> list.aggregate(aggregate));
        return groupingBy(keyMapper)
                .mapValue(valueMapper);
    }
    
    /** Group the elements by determining the grouping keys and aggregate the result */
    public default  FuncMap groupingBy(
            DoubleAggregation   keyAggregation,
            DoubleAggregation aggregate) {
        val keyMapper = keyAggregation.newAggregator();
        return groupingBy(keyMapper, aggregate);
    }
    
    /** Group the elements by determining the grouping keys and aggregate the result */
    public default  FuncMap groupingBy(
            DoubleFunction                               keyMapper,
            Supplier> collectorSupplier) {
        val valueMapper = f((DoubleFuncList list) -> list.collect(collectorSupplier.get()));
        return groupingBy(keyMapper)
                .mapValue(valueMapper);
    }
    
    /** Group the elements by determining the grouping keys and aggregate the result */
    public default  FuncMap groupingBy(
            DoubleAggregation                            keyAggregation,
            Supplier> collectorSupplier) {
        val keyMapper = keyAggregation.newAggregator();
        return groupingBy(keyMapper, collectorSupplier);
    }
    
}