Merge pull request #1540 from motlin/reduceBy

Implement RichIterable.reduceBy(). Fixes #134

eclipse-collections-api/src/main/java/org/eclipse/collections/api/RichIterable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -2363,6 +2363,42 @@ default <K, V, R extends MutableMapIterable<K, V>> R aggregateBy(
         return target;
     }
 
+    /**
+     * Applies an aggregate function over the iterable grouping results into a map based on the specific groupBy function.
+     * Aggregate results are allowed to be immutable as they will be replaced in place in the map.
+     *
+     * @since 12.0
+     *
+     */
+    default <K> MapIterable<K, T> reduceBy(
+            Function<? super T, ? extends K> groupBy,
+            Function2<? super T, ? super T, ? extends T> reduceFunction)
+    {
+        return this.reduceBy(
+                groupBy,
+                reduceFunction,
+                Maps.mutable.empty());
+    }
+
+    /**
+     * Applies an aggregate function over the iterable grouping results into a map based on the specific groupBy function.
+     * Aggregate results are allowed to be immutable as they will be replaced in place in the map.
+     *
+     * @since 12.0
+     */
+    default <K, R extends MutableMapIterable<K, T>> R reduceBy(
+            Function<? super T, ? extends K> groupBy,
+            Function2<? super T, ? super T, ? extends T> reduceFunction,
+            R target)
+    {
+        this.forEach(each ->
+        {
+            K key = groupBy.valueOf(each);
+            target.merge(key, each, reduceFunction);
+        });
+        return target;
+    }
+
     /**
      * Applies a groupBy function over the iterable, followed by a collect function.
      *

eclipse-collections-api/src/main/java/org/eclipse/collections/api/bag/Bag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -383,4 +383,21 @@ default <K, V, R extends MutableMapIterable<K, V>> R aggregateBy(
         });
         return target;
     }
+
+    @Override
+    default <K, R extends MutableMapIterable<K, T>> R reduceBy(
+            Function<? super T, ? extends K> groupBy,
+            Function2<? super T, ? super T, ? extends T> reduceFunction,
+            R target)
+    {
+        this.forEachWithOccurrences((each, occurrences) ->
+        {
+            K key = groupBy.valueOf(each);
+            for (int i = 0; i < occurrences; i++)
+            {
+                target.merge(key, each, reduceFunction);
+            }
+        });
+        return target;
+    }
 }

eclipse-collections-api/src/main/java/org/eclipse/collections/api/bimap/ImmutableBiMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -194,6 +194,15 @@ default <K1, V1, V2> ImmutableMap<K1, V2> aggregateBy(
         return map.toImmutable();
     }
 
+    @Override
+    default <KK> ImmutableMapIterable<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        MutableMap<KK, V> map = this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+        return map.toImmutable();
+    }
+
     /**
      * @deprecated in 8.0. Use {@link OrderedIterable#zip(Iterable)} instead.
      */

eclipse-collections-api/src/main/java/org/eclipse/collections/api/bimap/MutableBiMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs.
+ * Copyright (c) 2024 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.
@@ -167,6 +167,14 @@ default <K1, V1, V2> MutableMap<K1, V2> aggregateBy(
         return map;
     }
 
+    @Override
+    default <KK> MutableMap<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        return this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+    }
+
     @Override
     MutableBiMap<K, V> withKeyValue(K key, V value);
 

eclipse-collections-api/src/main/java/org/eclipse/collections/api/collection/ImmutableCollection.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -43,7 +43,9 @@
 import org.eclipse.collections.api.collection.primitive.ImmutableShortCollection;
 import org.eclipse.collections.api.factory.Maps;
 import org.eclipse.collections.api.map.ImmutableMap;
+import org.eclipse.collections.api.map.ImmutableMapIterable;
 import org.eclipse.collections.api.map.MutableMap;
+import org.eclipse.collections.api.map.MutableMapIterable;
 import org.eclipse.collections.api.map.primitive.ImmutableObjectDoubleMap;
 import org.eclipse.collections.api.map.primitive.ImmutableObjectLongMap;
 import org.eclipse.collections.api.multimap.ImmutableMultimap;
@@ -239,6 +241,15 @@ default <K, V> ImmutableMap<K, V> aggregateBy(
         return map.toImmutable();
     }
 
+    @Override
+    default <K> ImmutableMapIterable<K, T> reduceBy(
+            Function<? super T, ? extends K> groupBy,
+            Function2<? super T, ? super T, ? extends T> reduceFunction)
+    {
+        MutableMapIterable<K, T> map = this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+        return map.toImmutable();
+    }
+
     /**
      * @since 9.0
      */

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/ImmutableMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -231,6 +231,15 @@ default <K1, V1, V2> ImmutableMap<K1, V2> aggregateBy(
         return map.toImmutable();
     }
 
+    @Override
+    default <KK> ImmutableMap<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        MutableMap<KK, V> map = Maps.mutable.empty();
+        return this.reduceBy(groupBy, reduceFunction, map).toImmutable();
+    }
+
     @Override
     ImmutableMap<V, K> flipUniqueValues();
 }

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/ImmutableMapIterable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -173,4 +173,16 @@ default <K1, V1, V2> ImmutableMapIterable<K1, V2> aggregateBy(
                 valueFunction.valueOf(value)));
         return map.toImmutable();
     }
+
+    @Override
+    default <KK> ImmutableMapIterable<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        MutableMap<KK, V> map = this.reduceBy(
+                groupBy,
+                reduceFunction,
+                Maps.mutable.empty());
+        return map.toImmutable();
+    }
 }

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/ImmutableOrderedMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -178,4 +178,9 @@ default <K1, V1, V2> ImmutableOrderedMap<K1, V2> aggregateBy(
     {
         throw new UnsupportedOperationException("Not implemented");
     }
+
+    @Override
+    <KK> ImmutableOrderedMap<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction);
 }

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/MutableMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -228,6 +228,17 @@ default <K1, V1, V2> MutableMap<K1, V2> aggregateBy(
         return map;
     }
 
+    @Override
+    default <KK> MutableMap<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        return this.reduceBy(
+                groupBy,
+                reduceFunction,
+                Maps.mutable.empty());
+    }
+
     @Override
     MutableMap<V, K> flipUniqueValues();
 

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/MutableMapIterable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -435,6 +435,17 @@ default <K1, V1, V2> MutableMapIterable<K1, V2> aggregateBy(
         return map;
     }
 
+    @Override
+    default <KK> MutableMapIterable<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        return this.reduceBy(
+                groupBy,
+                reduceFunction,
+                Maps.mutable.empty());
+    }
+
     @Override
     default void forEach(BiConsumer<? super K, ? super V> action)
     {

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/primitive/ImmutablePrimitiveObjectMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs.
+ * Copyright (c) 2024 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.
@@ -77,6 +77,15 @@ default <K, VV> ImmutableMap<K, VV> aggregateBy(
         return map.toImmutable();
     }
 
+    @Override
+    default <K> ImmutableMap<K, V> reduceBy(
+            Function<? super V, ? extends K> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        MutableMap<K, V> map = this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+        return map.toImmutable();
+    }
+
     @Override
     <VV> ImmutableBagMultimap<VV, V> groupByEach(Function<? super V, ? extends Iterable<VV>> function);
 

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/primitive/MutablePrimitiveObjectMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs.
+ * Copyright (c) 2024 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.
@@ -58,6 +58,14 @@ default <K, VV> MutableMap<K, VV> aggregateBy(Function<? super V, ? extends K> g
                 Maps.mutable.empty());
     }
 
+    @Override
+    default <K> MutableMap<K, V> reduceBy(
+            Function<? super V, ? extends K> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        return this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+    }
+
     @Override
     <VV> MutableBagMultimap<VV, V> groupByEach(Function<? super V, ? extends Iterable<VV>> function);
 

eclipse-collections-api/src/main/java/org/eclipse/collections/api/map/sorted/ImmutableSortedMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -247,4 +247,13 @@ default <K1, V1, V2> ImmutableMap<K1, V2> aggregateBy(
                 valueFunction.valueOf(value)));
         return map.toImmutable();
     }
+
+    @Override
+    default <KK> ImmutableMap<KK, V> reduceBy(
+            Function<? super V, ? extends KK> groupBy,
+            Function2<? super V, ? super V, ? extends V> reduceFunction)
+    {
+        MutableMap<KK, V> map = this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+        return map.toImmutable();
+    }
 }

eclipse-collections-api/src/main/java/org/eclipse/collections/api/stack/ImmutableStack.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -236,6 +236,15 @@ default <K, V> ImmutableMap<K, V> aggregateBy(
         return map.toImmutable();
     }
 
+    @Override
+    default <K> ImmutableMap<K, T> reduceBy(
+            Function<? super T, ? extends K> groupBy,
+            Function2<? super T, ? super T, ? extends T> reduceFunction)
+    {
+        MutableMap<K, T> map = this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+        return map.toImmutable();
+    }
+
     @Override
     <V> ImmutableObjectLongMap<V> sumByInt(Function<? super T, ? extends V> groupBy, IntFunction<? super T> function);
 

eclipse-collections-api/src/main/java/org/eclipse/collections/api/stack/MutableStack.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Goldman Sachs and others.
+ * Copyright (c) 2024 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.
@@ -259,4 +259,12 @@ default <K, V> MutableMap<K, V> aggregateBy(
         });
         return map;
     }
+
+    @Override
+    default <K> MutableMap<K, T> reduceBy(
+            Function<? super T, ? extends K> groupBy,
+            Function2<? super T, ? super T, ? extends T> reduceFunction)
+    {
+        return this.reduceBy(groupBy, reduceFunction, Maps.mutable.empty());
+    }
 }