Merge pull request #17 from sergeysrabionyan/reduce-modification

Reduce modification with initial value param

Author: sokolovsky

src/WS/Utils/Collections/DummyStreamDecorator.php

@@ -108,9 +108,9 @@ public function reverse(): Stream
         return $this;
     }
 
-    public function reduce(callable $accumulator)
+    public function reduce(callable $accumulator, $initialValue = null)
     {
-        return $this->decoratedStream->reduce($accumulator);
+        return $this->decoratedStream->reduce($accumulator, $initialValue);
     }
 
     public function limit(int $size): Stream

src/WS/Utils/Collections/SerialStream.php

@@ -262,9 +262,9 @@ public function max(callable $comparator)
     /**
      * @inheritDoc
      */
-    public function reduce(callable $accumulator)
+    public function reduce(callable $accumulator, $initialValue = null)
     {
-        $accumulate = null;
+        $accumulate = $initialValue;
         foreach ($this->list as $item) {
             $accumulate = $accumulator($item, $accumulate);
         }

src/WS/Utils/Collections/Stream.php

@@ -126,13 +126,14 @@ public function sortByDesc(callable $extractor): Stream;
      * @return Stream
      */
     public function reverse(): Stream;
-    
+
     /**
      * Reduce collection to single value with accumulator
-     * @param callable $accumulator
+     * @param  callable  $accumulator
+     * @param  null  $initialValue
      * @return mixed
      */
-    public function reduce(callable $accumulator);
+    public function reduce(callable $accumulator, $initialValue = null);
 
     /**
      * Limits amount of stream collection elements

tests/WS/Utils/Collections/SerialStreamTest.php

@@ -33,6 +33,11 @@ private static function fSumAggregator(): callable
         };
     }
 
+    private static function fEmptyFunction(): callable
+    {
+        return static function () {};
+    }
+
     public function createCollection(array $els): Collection
     {
         return new ArrayList($els);
@@ -207,9 +212,10 @@ public function mapConvertingChecking($input, $modifier, $expected): void
     public function reduceCases(): array
     {
         return [
-            [[1,2,3], self::fSumAggregator(), 6],
-            [[1, 2, 4], self::fCountAggregator(), 3],
-            [[], self::fSumAggregator(), 0]
+            [[1,2,3], self::fSumAggregator(), 4, 10],
+            [[1, 2, 4], self::fCountAggregator(), 0, 3],
+            [[], self::fSumAggregator(), null, null],
+            [[], self::fEmptyFunction(), [], []]
         ];
     }
 
@@ -218,15 +224,16 @@ public function reduceCases(): array
      * @test
      * @param $input
      * @param $accumulator
+     * @param $initialValue
      * @param $expected
      */
-    public function reduceChecking($input, $accumulator, $expected): void
+    public function reduceChecking($input, $accumulator, $initialValue, $expected): void
     {
         $actual = $this->createCollection($input)
             ->stream()
-            ->reduce($accumulator);
+            ->reduce($accumulator, $initialValue);
 
-        $this->assertEquals($expected, $actual);
+        $this->assertSame($expected, $actual);
     }
 
     public function aggregateCases(): array