Optimize aggregate functions

CHANGELOG.md

@@ -1,11 +1,16 @@
+3.2.1 (20/6/15)
+===============
+ - Update join generator classes such that they dont perform unnecessary inner loop computations for every iteration.
+ - Optimize aggregate functions in `Traversable`
+
 3.2.0 (20/6/15)
 ===============
  - Fix return by reference issue in generator scheme for PHP versions >=5.6.8 
  - Refactor `Analysis\PhpTypeSystem::getTypeFromValue` method logic into new static method `Analysis\TypeId::fromValue`
  - Fix bug when attempting to parse function with a magic scope parameter type hint (eg `function (self $param) { ... }`.
  - Implement `Analysis\TolerantExpressionAnalyser` which will convert analysis exceptions into the *mixed* type.
  - Add `Providers\DSL\Compilation\Parameters\ParameterCollection::contains` to check whether the collection contains a parameter.
- - Add `Providers\DSL\Compilation\Parameters\ParameterCollection::remove` to remove a previously added parameter.\
+ - Add `Providers\DSL\Compilation\Parameters\ParameterCollection::remove` to remove a previously added parameter.
  - Introduce `Analysis\INativeType::TYPE_NUMERIC` acting as a union type for `Analysis\INativeType::TYPE_INT` and `Analysis\INativeType::TYPE_DOUBLE`  
  - Fix bug when joining to the same `ITraversable` instance with an `->indexBy(...)` only returning the first element.
 

Source/Traversable.php

@@ -517,7 +517,7 @@ public function aggregate(callable $function)
         $hasValue       = false;
         $aggregateValue = null;
 
-        foreach ($this->asArray() as $value) {
+        foreach ($this->elements as $value) {
             if (!$hasValue) {
                 $aggregateValue = $value;
                 $hasValue       = true;
@@ -530,21 +530,6 @@ public function aggregate(callable $function)
         return $aggregateValue;
     }
 
-    private function mapArray(callable $function = null)
-    {
-        if ($function === null) {
-            return $this->asArray();
-        } else {
-            return $this->scheme->toArray(
-                    $this->scheme->projectionIterator(
-                            $this->asOrderedMap(),
-                            null,
-                            $function
-                    )
-            );
-        }
-    }
-
     private function mapIterator(callable $function = null)
     {
         if ($function === null) {
@@ -560,30 +545,54 @@ private function mapIterator(callable $function = null)
 
     public function maximum(callable $function = null)
     {
-        $array = $this->mapArray($function);
+        $max = null;
+
+        foreach ($this->mapIterator($function) as $value) {
+            if ($value > $max) {
+                $max = $value;
+            }
+        }
 
-        return empty($array) ? null : max($array);
+        return $max;
     }
 
     public function minimum(callable $function = null)
     {
-        $array = $this->mapArray($function);
+        $min = null;
+        $first = true;
+
+        foreach ($this->mapIterator($function) as $value) {
+            if ($value < $min || $first) {
+                $min   = $value;
+                $first = false;
+            }
+        }
 
-        return empty($array) ? null : min($array);
+        return $min;
     }
 
     public function sum(callable $function = null)
     {
-        $array = $this->mapArray($function);
+        $sum = null;
 
-        return empty($array) ? null : array_sum($array);
+        foreach ($this->mapIterator($function) as $value) {
+            $sum += $value;
+        }
+
+        return $sum;
     }
 
     public function average(callable $function = null)
     {
-        $array = $this->mapArray($function);
+        $sum = null;
+        $count = 0;
 
-        return empty($array) ? null : array_sum($array) / count($array);
+        foreach ($this->mapIterator($function) as $value) {
+            $sum += $value;
+            $count++;
+        }
+
+        return $count === 0 ? null : $sum / $count;
     }
 
     public function all(callable $function = null)
@@ -610,7 +619,13 @@ public function any(callable $function = null)
 
     public function implode($delimiter, callable $function = null)
     {
-        return implode($delimiter, $this->mapArray($function));
+        $string = '';
+
+        foreach ($this->mapIterator($function) as $value) {
+            $string .= $delimiter . $value;
+        }
+
+        return $string === '' ? '' : substr($string, strlen($delimiter));
     }
 
     // </editor-fold>