Merge pull request #20 from worksolutions/group-aggregators

Group and Aggregation support

Author: sokolovsky

README.md

@@ -0,0 +1,25 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Functions\ObjectFunctions;
+
+abstract class AbstractFieldAggregator
+{
+
+    private $fieldName;
+
+    public function __construct(string $fieldName)
+    {
+        $this->fieldName = $fieldName;
+    }
+
+    protected function getValue($element)
+    {
+        return ObjectFunctions::getPropertyValue($element, $this->fieldName);
+    }
+
+}

doc/README.ru.md

@@ -0,0 +1,22 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+use WS\Utils\Collections\HashSet;
+
+class AddToSet extends AbstractFieldAggregator implements Aggregator
+{
+
+    public function __invoke(Collection $collection)
+    {
+        $set = new HashSet();
+        foreach ($collection as $element) {
+            $set->add($this->getValue($element));
+        }
+        return $set->toArray();
+    }
+}

src/WS/Utils/Collections/Functions/Group/Aggregator/AbstractFieldAggregator.php

@@ -0,0 +1,13 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+
+interface Aggregator
+{
+    public function __invoke(Collection $collection);
+}

src/WS/Utils/Collections/Functions/Group/Aggregator/AddToSet.php

@@ -0,0 +1,26 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+
+class Avg extends AbstractFieldAggregator implements Aggregator
+{
+
+    public function __invoke(Collection $collection)
+    {
+        $acc = null;
+        $cnt = 0;
+        foreach ($collection as $element) {
+            $acc += $this->getValue($element);
+            $cnt++;
+        }
+        if (!$cnt) {
+            return null;
+        }
+        return $acc / $cnt;
+    }
+}

src/WS/Utils/Collections/Functions/Group/Aggregator/Aggregator.php

@@ -0,0 +1,17 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+
+class Count implements Aggregator
+{
+
+    public function __invoke(Collection $collection)
+    {
+        return $collection->size();
+    }
+}

src/WS/Utils/Collections/Functions/Group/Aggregator/Avg.php

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+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+
+class First extends AbstractFieldAggregator implements Aggregator
+{
+
+    public function __invoke(Collection $collection)
+    {
+        if (!$first = $collection->stream()->findFirst()) {
+            return null;
+        }
+
+        return $this->getValue($first);
+    }
+}

src/WS/Utils/Collections/Functions/Group/Aggregator/Count.php

@@ -0,0 +1,20 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+
+class Last extends AbstractFieldAggregator implements Aggregator
+{
+
+    public function __invoke(Collection $collection)
+    {
+        if (!$last = $collection->stream()->findLast()) {
+            return null;
+        }
+        return $this->getValue($last);
+    }
+}

src/WS/Utils/Collections/Functions/Group/Aggregator/First.php

@@ -0,0 +1,24 @@
+<?php
+/**
+ * @author Igor Pomiluyko <pomiluyko@worksolutions.ru>
+ */
+
+namespace WS\Utils\Collections\Functions\Group\Aggregator;
+
+use WS\Utils\Collections\Collection;
+
+class Max extends AbstractFieldAggregator implements Aggregator
+{
+
+    public function __invoke(Collection $collection)
+    {
+        $max = null;
+        foreach ($collection as $element) {
+            $value = $this->getValue($element);
+            if ($max === null || $max < $value) {
+                $max = $value;
+            }
+        }
+        return $max;
+    }
+}