Rename Collection class to BaseCollection. Add BaseCollection::isValidType() method to validate type of element before add it to collection. Add BaseCollection ::prepareElements() method to allow preparation of elements in custom way.

src/Collection/BaseCollection.php

@@ -0,0 +1,81 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Meritoo\Common\Collection;
+
+use ArrayAccess;
+use Countable;
+use IteratorAggregate;
+use Meritoo\Common\Traits\CollectionTrait;
+
+/**
+ * Collection of elements with the same type
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ */
+abstract class BaseCollection implements Countable, ArrayAccess, IteratorAggregate
+{
+    use CollectionTrait;
+
+    /**
+     * Class constructor
+     *
+     * @param array $elements (optional) The elements of collection
+     */
+    public function __construct(array $elements = [])
+    {
+        $validated = $this->getElementsWithValidType($elements);
+        $this->elements = $this->prepareElements($validated);
+    }
+
+    /**
+     * Prepares elements to initialize the collection.
+     * Feel free to override and prepare elements in your way.
+     *
+     * @param array $elements The elements of collection to prepare
+     * @return array
+     */
+    protected function prepareElements(array $elements): array
+    {
+        return $elements;
+    }
+
+    /**
+     * Returns elements of collection with valid types
+     *
+     * @param array $elements The elements of collection to verify
+     * @return array
+     */
+    protected function getElementsWithValidType(array $elements): array
+    {
+        if (empty($elements)) {
+            return [];
+        }
+
+        $result = [];
+
+        foreach ($elements as $index => $element) {
+            if (!$this->isValidType($element)) {
+                continue;
+            }
+
+            $result[$index] = $element;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Returns information if given element has valid type
+     *
+     * @param mixed $element Element of collection
+     * @return bool
+     */
+    abstract protected function isValidType($element): bool;
+}

src/Collection/Collection.php

@@ -1,36 +0,0 @@
-<?php
-
-/**
- * (c) Meritoo.pl, http://www.meritoo.pl
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Meritoo\Common\Collection;
-
-use ArrayAccess;
-use Countable;
-use IteratorAggregate;
-use Meritoo\Common\Traits\CollectionTrait;
-
-/**
- * Collection of elements.
- * It's a set of some elements, e.g. objects.
- *
- * @author    Meritoo <github@meritoo.pl>
- * @copyright Meritoo <http://www.meritoo.pl>
- */
-class Collection implements Countable, ArrayAccess, IteratorAggregate
-{
-    use CollectionTrait;
-
-    /**
-     * Class constructor
-     *
-     * @param array $elements (optional) The elements of collection
-     */
-    public function __construct(array $elements = [])
-    {
-        $this->elements = $elements;
-    }
-}

src/Collection/DateTimeCollection.php

@@ -0,0 +1,27 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Meritoo\Common\Collection;
+
+use DateTime;
+
+/**
+ * Collection of DateTime instances
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ */
+class DateTimeCollection extends BaseCollection
+{
+    protected function isValidType($element): bool
+    {
+        return $element instanceof DateTime;
+    }
+}

src/Collection/IntegerCollection.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Meritoo\Common\Collection;
+
+/**
+ * Collection of integers
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ */
+class IntegerCollection extends BaseCollection
+{
+    protected function isValidType($element): bool
+    {
+        return is_int($element);
+    }
+}

src/Collection/StringCollection.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Meritoo\Common\Collection;
+
+/**
+ * Collection of strings
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ */
+class StringCollection extends BaseCollection
+{
+    protected function isValidType($element): bool
+    {
+        return is_string($element);
+    }
+}

src/Collection/Templates.php

@@ -19,7 +19,7 @@ use Meritoo\Common\ValueObject\Template;
  * @author    Meritoo <github@meritoo.pl>
  * @copyright Meritoo <http://www.meritoo.pl>
  */
-class Templates extends Collection
+class Templates extends BaseCollection
 {
     /**
      * Finds and returns template with given index
@@ -61,4 +61,12 @@ class Templates extends Collection
 
         return $result;
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function isValidType($element): bool
+    {
+        return $element instanceof Template;
+    }
 }

src/Traits/Collection/AddTrait.php

@@ -8,7 +8,7 @@
 
 namespace Meritoo\Common\Traits\Collection;
 
-use Meritoo\Common\Collection\Collection;
+use Meritoo\Common\Collection\BaseCollection;
 
 /**
  * Trait for the Collection with add*() methods
@@ -26,6 +26,10 @@ trait AddTrait
      */
     public function add($element, $index = null): void
     {
+        if (!$this->isValidType($element)) {
+            return;
+        }
+
         if (null === $index || '' === $index) {
             $this->elements[] = $element;
 
@@ -38,9 +42,9 @@ trait AddTrait
     /**
      * Adds given elements (at the end of collection)
      *
-     * @param array|Collection $elements   The elements to add
-     * @param bool|false       $useIndexes (optional) If is set to true, indexes of given elements will be used in
-     *                                     this collection. Otherwise - not.
+     * @param array|BaseCollection $elements   The elements to add
+     * @param bool                 $useIndexes (optional) If is set to true, indexes of given elements will be used in
+     *                                         this collection. Otherwise - not.
      */
     public function addMultiple($elements, bool $useIndexes = false): void
     {

src/Utilities/Reflection.php

@@ -10,7 +10,7 @@ namespace Meritoo\Common\Utilities;
 
 use Doctrine\Common\Inflector\Inflector;
 use Doctrine\Common\Persistence\Proxy;
-use Meritoo\Common\Collection\Collection;
+use Meritoo\Common\Collection\BaseCollection;
 use Meritoo\Common\Exception\Reflection\CannotResolveClassNameException;
 use Meritoo\Common\Exception\Reflection\MissingChildClassesException;
 use Meritoo\Common\Exception\Reflection\NotExistingPropertyException;
@@ -207,11 +207,11 @@ class Reflection
      * Returns values of given property for given objects.
      * Looks for proper getter for the property.
      *
-     * @param array|Collection|object $objects  The objects that should contain given property. It may be also one
-     *                                          object.
-     * @param string                  $property Name of the property that contains a value
-     * @param bool                    $force    (optional) If is set to true, try to retrieve value even if the
-     *                                          object does not have property. Otherwise - not.
+     * @param array|BaseCollection|object $objects  The objects that should contain given property. It may be also one
+     *                                              object.
+     * @param string                      $property Name of the property that contains a value
+     * @param bool                        $force    (optional) If is set to true, try to retrieve value even if the
+     *                                              object does not have property. Otherwise - not.
      * @return array
      */
     public static function getPropertyValues($objects, string $property, bool $force = false): array
@@ -224,7 +224,7 @@ class Reflection
             return [];
         }
 
-        if ($objects instanceof Collection) {
+        if ($objects instanceof BaseCollection) {
             $objects = $objects->toArray();
         }