Collection: Add and implement isEmpty(), add PHPStan assertions

Author: lkrms

src/Toolkit/Collection/ReadOnlyCollectionTrait.php

@@ -35,6 +35,14 @@ public function __construct($items = [])
         $this->Items = $this->getItemsArray($items);
     }
 
+    /**
+     * @inheritDoc
+     */
+    public function isEmpty(): bool
+    {
+        return !$this->Items;
+    }
+
     /**
      * @inheritDoc
      */

src/Toolkit/Contract/Collection/CollectionInterface.php

@@ -11,8 +11,6 @@
 use OutOfRangeException;
 
 /**
- * An array-like collection of items
- *
  * @api
  *
  * @template TKey of array-key
@@ -60,6 +58,15 @@ interface CollectionInterface extends
      */
     public function __construct($items = []);
 
+    /**
+     * Check if the collection is empty
+     *
+     * @phpstan-assert-if-false non-empty-array<TKey,TValue> $this->all()
+     * @phpstan-assert-if-false !null $this->first()
+     * @phpstan-assert-if-false !null $this->last()
+     */
+    public function isEmpty(): bool;
+
     /**
      * Add or replace an item with a given key
      *
@@ -73,6 +80,9 @@ public function set($key, $value);
      * Check if an item with a given key exists
      *
      * @param TKey $key
+     * @phpstan-assert-if-true non-empty-array<TKey,TValue> $this->all()
+     * @phpstan-assert-if-true !null $this->first()
+     * @phpstan-assert-if-true !null $this->last()
      */
     public function has($key): bool;
 
@@ -246,6 +256,9 @@ public function slice(int $offset, ?int $length = null);
      * Check if a value is in the collection
      *
      * @param TValue $value
+     * @phpstan-assert-if-true non-empty-array<TKey,TValue> $this->all()
+     * @phpstan-assert-if-true !null $this->first()
+     * @phpstan-assert-if-true !null $this->last()
      */
     public function hasValue($value, bool $strict = false): bool;