Work around is_a() not working for value-types with magic interfaces

e.g. `[] instanceof Traversable`, but ! `is_a([], Traversable::class)`

fixes #20

Author: fredemmott

src/TypeSpec/__Private/KeyedTraversableSpec.php

@@ -26,9 +26,24 @@ public function __construct(
   }
 
   public function assertType(mixed $value): T {
-    if (!is_a($value, $this->outer)) {
-      throw
-        IncorrectTypeException::withValue($this->getTrace(), $this->outer.'<Tk, Tv>', $value);
+    // Switch is needed as values such as PHP arrays pass instanceof, but not is_a()
+    switch ($this->outer) {
+      case KeyedContainer::class:
+        $valid_outer = $value instanceof KeyedContainer;
+        break;
+      case KeyedTraversable::class:
+        $valid_outer = $value instanceof KeyedTraversable;
+        break;
+      default:
+        $valid_outer = is_a($value, $this->outer);
+    }
+
+    if (!$valid_outer) {
+      throw IncorrectTypeException::withValue(
+        $this->getTrace(),
+        $this->outer.'<Tk, Tv>',
+        $value,
+      );
     }
 
     invariant(

src/TypeSpec/__Private/TraversableSpec.php

@@ -31,7 +31,19 @@ public function __construct(
   public function assertType(mixed $value): T {
     $frame = $this->outer.'<T>';
 
-    if (!is_a($value, $this->outer)) {
+    // Switch is needed as values such as PHP arrays pass instanceof, but not is_a()
+    switch ($this->outer) {
+      case Container::class:
+        $valid_outer = $value instanceof Container;
+        break;
+      case Traversable::class:
+        $valid_outer = $value instanceof Traversable;
+        break;
+      default:
+        $valid_outer = is_a($value, $this->outer);
+    }
+
+    if (!$valid_outer) {
       throw
         IncorrectTypeException::withValue($this->getTrace(), $frame, $value);
     }

tests/TypeStructureTest.php

@@ -55,6 +55,8 @@ public function getExampleValidTypes(): array<string, (mixed, mixed)> {
       ),
       'Traversable<int>' =>
         tuple(type_structure(C::class, 'TIntTraversable'), Vector { 123, 456 }),
+      'array as Container<int>' =>
+        tuple(type_structure(C::class, 'TIntContainer'), [123, 456]),
       'Container<int>' =>
         tuple(type_structure(C::class, 'TIntContainer'), Vector { 123, 456 }),
       'KeyedTraversable<string, int>' => tuple(
@@ -65,6 +67,10 @@ public function getExampleValidTypes(): array<string, (mixed, mixed)> {
         type_structure(C::class, 'TStringIntKeyedContainer'),
         Map { 'foo' => 123 },
       ),
+      'PHP array as KeyedContainer<string, int>' => tuple(
+        type_structure(C::class, 'TStringIntKeyedContainer'),
+        ['foo' => 123],
+      ),
       'empty Map<string, string>' =>
         tuple(type_structure(C::class, 'TStringStringMap'), Map {}),
       'Map<string, string>' => tuple(