Implement iterator

src/ByteArray.php

@@ -9,13 +9,16 @@
 /**
  * A class to hold an array of bytes
  */
-class ByteArray implements \Stringable, \Countable //@todo might implement ArrayAccess or Traversable
+class ByteArray implements \Stringable, \Countable, \Iterator
 {
+    private int $position = 0;
+
     private array $array = [];
 
     private function __construct()
     {
         // Private constructor
+        $this->position = 0;
     }
 
     /**
@@ -94,4 +97,25 @@ public function count(): int
     {
         return count($this->array);
     }
+
+    // Iterator implementation
+    public function rewind(): void {
+        $this->position = 0;
+    }
+
+    public function current(): int {
+        return $this->array[$this->position];
+    }
+
+    public function key(): int {
+        return $this->position;
+    }
+
+    public function next(): void {
+        ++$this->position;
+    }
+
+    public function valid(): bool {
+        return isset($this->array[$this->position]);
+    }
 }

tests/ByteArrayTest.php

@@ -119,4 +119,42 @@ public static function provideCount() : array
             [ByteArray::fromString('🚀'), 4],
         ];
     }
+
+    public function testIterator(): void
+    {
+        $expected = ['f0', '9f', '9a', '80'];
+
+        $i = 0;
+        foreach (ByteArray::fromString('🚀') as $byte) {
+            $this->assertSame($expected[$i++], dechex($byte));
+        }
+
+        $array = ByteArray::fromString('🚀🐸');
+        $this->assertSame(0, $array->key());
+        $this->assertTrue($array->valid());
+        $this->assertSame(240, $array->current()); // First byte
+        $array->next();
+        $this->assertTrue($array->valid());
+        $this->assertSame(159, $array->current()); // Second byte
+        for ($i = 0; $i < 6; $i++) { // Iterate the next 6 bytes
+            $array->next();
+            $this->assertTrue($array->valid());
+        }
+
+        $array->next(); // Now we should be out of range of the array
+        $this->assertFalse($array->valid());
+        $this->assertSame(8, $array->key());
+
+        // But we can keep iterating
+        $array->next();
+        $this->assertFalse($array->valid());
+        $this->assertSame(9, $array->key());
+
+        // And rewind
+        $array->rewind();
+        $this->assertSame(0, $array->key());
+        $this->assertTrue($array->valid());
+        $this->assertSame(240, $array->current()); // First byte
+    }
+
 }