Implement Countable in lazy BSON structures

Author: alcaeus

src/Model/LazyBSONArray.php

@@ -21,17 +21,20 @@
 use ArrayAccess;
 use ArrayIterator;
 use CallbackFilterIterator;
+use Countable;
 use IteratorAggregate;
 use MongoDB\BSON\PackedArray;
 use MongoDB\Codec\CodecLibrary;
 use MongoDB\Codec\LazyBSONCodecLibrary;
 use MongoDB\Exception\InvalidArgumentException;
 use ReturnTypeWillChange;
 
+use function array_filter;
 use function array_key_exists;
 use function array_keys;
 use function array_map;
 use function array_values;
+use function count;
 use function is_array;
 use function is_numeric;
 use function max;
@@ -51,7 +54,7 @@
  * @template-implements ArrayAccess<int, TValue>
  * @template-implements IteratorAggregate<int, TValue>
  */
-final class LazyBSONArray implements ArrayAccess, IteratorAggregate
+final class LazyBSONArray implements ArrayAccess, Countable, IteratorAggregate
 {
     /** @var PackedArray<TValue> */
     private PackedArray $bson;
@@ -106,6 +109,13 @@ public function __construct($input = null, ?CodecLibrary $codecLibrary = null)
         $this->codecLibrary = $codecLibrary ?? new LazyBSONCodecLibrary();
     }
 
+    public function count(): int
+    {
+        $this->readEntirePackedArray();
+
+        return count(array_filter($this->exists));
+    }
+
     /** @return AsListIterator<TValue> */
     public function getIterator(): AsListIterator
     {

src/Model/LazyBSONDocument.php

@@ -21,6 +21,7 @@
 use ArrayAccess;
 use ArrayIterator;
 use CallbackFilterIterator;
+use Countable;
 use Iterator;
 use IteratorAggregate;
 use MongoDB\BSON\Document;
@@ -29,7 +30,9 @@
 use MongoDB\Exception\InvalidArgumentException;
 use ReturnTypeWillChange;
 
+use function array_filter;
 use function array_key_exists;
+use function count;
 use function get_object_vars;
 use function is_array;
 use function is_object;
@@ -50,7 +53,7 @@
  * @template-implements ArrayAccess<string, TValue>
  * @template-implements IteratorAggregate<string, TValue>
  */
-final class LazyBSONDocument implements ArrayAccess, IteratorAggregate
+final class LazyBSONDocument implements ArrayAccess, Countable, IteratorAggregate
 {
     /** @var Document<TValue> */
     private Document $bson;
@@ -67,6 +70,8 @@ final class LazyBSONDocument implements ArrayAccess, IteratorAggregate
     /** @var array<string, true> */
     private array $unset = [];
 
+    private bool $entireDocumentRead = false;
+
     private CodecLibrary $codecLibrary;
 
     /**
@@ -140,6 +145,13 @@ public function __unset(string $name): void
         unset($this->set[$name]);
     }
 
+    public function count(): int
+    {
+        $this->readEntireDocument();
+
+        return count(array_filter($this->exists));
+    }
+
     /** @return Iterator<string, TValue> */
     public function getIterator(): CallbackIterator
     {
@@ -228,6 +240,23 @@ public function offsetUnset($offset): void
         $this->__unset($offset);
     }
 
+    private function readEntireDocument(): void
+    {
+        if ($this->entireDocumentRead) {
+            return;
+        }
+
+        foreach ($this->bson as $offset => $value) {
+            $this->read[$offset] = $value;
+
+            if (! isset($this->exists[$offset])) {
+                $this->exists[$offset] = true;
+            }
+        }
+
+        $this->entireDocumentRead = true;
+    }
+
     private function readFromBson(string $key): void
     {
         if (array_key_exists($key, $this->read)) {

tests/Model/LazyBSONArrayTest.php

@@ -239,4 +239,23 @@ public function testIterator(LazyBSONArray $array): void
         $this->assertInstanceOf(LazyBSONDocument::class, $items[0]);
         $this->assertSame('yay!', $items[1]);
     }
+
+    public function testCount(): void
+    {
+        $array = new LazyBSONArray(PackedArray::fromPHP(['foo', 'bar', 'baz']));
+
+        $this->assertCount(3, $array);
+
+        // Overwrite existing item, count must not change
+        $array[0] = 'yay';
+        $this->assertCount(3, $array);
+
+        // Unset existing element, count must decrease
+        unset($array[1]);
+        $this->assertCount(2, $array);
+
+        // Append element, count must increase again
+        $array[] = 'yay';
+        $this->assertCount(3, $array);
+    }
 }

tests/Model/LazyBSONDocumentTest.php

@@ -289,4 +289,23 @@ public function testIterator(LazyBSONDocument $document): void
         $this->assertInstanceOf(LazyBSONDocument::class, $items['document']);
         $this->assertSame('yay!', $items['new']);
     }
+
+    public function testCount(): void
+    {
+        $document = new LazyBSONDocument(Document::fromPHP(['foo' => 'bar', 'bar' => 'baz']));
+
+        $this->assertCount(2, $document);
+
+        // Overwrite existing item, count must not change
+        $document['foo'] = 'yay';
+        $this->assertCount(2, $document);
+
+        // Unset existing element, count must decrease
+        unset($document['bar']);
+        $this->assertCount(1, $document);
+
+        // Append element, count must increase again
+        $document['baz'] = 'yay';
+        $this->assertCount(2, $document);
+    }
 }