Allow empty strings

Author: grebaldi

src/Parser/Tokenizer/Buffer.php

@@ -47,6 +47,11 @@ public function value(): string
         return $this->fragment?->value ?? '';
     }
 
+    public function isEmpty(): bool
+    {
+        return $this->fragment === null;
+    }
+
     public function flush(TokenType $tokenType): \Iterator
     {
         if ($this->fragment !== null) {

src/Parser/Tokenizer/Token.php

@@ -48,6 +48,19 @@ public static function fromFragment(
         );
     }
 
+    public static function emptyFromDelimitingFragments(
+        TokenType $type,
+        Fragment $startFragment,
+        Fragment $endFragment
+    ): Token {
+        return new Token(
+            $type,
+            '',
+            Boundaries::fromPositions($startFragment->start, $endFragment->end),
+            $startFragment->source
+        );
+    }
+
     public function equals(Token $other): bool
     {
         return ($this->type === $other->type

src/Parser/Tokenizer/Tokenizer.php

@@ -123,15 +123,23 @@ private static function flushRemainder(Buffer $buffer): \Iterator
      */
     private static function string(\Iterator $fragments): \Iterator
     {
-        $delimiter = $fragments->current()->value;
+        $delimiter = $fragments->current();
         $fragments->next();
 
         $buffer = Buffer::empty();
 
         while ($fragments->valid()) {
             switch ($fragments->current()->value) {
-                case $delimiter:
-                    yield from $buffer->flush(TokenType::STRING_QUOTED);
+                case $delimiter->value:
+                    if ($buffer->isEmpty()) {
+                        yield Token::emptyFromDelimitingFragments(
+                            TokenType::STRING_QUOTED,
+                            $delimiter,
+                            $fragments->current()
+                        );
+                    } else {
+                        yield from $buffer->flush(TokenType::STRING_QUOTED);
+                    }
                     $fragments->next();
                     return;
 

test/Integration/Examples/ComponentEmpty/ComponentEmpty.afx

@@ -0,0 +1 @@
+export component Empty { return "" }

test/Integration/Examples/ComponentEmpty/ComponentEmpty.tokens.json

@@ -0,0 +1,58 @@
+[
+  {
+    "type": "KEYWORD_EXPORT",
+    "value": "export"
+  },
+  {
+    "type": "SPACE",
+    "value": " "
+  },
+  {
+    "type": "KEYWORD_COMPONENT",
+    "value": "component"
+  },
+  {
+    "type": "SPACE",
+    "value": " "
+  },
+  {
+    "type": "STRING",
+    "value": "Empty"
+  },
+  {
+    "type": "SPACE",
+    "value": " "
+  },
+  {
+    "type": "BRACKET_CURLY_OPEN",
+    "value": "{"
+  },
+  {
+    "type": "SPACE",
+    "value": " "
+  },
+  {
+    "type": "KEYWORD_RETURN",
+    "value": "return"
+  },
+  {
+    "type": "SPACE",
+    "value": " "
+  },
+  {
+    "type": "STRING_QUOTED",
+    "value": ""
+  },
+  {
+    "type": "SPACE",
+    "value": " "
+  },
+  {
+    "type": "BRACKET_CURLY_CLOSE",
+    "value": "}"
+  },
+  {
+    "type": "END_OF_LINE",
+    "value": "\n"
+  }
+]

test/Integration/TokenizerIntegrationTest.php

@@ -36,6 +36,7 @@ public function tokenizationExamples(): array
         return [
             'Comment' => ["Comment"],
             'Component' => ["Component"],
+            'ComponentEmpty' => ["ComponentEmpty"],
             'ComponentWithKeywords' => ["ComponentWithKeywords"],
             'ComponentWithNesting' => ["ComponentWithNesting"],
             'Enum' => ["Enum"],