Expose tokenCount on the DocumentNode

Replicates graphql/graphql-js@10cc0aca

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Cito

src/graphql/language/ast.py

@@ -411,6 +411,11 @@ class DocumentNode(Node):
     __slots__ = ("definitions",)
 
     definitions: Tuple["DefinitionNode", ...]
+    # The number of tokens in the parsed document. Set by the parser per instance
+    # and deliberately kept out of ``__slots__`` (and therefore out of ``keys``) so
+    # that it is not treated as a traversable attribute, the equivalent of the
+    # non-enumerable ``tokenCount`` property in graphql-js.
+    token_count: int = 0
 
 
 class DefinitionNode(Node):

src/graphql/language/parser.py

@@ -234,13 +234,21 @@ def parse_name(self) -> NameNode:
 
     # Implement the parsing rules in the Document section.
 
+    @property
+    def token_count(self) -> int:
+        """Get the number of tokens that have been parsed so far."""
+        return self._token_counter
+
     def parse_document(self) -> DocumentNode:
         """Document: Definition+"""
         start = self._lexer.token
-        return DocumentNode(
+        document = DocumentNode(
             definitions=self.many(TokenKind.SOF, self.parse_definition, TokenKind.EOF),
             loc=self.loc(start),
         )
+        # Expose the token count as a (non-traversable) attribute on the document.
+        document.token_count = self.token_count
+        return document
 
     _parse_type_system_definition_method_names: Dict[str, str] = {
         "schema": "schema_definition",
@@ -1177,12 +1185,12 @@ def delimited_many(
         return nodes
 
     def advance_lexer(self) -> None:
-        max_tokens = self._max_tokens
         token = self._lexer.advance()
 
-        if max_tokens is not None and token.kind != TokenKind.EOF:
+        if token.kind != TokenKind.EOF:
             self._token_counter += 1
-            if self._token_counter > max_tokens:
+            max_tokens = self._max_tokens
+            if max_tokens is not None and self._token_counter > max_tokens:
                 raise GraphQLSyntaxError(
                     self._lexer.source,
                     token.start,

tests/language/test_parser.py

@@ -87,6 +87,10 @@ def parse_provides_useful_error_when_using_source():
               |      ^
             """)
 
+    def exposes_the_token_count():
+        assert parse("{ foo }").token_count == 3
+        assert parse('{ foo(bar: "baz") }').token_count == 8
+
     def limits_maximum_number_of_tokens():
         assert parse("{ foo }", max_tokens=3)
         with raises(