Feb 15th 2023 update

external/graphqlparser/ast/c.py

@@ -0,0 +1,100 @@
+# Copyright 2019-present, GraphQL Foundation
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from casing import snake
+
+from license import C_LICENSE_COMMENT
+
+def struct_name(type):
+  return 'GraphQLAst' + type
+
+
+def return_type(type):
+  if type == 'OperationKind' or type == 'string':
+    return 'const char *'
+
+  if type == 'boolean':
+    return 'int'
+
+  return 'const struct %s *' % struct_name(type)
+
+
+def field_prototype(owning_type, type, name, nullable, plural):
+  st_name = struct_name(owning_type)
+  if plural:
+    return 'int %s_get_%s_size(const struct %s *node)' % (
+      st_name, snake(name), st_name)
+  else:
+    ret_type = return_type(type)
+    return '%s %s_get_%s(const struct %s *node)' % (
+      ret_type, st_name, snake(name), st_name)
+
+
+class Printer(object):
+  '''Printer for the pure C interface to the AST.
+
+  Merely a set of wrappers around the C++ interface; makes it possible
+  to use the AST from C code and simplifies the task of writing
+  bindings for other langugages.
+
+  The mapping is as follows:
+
+  - For each concrete type, you get an opaque C struct type,
+  accessible only by pointer.
+
+  - For each singular field of a concrete type, you get an accessor
+  function, returning said field in the obvious way.
+
+  - For each plural field of a concrete type, you get an accessor
+  function telling you its size. For access to elements of a plural
+  field, you can use the visitor API.
+
+  - For each union type, you get nothing specific (REVIEW), but you
+    can use the visitor API to work around this entirely.
+
+  '''
+
+  def __init__(self):
+    self._current_type = None
+
+  def start_file(self):
+    print C_LICENSE_COMMENT + '''/** @generated */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+'''
+
+  def end_file(self):
+    print '''
+
+#ifdef __cplusplus
+}
+#endif
+'''
+
+  def start_type(self, name):
+    # Forward declarations for AST nodes.
+    st_name = struct_name(name)
+    print 'struct ' + st_name + ';'
+    self._current_type = name
+
+  def field(self, type, name, nullable, plural):
+    print field_prototype(self._current_type, type, name, nullable, plural) + ';'
+
+  def end_type(self, name):
+    print
+
+  def start_union(self, name):
+    print 'struct ' + struct_name(name) + ';'
+
+  def union_option(self, option):
+    pass
+
+  def end_union(self, name):
+    print