json: support frozendict

Author: vstinner

Lib/json/encoder.py

@@ -82,7 +82,7 @@ class JSONEncoder(object):
     +-------------------+---------------+
     | Python            | JSON          |
     +===================+===============+
-    | dict              | object        |
+    | dict, frozendict  | object        |
     +-------------------+---------------+
     | list, tuple       | array         |
     +-------------------+---------------+
@@ -268,6 +268,7 @@ def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,
         ## HACK: hand-optimized bytecode; turn globals into locals
         ValueError=ValueError,
         dict=dict,
+        frozendict=frozendict,
         float=float,
         id=id,
         int=int,
@@ -320,7 +321,7 @@ def _iterencode_list(lst, _current_indent_level):
                     yield buf
                     if isinstance(value, (list, tuple)):
                         chunks = _iterencode_list(value, _current_indent_level)
-                    elif isinstance(value, dict):
+                    elif isinstance(value, (dict, frozendict)):
                         chunks = _iterencode_dict(value, _current_indent_level)
                     else:
                         chunks = _iterencode(value, _current_indent_level)
@@ -407,7 +408,7 @@ def _iterencode_dict(dct, _current_indent_level):
                 else:
                     if isinstance(value, (list, tuple)):
                         chunks = _iterencode_list(value, _current_indent_level)
-                    elif isinstance(value, dict):
+                    elif isinstance(value, (dict, frozendict)):
                         chunks = _iterencode_dict(value, _current_indent_level)
                     else:
                         chunks = _iterencode(value, _current_indent_level)
@@ -441,7 +442,7 @@ def _iterencode(o, _current_indent_level):
             yield _floatstr(o)
         elif isinstance(o, (list, tuple)):
             yield from _iterencode_list(o, _current_indent_level)
-        elif isinstance(o, dict):
+        elif isinstance(o, (dict, frozendict)):
             yield from _iterencode_dict(o, _current_indent_level)
         else:
             if markers is not None:

Modules/_json.c

@@ -1597,7 +1597,7 @@ encoder_listencode_obj(PyEncoderObject *s, PyUnicodeWriter *writer,
         _Py_LeaveRecursiveCall();
         return rv;
     }
-    else if (PyDict_Check(obj)) {
+    else if (PyDict_Check(obj) || PyFrozenDict_Check(obj)) {
         if (_Py_EnterRecursiveCall(" while encoding a JSON object"))
             return -1;
         rv = encoder_listencode_dict(s, writer, obj, indent_level, indent_cache);