pythongh-125196: Use PyUnicodeWriter for repr(dict) (python#125270)

Objects/dictobject.c

@@ -3200,83 +3200,83 @@ static PyObject *
 dict_repr_lock_held(PyObject *self)
 {
  PyDictObject *mp = (PyDictObject *)self;
- Py_ssize_t i;
  PyObject *key = NULL, *value = NULL;
- _PyUnicodeWriter writer;
- int first;
-
  ASSERT_DICT_LOCKED(mp);
 
- i = Py_ReprEnter((PyObject *)mp);
- if (i != 0) {
- return i > 0 ? PyUnicode_FromString("{...}") : NULL;
+ int res = Py_ReprEnter((PyObject *)mp);
+ if (res != 0) {
+ return (res > 0 ? PyUnicode_FromString("{...}") : NULL);
  }
 
  if (mp->ma_used == 0) {
  Py_ReprLeave((PyObject *)mp);
  return PyUnicode_FromString("{}");
  }
 
- _PyUnicodeWriter_Init(&writer);
- writer.overallocate = 1;
- /* "{" + "1: 2" + ", 3: 4" * (len - 1) + "}" */
- writer.min_length = 1 + 4 + (2 + 4) * (mp->ma_used - 1) + 1;
+ // "{" + "1: 2" + ", 3: 4" * (len - 1) + "}"
+ Py_ssize_t prealloc = 1 + 4 + 6 * (mp->ma_used - 1) + 1;
+ PyUnicodeWriter *writer = PyUnicodeWriter_Create(prealloc);
+ if (writer == NULL) {
+ goto error;
+ }
 
- if (_PyUnicodeWriter_WriteChar(&writer, '{') < 0)
+ if (PyUnicodeWriter_WriteChar(writer, '{') < 0) {
  goto error;
+ }
 
  /* Do repr() on each key+value pair, and insert ": " between them.
  Note that repr may mutate the dict. */
- i = 0;
- first = 1;
+ Py_ssize_t i = 0;
+ int first = 1;
  while (_PyDict_Next((PyObject *)mp, &i, &key, &value, NULL)) {
- PyObject *s;
- int res;
-
- /* Prevent repr from deleting key or value during key format. */
+ // Prevent repr from deleting key or value during key format.
  Py_INCREF(key);
  Py_INCREF(value);
 
  if (!first) {
- if (_PyUnicodeWriter_WriteASCIIString(&writer, ", ", 2) < 0)
+ // Write ", "
+ if (PyUnicodeWriter_WriteChar(writer, ',') < 0) {
+ goto error;
+ }
+ if (PyUnicodeWriter_WriteChar(writer, ' ') < 0) {
  goto error;
+ }
  }
  first = 0;
 
- s = PyObject_Repr(key);
- if (s == NULL)
- goto error;
- res = _PyUnicodeWriter_WriteStr(&writer, s);
- Py_DECREF(s);
- if (res < 0)
+ // Write repr(key)
+ if (PyUnicodeWriter_WriteRepr(writer, key) < 0) {
  goto error;
+ }
 
- if (_PyUnicodeWriter_WriteASCIIString(&writer, ": ", 2) < 0)
+ // Write ": "
+ if (PyUnicodeWriter_WriteChar(writer, ':') < 0) {
  goto error;
-
- s = PyObject_Repr(value);
- if (s == NULL)
+ }
+ if (PyUnicodeWriter_WriteChar(writer, ' ') < 0) {
  goto error;
- res = _PyUnicodeWriter_WriteStr(&writer, s);
- Py_DECREF(s);
- if (res < 0)
+ }
+
+ // Write repr(value)
+ if (PyUnicodeWriter_WriteRepr(writer, value) < 0) {
  goto error;
+ }
 
  Py_CLEAR(key);
  Py_CLEAR(value);
  }
 
- writer.overallocate = 0;
- if (_PyUnicodeWriter_WriteChar(&writer, '}') < 0)
+ if (PyUnicodeWriter_WriteChar(writer, '}') < 0) {
  goto error;
+ }
 
  Py_ReprLeave((PyObject *)mp);
 
- return _PyUnicodeWriter_Finish(&writer);
+ return PyUnicodeWriter_Finish(writer);
 
 error:
  Py_ReprLeave((PyObject *)mp);
- _PyUnicodeWriter_Dealloc(&writer);
+ PyUnicodeWriter_Discard(writer);
  Py_XDECREF(key);
  Py_XDECREF(value);
  return NULL;