Issue #14744: Use the new _PyUnicodeWriter internal API to speed up str%args and str.format(args)
* Formatting string, int, float and complex use the _PyUnicodeWriter API. It
avoids a temporary buffer in most cases.
* Add _PyUnicodeWriter_WriteStr() to restore the PyAccu optimization: just
keep a reference to the string if the output is only composed of one string
* Disable overallocation when formatting the last argument of str%args and
str.format(args)
* Overallocation allocates at least 100 characters: add min_length attribute
to the _PyUnicodeWriter structure
* Add new private functions: _PyUnicode_FastCopyCharacters(),
_PyUnicode_FastFill() and _PyUnicode_FromASCII()
The speed up is around 20% in average.
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 07d31b2..3c742c3 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -267,13 +267,15 @@
float_repr(PyFloatObject *v)
{
PyObject *result;
- char *buf = PyOS_double_to_string(PyFloat_AS_DOUBLE(v),
- 'r', 0,
- Py_DTSF_ADD_DOT_0,
- NULL);
+ char *buf;
+
+ buf = PyOS_double_to_string(PyFloat_AS_DOUBLE(v),
+ 'r', 0,
+ Py_DTSF_ADD_DOT_0,
+ NULL);
if (!buf)
return PyErr_NoMemory();
- result = PyUnicode_FromString(buf);
+ result = _PyUnicode_FromASCII(buf, strlen(buf));
PyMem_Free(buf);
return result;
}
@@ -1703,11 +1705,22 @@
float__format__(PyObject *self, PyObject *args)
{
PyObject *format_spec;
+ _PyUnicodeWriter writer;
+ int ret;
if (!PyArg_ParseTuple(args, "U:__format__", &format_spec))
return NULL;
- return _PyFloat_FormatAdvanced(self, format_spec, 0,
- PyUnicode_GET_LENGTH(format_spec));
+
+ _PyUnicodeWriter_Init(&writer, 0);
+ ret = _PyFloat_FormatAdvancedWriter(
+ &writer,
+ self,
+ format_spec, 0, PyUnicode_GET_LENGTH(format_spec));
+ if (ret == -1) {
+ _PyUnicodeWriter_Dealloc(&writer);
+ return NULL;
+ }
+ return _PyUnicodeWriter_Finish(&writer);
}
PyDoc_STRVAR(float__format__doc,