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Issue #14744: Use the new _PyUnicodeWriter internal API to speed up str%args and str.format(args)

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* 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.
This commit is contained in:
Victor Stinner 2012-05-29 12:57:52 +02:00
parent a1b0c9fc4d
commit d3f0882dfb
12 changed files with 878 additions and 437 deletions
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27
Objects/floatobject.c
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@ -267,13 +267,15 @@ static PyObject *
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 @@ static PyObject *
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,