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Backport of r63826. 

Optimization of str.format() for cases with str, unicode, int, long,
and float arguments.  This gives about 30% speed improvement for the
simplest (but most common) cases.  This patch skips the __format__
dispatch, and also avoids creating an object to hold the format_spec.

Unfortunately there's a complication in 2.6 with int, long, and float
because they always expect str format_specs.  So in the unicode
version of this optimization, just check for unicode objects.  int,
float, long, and str can be added later, if needed.
This commit is contained in:
Eric Smith 2008-08-18 14:27:38 +00:00
parent 8e439a16b2
commit e5bdccc77b
1 changed files with 42 additions and 6 deletions
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48
Objects/stringlib/string_format.h
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@ -483,13 +483,49 @@ render_field(PyObject *fieldobj, SubString *format_spec, OutputString *output)
{
int ok = 0;
PyObject *result = NULL;
PyObject *format_spec_object = NULL;
PyObject *(*formatter)(PyObject *, STRINGLIB_CHAR *, Py_ssize_t) = NULL;
STRINGLIB_CHAR* format_spec_start = format_spec->ptr ?
format_spec->ptr : NULL;
Py_ssize_t format_spec_len = format_spec->ptr ?
format_spec->end - format_spec->ptr : 0;
/* we need to create an object out of the pointers we have */
PyObject *format_spec_object = SubString_new_object_or_empty(format_spec);
if (format_spec_object == NULL)
goto done;
/* If we know the type exactly, skip the lookup of __format__ and just
call the formatter directly. */
#if STRINGLIB_IS_UNICODE
if (PyUnicode_CheckExact(fieldobj))
formatter = _PyUnicode_FormatAdvanced;
/* Unfortunately, there's a problem with checking for int, long,
and float here. If we're being included as unicode, their
formatters expect string format_spec args. For now, just skip
this optimization for unicode. This could be fixed, but it's a
hassle. */
#else
if (PyString_CheckExact(fieldobj))
formatter = _PyBytes_FormatAdvanced;
else if (PyInt_CheckExact(fieldobj))
formatter =_PyInt_FormatAdvanced;
else if (PyLong_CheckExact(fieldobj))
formatter =_PyLong_FormatAdvanced;
else if (PyFloat_CheckExact(fieldobj))
formatter = _PyFloat_FormatAdvanced;
#endif
result = PyObject_Format(fieldobj, format_spec_object);
if (formatter) {
/* we know exactly which formatter will be called when __format__ is
looked up, so call it directly, instead. */
result = formatter(fieldobj, format_spec_start, format_spec_len);
}
else {
/* We need to create an object out of the pointers we have, because
__format__ takes a string/unicode object for format_spec. */
format_spec_object = STRINGLIB_NEW(format_spec_start,
format_spec_len);
if (format_spec_object == NULL)
goto done;
result = PyObject_Format(fieldobj, format_spec_object);
}
if (result == NULL)
goto done;
@ -512,7 +548,7 @@ render_field(PyObject *fieldobj, SubString *format_spec, OutputString *output)
ok = output_data(output,
STRINGLIB_STR(result), STRINGLIB_LEN(result));
done:
Py_DECREF(format_spec_object);
Py_XDECREF(format_spec_object);
Py_XDECREF(result);
return ok;
}