Backport of PEP 3101, Advanced String Formatting, from py3k.
Highlights:
- Adding PyObject_Format.
- Adding string.Format class.
- Adding __format__ for str, unicode, int, long, float, datetime.
- Adding builtin format.
- Adding ''.format and u''.format.
- str/unicode fixups for formatters.
The files in Objects/stringlib that implement PEP 3101 (stringdefs.h,
unicodedefs.h, formatter.h, string_format.h) are identical in trunk
and py3k. Any changes from here on should be made to trunk, and
changes will propogate to py3k).
diff --git a/Objects/abstract.c b/Objects/abstract.c
index a377e76..071cbdc 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -348,6 +348,138 @@
return 0;
}
+PyObject *
+PyObject_Format(PyObject* obj, PyObject *format_spec)
+{
+ static PyObject * str__format__ = NULL;
+ PyObject *empty = NULL;
+ PyObject *result = NULL;
+ int spec_is_unicode;
+ int result_is_unicode;
+
+ /* Initialize cached value */
+ if (str__format__ == NULL) {
+ /* Initialize static variable needed by _PyType_Lookup */
+ str__format__ = PyString_InternFromString("__format__");
+ if (str__format__ == NULL)
+ goto done;
+ }
+
+ /* If no format_spec is provided, use an empty string */
+ if (format_spec == NULL) {
+ empty = PyString_FromStringAndSize(NULL, 0);
+ format_spec = empty;
+ }
+
+ /* Check the format_spec type, and make sure it's str or unicode */
+ if (PyUnicode_Check(format_spec))
+ spec_is_unicode = 1;
+ else if (PyString_Check(format_spec))
+ spec_is_unicode = 0;
+ else {
+ PyErr_Format(PyExc_TypeError,
+ "format expects arg 2 to be string "
+ "or unicode, not %.100s", Py_TYPE(format_spec)->tp_name);
+ goto done;
+ }
+
+ /* Make sure the type is initialized. float gets initialized late */
+ if (Py_TYPE(obj)->tp_dict == NULL)
+ if (PyType_Ready(Py_TYPE(obj)) < 0)
+ goto done;
+
+ /* Check for a __format__ method and call it. */
+ if (PyInstance_Check(obj)) {
+ /* We're an instance of a classic class */
+ PyObject *bound_method = PyObject_GetAttr(obj,
+ str__format__);
+ if (bound_method != NULL) {
+ result = PyObject_CallFunctionObjArgs(bound_method,
+ format_spec,
+ NULL);
+ Py_DECREF(bound_method);
+ } else {
+ PyObject *self_as_str;
+ PyObject *format_method;
+
+ PyErr_Clear();
+ /* Per the PEP, convert to str (or unicode,
+ depending on the type of the format
+ specifier). For new-style classes, this
+ logic is done by object.__format__(). */
+ if (spec_is_unicode)
+ self_as_str = PyObject_Unicode(obj);
+ else
+ self_as_str = PyObject_Str(obj);
+ if (self_as_str == NULL)
+ goto done;
+
+ /* Then call str.__format__ on that result */
+ format_method = PyObject_GetAttr(self_as_str,
+ str__format__);
+ if (format_method == NULL) {
+ Py_DECREF(self_as_str);
+ goto done;
+ }
+ result = PyObject_CallFunctionObjArgs(format_method,
+ format_spec,
+ NULL);
+ Py_DECREF(self_as_str);
+ Py_DECREF(format_method);
+ if (result == NULL)
+ goto done;
+ }
+ } else {
+ /* Not an instance of a classic class, use the code
+ from py3k */
+
+ /* Find the (unbound!) __format__ method (a borrowed
+ reference) */
+ PyObject *method = _PyType_Lookup(Py_TYPE(obj),
+ str__format__);
+ if (method == NULL) {
+ PyErr_Format(PyExc_TypeError,
+ "Type %.100s doesn't define __format__",
+ Py_TYPE(obj)->tp_name);
+ goto done;
+ }
+ /* And call it, binding it to the value */
+ result = PyObject_CallFunctionObjArgs(method, obj,
+ format_spec, NULL);
+ }
+
+ if (result == NULL)
+ goto done;
+
+ /* Check the result type, and make sure it's str or unicode */
+ if (PyUnicode_Check(result))
+ result_is_unicode = 1;
+ else if (PyString_Check(result))
+ result_is_unicode = 0;
+ else {
+ PyErr_Format(PyExc_TypeError,
+ "%.100s.__format__ must return string or "
+ "unicode, not %.100s", Py_TYPE(obj)->tp_name,
+ Py_TYPE(result)->tp_name);
+ Py_DECREF(result);
+ result = NULL;
+ goto done;
+ }
+
+ /* Convert to unicode, if needed. Required if spec is unicode
+ and result is str */
+ if (spec_is_unicode && !result_is_unicode) {
+ PyObject *tmp = PyObject_Unicode(result);
+ /* This logic works whether or not tmp is NULL */
+ Py_DECREF(result);
+ result = tmp;
+ }
+
+done:
+ Py_XDECREF(empty);
+ return result;
+}
+
/* Operations on numbers */
int