Improve performance of clean_xml_chars

This commit is contained in:
Flaviu Tamas 2018-09-30 19:51:46 -04:00
parent 115561dac4
commit 756113dd2b

View File

@ -361,34 +361,50 @@ clean_xml_chars(PyObject *self, PyObject *text) {
static PyObject*
clean_xml_chars(PyObject *self, PyObject *text) {
PyObject *result = NULL;
Py_UCS4 *ucs4_text = NULL;
void *result_text = NULL;
Py_ssize_t src_i, target_i;
enum PyUnicode_Kind text_kind;
Py_UCS4 ch;
if (!PyUnicode_Check(text)) {
PyErr_SetString(PyExc_TypeError, "A unicode string is required");
return NULL;
}
if(PyUnicode_READY(text) != 0) {
// just return null, an exception is already set by READY()
return NULL;
}
if(PyUnicode_GET_LENGTH(text) == 0) {
// make sure that malloc(0) will never happen
return text;
}
ucs4_text = PyUnicode_AsUCS4Copy(text);
if (ucs4_text == NULL) return PyErr_NoMemory();
text_kind = PyUnicode_KIND(text);
// Once we've called READY(), our string is in canonical form, which means
// it is encoded using UTF-{8,16,32}, such that each codepoint is one
// element in the array. The value of the Kind enum is the size of each
// character.
result_text = malloc(PyUnicode_GET_LENGTH(text) * text_kind);
if (result_text == NULL) return PyErr_NoMemory();
target_i = 0;
for (src_i = 0; src_i < PyUnicode_GET_LENGTH(text); src_i++) {
ch = ucs4_text[src_i];
ch = PyUnicode_READ(text_kind, PyUnicode_DATA(text), src_i);
// based on https://en.wikipedia.org/wiki/Valid_characters_in_XML#Non-restricted_characters
// python 3.3+ unicode strings never contain surrogate pairs, since if
// they did, they would be represented as UTF-32
if ((0x20 <= ch && ch <= 0xd7ff && ch != 0x7f) ||
ch == 9 || ch == 10 || ch == 13 ||
(0xe000 <= ch && ch <= 0xfffd) ||
(0xffff < ch && ch <= 0x10ffff)) {
// we can overwrite the same buffer that we're reading from because
// all our writes will occur at or before the current character
ucs4_text[target_i] = ch;
PyUnicode_WRITE(text_kind, result_text, target_i, ch);
target_i += 1;
}
}
result = PyUnicode_FromKindAndData(
PyUnicode_4BYTE_KIND, ucs4_text, target_i);
PyMem_Free(ucs4_text);
// using text_kind here is ok because we don't create any characters that
// are larger than might already exist
result = PyUnicode_FromKindAndData(text_kind, result_text, target_i);
free(result_text);
return result;
}
#endif