Issue #27938: Add a fast-path for us-ascii encoding

Other changes:

* Rewrite _Py_normalize_encoding() as a C implementation of
  encodings.normalize_encoding(). For example, " utf-8 " is now normalized to
  "utf_8". So the fast path is now used for more name variants of the same
  encoding.
* Avoid strcpy() when encoding is NULL: call directly the UTF-8 codec
This commit is contained in:
Victor Stinner 2016-09-05 15:40:10 -07:00
parent a9ab165cd2
commit 942889aae2
1 changed files with 110 additions and 56 deletions

View File

@ -3100,9 +3100,9 @@ PyUnicode_FromEncodedObject(PyObject *obj,
return v;
}
/* Convert encoding to lower case and replace '_' with '-' in order to
catch e.g. UTF_8. Return 0 on error (encoding is longer than lower_len-1),
1 on success. */
/* Normalize an encoding name: C implementation of
encodings.normalize_encoding(). Return 1 on success, or 0 on error (encoding
is longer than lower_len-1). */
int
_Py_normalize_encoding(const char *encoding,
char *lower,
@ -3111,30 +3111,39 @@ _Py_normalize_encoding(const char *encoding,
const char *e;
char *l;
char *l_end;
int punct;
assert(encoding != NULL);
if (encoding == NULL) {
/* 6 == strlen("utf-8") + 1 */
if (lower_len < 6)
return 0;
strcpy(lower, "utf-8");
return 1;
}
e = encoding;
l = lower;
l_end = &lower[lower_len - 1];
while (*e) {
if (l == l_end)
return 0;
if (Py_ISUPPER(*e)) {
*l++ = Py_TOLOWER(*e++);
punct = 0;
while (1) {
char c = *e;
if (c == 0) {
break;
}
else if (*e == '_') {
*l++ = '-';
e++;
if (Py_ISALNUM(c) || c == '.') {
if (punct && l != lower) {
if (l == l_end) {
return 0;
}
*l++ = '_';
}
punct = 0;
if (l == l_end) {
return 0;
}
*l++ = Py_TOLOWER(c);
}
else {
*l++ = *e++;
punct = 1;
}
e++;
}
*l = '\0';
return 1;
@ -3148,28 +3157,51 @@ PyUnicode_Decode(const char *s,
{
PyObject *buffer = NULL, *unicode;
Py_buffer info;
char lower[11]; /* Enough for any encoding shortcut */
char buflower[11]; /* strlen("iso-8859-1\0") == 11, longest shortcut */
if (encoding == NULL) {
return PyUnicode_DecodeUTF8Stateful(s, size, errors, NULL);
}
/* Shortcuts for common default encodings */
if (_Py_normalize_encoding(encoding, lower, sizeof(lower))) {
if ((strcmp(lower, "utf-8") == 0) ||
(strcmp(lower, "utf8") == 0))
return PyUnicode_DecodeUTF8Stateful(s, size, errors, NULL);
else if ((strcmp(lower, "latin-1") == 0) ||
(strcmp(lower, "latin1") == 0) ||
(strcmp(lower, "iso-8859-1") == 0) ||
(strcmp(lower, "iso8859-1") == 0))
return PyUnicode_DecodeLatin1(s, size, errors);
#ifdef HAVE_MBCS
else if (strcmp(lower, "mbcs") == 0)
return PyUnicode_DecodeMBCS(s, size, errors);
#endif
else if (strcmp(lower, "ascii") == 0)
return PyUnicode_DecodeASCII(s, size, errors);
else if (strcmp(lower, "utf-16") == 0)
return PyUnicode_DecodeUTF16(s, size, errors, 0);
else if (strcmp(lower, "utf-32") == 0)
return PyUnicode_DecodeUTF32(s, size, errors, 0);
if (_Py_normalize_encoding(encoding, buflower, sizeof(buflower))) {
char *lower = buflower;
/* Fast paths */
if (lower[0] == 'u' && lower[1] == 't' && lower[2] == 'f') {
lower += 3;
if (*lower == '_') {
/* Match "utf8" and "utf_8" */
lower++;
}
if (lower[0] == '8' && lower[1] == 0) {
return PyUnicode_DecodeUTF8Stateful(s, size, errors, NULL);
}
else if (lower[0] == '1' && lower[1] == '6' && lower[2] == 0) {
return PyUnicode_DecodeUTF16(s, size, errors, 0);
}
else if (lower[0] == '3' && lower[1] == '2' && lower[2] == 0) {
return PyUnicode_DecodeUTF32(s, size, errors, 0);
}
}
else {
if (strcmp(lower, "ascii") == 0
|| strcmp(lower, "us_ascii") == 0) {
return PyUnicode_DecodeASCII(s, size, errors);
}
#ifdef HAVE_MBCS
else if (strcmp(lower, "mbcs") == 0) {
return PyUnicode_DecodeMBCS(s, size, errors);
}
#endif
else if (strcmp(lower, "latin1") == 0
|| strcmp(lower, "latin_1") == 0
|| strcmp(lower, "iso_8859_1") == 0
|| strcmp(lower, "iso8859_1") == 0) {
return PyUnicode_DecodeLatin1(s, size, errors);
}
}
}
/* Decode via the codec registry */
@ -3512,34 +3544,56 @@ PyUnicode_AsEncodedString(PyObject *unicode,
const char *errors)
{
PyObject *v;
char lower[11]; /* Enough for any encoding shortcut */
char buflower[11]; /* strlen("iso_8859_1\0") == 11, longest shortcut */
if (!PyUnicode_Check(unicode)) {
PyErr_BadArgument();
return NULL;
}
if (encoding == NULL) {
return _PyUnicode_AsUTF8String(unicode, errors);
}
/* Shortcuts for common default encodings */
if (_Py_normalize_encoding(encoding, lower, sizeof(lower))) {
if ((strcmp(lower, "utf-8") == 0) ||
(strcmp(lower, "utf8") == 0))
{
if (errors == NULL || strcmp(errors, "strict") == 0)
return _PyUnicode_AsUTF8String(unicode, NULL);
else
if (_Py_normalize_encoding(encoding, buflower, sizeof(buflower))) {
char *lower = buflower;
/* Fast paths */
if (lower[0] == 'u' && lower[1] == 't' && lower[2] == 'f') {
lower += 3;
if (*lower == '_') {
/* Match "utf8" and "utf_8" */
lower++;
}
if (lower[0] == '8' && lower[1] == 0) {
return _PyUnicode_AsUTF8String(unicode, errors);
}
else if (lower[0] == '1' && lower[1] == '6' && lower[2] == 0) {
return _PyUnicode_EncodeUTF16(unicode, errors, 0);
}
else if (lower[0] == '3' && lower[1] == '2' && lower[2] == 0) {
return _PyUnicode_EncodeUTF32(unicode, errors, 0);
}
}
else if ((strcmp(lower, "latin-1") == 0) ||
(strcmp(lower, "latin1") == 0) ||
(strcmp(lower, "iso-8859-1") == 0) ||
(strcmp(lower, "iso8859-1") == 0))
return _PyUnicode_AsLatin1String(unicode, errors);
else {
if (strcmp(lower, "ascii") == 0
|| strcmp(lower, "us_ascii") == 0) {
return _PyUnicode_AsASCIIString(unicode, errors);
}
#ifdef HAVE_MBCS
else if (strcmp(lower, "mbcs") == 0)
return PyUnicode_EncodeCodePage(CP_ACP, unicode, errors);
else if (strcmp(lower, "mbcs") == 0) {
return PyUnicode_EncodeCodePage(CP_ACP, unicode, errors);
}
#endif
else if (strcmp(lower, "ascii") == 0)
return _PyUnicode_AsASCIIString(unicode, errors);
else if (strcmp(lower, "latin1") == 0 ||
strcmp(lower, "latin_1") == 0 ||
strcmp(lower, "iso_8859_1") == 0 ||
strcmp(lower, "iso8859_1") == 0) {
return _PyUnicode_AsLatin1String(unicode, errors);
}
}
}
/* Encode via the codec registry */