Patch #1691070 from Roger Upole: Speed up PyArg_ParseTupleAndKeywords() and improve error msg

My tests don't show the promised speed up of 10%. The code is as fast as the old code for simple cases and slightly faster for complex cases with several of args and kwargs. But the patch simplifies the code, too.

1 files changed, 109 insertions, 154 deletions

diff --git a/Python/getargs.c b/Python/getargs.c
index f9205d0..162cf6f 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -1345,6 +1345,7 @@ _PyArg_VaParseTupleAndKeywords_SizeT(PyObject *args,
 	return retval;
 }
 
+#define IS_END_OF_FORMAT(c) (c == '\0' || c == ';' || c == ':')
 
 static int
 vgetargskeywords(PyObject *args, PyObject *keywords, const char *format,
@@ -1352,13 +1353,10 @@ vgetargskeywords(PyObject *args, PyObject *keywords, const char *format,
 {
 	char msgbuf[512];
 	int levels[32];
-	const char *fname, *message;
-	int min, max;
-	const char *formatsave;
+	const char *fname, *msg, *custom_msg, *keyword;
+	int min = INT_MAX;
 	int i, len, nargs, nkeywords;
-	const char *msg;
-	char **p;
-	PyObject *freelist = NULL;
+	PyObject *freelist = NULL, *current_arg;
 
 	assert(args != NULL && PyTuple_Check(args));
 	assert(keywords == NULL || PyDict_Check(keywords));
@@ -1366,168 +1364,108 @@ vgetargskeywords(PyObject *args, PyObject *keywords, const char *format,
 	assert(kwlist != NULL);
 	assert(p_va != NULL);
 
-	/* Search the format:
-	   message <- error msg, if any (else NULL).
-	   fname <- routine name, if any (else NULL).
-	   min <- # of required arguments, or -1 if all are required.
-	   max <- most arguments (required + optional).
-	   Check that kwlist has a non-NULL entry for each arg.
-	   Raise error if a tuple arg spec is found.
-	*/
-	fname = message = NULL;
-	formatsave = format;
-	p = kwlist;
-	min = -1;
-	max = 0;
-	while ((i = *format++) != '\0') {
-		if (isalpha(Py_CHARMASK(i)) && i != 'e') {
-			max++;
-			if (*p == NULL) {
-				PyErr_SetString(PyExc_RuntimeError,
-					"more argument specifiers than "
-					"keyword list entries");
-				return 0;
-			}
-			p++;
-		}
-		else if (i == '|')
-			min = max;
-		else if (i == ':') {
-			fname = format;
-			break;
-		}
-		else if (i == ';') {
-			message = format;
-			break;
-		}
-		else if (i == '(') {
-			PyErr_SetString(PyExc_RuntimeError,
-				"tuple found in format when using keyword "
-				"arguments");
-			return 0;
-		}
-	}
-	format = formatsave;
-	if (*p != NULL) {
-		PyErr_SetString(PyExc_RuntimeError,
-			"more keyword list entries than "
-			"argument specifiers");
-		return 0;
-	}
-	if (min < 0) {
-		/* All arguments are required. */
-		min = max;
+	/* grab the function name or custom error msg first (mutually exclusive) */
+	fname = strchr(format, ':');
+	if (fname) {
+		fname++;
+		custom_msg = NULL;
 	}
-
-	nargs = PyTuple_GET_SIZE(args);
-	nkeywords = keywords == NULL ? 0 : PyDict_Size(keywords);
-
-	/* make sure there are no duplicate values for an argument;
-	   its not clear when to use the term "keyword argument vs. 
-	   keyword parameter in messages */
-	if (nkeywords > 0) {
-		for (i = 0; i < nargs; i++) {
-			const char *thiskw = kwlist[i];
-			if (thiskw == NULL)
-				break;
-			if (PyDict_GetItemString(keywords, thiskw)) {
-				PyErr_Format(PyExc_TypeError,
-					"keyword parameter '%s' was given "
-					"by position and by name",
-					thiskw);
-				return 0;
-			}
-			else if (PyErr_Occurred())
-				return 0;
-		}
+	else {
+		custom_msg = strchr(format,';');
+		if (custom_msg)
+			custom_msg++;
 	}
 
-	/* required arguments missing from args can be supplied by keyword 
-	   arguments; set len to the number of positional arguments, and,
-	   if that's less than the minimum required, add in the number of
-	   required arguments that are supplied by keywords */
-	len = nargs;
-	if (nkeywords > 0 && nargs < min) {
-		for (i = nargs; i < min; i++) {
-			if (PyDict_GetItemString(keywords, kwlist[i]))
-				len++;
-			else if (PyErr_Occurred())
-				return 0;
-		}
-	}
+	/* scan kwlist and get greatest possible nbr of args */
+	for (len=0; kwlist[len]; len++)
+		continue;
 
-	/* make sure we got an acceptable number of arguments; the message
-	   is a little confusing with keywords since keyword arguments
-	   which are supplied, but don't match the required arguments
-	   are not included in the "%d given" part of the message 
-	   XXX and this isn't a bug!? */
-	if (len < min || max < len) {
-		if (message == NULL) {
-			PyOS_snprintf(msgbuf, sizeof(msgbuf),
-				      "%.200s%s takes %s %d argument%s "
-				      "(%d given)",
-				      fname==NULL ? "function" : fname,
-				      fname==NULL ? "" : "()",
-				      min==max ? "exactly"
-			              : len < min ? "at least" : "at most",
-				      len < min ? min : max,
-				      (len < min ? min : max) == 1 ? "" : "s",
-				      len);
-			message = msgbuf;
-		}
-		PyErr_SetString(PyExc_TypeError, message);
+	nargs = PyTuple_GET_SIZE(args);
+	nkeywords = (keywords == NULL) ? 0 : PyDict_Size(keywords);
+	if (nargs + nkeywords > len) {
+		PyErr_Format(PyExc_TypeError, "%s%s takes at most %d "
+			     "argument%s (%d given)",
+			     (fname == NULL) ? "function" : fname,
+			     (fname == NULL) ? "" : "()",
+			     len,
+			     (len == 1) ? "" : "s",
+			     nargs + nkeywords);
 		return 0;
 	}
 
-	/* convert the positional arguments */
-	for (i = 0; i < nargs; i++) {
-		if (*format == '|')
+	/* convert tuple args and keyword args in same loop, using kwlist to drive process */
+	for (i = 0; i < len; i++) {
+		keyword = kwlist[i];
+		if (*format == '|') {
+			min = i;
 			format++;
-		msg = convertitem(PyTuple_GET_ITEM(args, i), &format, p_va,
-				  flags, levels, msgbuf, sizeof(msgbuf), 
-				  &freelist);
-		if (msg) {
-			seterror(i+1, msg, levels, fname, message);
+		}
+		if (IS_END_OF_FORMAT(*format)) {
+			PyErr_Format(PyExc_RuntimeError,
+				     "More keyword list entries (%d) than "
+				     "format specifiers (%d)", len, i);
 			return cleanreturn(0, freelist);
 		}
-	}
-
-	/* handle no keyword parameters in call */	
-	if (nkeywords == 0)
-		return cleanreturn(1, freelist);
-
-	/* convert the keyword arguments; this uses the format 
-	   string where it was left after processing args */
-	for (i = nargs; i < max; i++) {
-		PyObject *item;
-		if (*format == '|')
-			format++;
-		item = PyDict_GetItemString(keywords, kwlist[i]);
-		if (item != NULL) {
-			Py_INCREF(item);
-			msg = convertitem(item, &format, p_va, flags, levels, 
-					  msgbuf, sizeof(msgbuf), &freelist);
-			Py_DECREF(item);
-			if (msg) {
-				seterror(i+1, msg, levels, fname, message);
+		current_arg = NULL;
+		if (nkeywords) {
+			current_arg = PyDict_GetItemString(keywords, keyword);
+		}
+		if (current_arg) {
+			--nkeywords;
+			if (i < nargs) {
+				/* arg present in tuple and in dict */
+				PyErr_Format(PyExc_TypeError,
+					     "Argument given by name ('%s') "
+					     "and position (%d)",
+					     keyword, i+1);
 				return cleanreturn(0, freelist);
 			}
-			--nkeywords;
-			if (nkeywords == 0)
-				break;
 		}
-		else if (PyErr_Occurred())
+		else if (nkeywords && PyErr_Occurred())
 			return cleanreturn(0, freelist);
-		else {
-			msg = skipitem(&format, p_va, flags);
+		else if (i < nargs)
+			current_arg = PyTuple_GET_ITEM(args, i);
+			
+		if (current_arg) {
+			msg = convertitem(current_arg, &format, p_va, flags,
+				levels, msgbuf, sizeof(msgbuf), &freelist);
 			if (msg) {
-				levels[0] = 0;
-				seterror(i+1, msg, levels, fname, message);
+				seterror(i+1, msg, levels, fname, custom_msg);
 				return cleanreturn(0, freelist);
 			}
+			continue;
+		}
+
+		if (i < min) {
+			PyErr_Format(PyExc_TypeError, "Required argument "
+				     "'%s' (pos %d) not found",
+				     keyword, i+1);
+			return cleanreturn(0, freelist);
+		}
+		/* current code reports success when all required args
+		 * fulfilled and no keyword args left, with no further
+		 * validation. XXX Maybe skip this in debug build ?
+		 */
+		if (!nkeywords)
+			return cleanreturn(1, freelist);
+
+		/* We are into optional args, skip thru to any remaining
+		 * keyword args */
+		msg = skipitem(&format, p_va, flags);
+		if (msg) {
+			PyErr_Format(PyExc_RuntimeError, "%s: '%s'", msg,
+				     format);
+			return cleanreturn(0, freelist);
 		}
 	}
 
+	if (!IS_END_OF_FORMAT(*format)) {
+		PyErr_Format(PyExc_RuntimeError,
+			"more argument specifiers than keyword list entries "
+			"(remaining format:'%s')", format);
+		return cleanreturn(0, freelist);
+	}
+
 	/* make sure there are no extraneous keyword arguments */
 	if (nkeywords > 0) {
 		PyObject *key, *value;
@@ -1541,7 +1479,7 @@ vgetargskeywords(PyObject *args, PyObject *keywords, const char *format,
 				return cleanreturn(0, freelist);
 			}
 			ks = PyString_AsString(key);
-			for (i = 0; i < max; i++) {
+			for (i = 0; i < len; i++) {
 				if (!strcmp(ks, kwlist[i])) {
 					match = 1;
 					break;
@@ -1564,7 +1502,7 @@ vgetargskeywords(PyObject *args, PyObject *keywords, const char *format,
 static char *
 skipitem(const char **p_format, va_list *p_va, int flags)
 {
-        const char *format = *p_format;
+	const char *format = *p_format;
 	char c = *format++;
 	
 	switch (c) {
@@ -1671,16 +1609,33 @@ skipitem(const char **p_format, va_list *p_va, int flags)
 			}
 			break;
 		}
-	
+
+	case '(':	/* bypass tuple, not handled at all previously */
+		{
+			char *msg;
+			for (;;) {
+				if (*format==')')
+					break;
+				if (IS_END_OF_FORMAT(*format))
+					return "Unmatched left paren in format "
+					       "string";
+				msg = skipitem(&format, p_va, flags);
+				if (msg)
+					return msg;
+			}
+			format++;
+			break;
+		}
+
+	case ')':
+		return "Unmatched right paren in format string";
+
 	default:
 err:
 		return "impossible<bad format char>";
 	
 	}
 
-	/* The "(...)" format code for tuples is not handled here because
-	 * it is not allowed with keyword args. */
-	
 	*p_format = format;
 	return NULL;
 }