perf: Various micro optimizations

Sort regular expressions to match most common pattern first. Use re.findall() instead of re.finditer(). Reduce allocations for new strings.

multipart.py

@@ -138,13 +138,14 @@ def __get__(self, obj, cls):
 # Header Parser
 # -------------
 
-
-_special = re.escape('()<>@,;:"\\/[]?={} \t')
-_re_special = re.compile(r'[%s]' % _special)
-_quoted_string = r'"(?:\\.|[^"])*"'  # Quoted string
-_value = r'(?:[^%s]+|%s)' % (_special, _quoted_string)  # Save or quoted string
-_option = r'(?:;|^)\s*([^%s]+)\s*=\s*(%s)' % (_special, _value)
-_re_option = re.compile(_option)  # key=value part of an Content-Type like header
+# ASCII minus control or special chars
+_token="[a-zA-Z0-9-!#$%&'*+.^_`|~]+" 
+_re_istoken = re.compile("^%s$" % _token, re.ASCII)
+# A token or quoted-string (simple qs | token | slow qs)
+_value = r'"[^\\"]*"|%s|"(?:\\.|[^"])*"' % _token
+# A "; key=value" pair from content-disposition header
+_option = r'; *(%s) *= *(%s)' % (_token, _value)
+_re_option = re.compile(_option)
 
 
 def header_quote(val):
@@ -153,7 +154,7 @@ def header_quote(val):
         Note: This is NOT the way modern browsers quote field names or filenames
         in Content-Disposition headers. See :func:`content_disposition_quote`
     """
-    if not _re_special.search(val):
+    if _re_istoken.match(val):
         return val
 
     return '"' + val.replace("\\", "\\\\").replace('"', '\\"') + '"'
@@ -216,17 +217,17 @@ def parse_options_header(header, options=None, unquote=header_unquote):
         function. See `content_disposition_unquote`.
 
     """
-    value, sep, tail = header.partition(";")
-    if not sep:
+
+    i = header.find(";")
+    if i < 0:
         return header.lower().strip(), {}
 
     options = options or {}
-    for match in _re_option.finditer(tail):
-        key, val = match.groups()
+    for key, val in _re_option.findall(header, i):
         key = key.lower()
         options[key] = unquote(val, key == "filename")
 
-    return value.lower(), options
+    return header[:i].lower().strip(), options
 
 
 ##############################################################################
@@ -552,7 +553,7 @@ def _close_headers(self):
                     raise self._fail("Invalid Content-Disposition segment header: Wrong type")
                 if "name" not in args and self._parser.strict:
                     raise self._fail("Invalid Content-Disposition segment header: Missing name option")
-                self.name = args.get("name", "")
+                self.name = args.get("name") or ""
                 self.filename = args.get("filename")
             elif h == "Content-Type":
                 self.content_type, args = parse_options_header(v)