SF patch 670194: Performance enhancement for _strptime.py.
From Brett Cannon. Mostly speedups via caching format string ->
compiled regexp.
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index 1694456..0863426 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -24,7 +24,6 @@
import calendar
from re import compile as re_compile
from re import IGNORECASE
-from string import whitespace as whitespace_string
__author__ = "Brett Cannon"
__email__ = "drifty@bigfoot.com"
@@ -33,6 +32,17 @@
RegexpType = type(re_compile(''))
+def _getlang():
+ # Figure out what the current language is set to.
+ current_lang = locale.getlocale(locale.LC_TIME)[0]
+ if current_lang:
+ return current_lang
+ else:
+ current_lang = locale.getdefaultlocale()[0]
+ if current_lang:
+ return current_lang
+ else:
+ return ''
class LocaleTime(object):
"""Stores and handles locale-specific information related to time.
@@ -285,19 +295,9 @@
self.__timezone = self.__pad(time.tzname, 0)
def __calc_lang(self):
- # Set self.__lang by using locale.getlocale() or
- # locale.getdefaultlocale(). If both turn up empty, set the attribute
- # to ''. This is to stop calls to this method and to make sure
- # strptime() can produce an re object correctly.
- current_lang = locale.getlocale(locale.LC_TIME)[0]
- if current_lang:
- self.__lang = current_lang
- else:
- current_lang = locale.getdefaultlocale()[0]
- if current_lang:
- self.__lang = current_lang
- else:
- self.__lang = ''
+ # Set self.__lang by using __getlang().
+ self.__lang = _getlang()
+
class TimeRE(dict):
@@ -382,8 +382,8 @@
def pattern(self, format):
"""Return re pattern for the format string."""
processed_format = ''
- for whitespace in whitespace_string:
- format = format.replace(whitespace, r'\s*')
+ whitespace_replacement = re_compile('\s+')
+ format = whitespace_replacement.sub('\s*', format)
while format.find('%') != -1:
directive_index = format.index('%')+1
processed_format = "%s%s%s" % (processed_format,
@@ -394,15 +394,31 @@
def compile(self, format):
"""Return a compiled re object for the format string."""
- format = "(?#%s)%s" % (self.locale_time.lang,format)
return re_compile(self.pattern(format), IGNORECASE)
+# Cached TimeRE; probably only need one instance ever so cache it for performance
+_locale_cache = TimeRE()
+# Cached regex objects; same reason as for TimeRE cache
+_regex_cache = dict()
def strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
"""Return a time struct based on the input data and the format string."""
- locale_time = LocaleTime()
- compiled_re = TimeRE(locale_time).compile(format)
- found = compiled_re.match(data_string)
+ global _locale_cache
+ global _regex_cache
+ locale_time = _locale_cache.locale_time
+ # If the language changes, caches are invalidated, so clear them
+ if locale_time.lang != _getlang():
+ _locale_cache = TimeRE()
+ _regex_cache.clear()
+ format_regex = _regex_cache.get(format)
+ if not format_regex:
+ # Limit regex cache size to prevent major bloating of the module;
+ # The value 5 is arbitrary
+ if len(_regex_cache) > 5:
+ _regex_cache.clear()
+ format_regex = _locale_cache.compile(format)
+ _regex_cache[format] = format_regex
+ found = format_regex.match(data_string)
if not found:
raise ValueError("time data did not match format")
year = 1900