Python Utils (GAE, Tornado, etc)

utils.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright (c) 2011 The Octopus Apps Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# Author: Alejandro M. Bernardis
# Email: alejandro.m.bernardis at gmail.com
# Created: May 8, 2012, 2:15:08 PM 

import datetime
import re

from itertools import izip

#: -- helpers ------------------------------------------------------------------

__all__ = [
   "safe_str_cmp",
   "is_email",
   "bool_to_str",
   "unicode_to_str",
   "datetime_to_str",
   "datetimefull_to_str",
   "date_to_str",
   "time_to_str",
   "timefull_to_str",
   "str_to_unicode",
   "str_to_date",
   "str_to_time",
   "str_to_datetime",
   "get_plural",
   "get_str_plural",
   "regex_email",
   "regex_email_str",
   "regex_username_str",
   "regex_password_str",
   "is_primitive",
]

#: -- safe_str_cmp -------------------------------------------------------------

def safe_str_cmp(a, b):
    if len(a) != len(b):
        return False
    result = 0
    for x, y in izip(a, b):
        result |= ord(x) ^ ord(y)
    return result == 0

#: -- regex_* ------------------------------------------------------------------

regex_username_str = r"^([a-zA-Z0-9_\-\.@]+)$"

regex_password_str = r"^[a-zA-Z0-9+_\-!\$\.#@%]+$"

regex_email_str = r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*"\
                  r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-011\013\014\016-\177])*"'\
                  r')@(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?$'
 
#: -- is_email -----------------------------------------------------------------

regex_email = re.compile(regex_email_str, re.IGNORECASE)

def is_email(value):
    return True if bool(regex_email.match(value)) else False

#: -- wrapper ------------------------------------------------------------------

def swallow_args(func):
    def Decorator(arg, *unused_args):
        if not arg: 
            return None
        return func(arg)
    return Decorator

#: -- convert ------------------------------------------------------------------

@swallow_args
def bool_to_str(arg):
    return str(arg).lower()

@swallow_args
def unicode_to_str(arg):
    return arg.encode("utf-8")

@swallow_args
def datetime_to_str(arg):
    return "%d-%02d-%02d %02d:%02d:%02d" %\
           (arg.year, arg.month, arg.day, 
            arg.hour, arg.minute, arg.second)

@swallow_args
def datetimefull_to_str(arg):
    return "%d-%02d-%02d %02d:%02d:%02d.%06d" %\
           (arg.year, arg.month, arg.day, 
            arg.hour, arg.minute, arg.second, arg.microsecond)

@swallow_args
def date_to_str(arg):
    return arg.strftime("%Y-%m-%d")

@swallow_args
def time_to_str(arg):
    return "%02d:%02d:%02d" %\
           (arg.hour, arg.minute, arg.second)
    
@swallow_args
def timefull_to_str(arg):
    return "%02d:%02d:%02d.%06d" %\
           (arg.hour, arg.minute, arg.second, arg.microsecond)
    
#: -----------------------------------------------------------------------------

def _strptime(arg, strptime_format):
    split_arg = arg.split(".")
    datetime_obj = datetime.datetime.strptime(split_arg[0], strptime_format)
    if len(split_arg) == 2:
        datetime_obj = datetime_obj.replace(microsecond=int(split_arg[1]))
    return datetime_obj

#: -----------------------------------------------------------------------------

def str_to_unicode(arg):
    return unicode(arg, "utf-8")

def str_to_date(arg):
    return _strptime(arg, "%Y-%m-%d").date()

def str_to_time(arg):
    return _strptime(arg, "%H:%M:%S").time()

def str_to_datetime(arg):
    return _strptime(arg, "%Y-%m-%d %H:%M:%S")

#: -- plural -------------------------------------------------------------------

def get_plural(value, singular, plural, message=""):
    try: return plural if value > 1 else singular
    except: return message
    
def get_str_plural(value, singular, plural, message="", template=u"%s %s"):
    return template % (value, get_plural(value, singular, plural))

#: -- minsc --------------------------------------------------------------------

def is_primitive(value):
    primitive = [complex, int, float, long, 
                 bool, str, basestring, unicode, tuple, list]
    return type(value) in primitive