codekingpro/portable-devtools

1# -*- coding: utf-8 -*-2r"""3    speaklater4    ~~~~~~~~~~5 6    A module that provides lazy strings for translations.  Basically you7    get an object that appears to be a string but changes the value every8    time the value is evaluated based on a callable you provide.9 10    For example you can have a global `lazy_gettext` function that returns11    a lazy string with the value of the current set language.12 13    Example:14 15    >>> from speaklater import make_lazy_string, text_type16    >>> sval = u'Hello World'17    >>> string = make_lazy_string(lambda: sval)18 19    This lazy string will evaluate to the value of the `sval` variable.20 21    >>> string22    l'Hello World'23    >>> text_type(string) == u'Hello World'24    True25    >>> string.upper() == u'HELLO WORLD'26    True27 28    If you change the value, the lazy string will change as well:29 30    >>> sval = u'Hallo Welt'31    >>> string.upper() == u'HALLO WELT'32    True33 34    This is especially handy when combined with a thread local and gettext35    translations or dicts of translatable strings:36 37    >>> from speaklater import make_lazy_gettext38    >>> from threading import local39    >>> l = local()40    >>> l.translations = {u'Yes': 'Ja'}41    >>> lazy_gettext = make_lazy_gettext(lambda: l.translations.get)42    >>> yes = lazy_gettext(u'Yes')43    >>> print(yes)44    Ja45    >>> l.translations[u'Yes'] = u'Si'46    >>> print(yes)47    Si48 49    Lazy strings are no real strings so if you pass this sort of string to50    a function that performs an instance check, it will fail.  In that case51    you have to explicitly convert it with `unicode` and/or `string` depending52    on what string type the lazy string encapsulates.53 54    To check if a string is lazy, you can use the `is_lazy_string` function:55 56    >>> from speaklater import is_lazy_string57    >>> is_lazy_string(u'yes')58    False59    >>> is_lazy_string(yes)60    True61 62    New in version 1.4: python >= 3.3 (and also 2.6 and 2.7) support,63                        repr(lazystring) is l"foo" on py2 and py3 - no "u" on py2!64 65    New in version 1.2: It's now also possible to pass keyword arguments to66    the callback used with `make_lazy_string`.67 68    :copyright: (c) 2010 by Armin Ronacher.69    :license: BSD, see LICENSE for more details.70"""71 72import sys73 74PY2 = sys.version_info[0] == 275_identity = lambda x: x76 77if not PY2:78    text_type = str79    implements_to_string = _identity80    implements_bool = _identity81else:82    text_type = unicode83 84    def implements_to_string(cls):85        cls.__unicode__ = cls.__str__86        cls.__str__ = lambda x: x.__unicode__().encode('utf-8')87        return cls88 89    def implements_bool(cls):90        cls.__nonzero__ = cls.__bool__91        del cls.__bool__92        return cls93 94 95def is_lazy_string(obj):96    """Checks if the given object is a lazy string."""97    return isinstance(obj, _LazyString)98 99 100def make_lazy_string(__func, *args, **kwargs):101    """Creates a lazy string by invoking func with args."""102    return _LazyString(__func, args, kwargs)103 104 105def make_lazy_gettext(lookup_func):106    """Creates a lazy gettext function dispatches to a gettext107    function as returned by `lookup_func`.108 109    Example:110 111    >>> translations = {u'Yes': u'Ja'}112    >>> lazy_gettext = make_lazy_gettext(lambda: translations.get)113    >>> x = lazy_gettext(u'Yes')114    >>> x115    l'Ja'116    >>> translations[u'Yes'] = u'Si'117    >>> x118    l'Si'119    """120    def lazy_gettext(string):121        if is_lazy_string(string):122            return string123        return make_lazy_string(lookup_func(), string)124    return lazy_gettext125 126 127@implements_bool128@implements_to_string129class _LazyString(object):130    """Class for strings created by a function call.131 132    The proxy implementation attempts to be as complete as possible, so that133    the lazy objects should mostly work as expected, for example for sorting.134    """135    __slots__ = ('_func', '_args', '_kwargs')136 137    def __init__(self, func, args, kwargs):138        self._func = func139        self._args = args140        self._kwargs = kwargs141 142    value = property(lambda x: x._func(*x._args, **x._kwargs))143 144    def __contains__(self, key):145        return key in self.value146 147    def __bool__(self):148        return bool(self.value)149 150    def __dir__(self):151        return dir(text_type)152 153    def __iter__(self):154        return iter(self.value)155 156    def __len__(self):157        return len(self.value)158 159    def __str__(self):160        return text_type(self.value)161 162    def __add__(self, other):163        return self.value + other164 165    def __radd__(self, other):166        return other + self.value167 168    def __mod__(self, other):169        return self.value % other170 171    def __rmod__(self, other):172        return other % self.value173 174    def __mul__(self, other):175        return self.value * other176 177    def __rmul__(self, other):178        return other * self.value179 180    def __lt__(self, other):181        return self.value < other182 183    def __le__(self, other):184        return self.value <= other185 186    def __eq__(self, other):187        return self.value == other188 189    def __ne__(self, other):190        return self.value != other191 192    def __gt__(self, other):193        return self.value > other194 195    def __ge__(self, other):196        return self.value >= other197 198    def __getattr__(self, name):199        if name == '__members__':200            return self.__dir__()201        return getattr(self.value, name)202 203    def __getstate__(self):204        return self._func, self._args, self._kwargs205 206    def __setstate__(self, tup):207        self._func, self._args, self._kwargs = tup208 209    def __getitem__(self, key):210        return self.value[key]211 212    def __copy__(self):213        return self214 215    def __repr__(self):216        try:217            r = repr(self.value)218            if PY2 and r.startswith('u'):219                r = r[1:]  # make it look same as on py3220            return 'l' + r221        except Exception:222            return '<%s broken>' % self.__class__.__name__223 224 225if __name__ == '__main__':226    import doctest227    doctest.testmod()228