U ku f&@sZdZddlZddlmZddlmZmZmZdddd gZd dZ edfd dZ d d Z dS) z Commonly useful converters. N)_AnnotationExtractor)NOTHINGFactorypipedefault_if_noneoptionalrto_boolcsPfdd}t}|}|r0tj||jd<|}|rLtj||jd<|S)aO A converter that allows an attribute to be optional. An optional attribute is one which can be set to ``None``. Type annotations will be inferred from the wrapped converter's, if it has any. :param callable converter: the converter that is used for non-``None`` values. .. versionadded:: 17.1.0 cs|dkr dS|SNval converterr 3/tmp/pip-unpacked-wheel-563mi0su/attr/converters.pyoptional_converter$sz$optional..optional_converterr return)rZget_first_param_typetypingOptional__annotations__Zget_return_type)rrZxtrtrtr rrrs cstkr|dkrd}t|tk r8|dk r8d}t||dk rHt|ttrrjrdd}t|fdd}n fdd}|S)a A converter that allows to replace ``None`` values by *default* or the result of *factory*. :param default: Value to be used if ``None`` is passed. Passing an instance of `attrs.Factory` is supported, however the ``takes_self`` option is *not*. :param callable factory: A callable that takes no parameters whose result is used if ``None`` is passed. :raises TypeError: If **neither** *default* or *factory* is passed. :raises TypeError: If **both** *default* and *factory* are passed. :raises ValueError: If an instance of `attrs.Factory` is passed with ``takes_self=True``. .. versionadded:: 18.2.0 Nz(Must pass either `default` or `factory`.z5Must pass either `default` or `factory` but not both.z1`takes_self` is not supported by default_if_none.cs|dk r |SSr )factoryr defaultr rdefault_if_none_converterXsz2default_if_none..default_if_none_convertercs|dk r |SSr r r rr rr`s)r TypeErrorr isinstanceZ takes_self ValueError)rrmsgrr rrr6s  cCst|tr|}ddddddddh}d d d d d dddh}z ||krJWdS||krXWd SWntk rnYnXd|}t|dS)a Convert "boolean" strings (e.g., from env. vars.) to real booleans. Values mapping to :code:`True`: - :code:`True` - :code:`"true"` / :code:`"t"` - :code:`"yes"` / :code:`"y"` - :code:`"on"` - :code:`"1"` - :code:`1` Values mapping to :code:`False`: - :code:`False` - :code:`"false"` / :code:`"f"` - :code:`"no"` / :code:`"n"` - :code:`"off"` - :code:`"0"` - :code:`0` :raises ValueError: for any other value. .. versionadded:: 21.3.0 Ttrueryesyon1rFfalsefnonoff0rzCannot convert value to bool: N)rstrlowerrr)r ZtruthyZfalsyrr r rr is   ) __doc__r_compatr_makerrr__all__rrr r r r rs  3