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# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of astroid.

#

# astroid is free software: you can redistribute it and/or modify it

# under the terms of the GNU Lesser General Public License as published by the

# Free Software Foundation, either version 2.1 of the License, or (at your

# option) any later version.

#

# astroid is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License

# for more details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with astroid. If not, see <http://www.gnu.org/licenses/>.

#

# The code in this file was originally part of logilab-common, licensed under

# the same license.

""" A few useful function/method decorators."""

import wrapt

@wrapt.decorator

def cached(func, instance, args, kwargs):

    """Simple decorator to cache result of method calls without args."""

    cache = getattr(instance, '__cache', None)

    if cache is None:

        instance.__cache = cache = {}

    try:

        return cache[func]

    except KeyError:

        cache[func] = result = func(*args, **kwargs)

        return result

class cachedproperty(object):

    """ Provides a cached property equivalent to the stacking of

    @cached and @property, but more efficient.

    After first usage, the <property_name> becomes part of the object's

    __dict__. Doing:

      del obj.<property_name> empties the cache.

    Idea taken from the pyramid_ framework and the mercurial_ project.

    .. _pyramid: http://pypi.python.org/pypi/pyramid

    .. _mercurial: http://pypi.python.org/pypi/Mercurial

    """

    __slots__ = ('wrapped',)

    def __init__(self, wrapped):

        try:

            wrapped.__name__

        except AttributeError:

            raise TypeError('%s must have a __name__ attribute' %

                            wrapped)

        self.wrapped = wrapped

    @property

    def __doc__(self):

        doc = getattr(self.wrapped, '__doc__', None)

        return ('<wrapped by the cachedproperty decorator>%s'

                % ('\n%s' % doc if doc else ''))

    def __get__(self, inst, objtype=None):

        if inst is None:

            return self

        val = self.wrapped(inst)

        setattr(inst, self.wrapped.__name__, val)

        return val