| # License for code in this file that was taken from Python 2.5. |
| |
| # PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2 |
| # -------------------------------------------- |
| # |
| # 1. This LICENSE AGREEMENT is between the Python Software Foundation |
| # ("PSF"), and the Individual or Organization ("Licensee") accessing and |
| # otherwise using this software ("Python") in source or binary form and |
| # its associated documentation. |
| # |
| # 2. Subject to the terms and conditions of this License Agreement, PSF |
| # hereby grants Licensee a nonexclusive, royalty-free, world-wide |
| # license to reproduce, analyze, test, perform and/or display publicly, |
| # prepare derivative works, distribute, and otherwise use Python |
| # alone or in any derivative version, provided, however, that PSF's |
| # License Agreement and PSF's notice of copyright, i.e., "Copyright (c) |
| # 2001, 2002, 2003, 2004, 2005, 2006, 2007 Python Software Foundation; |
| # All Rights Reserved" are retained in Python alone or in any derivative |
| # version prepared by Licensee. |
| # |
| # 3. In the event Licensee prepares a derivative work that is based on |
| # or incorporates Python or any part thereof, and wants to make |
| # the derivative work available to others as provided herein, then |
| # Licensee hereby agrees to include in any such work a brief summary of |
| # the changes made to Python. |
| # |
| # 4. PSF is making Python available to Licensee on an "AS IS" |
| # basis. PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR |
| # IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND |
| # DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS |
| # FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT |
| # INFRINGE ANY THIRD PARTY RIGHTS. |
| # |
| # 5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON |
| # FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS |
| # A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON, |
| # OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF. |
| # |
| # 6. This License Agreement will automatically terminate upon a material |
| # breach of its terms and conditions. |
| # |
| # 7. Nothing in this License Agreement shall be deemed to create any |
| # relationship of agency, partnership, or joint venture between PSF and |
| # Licensee. This License Agreement does not grant permission to use PSF |
| # trademarks or trade name in a trademark sense to endorse or promote |
| # products or services of Licensee, or any third party. |
| # |
| # 8. By copying, installing or otherwise using Python, Licensee |
| # agrees to be bound by the terms and conditions of this License |
| # Agreement. |
| |
| |
| def curry(_curried_func, *args, **kwargs): |
| def _curried(*moreargs, **morekwargs): |
| return _curried_func(*(args+moreargs), **dict(kwargs, **morekwargs)) |
| return _curried |
| |
| ### Begin from Python 2.5 functools.py ######################################## |
| |
| # Summary of changes made to the Python 2.5 code below: |
| # * swapped ``partial`` for ``curry`` to maintain backwards-compatibility |
| # in Django. |
| # * Wrapped the ``setattr`` call in ``update_wrapper`` with a try-except |
| # block to make it compatible with Python 2.3, which doesn't allow |
| # assigning to ``__name__``. |
| |
| # Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007 Python Software Foundation. |
| # All Rights Reserved. |
| |
| ############################################################################### |
| |
| # update_wrapper() and wraps() are tools to help write |
| # wrapper functions that can handle naive introspection |
| |
| WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__') |
| WRAPPER_UPDATES = ('__dict__',) |
| def update_wrapper(wrapper, |
| wrapped, |
| assigned = WRAPPER_ASSIGNMENTS, |
| updated = WRAPPER_UPDATES): |
| """Update a wrapper function to look like the wrapped function |
| |
| wrapper is the function to be updated |
| wrapped is the original function |
| assigned is a tuple naming the attributes assigned directly |
| from the wrapped function to the wrapper function (defaults to |
| functools.WRAPPER_ASSIGNMENTS) |
| updated is a tuple naming the attributes off the wrapper that |
| are updated with the corresponding attribute from the wrapped |
| function (defaults to functools.WRAPPER_UPDATES) |
| """ |
| for attr in assigned: |
| try: |
| setattr(wrapper, attr, getattr(wrapped, attr)) |
| except TypeError: # Python 2.3 doesn't allow assigning to __name__. |
| pass |
| for attr in updated: |
| getattr(wrapper, attr).update(getattr(wrapped, attr)) |
| # Return the wrapper so this can be used as a decorator via curry() |
| return wrapper |
| |
| def wraps(wrapped, |
| assigned = WRAPPER_ASSIGNMENTS, |
| updated = WRAPPER_UPDATES): |
| """Decorator factory to apply update_wrapper() to a wrapper function |
| |
| Returns a decorator that invokes update_wrapper() with the decorated |
| function as the wrapper argument and the arguments to wraps() as the |
| remaining arguments. Default arguments are as for update_wrapper(). |
| This is a convenience function to simplify applying curry() to |
| update_wrapper(). |
| """ |
| return curry(update_wrapper, wrapped=wrapped, |
| assigned=assigned, updated=updated) |
| |
| ### End from Python 2.5 functools.py ########################################## |
| |
| def memoize(func, cache, num_args): |
| """ |
| Wrap a function so that results for any argument tuple are stored in |
| 'cache'. Note that the args to the function must be usable as dictionary |
| keys. |
| |
| Only the first num_args are considered when creating the key. |
| """ |
| def wrapper(*args): |
| mem_args = args[:num_args] |
| if mem_args in cache: |
| return cache[mem_args] |
| result = func(*args) |
| cache[mem_args] = result |
| return result |
| return wraps(func)(wrapper) |
| |
| class Promise(object): |
| """ |
| This is just a base class for the proxy class created in |
| the closure of the lazy function. It can be used to recognize |
| promises in code. |
| """ |
| pass |
| |
| def lazy(func, *resultclasses): |
| """ |
| Turns any callable into a lazy evaluated callable. You need to give result |
| classes or types -- at least one is needed so that the automatic forcing of |
| the lazy evaluation code is triggered. Results are not memoized; the |
| function is evaluated on every access. |
| """ |
| class __proxy__(Promise): |
| """ |
| Encapsulate a function call and act as a proxy for methods that are |
| called on the result of that function. The function is not evaluated |
| until one of the methods on the result is called. |
| """ |
| __dispatch = None |
| |
| def __init__(self, args, kw): |
| self.__func = func |
| self.__args = args |
| self.__kw = kw |
| if self.__dispatch is None: |
| self.__prepare_class__() |
| |
| def __prepare_class__(cls): |
| cls.__dispatch = {} |
| for resultclass in resultclasses: |
| cls.__dispatch[resultclass] = {} |
| for (k, v) in resultclass.__dict__.items(): |
| if hasattr(cls, k): |
| continue |
| setattr(cls, k, cls.__promise__(resultclass, k, v)) |
| cls._delegate_str = str in resultclasses |
| cls._delegate_unicode = unicode in resultclasses |
| assert not (cls._delegate_str and cls._delegate_unicode), "Cannot call lazy() with both str and unicode return types." |
| if cls._delegate_unicode: |
| cls.__unicode__ = cls.__unicode_cast |
| elif cls._delegate_str: |
| cls.__str__ = cls.__str_cast |
| __prepare_class__ = classmethod(__prepare_class__) |
| |
| def __promise__(cls, klass, funcname, func): |
| # Builds a wrapper around some magic method and registers that magic |
| # method for the given type and method name. |
| def __wrapper__(self, *args, **kw): |
| # Automatically triggers the evaluation of a lazy value and |
| # applies the given magic method of the result type. |
| res = self.__func(*self.__args, **self.__kw) |
| for t in type(res).mro(): |
| if t in self.__dispatch: |
| return self.__dispatch[t][funcname](res, *args, **kw) |
| raise TypeError("Lazy object returned unexpected type.") |
| |
| if klass not in cls.__dispatch: |
| cls.__dispatch[klass] = {} |
| cls.__dispatch[klass][funcname] = func |
| return __wrapper__ |
| __promise__ = classmethod(__promise__) |
| |
| def __unicode_cast(self): |
| return self.__func(*self.__args, **self.__kw) |
| |
| def __str_cast(self): |
| return str(self.__func(*self.__args, **self.__kw)) |
| |
| def __cmp__(self, rhs): |
| if self._delegate_str: |
| s = str(self.__func(*self.__args, **self.__kw)) |
| elif self._delegate_unicode: |
| s = unicode(self.__func(*self.__args, **self.__kw)) |
| else: |
| s = self.__func(*self.__args, **self.__kw) |
| if isinstance(rhs, Promise): |
| return -cmp(rhs, s) |
| else: |
| return cmp(s, rhs) |
| |
| def __mod__(self, rhs): |
| if self._delegate_str: |
| return str(self) % rhs |
| elif self._delegate_unicode: |
| return unicode(self) % rhs |
| else: |
| raise AssertionError('__mod__ not supported for non-string types') |
| |
| def __deepcopy__(self, memo): |
| # Instances of this class are effectively immutable. It's just a |
| # collection of functions. So we don't need to do anything |
| # complicated for copying. |
| memo[id(self)] = self |
| return self |
| |
| def __wrapper__(*args, **kw): |
| # Creates the proxy object, instead of the actual value. |
| return __proxy__(args, kw) |
| |
| return wraps(func)(__wrapper__) |
| |
| def allow_lazy(func, *resultclasses): |
| """ |
| A decorator that allows a function to be called with one or more lazy |
| arguments. If none of the args are lazy, the function is evaluated |
| immediately, otherwise a __proxy__ is returned that will evaluate the |
| function when needed. |
| """ |
| def wrapper(*args, **kwargs): |
| for arg in list(args) + kwargs.values(): |
| if isinstance(arg, Promise): |
| break |
| else: |
| return func(*args, **kwargs) |
| return lazy(func, *resultclasses)(*args, **kwargs) |
| return wraps(func)(wrapper) |
