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# ######################### LICENSE ############################ #
# Copyright (c) 2005-2016, Michele Simionato
# All rights reserved.
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
# Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# Redistributions in bytecode form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in
# the documentation and/or other materials provided with the
# distribution.
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
# TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
# DAMAGE.
"""
Decorator module, see http://pypi.python.org/pypi/decorator
for the documentation.
"""
from __future__ import print_function
import collections
import inspect
import itertools
import operator
import re
import sys
__version__ = '4.0.10'
if sys.version_info >= (3,):
from inspect import getfullargspec
def get_init(cls):
return cls.__init__
else:
class getfullargspec(object):
"A quick and dirty replacement for getfullargspec for Python 2.X"
def __init__(self, f):
self.args, self.varargs, self.varkw, self.defaults = \
inspect.getargspec(f)
self.kwonlyargs = []
self.kwonlydefaults = None
def __iter__(self):
yield self.args
yield self.varargs
yield self.varkw
yield self.defaults
getargspec = inspect.getargspec
def get_init(cls):
return cls.__init__.__func__
# getargspec has been deprecated in Python 3.5
ArgSpec = collections.namedtuple(
'ArgSpec', 'args varargs varkw defaults')
def getargspec(f):
"""A replacement for inspect.getargspec"""
spec = getfullargspec(f)
return ArgSpec(spec.args, spec.varargs, spec.varkw, spec.defaults)
DEF = re.compile(r'\s*def\s*([_\w][_\w\d]*)\s*\(')
# basic functionality
class FunctionMaker(object):
"""
An object with the ability to create functions with a given signature.
It has attributes name, doc, module, signature, defaults, dict and
methods update and make.
"""
# Atomic get-and-increment provided by the GIL
_compile_count = itertools.count()
def __init__(self, func=None, name=None, signature=None,
defaults=None, doc=None, module=None, funcdict=None):
self.shortsignature = signature
if func:
# func can be a class or a callable, but not an instance method
self.name = func.__name__
if self.name == '<lambda>': # small hack for lambda functions
self.name = '_lambda_'
self.doc = func.__doc__
self.module = func.__module__
if inspect.isfunction(func):
argspec = getfullargspec(func)
self.annotations = getattr(func, '__annotations__', {})
for a in ('args', 'varargs', 'varkw', 'defaults', 'kwonlyargs',
'kwonlydefaults'):
setattr(self, a, getattr(argspec, a))
for i, arg in enumerate(self.args):
setattr(self, 'arg%d' % i, arg)
if sys.version_info < (3,): # easy way
self.shortsignature = self.signature = (
inspect.formatargspec(
formatvalue=lambda val: "", *argspec)[1:-1])
else: # Python 3 way
allargs = list(self.args)
allshortargs = list(self.args)
if self.varargs:
allargs.append('*' + self.varargs)
allshortargs.append('*' + self.varargs)
elif self.kwonlyargs:
allargs.append('*') # single star syntax
for a in self.kwonlyargs:
allargs.append('%s=None' % a)
allshortargs.append('%s=%s' % (a, a))
if self.varkw:
allargs.append('**' + self.varkw)
allshortargs.append('**' + self.varkw)
self.signature = ', '.join(allargs)
self.shortsignature = ', '.join(allshortargs)
self.dict = func.__dict__.copy()
# func=None happens when decorating a caller
if name:
self.name = name
if signature is not None:
self.signature = signature
if defaults:
self.defaults = defaults
if doc:
self.doc = doc
if module:
self.module = module
if funcdict:
self.dict = funcdict
# check existence required attributes
assert hasattr(self, 'name')
if not hasattr(self, 'signature'):
raise TypeError('You are decorating a non function: %s' % func)
def update(self, func, **kw):
"Update the signature of func with the data in self"
func.__name__ = self.name
func.__doc__ = getattr(self, 'doc', None)
func.__dict__ = getattr(self, 'dict', {})
func.__defaults__ = getattr(self, 'defaults', ())
func.__kwdefaults__ = getattr(self, 'kwonlydefaults', None)
func.__annotations__ = getattr(self, 'annotations', None)
try:
frame = sys._getframe(3)
except AttributeError: # for IronPython and similar implementations
callermodule = '?'
else:
callermodule = frame.f_globals.get('__name__', '?')
func.__module__ = getattr(self, 'module', callermodule)
func.__dict__.update(kw)
def make(self, src_templ, evaldict=None, addsource=False, **attrs):
"Make a new function from a given template and update the signature"
src = src_templ % vars(self) # expand name and signature
evaldict = evaldict or {}
mo = DEF.match(src)
if mo is None:
raise SyntaxError('not a valid function template\n%s' % src)
name = mo.group(1) # extract the function name
names = set([name] + [arg.strip(' *') for arg in
self.shortsignature.split(',')])
for n in names:
if n in ('_func_', '_call_'):
raise NameError('%s is overridden in\n%s' % (n, src))
if not src.endswith('\n'): # add a newline for old Pythons
src += '\n'
# Ensure each generated function has a unique filename for profilers
# (such as cProfile) that depend on the tuple of (<filename>,
# <definition line>, <function name>) being unique.
filename = '<decorator-gen-%d>' % (next(self._compile_count),)
try:
code = compile(src, filename, 'single')
exec(code, evaldict)
except:
print('Error in generated code:', file=sys.stderr)
print(src, file=sys.stderr)
raise
func = evaldict[name]
if addsource:
attrs['__source__'] = src
self.update(func, **attrs)
return func
@classmethod
def create(cls, obj, body, evaldict, defaults=None,
doc=None, module=None, addsource=True, **attrs):
"""
Create a function from the strings name, signature and body.
evaldict is the evaluation dictionary. If addsource is true an
attribute __source__ is added to the result. The attributes attrs
are added, if any.
"""
if isinstance(obj, str): # "name(signature)"
name, rest = obj.strip().split('(', 1)
signature = rest[:-1] # strip a right parens
func = None
else: # a function
name = None
signature = None
func = obj
self = cls(func, name, signature, defaults, doc, module)
ibody = '\n'.join(' ' + line for line in body.splitlines())
return self.make('def %(name)s(%(signature)s):\n' + ibody,
evaldict, addsource, **attrs)
def decorate(func, caller):
"""
decorate(func, caller) decorates a function using a caller.
"""
evaldict = dict(_call_=caller, _func_=func)
fun = FunctionMaker.create(
func, "return _call_(_func_, %(shortsignature)s)",
evaldict, __wrapped__=func)
if hasattr(func, '__qualname__'):
fun.__qualname__ = func.__qualname__
return fun
def decorator(caller, _func=None):
"""decorator(caller) converts a caller function into a decorator"""
if _func is not None: # return a decorated function
# this is obsolete behavior; you should use decorate instead
return decorate(_func, caller)
# else return a decorator function
if inspect.isclass(caller):
name = caller.__name__.lower()
doc = 'decorator(%s) converts functions/generators into ' \
'factories of %s objects' % (caller.__name__, caller.__name__)
elif inspect.isfunction(caller):
if caller.__name__ == '<lambda>':
name = '_lambda_'
else:
name = caller.__name__
doc = caller.__doc__
else: # assume caller is an object with a __call__ method
name = caller.__class__.__name__.lower()
doc = caller.__call__.__doc__
evaldict = dict(_call_=caller, _decorate_=decorate)
return FunctionMaker.create(
'%s(func)' % name, 'return _decorate_(func, _call_)',
evaldict, doc=doc, module=caller.__module__,
__wrapped__=caller)
# ####################### contextmanager ####################### #
try: # Python >= 3.2
from contextlib import _GeneratorContextManager
except ImportError: # Python >= 2.5
from contextlib import GeneratorContextManager as _GeneratorContextManager
class ContextManager(_GeneratorContextManager):
def __call__(self, func):
"""Context manager decorator"""
return FunctionMaker.create(
func, "with _self_: return _func_(%(shortsignature)s)",
dict(_self_=self, _func_=func), __wrapped__=func)
init = getfullargspec(_GeneratorContextManager.__init__)
n_args = len(init.args)
if n_args == 2 and not init.varargs: # (self, genobj) Python 2.7
def __init__(self, g, *a, **k):
return _GeneratorContextManager.__init__(self, g(*a, **k))
ContextManager.__init__ = __init__
elif n_args == 2 and init.varargs: # (self, gen, *a, **k) Python 3.4
pass
elif n_args == 4: # (self, gen, args, kwds) Python 3.5
def __init__(self, g, *a, **k):
return _GeneratorContextManager.__init__(self, g, a, k)
ContextManager.__init__ = __init__
contextmanager = decorator(ContextManager)
# ############################ dispatch_on ############################ #
def append(a, vancestors):
"""
Append ``a`` to the list of the virtual ancestors, unless it is already
included.
"""
add = True
for j, va in enumerate(vancestors):
if issubclass(va, a):
add = False
break
if issubclass(a, va):
vancestors[j] = a
add = False
if add:
vancestors.append(a)
# inspired from simplegeneric by P.J. Eby and functools.singledispatch
def dispatch_on(*dispatch_args):
"""
Factory of decorators turning a function into a generic function
dispatching on the given arguments.
"""
assert dispatch_args, 'No dispatch args passed'
dispatch_str = '(%s,)' % ', '.join(dispatch_args)
def check(arguments, wrong=operator.ne, msg=''):
"""Make sure one passes the expected number of arguments"""
if wrong(len(arguments), len(dispatch_args)):
raise TypeError('Expected %d arguments, got %d%s' %
(len(dispatch_args), len(arguments), msg))
def gen_func_dec(func):
"""Decorator turning a function into a generic function"""
# first check the dispatch arguments
argset = set(getfullargspec(func).args)
if not set(dispatch_args) <= argset:
raise NameError('Unknown dispatch arguments %s' % dispatch_str)
typemap = {}
def vancestors(*types):
"""
Get a list of sets of virtual ancestors for the given types
"""
check(types)
ras = [[] for _ in range(len(dispatch_args))]
for types_ in typemap:
for t, type_, ra in zip(types, types_, ras):
if issubclass(t, type_) and type_ not in t.__mro__:
append(type_, ra)
return [set(ra) for ra in ras]
def ancestors(*types):
"""
Get a list of virtual MROs, one for each type
"""
check(types)
lists = []
for t, vas in zip(types, vancestors(*types)):
n_vas = len(vas)
if n_vas > 1:
raise RuntimeError(
'Ambiguous dispatch for %s: %s' % (t, vas))
elif n_vas == 1:
va, = vas
mro = type('t', (t, va), {}).__mro__[1:]
else:
mro = t.__mro__
lists.append(mro[:-1]) # discard t and object
return lists
def register(*types):
"""
Decorator to register an implementation for the given types
"""
check(types)
def dec(f):
check(getfullargspec(f).args, operator.lt, ' in ' + f.__name__)
typemap[types] = f
return f
return dec
def dispatch_info(*types):
"""
An utility to introspect the dispatch algorithm
"""
check(types)
lst = []
for anc in itertools.product(*ancestors(*types)):
lst.append(tuple(a.__name__ for a in anc))
return lst
def _dispatch(dispatch_args, *args, **kw):
types = tuple(type(arg) for arg in dispatch_args)
try: # fast path
f = typemap[types]
except KeyError:
pass
else:
return f(*args, **kw)
combinations = itertools.product(*ancestors(*types))
next(combinations) # the first one has been already tried
for types_ in combinations:
f = typemap.get(types_)
if f is not None:
return f(*args, **kw)
# else call the default implementation
return func(*args, **kw)
return FunctionMaker.create(
func, 'return _f_(%s, %%(shortsignature)s)' % dispatch_str,
dict(_f_=_dispatch), register=register, default=func,
typemap=typemap, vancestors=vancestors, ancestors=ancestors,
dispatch_info=dispatch_info, __wrapped__=func)
gen_func_dec.__name__ = 'dispatch_on' + dispatch_str
return gen_func_dec
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