Move common libs to libs/common

libs/common/decorator.py

@@ -0,0 +1,432 @@
+# #########################     LICENSE     ############################ #
+
+# Copyright (c) 2005-2018, 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 re
+import sys
+import inspect
+import operator
+import itertools
+import collections
+
+__version__ = '4.3.0'
+
+if sys.version >= '3':
+    from inspect import getfullargspec
+
+    def get_init(cls):
+        return cls.__init__
+else:
+    FullArgSpec = collections.namedtuple(
+        'FullArgSpec', 'args varargs varkw defaults '
+        'kwonlyargs kwonlydefaults annotations')
+
+    def getfullargspec(f):
+        "A quick and dirty replacement for getfullargspec for Python 2.X"
+        return FullArgSpec._make(inspect.getargspec(f) + ([], None, {}))
+
+    def get_init(cls):
+        return cls.__init__.__func__
+
+try:
+    iscoroutinefunction = inspect.iscoroutinefunction
+except AttributeError:
+    # let's assume there are no coroutine functions in old Python
+    def iscoroutinefunction(f):
+        return False
+
+
+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()
+
+    # make pylint happy
+    args = varargs = varkw = defaults = kwonlyargs = kwonlydefaults = ()
+
+    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)
+                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__ = self.defaults
+        func.__kwdefaults__ = self.kwonlydefaults or 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.search(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 Exception:
+            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())
+        caller = evaldict.get('_call_')  # when called from `decorate`
+        if caller and iscoroutinefunction(caller):
+            body = ('async def %(name)s(%(signature)s):\n' + ibody).replace(
+                'return', 'return await')
+        else:
+            body = 'def %(name)s(%(signature)s):\n' + ibody
+        return self.make(body, evaldict, addsource, **attrs)
+
+
+def decorate(func, caller, extras=()):
+    """
+    decorate(func, caller) decorates a function using a caller.
+    """
+    evaldict = dict(_call_=caller, _func_=func)
+    es = ''
+    for i, extra in enumerate(extras):
+        ex = '_e%d_' % i
+        evaldict[ex] = extra
+        es += ex + ', '
+    fun = FunctionMaker.create(
+        func, "return _call_(_func_, %s%%(shortsignature)s)" % es,
+        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
+    defaultargs, defaults = '', ()
+    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__
+        nargs = caller.__code__.co_argcount
+        ndefs = len(caller.__defaults__ or ())
+        defaultargs = ', '.join(caller.__code__.co_varnames[nargs-ndefs:nargs])
+        if defaultargs:
+            defaultargs += ','
+        defaults = caller.__defaults__
+    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)
+    dec = FunctionMaker.create(
+        '%s(%s func)' % (name, defaultargs),
+        'if func is None: return lambda func:  _decorate_(func, _call, (%s))\n'
+        'return _decorate_(func, _call, (%s))' % (defaultargs, defaultargs),
+        evaldict, doc=doc, module=caller.__module__, __wrapped__=caller)
+    if defaults:
+        dec.__defaults__ = defaults + (None,)
+    return dec
+
+
+# ####################### 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)
+
+
+def contextmanager(func):
+    # Enable Pylint config: contextmanager-decorators=decorator.contextmanager
+    return _contextmanager(func)
+
+
+# ############################ 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