from contextlib import contextmanager
import functools
try:
# py2.7.7+ and py3.3+ have native comparison support
from hmac import compare_digest
except ImportError: # pragma: no cover
compare_digest = None
import inspect
import weakref
from pyramid.exceptions import ConfigurationError, CyclicDependencyError
from pyramid.compat import (
getargspec,
im_func,
is_nonstr_iter,
integer_types,
string_types,
bytes_,
text_,
PY2,
native_,
)
from pyramid.path import DottedNameResolver as _DottedNameResolver
_marker = object()
class DottedNameResolver(_DottedNameResolver):
def __init__(
self, package=None
): # default to package = None for bw compat
_DottedNameResolver.__init__(self, package)
def is_string_or_iterable(v):
if isinstance(v, string_types):
return True
if hasattr(v, '__iter__'):
return True
def as_sorted_tuple(val):
if not is_nonstr_iter(val):
val = (val,)
val = tuple(sorted(val))
return val
class InstancePropertyHelper(object):
"""A helper object for assigning properties and descriptors to instances.
It is not normally possible to do this because descriptors must be
defined on the class itself.
This class is optimized for adding multiple properties at once to an
instance. This is done by calling :meth:`.add_property` once
per-property and then invoking :meth:`.apply` on target objects.
"""
def __init__(self):
self.properties = {}
@classmethod
def make_property(cls, callable, name=None, reify=False):
"""Convert a callable into one suitable for adding to the
instance. This will return a 2-tuple containing the computed
(name, property) pair.
"""
is_property = isinstance(callable, property)
if is_property:
fn = callable
if name is None:
raise ValueError('must specify "name" for a property')
if reify:
raise ValueError('cannot reify a property')
elif name is not None:
fn = lambda this: callable(this)
fn.__name__ = get_callable_name(name)
fn.__doc__ = callable.__doc__
else:
name = callable.__name__
fn = callable
if reify:
import pyramid.decorator # avoid circular import
fn = pyramid.decorator.reify(fn)
elif not is_property:
fn = property(fn)
return name, fn
@classmethod
def apply_properties(cls, target, properties):
"""Accept a list or dict of ``properties`` generated from
:meth:`.make_property` and apply them to a ``target`` object.
"""
attrs = dict(properties)
if attrs:
parent = target.__class__
# fix the module name so it appears to still be the parent
# e.g. pyramid.request instead of pyramid.util
attrs.setdefault('__module__', parent.__module__)
newcls = type(parent.__name__, (parent, object), attrs)
# We assign __provides__ and __implemented__ below to prevent a
# memory leak that results from from the usage of this instance's
# eventual use in an adapter lookup. Adapter lookup results in
# ``zope.interface.implementedBy`` being called with the
# newly-created class as an argument. Because the newly-created
# class has no interface specification data of its own, lookup
# causes new ClassProvides and Implements instances related to our
# just-generated class to be created and set into the newly-created
# class' __dict__. We don't want these instances to be created; we
# want this new class to behave exactly like it is the parent class
# instead. See GitHub issues #1212, #1529 and #1568 for more
# information.
for name in ('__implemented__', '__provides__'):
# we assign these attributes conditionally to make it possible
# to test this class in isolation without having any interfaces
# attached to it
val = getattr(parent, name, _marker)
if val is not _marker:
setattr(newcls, name, val)
target.__class__ = newcls
@classmethod
def set_property(cls, target, callable, name=None, reify=False):
"""A helper method to apply a single property to an instance."""
prop = cls.make_property(callable, name=name, reify=reify)
cls.apply_properties(target, [prop])
def add_property(self, callable, name=None, reify=False):
"""Add a new property configuration.
This should be used in combination with :meth:`.apply` as a
more efficient version of :meth:`.set_property`.
"""
name, fn = self.make_property(callable, name=name, reify=reify)
self.properties[name] = fn
def apply(self, target):
""" Apply all configured properties to the ``target`` instance."""
if self.properties:
self.apply_properties(target, self.properties)
class InstancePropertyMixin(object):
"""Mixin that will allow an instance to add properties at
run-time as if they had been defined via @property or @reify
on the class itself.
"""
def set_property(self, callable, name=None, reify=False):
"""Add a callable or a property descriptor to the instance.
Properties, unlike attributes, are lazily evaluated by executing
an underlying callable when accessed. They can be useful for
adding features to an object without any cost if those features
go unused.
A property may also be reified via the
:class:`pyramid.decorator.reify` decorator by setting
``reify=True``, allowing the result of the evaluation to be
cached. Using this method, the value of the property is only
computed once for the lifetime of the object.
``callable`` can either be a callable that accepts the instance
as its single positional parameter, or it can be a property
descriptor.
If the ``callable`` is a property descriptor, the ``name``
parameter must be supplied or a ``ValueError`` will be raised.
Also note that a property descriptor cannot be reified, so
``reify`` must be ``False``.
If ``name`` is None, the name of the property will be computed
from the name of the ``callable``.
.. code-block:: python
:linenos:
class Foo(InstancePropertyMixin):
_x = 1
def _get_x(self):
return _x
def _set_x(self, value):
self._x = value
foo = Foo()
foo.set_property(property(_get_x, _set_x), name='x')
foo.set_property(_get_x, name='y', reify=True)
>>> foo.x
1
>>> foo.y
1
>>> foo.x = 5
>>> foo.x
5
>>> foo.y # notice y keeps the original value
1
"""
InstancePropertyHelper.set_property(
self, callable, name=name, reify=reify
)
class WeakOrderedSet(object):
"""Maintain a set of items.
Each item is stored as a weakref to avoid extending their lifetime.
The values may be iterated over or the last item added may be
accessed via the ``last`` property.
If items are added more than once, the most recent addition will
be remembered in the order:
order = WeakOrderedSet()
order.add('1')
order.add('2')
order.add('1')
list(order) == ['2', '1']
order.last == '1'
"""
def __init__(self):
self._items = {}
self._order = []
def add(self, item):
""" Add an item to the set."""
oid = id(item)
if oid in self._items:
self._order.remove(oid)
self._order.append(oid)
return
ref = weakref.ref(item, lambda x: self._remove_by_id(oid))
self._items[oid] = ref
self._order.append(oid)
def _remove_by_id(self, oid):
""" Remove an item from the set."""
if oid in self._items:
del self._items[oid]
self._order.remove(oid)
def remove(self, item):
""" Remove an item from the set."""
self._remove_by_id(id(item))
def empty(self):
""" Clear all objects from the set."""
self._items = {}
self._order = []
def __len__(self):
return len(self._order)
def __contains__(self, item):
oid = id(item)
return oid in self._items
def __iter__(self):
return (self._items[oid]() for oid in self._order)
@property
def last(self):
if self._order:
oid = self._order[-1]
return self._items[oid]()
def strings_differ(string1, string2, compare_digest=compare_digest):
"""Check whether two strings differ while avoiding timing attacks.
This function returns True if the given strings differ and False
if they are equal. It's careful not to leak information about *where*
they differ as a result of its running time, which can be very important
to avoid certain timing-related crypto attacks:
http://seb.dbzteam.org/crypto/python-oauth-timing-hmac.pdf
.. versionchanged:: 1.6
Support :func:`hmac.compare_digest` if it is available (Python 2.7.7+
and Python 3.3+).
"""
len_eq = len(string1) == len(string2)
if len_eq:
invalid_bits = 0
left = string1
else:
invalid_bits = 1
left = string2
right = string2
if compare_digest is not None:
invalid_bits += not compare_digest(left, right)
else:
for a, b in zip(left, right):
invalid_bits += a != b
return invalid_bits != 0
def object_description(object):
"""Produce a human-consumable text description of ``object``,
usually involving a Python dotted name. For example:
>>> object_description(None)
u'None'
>>> from xml.dom import minidom
>>> object_description(minidom)
u'module xml.dom.minidom'
>>> object_description(minidom.Attr)
u'class xml.dom.minidom.Attr'
>>> object_description(minidom.Attr.appendChild)
u'method appendChild of class xml.dom.minidom.Attr'
If this method cannot identify the type of the object, a generic
description ala ``object <object.__name__>`` will be returned.
If the object passed is already a string, it is simply returned. If it
is a boolean, an integer, a list, a tuple, a set, or ``None``, a
(possibly shortened) string representation is returned.
"""
if isinstance(object, string_types):
return text_(object)
if isinstance(object, integer_types):
return text_(str(object))
if isinstance(object, (bool, float, type(None))):
return text_(str(object))
if isinstance(object, set):
if PY2:
return shortrepr(object, ')')
else:
return shortrepr(object, '}')
if isinstance(object, tuple):
return shortrepr(object, ')')
if isinstance(object, list):
return shortrepr(object, ']')
if isinstance(object, dict):
return shortrepr(object, '}')
module = inspect.getmodule(object)
if module is None:
return text_('object %s' % str(object))
modulename = module.__name__
if inspect.ismodule(object):
return text_('module %s' % modulename)
if inspect.ismethod(object):
oself = getattr(object, '__self__', None)
if oself is None: # pragma: no cover
oself = getattr(object, 'im_self', None)
return text_(
'method %s of class %s.%s'
% (object.__name__, modulename, oself.__class__.__name__)
)
if inspect.isclass(object):
dottedname = '%s.%s' % (modulename, object.__name__)
return text_('class %s' % dottedname)
if inspect.isfunction(object):
dottedname = '%s.%s' % (modulename, object.__name__)
return text_('function %s' % dottedname)
return text_('object %s' % str(object))
def shortrepr(object, closer):
r = str(object)
if len(r) > 100:
r = r[:100] + ' ... %s' % closer
return r
class Sentinel(object):
def __init__(self, repr):
self.repr = repr
def __repr__(self):
return self.repr
FIRST = Sentinel('FIRST')
LAST = Sentinel('LAST')
class TopologicalSorter(object):
"""A utility class which can be used to perform topological sorts against
tuple-like data."""
def __init__(
self, default_before=LAST, default_after=None, first=FIRST, last=LAST
):
self.names = []
self.req_before = set()
self.req_after = set()
self.name2before = {}
self.name2after = {}
self.name2val = {}
self.order = []
self.default_before = default_before
self.default_after = default_after
self.first = first
self.last = last
def values(self):
return self.name2val.values()
def remove(self, name):
""" Remove a node from the sort input """
self.names.remove(name)
del self.name2val[name]
after = self.name2after.pop(name, [])
if after:
self.req_after.remove(name)
for u in after:
self.order.remove((u, name))
before = self.name2before.pop(name, [])
if before:
self.req_before.remove(name)
for u in before:
self.order.remove((name, u))
def add(self, name, val, after=None, before=None):
"""Add a node to the sort input. The ``name`` should be a string or
any other hashable object, the ``val`` should be the sortable (doesn't
need to be hashable). ``after`` and ``before`` represents the name of
one of the other sortables (or a sequence of such named) or one of the
special sentinel values :attr:`pyramid.util.FIRST`` or
:attr:`pyramid.util.LAST` representing the first or last positions
respectively. ``FIRST`` and ``LAST`` can also be part of a sequence
passed as ``before`` or ``after``. A sortable should not be added
after LAST or before FIRST. An example::
sorter = TopologicalSorter()
sorter.add('a', {'a':1}, before=LAST, after='b')
sorter.add('b', {'b':2}, before=LAST, after='c')
sorter.add('c', {'c':3})
sorter.sorted() # will be {'c':3}, {'b':2}, {'a':1}
"""
if name in self.names:
self.remove(name)
self.names.append(name)
self.name2val[name] = val
if after is None and before is None:
before = self.default_before
after = self.default_after
if after is not None:
if not is_nonstr_iter(after):
after = (after,)
self.name2after[name] = after
self.order += [(u, name) for u in after]
self.req_after.add(name)
if before is not None:
if not is_nonstr_iter(before):
before = (before,)
self.name2before[name] = before
self.order += [(name, o) for o in before]
self.req_before.add(name)
def sorted(self):
""" Returns the sort input values in topologically sorted order"""
order = [(self.first, self.last)]
roots = []
graph = {}
names = [self.first, self.last]
names.extend(self.names)
for a, b in self.order:
order.append((a, b))
def add_node(node):
if node not in graph:
roots.append(node)
graph[node] = [0] # 0 = number of arcs coming into this node
def add_arc(fromnode, tonode):
graph[fromnode].append(tonode)
graph[tonode][0] += 1
if tonode in roots:
roots.remove(tonode)
for name in names:
add_node(name)
has_before, has_after = set(), set()
for a, b in order:
if a in names and b in names: # deal with missing dependencies
add_arc(a, b)
has_before.add(a)
has_after.add(b)
if not self.req_before.issubset(has_before):
raise ConfigurationError(
'Unsatisfied before dependencies: %s'
% (', '.join(sorted(self.req_before - has_before)))
)
if not self.req_after.issubset(has_after):
raise ConfigurationError(
'Unsatisfied after dependencies: %s'
% (', '.join(sorted(self.req_after - has_after)))
)
sorted_names = []
while roots:
root = roots.pop(0)
sorted_names.append(root)
children = graph[root][1:]
for child in children:
arcs = graph[child][0]
arcs -= 1
graph[child][0] = arcs
if arcs == 0:
roots.insert(0, child)
del graph[root]
if graph:
# loop in input
cycledeps = {}
for k, v in graph.items():
cycledeps[k] = v[1:]
raise CyclicDependencyError(cycledeps)
result = []
for name in sorted_names:
if name in self.names:
result.append((name, self.name2val[name]))
return result
def get_callable_name(name):
"""
Verifies that the ``name`` is ascii and will raise a ``ConfigurationError``
if it is not.
"""
try:
return native_(name, 'ascii')
except (UnicodeEncodeError, UnicodeDecodeError):
msg = (
'`name="%s"` is invalid. `name` must be ascii because it is '
'used on __name__ of the method'
)
raise ConfigurationError(msg % name)
@contextmanager
def hide_attrs(obj, *attrs):
"""
Temporarily delete object attrs and restore afterward.
"""
obj_vals = obj.__dict__ if obj is not None else {}
saved_vals = {}
for name in attrs:
saved_vals[name] = obj_vals.pop(name, _marker)
try:
yield
finally:
for name in attrs:
saved_val = saved_vals[name]
if saved_val is not _marker:
obj_vals[name] = saved_val
elif name in obj_vals:
del obj_vals[name]
def is_same_domain(host, pattern):
"""
Return ``True`` if the host is either an exact match or a match
to the wildcard pattern.
Any pattern beginning with a period matches a domain and all of its
subdomains. (e.g. ``.example.com`` matches ``example.com`` and
``foo.example.com``). Anything else is an exact string match.
"""
if not pattern:
return False
pattern = pattern.lower()
return (
pattern[0] == "."
and (host.endswith(pattern) or host == pattern[1:])
or pattern == host
)
def make_contextmanager(fn):
if inspect.isgeneratorfunction(fn):
return contextmanager(fn)
if fn is None:
fn = lambda *a, **kw: None
@contextmanager
@functools.wraps(fn)
def wrapper(*a, **kw):
yield fn(*a, **kw)
return wrapper
def takes_one_arg(callee, attr=None, argname=None):
ismethod = False
if attr is None:
attr = '__call__'
if inspect.isroutine(callee):
fn = callee
elif inspect.isclass(callee):
try:
fn = callee.__init__
except AttributeError:
return False
ismethod = hasattr(fn, '__call__')
else:
try:
fn = getattr(callee, attr)
except AttributeError:
return False
try:
argspec = getargspec(fn)
except TypeError:
return False
args = argspec[0]
if hasattr(fn, im_func) or ismethod:
# it's an instance method (or unbound method on py2)
if not args:
return False
args = args[1:]
if not args:
return False
if len(args) == 1:
return True
if argname:
defaults = argspec[3]
if defaults is None:
defaults = ()
if args[0] == argname:
if len(args) - len(defaults) == 1:
return True
return False
class SimpleSerializer(object):
def loads(self, bstruct):
return native_(bstruct)
def dumps(self, appstruct):
return bytes_(appstruct)
