# util/langhelpers.py # Copyright (C) 2005-2022 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php """Routines to help with the creation, loading and introspection of modules, classes, hierarchies, attributes, functions, and methods. """ import collections from functools import update_wrapper import hashlib import inspect import itertools import operator import re import sys import textwrap import types import warnings from . import _collections from . import compat from .. import exc def md5_hex(x): if compat.py3k: x = x.encode("utf-8") m = hashlib.md5() m.update(x) return m.hexdigest() class safe_reraise(object): """Reraise an exception after invoking some handler code. Stores the existing exception info before invoking so that it is maintained across a potential coroutine context switch. e.g.:: try: sess.commit() except: with safe_reraise(): sess.rollback() """ __slots__ = ("warn_only", "_exc_info") def __init__(self, warn_only=False): self.warn_only = warn_only def __enter__(self): self._exc_info = sys.exc_info() def __exit__(self, type_, value, traceback): # see #2703 for notes if type_ is None: exc_type, exc_value, exc_tb = self._exc_info self._exc_info = None # remove potential circular references if not self.warn_only: compat.raise_( exc_value, with_traceback=exc_tb, ) else: if not compat.py3k and self._exc_info and self._exc_info[1]: # emulate Py3K's behavior of telling us when an exception # occurs in an exception handler. warn( "An exception has occurred during handling of a " "previous exception. The previous exception " "is:\n %s %s\n" % (self._exc_info[0], self._exc_info[1]) ) self._exc_info = None # remove potential circular references compat.raise_(value, with_traceback=traceback) def walk_subclasses(cls): seen = set() stack = [cls] while stack: cls = stack.pop() if cls in seen: continue else: seen.add(cls) stack.extend(cls.__subclasses__()) yield cls def string_or_unprintable(element): if isinstance(element, compat.string_types): return element else: try: return str(element) except Exception: return "unprintable element %r" % element def clsname_as_plain_name(cls): return " ".join( n.lower() for n in re.findall(r"([A-Z][a-z]+)", cls.__name__) ) def method_is_overridden(instance_or_cls, against_method): """Return True if the two class methods don't match.""" if not isinstance(instance_or_cls, type): current_cls = instance_or_cls.__class__ else: current_cls = instance_or_cls method_name = against_method.__name__ current_method = getattr(current_cls, method_name) return current_method != against_method def decode_slice(slc): """decode a slice object as sent to __getitem__. takes into account the 2.5 __index__() method, basically. """ ret = [] for x in slc.start, slc.stop, slc.step: if hasattr(x, "__index__"): x = x.__index__() ret.append(x) return tuple(ret) def _unique_symbols(used, *bases): used = set(used) for base in bases: pool = itertools.chain( (base,), compat.itertools_imap(lambda i: base + str(i), range(1000)), ) for sym in pool: if sym not in used: used.add(sym) yield sym break else: raise NameError("exhausted namespace for symbol base %s" % base) def map_bits(fn, n): """Call the given function given each nonzero bit from n.""" while n: b = n & (~n + 1) yield fn(b) n ^= b def decorator(target): """A signature-matching decorator factory.""" def decorate(fn): if not inspect.isfunction(fn) and not inspect.ismethod(fn): raise Exception("not a decoratable function") spec = compat.inspect_getfullargspec(fn) env = {} spec = _update_argspec_defaults_into_env(spec, env) names = tuple(spec[0]) + spec[1:3] + (fn.__name__,) targ_name, fn_name = _unique_symbols(names, "target", "fn") metadata = dict(target=targ_name, fn=fn_name) metadata.update(format_argspec_plus(spec, grouped=False)) metadata["name"] = fn.__name__ code = ( """\ def %(name)s(%(args)s): return %(target)s(%(fn)s, %(apply_kw)s) """ % metadata ) env.update({targ_name: target, fn_name: fn, "__name__": fn.__module__}) decorated = _exec_code_in_env(code, env, fn.__name__) decorated.__defaults__ = getattr(fn, "__func__", fn).__defaults__ decorated.__wrapped__ = fn return update_wrapper(decorated, fn) return update_wrapper(decorate, target) def _update_argspec_defaults_into_env(spec, env): """given a FullArgSpec, convert defaults to be symbol names in an env.""" if spec.defaults: new_defaults = [] i = 0 for arg in spec.defaults: if type(arg).__module__ not in ("builtins", "__builtin__"): name = "x%d" % i env[name] = arg new_defaults.append(name) i += 1 else: new_defaults.append(arg) elem = list(spec) elem[3] = tuple(new_defaults) return compat.FullArgSpec(*elem) else: return spec def _exec_code_in_env(code, env, fn_name): exec(code, env) return env[fn_name] def public_factory(target, location, class_location=None): """Produce a wrapping function for the given cls or classmethod. Rationale here is so that the __init__ method of the class can serve as documentation for the function. """ if isinstance(target, type): fn = target.__init__ callable_ = target doc = ( "Construct a new :class:`%s` object. \n\n" "This constructor is mirrored as a public API function; " "see :func:`sqlalchemy%s` " "for a full usage and argument description." % ( class_location if class_location else ".%s" % target.__name__, location, ) ) else: fn = callable_ = target doc = ( "This function is mirrored; see :func:`sqlalchemy%s` " "for a description of arguments." % location ) location_name = location.split(".")[-1] spec = compat.inspect_getfullargspec(fn) del spec[0][0] metadata = format_argspec_plus(spec, grouped=False) metadata["name"] = location_name code = ( """\ def %(name)s(%(args)s): return cls(%(apply_kw)s) """ % metadata ) env = { "cls": callable_, "symbol": symbol, "__name__": callable_.__module__, } exec(code, env) decorated = env[location_name] if hasattr(fn, "_linked_to"): linked_to, linked_to_location = fn._linked_to linked_to_doc = linked_to.__doc__ if class_location is None: class_location = "%s.%s" % (target.__module__, target.__name__) linked_to_doc = inject_docstring_text( linked_to_doc, ".. container:: inherited_member\n\n " "This documentation is inherited from :func:`sqlalchemy%s`; " "this constructor, :func:`sqlalchemy%s`, " "creates a :class:`sqlalchemy%s` object. See that class for " "additional details describing this subclass." % (linked_to_location, location, class_location), 1, ) decorated.__doc__ = linked_to_doc else: decorated.__doc__ = fn.__doc__ decorated.__module__ = "sqlalchemy" + location.rsplit(".", 1)[0] if decorated.__module__ not in sys.modules: raise ImportError( "public_factory location %s is not in sys.modules" % (decorated.__module__,) ) if compat.py2k or hasattr(fn, "__func__"): fn.__func__.__doc__ = doc if not hasattr(fn.__func__, "_linked_to"): fn.__func__._linked_to = (decorated, location) else: fn.__doc__ = doc if not hasattr(fn, "_linked_to"): fn._linked_to = (decorated, location) return decorated class PluginLoader(object): def __init__(self, group, auto_fn=None): self.group = group self.impls = {} self.auto_fn = auto_fn def clear(self): self.impls.clear() def load(self, name): if name in self.impls: return self.impls[name]() if self.auto_fn: loader = self.auto_fn(name) if loader: self.impls[name] = loader return loader() for impl in compat.importlib_metadata_get(self.group): if impl.name == name: self.impls[name] = impl.load return impl.load() raise exc.NoSuchModuleError( "Can't load plugin: %s:%s" % (self.group, name) ) def register(self, name, modulepath, objname): def load(): mod = compat.import_(modulepath) for token in modulepath.split(".")[1:]: mod = getattr(mod, token) return getattr(mod, objname) self.impls[name] = load def _inspect_func_args(fn): try: co_varkeywords = inspect.CO_VARKEYWORDS except AttributeError: # https://docs.python.org/3/library/inspect.html # The flags are specific to CPython, and may not be defined in other # Python implementations. Furthermore, the flags are an implementation # detail, and can be removed or deprecated in future Python releases. spec = compat.inspect_getfullargspec(fn) return spec[0], bool(spec[2]) else: # use fn.__code__ plus flags to reduce method call overhead co = fn.__code__ nargs = co.co_argcount return ( list(co.co_varnames[:nargs]), bool(co.co_flags & co_varkeywords), ) def get_cls_kwargs(cls, _set=None): r"""Return the full set of inherited kwargs for the given `cls`. Probes a class's __init__ method, collecting all named arguments. If the __init__ defines a \**kwargs catch-all, then the constructor is presumed to pass along unrecognized keywords to its base classes, and the collection process is repeated recursively on each of the bases. Uses a subset of inspect.getfullargspec() to cut down on method overhead, as this is used within the Core typing system to create copies of type objects which is a performance-sensitive operation. No anonymous tuple arguments please ! """ toplevel = _set is None if toplevel: _set = set() ctr = cls.__dict__.get("__init__", False) has_init = ( ctr and isinstance(ctr, types.FunctionType) and isinstance(ctr.__code__, types.CodeType) ) if has_init: names, has_kw = _inspect_func_args(ctr) _set.update(names) if not has_kw and not toplevel: return None if not has_init or has_kw: for c in cls.__bases__: if get_cls_kwargs(c, _set) is None: break _set.discard("self") return _set def get_func_kwargs(func): """Return the set of legal kwargs for the given `func`. Uses getargspec so is safe to call for methods, functions, etc. """ return compat.inspect_getfullargspec(func)[0] def get_callable_argspec(fn, no_self=False, _is_init=False): """Return the argument signature for any callable. All pure-Python callables are accepted, including functions, methods, classes, objects with __call__; builtins and other edge cases like functools.partial() objects raise a TypeError. """ if inspect.isbuiltin(fn): raise TypeError("Can't inspect builtin: %s" % fn) elif inspect.isfunction(fn): if _is_init and no_self: spec = compat.inspect_getfullargspec(fn) return compat.FullArgSpec( spec.args[1:], spec.varargs, spec.varkw, spec.defaults, spec.kwonlyargs, spec.kwonlydefaults, spec.annotations, ) else: return compat.inspect_getfullargspec(fn) elif inspect.ismethod(fn): if no_self and (_is_init or fn.__self__): spec = compat.inspect_getfullargspec(fn.__func__) return compat.FullArgSpec( spec.args[1:], spec.varargs, spec.varkw, spec.defaults, spec.kwonlyargs, spec.kwonlydefaults, spec.annotations, ) else: return compat.inspect_getfullargspec(fn.__func__) elif inspect.isclass(fn): return get_callable_argspec( fn.__init__, no_self=no_self, _is_init=True ) elif hasattr(fn, "__func__"): return compat.inspect_getfullargspec(fn.__func__) elif hasattr(fn, "__call__"): if inspect.ismethod(fn.__call__): return get_callable_argspec(fn.__call__, no_self=no_self) else: raise TypeError("Can't inspect callable: %s" % fn) else: raise TypeError("Can't inspect callable: %s" % fn) def format_argspec_plus(fn, grouped=True): """Returns a dictionary of formatted, introspected function arguments. A enhanced variant of inspect.formatargspec to support code generation. fn An inspectable callable or tuple of inspect getargspec() results. grouped Defaults to True; include (parens, around, argument) lists Returns: args Full inspect.formatargspec for fn self_arg The name of the first positional argument, varargs[0], or None if the function defines no positional arguments. apply_pos args, re-written in calling rather than receiving syntax. Arguments are passed positionally. apply_kw Like apply_pos, except keyword-ish args are passed as keywords. apply_pos_proxied Like apply_pos but omits the self/cls argument Example:: >>> format_argspec_plus(lambda self, a, b, c=3, **d: 123) {'args': '(self, a, b, c=3, **d)', 'self_arg': 'self', 'apply_kw': '(self, a, b, c=c, **d)', 'apply_pos': '(self, a, b, c, **d)'} """ if compat.callable(fn): spec = compat.inspect_getfullargspec(fn) else: spec = fn args = compat.inspect_formatargspec(*spec) apply_pos = compat.inspect_formatargspec( spec[0], spec[1], spec[2], None, spec[4] ) if spec[0]: self_arg = spec[0][0] apply_pos_proxied = compat.inspect_formatargspec( spec[0][1:], spec[1], spec[2], None, spec[4] ) elif spec[1]: # I'm not sure what this is self_arg = "%s[0]" % spec[1] apply_pos_proxied = apply_pos else: self_arg = None apply_pos_proxied = apply_pos num_defaults = 0 if spec[3]: num_defaults += len(spec[3]) if spec[4]: num_defaults += len(spec[4]) name_args = spec[0] + spec[4] if num_defaults: defaulted_vals = name_args[0 - num_defaults :] else: defaulted_vals = () apply_kw = compat.inspect_formatargspec( name_args, spec[1], spec[2], defaulted_vals, formatvalue=lambda x: "=" + x, ) if spec[0]: apply_kw_proxied = compat.inspect_formatargspec( name_args[1:], spec[1], spec[2], defaulted_vals, formatvalue=lambda x: "=" + x, ) else: apply_kw_proxied = apply_kw if grouped: return dict( args=args, self_arg=self_arg, apply_pos=apply_pos, apply_kw=apply_kw, apply_pos_proxied=apply_pos_proxied, apply_kw_proxied=apply_kw_proxied, ) else: return dict( args=args[1:-1], self_arg=self_arg, apply_pos=apply_pos[1:-1], apply_kw=apply_kw[1:-1], apply_pos_proxied=apply_pos_proxied[1:-1], apply_kw_proxied=apply_kw_proxied[1:-1], ) def format_argspec_init(method, grouped=True): """format_argspec_plus with considerations for typical __init__ methods Wraps format_argspec_plus with error handling strategies for typical __init__ cases:: object.__init__ -> (self) other unreflectable (usually C) -> (self, *args, **kwargs) """ if method is object.__init__: args = "(self)" if grouped else "self" proxied = "()" if grouped else "" else: try: return format_argspec_plus(method, grouped=grouped) except TypeError: args = ( "(self, *args, **kwargs)" if grouped else "self, *args, **kwargs" ) proxied = "(*args, **kwargs)" if grouped else "*args, **kwargs" return dict( self_arg="self", args=args, apply_pos=args, apply_kw=args, apply_pos_proxied=proxied, apply_kw_proxied=proxied, ) def create_proxy_methods( target_cls, target_cls_sphinx_name, proxy_cls_sphinx_name, classmethods=(), methods=(), attributes=(), ): """A class decorator that will copy attributes to a proxy class. The class to be instrumented must define a single accessor "_proxied". """ def decorate(cls): def instrument(name, clslevel=False): fn = getattr(target_cls, name) spec = compat.inspect_getfullargspec(fn) env = {"__name__": fn.__module__} spec = _update_argspec_defaults_into_env(spec, env) caller_argspec = format_argspec_plus(spec, grouped=False) metadata = { "name": fn.__name__, "apply_pos_proxied": caller_argspec["apply_pos_proxied"], "apply_kw_proxied": caller_argspec["apply_kw_proxied"], "args": caller_argspec["args"], "self_arg": caller_argspec["self_arg"], } if clslevel: code = ( "def %(name)s(%(args)s):\n" " return target_cls.%(name)s(%(apply_kw_proxied)s)" % metadata ) env["target_cls"] = target_cls else: code = ( "def %(name)s(%(args)s):\n" " return %(self_arg)s._proxied.%(name)s(%(apply_kw_proxied)s)" # noqa E501 % metadata ) proxy_fn = _exec_code_in_env(code, env, fn.__name__) proxy_fn.__defaults__ = getattr(fn, "__func__", fn).__defaults__ proxy_fn.__doc__ = inject_docstring_text( fn.__doc__, ".. container:: class_bases\n\n " "Proxied for the %s class on behalf of the %s class." % (target_cls_sphinx_name, proxy_cls_sphinx_name), 1, ) if clslevel: proxy_fn = classmethod(proxy_fn) return proxy_fn def makeprop(name): attr = target_cls.__dict__.get(name, None) if attr is not None: doc = inject_docstring_text( attr.__doc__, ".. container:: class_bases\n\n " "Proxied for the %s class on behalf of the %s class." % ( target_cls_sphinx_name, proxy_cls_sphinx_name, ), 1, ) else: doc = None code = ( "def set_(self, attr):\n" " self._proxied.%(name)s = attr\n" "def get(self):\n" " return self._proxied.%(name)s\n" "get.__doc__ = doc\n" "getset = property(get, set_)" ) % {"name": name} getset = _exec_code_in_env(code, {"doc": doc}, "getset") return getset for meth in methods: if hasattr(cls, meth): raise TypeError( "class %s already has a method %s" % (cls, meth) ) setattr(cls, meth, instrument(meth)) for prop in attributes: if hasattr(cls, prop): raise TypeError( "class %s already has a method %s" % (cls, prop) ) setattr(cls, prop, makeprop(prop)) for prop in classmethods: if hasattr(cls, prop): raise TypeError( "class %s already has a method %s" % (cls, prop) ) setattr(cls, prop, instrument(prop, clslevel=True)) return cls return decorate def getargspec_init(method): """inspect.getargspec with considerations for typical __init__ methods Wraps inspect.getargspec with error handling for typical __init__ cases:: object.__init__ -> (self) other unreflectable (usually C) -> (self, *args, **kwargs) """ try: return compat.inspect_getfullargspec(method) except TypeError: if method is object.__init__: return (["self"], None, None, None) else: return (["self"], "args", "kwargs", None) def unbound_method_to_callable(func_or_cls): """Adjust the incoming callable such that a 'self' argument is not required. """ if isinstance(func_or_cls, types.MethodType) and not func_or_cls.__self__: return func_or_cls.__func__ else: return func_or_cls def generic_repr(obj, additional_kw=(), to_inspect=None, omit_kwarg=()): """Produce a __repr__() based on direct association of the __init__() specification vs. same-named attributes present. """ if to_inspect is None: to_inspect = [obj] else: to_inspect = _collections.to_list(to_inspect) missing = object() pos_args = [] kw_args = _collections.OrderedDict() vargs = None for i, insp in enumerate(to_inspect): try: spec = compat.inspect_getfullargspec(insp.__init__) except TypeError: continue else: default_len = spec.defaults and len(spec.defaults) or 0 if i == 0: if spec.varargs: vargs = spec.varargs if default_len: pos_args.extend(spec.args[1:-default_len]) else: pos_args.extend(spec.args[1:]) else: kw_args.update( [(arg, missing) for arg in spec.args[1:-default_len]] ) if default_len: kw_args.update( [ (arg, default) for arg, default in zip( spec.args[-default_len:], spec.defaults ) ] ) output = [] output.extend(repr(getattr(obj, arg, None)) for arg in pos_args) if vargs is not None and hasattr(obj, vargs): output.extend([repr(val) for val in getattr(obj, vargs)]) for arg, defval in kw_args.items(): if arg in omit_kwarg: continue try: val = getattr(obj, arg, missing) if val is not missing and val != defval: output.append("%s=%r" % (arg, val)) except Exception: pass if additional_kw: for arg, defval in additional_kw: try: val = getattr(obj, arg, missing) if val is not missing and val != defval: output.append("%s=%r" % (arg, val)) except Exception: pass return "%s(%s)" % (obj.__class__.__name__, ", ".join(output)) class portable_instancemethod(object): """Turn an instancemethod into a (parent, name) pair to produce a serializable callable. """ __slots__ = "target", "name", "kwargs", "__weakref__" def __getstate__(self): return { "target": self.target, "name": self.name, "kwargs": self.kwargs, } def __setstate__(self, state): self.target = state["target"] self.name = state["name"] self.kwargs = state.get("kwargs", ()) def __init__(self, meth, kwargs=()): self.target = meth.__self__ self.name = meth.__name__ self.kwargs = kwargs def __call__(self, *arg, **kw): kw.update(self.kwargs) return getattr(self.target, self.name)(*arg, **kw) def class_hierarchy(cls): """Return an unordered sequence of all classes related to cls. Traverses diamond hierarchies. Fibs slightly: subclasses of builtin types are not returned. Thus class_hierarchy(class A(object)) returns (A, object), not A plus every class systemwide that derives from object. Old-style classes are discarded and hierarchies rooted on them will not be descended. """ if compat.py2k: if isinstance(cls, types.ClassType): return list() hier = {cls} process = list(cls.__mro__) while process: c = process.pop() if compat.py2k: if isinstance(c, types.ClassType): continue bases = ( _ for _ in c.__bases__ if _ not in hier and not isinstance(_, types.ClassType) ) else: bases = (_ for _ in c.__bases__ if _ not in hier) for b in bases: process.append(b) hier.add(b) if compat.py3k: if c.__module__ == "builtins" or not hasattr(c, "__subclasses__"): continue else: if c.__module__ == "__builtin__" or not hasattr( c, "__subclasses__" ): continue for s in [_ for _ in c.__subclasses__() if _ not in hier]: process.append(s) hier.add(s) return list(hier) def iterate_attributes(cls): """iterate all the keys and attributes associated with a class, without using getattr(). Does not use getattr() so that class-sensitive descriptors (i.e. property.__get__()) are not called. """ keys = dir(cls) for key in keys: for c in cls.__mro__: if key in c.__dict__: yield (key, c.__dict__[key]) break def monkeypatch_proxied_specials( into_cls, from_cls, skip=None, only=None, name="self.proxy", from_instance=None, ): """Automates delegation of __specials__ for a proxying type.""" if only: dunders = only else: if skip is None: skip = ( "__slots__", "__del__", "__getattribute__", "__metaclass__", "__getstate__", "__setstate__", ) dunders = [ m for m in dir(from_cls) if ( m.startswith("__") and m.endswith("__") and not hasattr(into_cls, m) and m not in skip ) ] for method in dunders: try: fn = getattr(from_cls, method) if not hasattr(fn, "__call__"): continue fn = getattr(fn, "__func__", fn) except AttributeError: continue try: spec = compat.inspect_getfullargspec(fn) fn_args = compat.inspect_formatargspec(spec[0]) d_args = compat.inspect_formatargspec(spec[0][1:]) except TypeError: fn_args = "(self, *args, **kw)" d_args = "(*args, **kw)" py = ( "def %(method)s%(fn_args)s: " "return %(name)s.%(method)s%(d_args)s" % locals() ) env = from_instance is not None and {name: from_instance} or {} compat.exec_(py, env) try: env[method].__defaults__ = fn.__defaults__ except AttributeError: pass setattr(into_cls, method, env[method]) def methods_equivalent(meth1, meth2): """Return True if the two methods are the same implementation.""" return getattr(meth1, "__func__", meth1) is getattr( meth2, "__func__", meth2 ) def as_interface(obj, cls=None, methods=None, required=None): """Ensure basic interface compliance for an instance or dict of callables. Checks that ``obj`` implements public methods of ``cls`` or has members listed in ``methods``. If ``required`` is not supplied, implementing at least one interface method is sufficient. Methods present on ``obj`` that are not in the interface are ignored. If ``obj`` is a dict and ``dict`` does not meet the interface requirements, the keys of the dictionary are inspected. Keys present in ``obj`` that are not in the interface will raise TypeErrors. Raises TypeError if ``obj`` does not meet the interface criteria. In all passing cases, an object with callable members is returned. In the simple case, ``obj`` is returned as-is; if dict processing kicks in then an anonymous class is returned. obj A type, instance, or dictionary of callables. cls Optional, a type. All public methods of cls are considered the interface. An ``obj`` instance of cls will always pass, ignoring ``required``.. methods Optional, a sequence of method names to consider as the interface. required Optional, a sequence of mandatory implementations. If omitted, an ``obj`` that provides at least one interface method is considered sufficient. As a convenience, required may be a type, in which case all public methods of the type are required. """ if not cls and not methods: raise TypeError("a class or collection of method names are required") if isinstance(cls, type) and isinstance(obj, cls): return obj interface = set(methods or [m for m in dir(cls) if not m.startswith("_")]) implemented = set(dir(obj)) complies = operator.ge if isinstance(required, type): required = interface elif not required: required = set() complies = operator.gt else: required = set(required) if complies(implemented.intersection(interface), required): return obj # No dict duck typing here. if not isinstance(obj, dict): qualifier = complies is operator.gt and "any of" or "all of" raise TypeError( "%r does not implement %s: %s" % (obj, qualifier, ", ".join(interface)) ) class AnonymousInterface(object): """A callable-holding shell.""" if cls: AnonymousInterface.__name__ = "Anonymous" + cls.__name__ found = set() for method, impl in dictlike_iteritems(obj): if method not in interface: raise TypeError("%r: unknown in this interface" % method) if not compat.callable(impl): raise TypeError("%r=%r is not callable" % (method, impl)) setattr(AnonymousInterface, method, staticmethod(impl)) found.add(method) if complies(found, required): return AnonymousInterface raise TypeError( "dictionary does not contain required keys %s" % ", ".join(required - found) ) class memoized_property(object): """A read-only @property that is only evaluated once.""" def __init__(self, fget, doc=None): self.fget = fget self.__doc__ = doc or fget.__doc__ self.__name__ = fget.__name__ def __get__(self, obj, cls): if obj is None: return self obj.__dict__[self.__name__] = result = self.fget(obj) return result def _reset(self, obj): memoized_property.reset(obj, self.__name__) @classmethod def reset(cls, obj, name): obj.__dict__.pop(name, None) def memoized_instancemethod(fn): """Decorate a method memoize its return value. Best applied to no-arg methods: memoization is not sensitive to argument values, and will always return the same value even when called with different arguments. """ def oneshot(self, *args, **kw): result = fn(self, *args, **kw) def memo(*a, **kw): return result memo.__name__ = fn.__name__ memo.__doc__ = fn.__doc__ self.__dict__[fn.__name__] = memo return result return update_wrapper(oneshot, fn) class HasMemoized(object): """A class that maintains the names of memoized elements in a collection for easy cache clearing, generative, etc. """ __slots__ = () _memoized_keys = frozenset() def _reset_memoizations(self): for elem in self._memoized_keys: self.__dict__.pop(elem, None) def _assert_no_memoizations(self): for elem in self._memoized_keys: assert elem not in self.__dict__ def _set_memoized_attribute(self, key, value): self.__dict__[key] = value self._memoized_keys |= {key} class memoized_attribute(object): """A read-only @property that is only evaluated once.""" def __init__(self, fget, doc=None): self.fget = fget self.__doc__ = doc or fget.__doc__ self.__name__ = fget.__name__ def __get__(self, obj, cls): if obj is None: return self obj.__dict__[self.__name__] = result = self.fget(obj) obj._memoized_keys |= {self.__name__} return result @classmethod def memoized_instancemethod(cls, fn): """Decorate a method memoize its return value.""" def oneshot(self, *args, **kw): result = fn(self, *args, **kw) def memo(*a, **kw): return result memo.__name__ = fn.__name__ memo.__doc__ = fn.__doc__ self.__dict__[fn.__name__] = memo self._memoized_keys |= {fn.__name__} return result return update_wrapper(oneshot, fn) class MemoizedSlots(object): """Apply memoized items to an object using a __getattr__ scheme. This allows the functionality of memoized_property and memoized_instancemethod to be available to a class using __slots__. """ __slots__ = () def _fallback_getattr(self, key): raise AttributeError(key) def __getattr__(self, key): if key.startswith("_memoized"): raise AttributeError(key) elif hasattr(self, "_memoized_attr_%s" % key): value = getattr(self, "_memoized_attr_%s" % key)() setattr(self, key, value) return value elif hasattr(self, "_memoized_method_%s" % key): fn = getattr(self, "_memoized_method_%s" % key) def oneshot(*args, **kw): result = fn(*args, **kw) def memo(*a, **kw): return result memo.__name__ = fn.__name__ memo.__doc__ = fn.__doc__ setattr(self, key, memo) return result oneshot.__doc__ = fn.__doc__ return oneshot else: return self._fallback_getattr(key) # from paste.deploy.converters def asbool(obj): if isinstance(obj, compat.string_types): obj = obj.strip().lower() if obj in ["true", "yes", "on", "y", "t", "1"]: return True elif obj in ["false", "no", "off", "n", "f", "0"]: return False else: raise ValueError("String is not true/false: %r" % obj) return bool(obj) def bool_or_str(*text): """Return a callable that will evaluate a string as boolean, or one of a set of "alternate" string values. """ def bool_or_value(obj): if obj in text: return obj else: return asbool(obj) return bool_or_value def asint(value): """Coerce to integer.""" if value is None: return value return int(value) def coerce_kw_type(kw, key, type_, flexi_bool=True, dest=None): r"""If 'key' is present in dict 'kw', coerce its value to type 'type\_' if necessary. If 'flexi_bool' is True, the string '0' is considered false when coercing to boolean. """ if dest is None: dest = kw if ( key in kw and (not isinstance(type_, type) or not isinstance(kw[key], type_)) and kw[key] is not None ): if type_ is bool and flexi_bool: dest[key] = asbool(kw[key]) else: dest[key] = type_(kw[key]) def constructor_key(obj, cls): """Produce a tuple structure that is cacheable using the __dict__ of obj to retrieve values """ names = get_cls_kwargs(cls) return (cls,) + tuple( (k, obj.__dict__[k]) for k in names if k in obj.__dict__ ) def constructor_copy(obj, cls, *args, **kw): """Instantiate cls using the __dict__ of obj as constructor arguments. Uses inspect to match the named arguments of ``cls``. """ names = get_cls_kwargs(cls) kw.update( (k, obj.__dict__[k]) for k in names.difference(kw) if k in obj.__dict__ ) return cls(*args, **kw) def counter(): """Return a threadsafe counter function.""" lock = compat.threading.Lock() counter = itertools.count(1) # avoid the 2to3 "next" transformation... def _next(): with lock: return next(counter) return _next def duck_type_collection(specimen, default=None): """Given an instance or class, guess if it is or is acting as one of the basic collection types: list, set and dict. If the __emulates__ property is present, return that preferentially. """ if hasattr(specimen, "__emulates__"): # canonicalize set vs sets.Set to a standard: the builtin set if specimen.__emulates__ is not None and issubclass( specimen.__emulates__, set ): return set else: return specimen.__emulates__ isa = isinstance(specimen, type) and issubclass or isinstance if isa(specimen, list): return list elif isa(specimen, set): return set elif isa(specimen, dict): return dict if hasattr(specimen, "append"): return list elif hasattr(specimen, "add"): return set elif hasattr(specimen, "set"): return dict else: return default def assert_arg_type(arg, argtype, name): if isinstance(arg, argtype): return arg else: if isinstance(argtype, tuple): raise exc.ArgumentError( "Argument '%s' is expected to be one of type %s, got '%s'" % (name, " or ".join("'%s'" % a for a in argtype), type(arg)) ) else: raise exc.ArgumentError( "Argument '%s' is expected to be of type '%s', got '%s'" % (name, argtype, type(arg)) ) def dictlike_iteritems(dictlike): """Return a (key, value) iterator for almost any dict-like object.""" if compat.py3k: if hasattr(dictlike, "items"): return list(dictlike.items()) else: if hasattr(dictlike, "iteritems"): return dictlike.iteritems() elif hasattr(dictlike, "items"): return iter(dictlike.items()) getter = getattr(dictlike, "__getitem__", getattr(dictlike, "get", None)) if getter is None: raise TypeError("Object '%r' is not dict-like" % dictlike) if hasattr(dictlike, "iterkeys"): def iterator(): for key in dictlike.iterkeys(): yield key, getter(key) return iterator() elif hasattr(dictlike, "keys"): return iter((key, getter(key)) for key in dictlike.keys()) else: raise TypeError("Object '%r' is not dict-like" % dictlike) class classproperty(property): """A decorator that behaves like @property except that operates on classes rather than instances. The decorator is currently special when using the declarative module, but note that the :class:`~.sqlalchemy.ext.declarative.declared_attr` decorator should be used for this purpose with declarative. """ def __init__(self, fget, *arg, **kw): super(classproperty, self).__init__(fget, *arg, **kw) self.__doc__ = fget.__doc__ def __get__(desc, self, cls): return desc.fget(cls) class hybridproperty(object): def __init__(self, func): self.func = func self.clslevel = func def __get__(self, instance, owner): if instance is None: clsval = self.clslevel(owner) return clsval else: return self.func(instance) def classlevel(self, func): self.clslevel = func return self class hybridmethod(object): """Decorate a function as cls- or instance- level.""" def __init__(self, func): self.func = self.__func__ = func self.clslevel = func def __get__(self, instance, owner): if instance is None: return self.clslevel.__get__(owner, owner.__class__) else: return self.func.__get__(instance, owner) def classlevel(self, func): self.clslevel = func return self class _symbol(int): def __new__(self, name, doc=None, canonical=None): """Construct a new named symbol.""" assert isinstance(name, compat.string_types) if canonical is None: canonical = hash(name) v = int.__new__(_symbol, canonical) v.name = name if doc: v.__doc__ = doc return v def __reduce__(self): return symbol, (self.name, "x", int(self)) def __str__(self): return repr(self) def __repr__(self): return "symbol(%r)" % self.name _symbol.__name__ = "symbol" class symbol(object): """A constant symbol. >>> symbol('foo') is symbol('foo') True >>> symbol('foo') A slight refinement of the MAGICCOOKIE=object() pattern. The primary advantage of symbol() is its repr(). They are also singletons. Repeated calls of symbol('name') will all return the same instance. The optional ``doc`` argument assigns to ``__doc__``. This is strictly so that Sphinx autoattr picks up the docstring we want (it doesn't appear to pick up the in-module docstring if the datamember is in a different module - autoattribute also blows up completely). If Sphinx fixes/improves this then we would no longer need ``doc`` here. """ symbols = {} _lock = compat.threading.Lock() def __new__(cls, name, doc=None, canonical=None): with cls._lock: sym = cls.symbols.get(name) if sym is None: cls.symbols[name] = sym = _symbol(name, doc, canonical) return sym @classmethod def parse_user_argument( cls, arg, choices, name, resolve_symbol_names=False ): """Given a user parameter, parse the parameter into a chosen symbol. The user argument can be a string name that matches the name of a symbol, or the symbol object itself, or any number of alternate choices such as True/False/ None etc. :param arg: the user argument. :param choices: dictionary of symbol object to list of possible entries. :param name: name of the argument. Used in an :class:`.ArgumentError` that is raised if the parameter doesn't match any available argument. :param resolve_symbol_names: include the name of each symbol as a valid entry. """ # note using hash lookup is tricky here because symbol's `__hash__` # is its int value which we don't want included in the lookup # explicitly, so we iterate and compare each. for sym, choice in choices.items(): if arg is sym: return sym elif resolve_symbol_names and arg == sym.name: return sym elif arg in choice: return sym if arg is None: return None raise exc.ArgumentError("Invalid value for '%s': %r" % (name, arg)) _creation_order = 1 def set_creation_order(instance): """Assign a '_creation_order' sequence to the given instance. This allows multiple instances to be sorted in order of creation (typically within a single thread; the counter is not particularly threadsafe). """ global _creation_order instance._creation_order = _creation_order _creation_order += 1 def warn_exception(func, *args, **kwargs): """executes the given function, catches all exceptions and converts to a warning. """ try: return func(*args, **kwargs) except Exception: warn("%s('%s') ignored" % sys.exc_info()[0:2]) def ellipses_string(value, len_=25): try: if len(value) > len_: return "%s..." % value[0:len_] else: return value except TypeError: return value class _hash_limit_string(compat.text_type): """A string subclass that can only be hashed on a maximum amount of unique values. This is used for warnings so that we can send out parameterized warnings without the __warningregistry__ of the module, or the non-overridable "once" registry within warnings.py, overloading memory, """ def __new__(cls, value, num, args): interpolated = (value % args) + ( " (this warning may be suppressed after %d occurrences)" % num ) self = super(_hash_limit_string, cls).__new__(cls, interpolated) self._hash = hash("%s_%d" % (value, hash(interpolated) % num)) return self def __hash__(self): return self._hash def __eq__(self, other): return hash(self) == hash(other) def warn(msg, code=None): """Issue a warning. If msg is a string, :class:`.exc.SAWarning` is used as the category. """ if code: _warnings_warn(exc.SAWarning(msg, code=code)) else: _warnings_warn(msg, exc.SAWarning) def warn_limited(msg, args): """Issue a warning with a parameterized string, limiting the number of registrations. """ if args: msg = _hash_limit_string(msg, 10, args) _warnings_warn(msg, exc.SAWarning) def _warnings_warn(message, category=None, stacklevel=2): # adjust the given stacklevel to be outside of SQLAlchemy try: frame = sys._getframe(stacklevel) except ValueError: # being called from less than 3 (or given) stacklevels, weird, # but don't crash stacklevel = 0 except: # _getframe() doesn't work, weird interpreter issue, weird, # ok, but don't crash stacklevel = 0 else: # using __name__ here requires that we have __name__ in the # __globals__ of the decorated string functions we make also. # we generate this using {"__name__": fn.__module__} while frame is not None and re.match( r"^(?:sqlalchemy\.|alembic\.)", frame.f_globals.get("__name__", "") ): frame = frame.f_back stacklevel += 1 if category is not None: warnings.warn(message, category, stacklevel=stacklevel + 1) else: warnings.warn(message, stacklevel=stacklevel + 1) def only_once(fn, retry_on_exception): """Decorate the given function to be a no-op after it is called exactly once.""" once = [fn] def go(*arg, **kw): # strong reference fn so that it isn't garbage collected, # which interferes with the event system's expectations strong_fn = fn # noqa if once: once_fn = once.pop() try: return once_fn(*arg, **kw) except: if retry_on_exception: once.insert(0, once_fn) raise return go _SQLA_RE = re.compile(r"sqlalchemy/([a-z_]+/){0,2}[a-z_]+\.py") _UNITTEST_RE = re.compile(r"unit(?:2|test2?/)") def chop_traceback(tb, exclude_prefix=_UNITTEST_RE, exclude_suffix=_SQLA_RE): """Chop extraneous lines off beginning and end of a traceback. :param tb: a list of traceback lines as returned by ``traceback.format_stack()`` :param exclude_prefix: a regular expression object matching lines to skip at beginning of ``tb`` :param exclude_suffix: a regular expression object matching lines to skip at end of ``tb`` """ start = 0 end = len(tb) - 1 while start <= end and exclude_prefix.search(tb[start]): start += 1 while start <= end and exclude_suffix.search(tb[end]): end -= 1 return tb[start : end + 1] NoneType = type(None) def attrsetter(attrname): code = "def set(obj, value):" " obj.%s = value" % attrname env = locals().copy() exec(code, env) return env["set"] class EnsureKWArgType(type): r"""Apply translation of functions to accept \**kw arguments if they don't already. """ def __init__(cls, clsname, bases, clsdict): fn_reg = cls.ensure_kwarg if fn_reg: for key in clsdict: m = re.match(fn_reg, key) if m: fn = clsdict[key] spec = compat.inspect_getfullargspec(fn) if not spec.varkw: clsdict[key] = wrapped = cls._wrap_w_kw(fn) setattr(cls, key, wrapped) super(EnsureKWArgType, cls).__init__(clsname, bases, clsdict) def _wrap_w_kw(self, fn): def wrap(*arg, **kw): return fn(*arg) return update_wrapper(wrap, fn) def wrap_callable(wrapper, fn): """Augment functools.update_wrapper() to work with objects with a ``__call__()`` method. :param fn: object with __call__ method """ if hasattr(fn, "__name__"): return update_wrapper(wrapper, fn) else: _f = wrapper _f.__name__ = fn.__class__.__name__ if hasattr(fn, "__module__"): _f.__module__ = fn.__module__ if hasattr(fn.__call__, "__doc__") and fn.__call__.__doc__: _f.__doc__ = fn.__call__.__doc__ elif fn.__doc__: _f.__doc__ = fn.__doc__ return _f def quoted_token_parser(value): """Parse a dotted identifier with accommodation for quoted names. Includes support for SQL-style double quotes as a literal character. E.g.:: >>> quoted_token_parser("name") ["name"] >>> quoted_token_parser("schema.name") ["schema", "name"] >>> quoted_token_parser('"Schema"."Name"') ['Schema', 'Name'] >>> quoted_token_parser('"Schema"."Name""Foo"') ['Schema', 'Name""Foo'] """ if '"' not in value: return value.split(".") # 0 = outside of quotes # 1 = inside of quotes state = 0 result = [[]] idx = 0 lv = len(value) while idx < lv: char = value[idx] if char == '"': if state == 1 and idx < lv - 1 and value[idx + 1] == '"': result[-1].append('"') idx += 1 else: state ^= 1 elif char == "." and state == 0: result.append([]) else: result[-1].append(char) idx += 1 return ["".join(token) for token in result] def add_parameter_text(params, text): params = _collections.to_list(params) def decorate(fn): doc = fn.__doc__ is not None and fn.__doc__ or "" if doc: doc = inject_param_text(doc, {param: text for param in params}) fn.__doc__ = doc return fn return decorate def _dedent_docstring(text): split_text = text.split("\n", 1) if len(split_text) == 1: return text else: firstline, remaining = split_text if not firstline.startswith(" "): return firstline + "\n" + textwrap.dedent(remaining) else: return textwrap.dedent(text) def inject_docstring_text(doctext, injecttext, pos): doctext = _dedent_docstring(doctext or "") lines = doctext.split("\n") if len(lines) == 1: lines.append("") injectlines = textwrap.dedent(injecttext).split("\n") if injectlines[0]: injectlines.insert(0, "") blanks = [num for num, line in enumerate(lines) if not line.strip()] blanks.insert(0, 0) inject_pos = blanks[min(pos, len(blanks) - 1)] lines = lines[0:inject_pos] + injectlines + lines[inject_pos:] return "\n".join(lines) _param_reg = re.compile(r"(\s+):param (.+?):") def inject_param_text(doctext, inject_params): doclines = collections.deque(doctext.splitlines()) lines = [] # TODO: this is not working for params like ":param case_sensitive=True:" to_inject = None while doclines: line = doclines.popleft() m = _param_reg.match(line) if to_inject is None: if m: param = m.group(2).lstrip("*") if param in inject_params: # default indent to that of :param: plus one indent = " " * len(m.group(1)) + " " # but if the next line has text, use that line's # indentation if doclines: m2 = re.match(r"(\s+)\S", doclines[0]) if m2: indent = " " * len(m2.group(1)) to_inject = indent + inject_params[param] elif m: lines.extend(["\n", to_inject, "\n"]) to_inject = None elif not line.rstrip(): lines.extend([line, to_inject, "\n"]) to_inject = None elif line.endswith("::"): # TODO: this still wont cover if the code example itself has blank # lines in it, need to detect those via indentation. lines.extend([line, doclines.popleft()]) continue lines.append(line) return "\n".join(lines) def repr_tuple_names(names): """Trims a list of strings from the middle and return a string of up to four elements. Strings greater than 11 characters will be truncated""" if len(names) == 0: return None flag = len(names) <= 4 names = names[0:4] if flag else names[0:3] + names[-1:] res = ["%s.." % name[:11] if len(name) > 11 else name for name in names] if flag: return ", ".join(res) else: return "%s, ..., %s" % (", ".join(res[0:3]), res[-1]) def has_compiled_ext(): try: from sqlalchemy import cimmutabledict # noqa F401 from sqlalchemy import cprocessors # noqa F401 from sqlalchemy import cresultproxy # noqa F401 return True except ImportError: return False