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# This file is part of daf_butler. 

# 

# Developed for the LSST Data Management System. 

# This product includes software developed by the LSST Project 

# (http://www.lsst.org). 

# See the COPYRIGHT file at the top-level directory of this distribution 

# for details of code ownership. 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 3 of the License, or 

# (at your option) any later version. 

# 

# This program is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

# GNU General Public License for more details. 

# 

# You should have received a copy of the GNU General Public License 

# along with this program. If not, see <http://www.gnu.org/licenses/>. 

 

__all__ = ("iterable", "allSlots", "slotValuesAreEqual", "slotValuesToHash", 

"getFullTypeName", "getInstanceOf", "Singleton", "transactional", 

"getObjectSize", "stripIfNotNone", "PrivateConstructorMeta", 

"NamedKeyDict") 

 

import builtins 

import sys 

import functools 

from collections.abc import MutableMapping 

 

from lsst.utils import doImport 

 

 

def iterable(a): 

"""Make input iterable. 

 

There are three cases, when the input is: 

 

- iterable, but not a `str` -> iterate over elements 

(e.g. ``[i for i in a]``) 

- a `str` -> return single element iterable (e.g. ``[a]``) 

- not iterable -> return single elment iterable (e.g. ``[a]``). 

 

Parameters 

---------- 

a : iterable or `str` or not iterable 

Argument to be converted to an iterable. 

 

Returns 

------- 

i : `generator` 

Iterable version of the input value. 

""" 

if isinstance(a, str): 

yield a 

return 

try: 

yield from a 

except Exception: 

yield a 

 

 

def allSlots(self): 

""" 

Return combined ``__slots__`` for all classes in objects mro. 

 

Parameters 

---------- 

self : `object` 

Instance to be inspected. 

 

Returns 

------- 

slots : `itertools.chain` 

All the slots as an iterable. 

""" 

from itertools import chain 

return chain.from_iterable(getattr(cls, "__slots__", []) for cls in self.__class__.__mro__) 

 

 

def slotValuesAreEqual(self, other): 

""" 

Test for equality by the contents of all slots, including those of its 

parents. 

 

Parameters 

---------- 

self : `object` 

Reference instance. 

other : `object` 

Comparison instance. 

 

Returns 

------- 

equal : `bool` 

Returns True if all the slots are equal in both arguments. 

""" 

return all((getattr(self, slot) == getattr(other, slot) for slot in allSlots(self))) 

 

 

def slotValuesToHash(self): 

""" 

Generate a hash from slot values. 

 

Parameters 

---------- 

self : `object` 

Instance to be hashed. 

 

Returns 

------- 

h : `int` 

Hashed value generated from the slot values. 

""" 

return hash(tuple(getattr(self, slot) for slot in allSlots(self))) 

 

 

def getFullTypeName(cls): 

"""Return full type name of the supplied entity. 

 

Parameters 

---------- 

cls : `type` or `object` 

Entity from which to obtain the full name. Can be an instance 

or a `type`. 

 

Returns 

------- 

name : `str` 

Full name of type. 

 

Notes 

----- 

Builtins are returned without the ``builtins`` specifier included. This 

allows `str` to be returned as "str" rather than "builtins.str". 

""" 

# If we have an instance we need to convert to a type 

139 ↛ 140line 139 didn't jump to line 140, because the condition on line 139 was never true if not hasattr(cls, "__qualname__"): 

cls = type(cls) 

141 ↛ 143line 141 didn't jump to line 143, because the condition on line 141 was never true if hasattr(builtins, cls.__qualname__): 

# Special case builtins such as str and dict 

return cls.__qualname__ 

return cls.__module__ + "." + cls.__qualname__ 

 

 

def getClassOf(typeOrName): 

"""Given the type name or a type, return the python type. 

 

If a type name is given, an attempt will be made to import the type. 

 

Parameters 

---------- 

typeOrName : `str` or Python class 

A string describing the Python class to load or a Python type. 

 

Returns 

------- 

type_ : `type` 

Directly returns the Python type if a type was provided, else 

tries to import the given string and returns the resulting type. 

 

Notes 

----- 

This is a thin wrapper around `~lsst.utils.doImport`. 

""" 

if isinstance(typeOrName, str): 

cls = doImport(typeOrName) 

else: 

cls = typeOrName 

return cls 

 

 

def getInstanceOf(typeOrName, *args, **kwargs): 

"""Given the type name or a type, instantiate an object of that type. 

 

If a type name is given, an attempt will be made to import the type. 

 

Parameters 

---------- 

typeOrName : `str` or Python class 

A string describing the Python class to load or a Python type. 

args : `tuple` 

Positional arguments to use pass to the object constructor. 

kwargs : `dict` 

Keyword arguments to pass to object constructor. 

 

Returns 

------- 

instance : `object` 

Instance of the requested type, instantiated with the provided 

parameters. 

""" 

cls = getClassOf(typeOrName) 

return cls(*args, **kwargs) 

 

 

class Singleton(type): 

"""Metaclass to convert a class to a Singleton. 

 

If this metaclass is used the constructor for the singleton class must 

take no arguments. This is because a singleton class will only accept 

the arguments the first time an instance is instantiated. 

Therefore since you do not know if the constructor has been called yet it 

is safer to always call it with no arguments and then call a method to 

adjust state of the singleton. 

""" 

 

_instances = {} 

 

def __call__(cls): 

if cls not in cls._instances: 

cls._instances[cls] = super(Singleton, cls).__call__() 

return cls._instances[cls] 

 

 

def transactional(func): 

"""Decorator that wraps a method and makes it transactional. 

 

This depends on the class also defining a `transaction` method 

that takes no arguments and acts as a context manager. 

""" 

@functools.wraps(func) 

def inner(self, *args, **kwargs): 

with self.transaction(): 

return func(self, *args, **kwargs) 

return inner 

 

 

def getObjectSize(obj, seen=None): 

"""Recursively finds size of objects. 

 

Only works well for pure python objects. For example it does not work for 

``Exposure`` objects where all the content is behind getter methods. 

 

Parameters 

---------- 

obj : `object` 

Instance for which size is to be calculated. 

seen : `set`, optional 

Used internally to keep track of objects already sized during 

recursion. 

 

Returns 

------- 

size : `int` 

Size in bytes. 

 

See Also 

-------- 

sys.getsizeof 

 

Notes 

----- 

See https://goshippo.com/blog/measure-real-size-any-python-object/ 

""" 

size = sys.getsizeof(obj) 

if seen is None: 

seen = set() 

obj_id = id(obj) 

if obj_id in seen: 

return 0 

# Important mark as seen *before* entering recursion to gracefully handle 

# self-referential objects 

seen.add(obj_id) 

if isinstance(obj, dict): 

size += sum([getObjectSize(v, seen) for v in obj.values()]) 

size += sum([getObjectSize(k, seen) for k in obj.keys()]) 

elif hasattr(obj, "__dict__"): 

size += getObjectSize(obj.__dict__, seen) 

elif hasattr(obj, "__iter__") and not isinstance(obj, (str, bytes, bytearray)): 

size += sum([getObjectSize(i, seen) for i in obj]) 

 

return size 

 

 

def stripIfNotNone(s): 

"""Strip leading and trailing whitespace if the given object is not None. 

 

Parameters 

---------- 

s : `str`, optional 

Input string. 

 

Returns 

------- 

r : `str` or `None` 

A string with leading and trailing whitespace stripped if `s` is not 

`None`, or `None` if `s` is `None`. 

""" 

if s is not None: 

s = s.strip() 

return s 

 

 

class PrivateConstructorMeta(type): 

"""A metaclass that disables regular construction syntax. 

 

A class that uses PrivateConstructorMeta may have an ``__init__`` and/or 

``__new__`` method, but these can't be invoked by "calling" the class 

(that will always raise `TypeError`). Instead, such classes can be called 

by calling the metaclass-provided `_construct` class method with the same 

arguments. 

 

As is usual in Python, there are no actual prohibitions on what code can 

call `_construct`; the purpose of this metaclass is just to prevent 

instances from being created normally when that can't do what users would 

expect. 

 

..note:: 

 

Classes that inherit from PrivateConstructorMeta also inherit 

the hidden-constructor behavior. If you just want to disable 

construction of the base class, `abc.ABCMeta` may be a better 

option. 

 

Examples 

-------- 

Given this class definition:: 

class Hidden(metaclass=PrivateConstructorMeta): 

 

def __init__(self, a, b): 

self.a = a 

self.b = b 

 

This doesn't work: 

 

>>> instance = Hidden(a=1, b="two") 

TypeError: Hidden objects cannot be constructed directly. 

 

But this does: 

 

>>> instance = Hidden._construct(a=1, b="two") 

 

""" 

 

def __call__(cls, *args, **kwds): 

"""Disabled class construction interface; always raises `TypeError.` 

""" 

raise TypeError(f"{cls.__name__} objects cannot be constructed directly.") 

 

def _construct(cls, *args, **kwds): 

"""Private class construction interface. 

 

All arguments are forwarded to ``__init__`` and/or ``__new__`` 

in the usual way. 

""" 

return type.__call__(cls, *args, **kwds) 

 

 

class NamedKeyDict(MutableMapping): 

"""A dictionary wrapper that require keys to have a ``.name`` attribute, 

and permits lookups using either key objects or their names. 

 

Names can be used in place of keys when updating existing items, but not 

when adding new items. 

 

It is assumed (but asserted) that all name equality is equivalent to key 

equality, either because the key objects define equality this way, or 

because different objects with the same name are never included in the same 

dictionary. 

 

Parameters 

---------- 

args 

All positional constructor arguments are forwarded directly to `dict`. 

Keyword arguments are not accepted, because plain strings are not valid 

keys for `NamedKeyDict`. 

 

Raises 

------ 

AttributeError 

Raised when an attempt is made to add an object with no ``.name`` 

attribute to the dictionary. 

AssertionError 

Raised when multiple keys have the same name. 

""" 

 

__slots__ = ("_dict", "_names",) 

 

def __init__(self, *args): 

self._dict = dict(*args) 

self._names = {key.name: key for key in self._dict} 

assert len(self._names) == len(self._dict), "Duplicate names in keys." 

 

@property 

def names(self): 

"""The set of names associated with the keys, in the same order 

(`~collections.abc.KeysView`). 

""" 

return self._names.keys() 

 

def byName(self): 

"""Return a `dict` with names as keys and the same values as ``self``. 

""" 

return dict(zip(self._names.keys(), self._dict.values())) 

 

def __len__(self): 

return len(self._dict) 

 

def __iter__(self): 

return iter(self._dict) 

 

def __getitem__(self, key): 

if hasattr(key, "name"): 

return self._dict[key] 

else: 

return self._dict[self._names[key]] 

 

def __setitem__(self, key, value): 

if hasattr(key, "name"): 

assert self._names.get(key.name, key) == key, "Name is already associated with a different key." 

self._dict[key] = value 

self._names[key.name] = key 

else: 

self._dict[self._names[key]] = value 

 

def __delitem__(self, key): 

if hasattr(key, "name"): 

del self._dict[key] 

del self._names[key.name] 

else: 

del self._dict[self._names[key]] 

del self._names[key] 

 

def keys(self): 

return self._dict.keys() 

 

def values(self): 

return self._dict.values() 

 

def items(self): 

return self._dict.items()