SP/web2py/gluon/storage.py
Saturneic 064f602b1a Add.
2018-10-25 23:33:13 +08:00

324 lines
8.7 KiB
Python

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
| This file is part of the web2py Web Framework
| Copyrighted by Massimo Di Pierro <mdipierro@cs.depaul.edu>
| License: LGPLv3 (http://www.gnu.org/licenses/lgpl.html)
Provides:
- List; like list but returns None instead of IndexOutOfBounds
- Storage; like dictionary allowing also for `obj.foo` for `obj['foo']`
"""
from pydal.contrib import portalocker
from gluon._compat import copyreg, pickle, PY2
__all__ = ['List', 'Storage', 'Settings', 'Messages',
'StorageList', 'load_storage', 'save_storage']
DEFAULT = lambda: 0
class Storage(dict):
"""
A Storage object is like a dictionary except `obj.foo` can be used
in addition to `obj['foo']`, and setting obj.foo = None deletes item foo.
Example::
>>> o = Storage(a=1)
>>> print o.a
1
>>> o['a']
1
>>> o.a = 2
>>> print o['a']
2
>>> del o.a
>>> print o.a
None
"""
__slots__ = ()
__setattr__ = dict.__setitem__
__delattr__ = dict.__delitem__
__getitem__ = dict.get
__getattr__ = dict.get
__getnewargs__ = lambda self: getattr(dict,self).__getnewargs__(self)
__repr__ = lambda self: '<Storage %s>' % dict.__repr__(self)
# http://stackoverflow.com/questions/5247250/why-does-pickle-getstate-accept-as-a-return-value-the-very-instance-it-requi
__getstate__ = lambda self: None
__copy__ = lambda self: Storage(self)
def getlist(self, key):
"""
Returns a Storage value as a list.
If the value is a list it will be returned as-is.
If object is None, an empty list will be returned.
Otherwise, `[value]` will be returned.
Example output for a query string of `?x=abc&y=abc&y=def`::
>>> request = Storage()
>>> request.vars = Storage()
>>> request.vars.x = 'abc'
>>> request.vars.y = ['abc', 'def']
>>> request.vars.getlist('x')
['abc']
>>> request.vars.getlist('y')
['abc', 'def']
>>> request.vars.getlist('z')
[]
"""
value = self.get(key, [])
if value is None or isinstance(value, (list, tuple)):
return value
else:
return [value]
def getfirst(self, key, default=None):
"""
Returns the first value of a list or the value itself when given a
`request.vars` style key.
If the value is a list, its first item will be returned;
otherwise, the value will be returned as-is.
Example output for a query string of `?x=abc&y=abc&y=def`::
>>> request = Storage()
>>> request.vars = Storage()
>>> request.vars.x = 'abc'
>>> request.vars.y = ['abc', 'def']
>>> request.vars.getfirst('x')
'abc'
>>> request.vars.getfirst('y')
'abc'
>>> request.vars.getfirst('z')
"""
values = self.getlist(key)
return values[0] if values else default
def getlast(self, key, default=None):
"""
Returns the last value of a list or value itself when given a
`request.vars` style key.
If the value is a list, the last item will be returned;
otherwise, the value will be returned as-is.
Simulated output with a query string of `?x=abc&y=abc&y=def`::
>>> request = Storage()
>>> request.vars = Storage()
>>> request.vars.x = 'abc'
>>> request.vars.y = ['abc', 'def']
>>> request.vars.getlast('x')
'abc'
>>> request.vars.getlast('y')
'def'
>>> request.vars.getlast('z')
"""
values = self.getlist(key)
return values[-1] if values else default
def pickle_storage(s):
return Storage, (dict(s),)
copyreg.pickle(Storage, pickle_storage)
if PY2:
PICKABLE = (str, int, long, float, bool, list, dict, tuple, set)
else:
PICKABLE = (str, int, float, bool, list, dict, tuple, set)
class StorageList(Storage):
"""
Behaves like Storage but missing elements defaults to [] instead of None
"""
def __getitem__(self, key):
return self.__getattr__(key)
def __getattr__(self, key):
if key in self:
return self.get(key)
else:
r = []
self[key] = r
return r
def load_storage(filename):
fp = None
try:
fp = portalocker.LockedFile(filename, 'rb')
storage = pickle.load(fp)
finally:
if fp:
fp.close()
return Storage(storage)
def save_storage(storage, filename):
fp = None
try:
fp = portalocker.LockedFile(filename, 'wb')
pickle.dump(dict(storage), fp)
finally:
if fp:
fp.close()
class Settings(Storage):
def __setattr__(self, key, value):
if key != 'lock_keys' and self['lock_keys'] and key not in self:
raise SyntaxError('setting key \'%s\' does not exist' % key)
if key != 'lock_values' and self['lock_values']:
raise SyntaxError('setting value cannot be changed: %s' % key)
self[key] = value
class Messages(Settings):
def __init__(self, T):
Storage.__init__(self, T=T)
def __getattr__(self, key):
value = self[key]
if isinstance(value, str):
return self.T(value)
return value
class FastStorage(dict):
"""
Eventually this should replace class Storage but causes memory leak
because of http://bugs.python.org/issue1469629
>>> s = FastStorage()
>>> s.a = 1
>>> s.a
1
>>> s['a']
1
>>> s.b
>>> s['b']
>>> s['b']=2
>>> s['b']
2
>>> s.b
2
>>> isinstance(s,dict)
True
>>> dict(s)
{'a': 1, 'b': 2}
>>> dict(FastStorage(s))
{'a': 1, 'b': 2}
>>> import pickle
>>> s = pickle.loads(pickle.dumps(s))
>>> dict(s)
{'a': 1, 'b': 2}
>>> del s.b
>>> del s.a
>>> s.a
>>> s.b
>>> s['a']
>>> s['b']
"""
def __init__(self, *args, **kwargs):
dict.__init__(self, *args, **kwargs)
self.__dict__ = self
def __getattr__(self, key):
return getattr(self, key) if key in self else None
def __getitem__(self, key):
return dict.get(self, key, None)
def copy(self):
self.__dict__ = {}
s = FastStorage(self)
self.__dict__ = self
return s
def __repr__(self):
return '<Storage %s>' % dict.__repr__(self)
def __getstate__(self):
return dict(self)
def __setstate__(self, sdict):
dict.__init__(self, sdict)
self.__dict__ = self
def update(self, *args, **kwargs):
dict.__init__(self, *args, **kwargs)
self.__dict__ = self
class List(list):
"""
Like a regular python list but callable.
When a(i) is called if i is out of bounds returns None
instead of `IndexError`.
"""
def __call__(self, i, default=DEFAULT, cast=None, otherwise=None):
"""Allows to use a special syntax for fast-check of
`request.args()` validity.
:params:
i: index
default: use this value if arg not found
cast: type cast
otherwise:
will be executed when:
- casts fail
- value not found, dont have default and otherwise is
especified
can be:
- None: results in a 404
- str: redirect to this address
- callable: calls the function (nothing is passed)
Example:
You can use::
request.args(0,default=0,cast=int,otherwise='http://error_url')
request.args(0,default=0,cast=int,otherwise=lambda:...)
"""
n = len(self)
if 0 <= i < n or -n <= i < 0:
value = self[i]
elif default is DEFAULT:
value = None
else:
value, cast, otherwise = default, False, False
try:
if cast:
value = cast(value)
if not value and otherwise:
raise ValueError('Otherwise will raised.')
except (ValueError, TypeError):
from gluon.http import HTTP, redirect
if otherwise is None:
raise HTTP(404)
elif isinstance(otherwise, str):
redirect(otherwise)
elif callable(otherwise):
return otherwise()
else:
raise RuntimeError("invalid otherwise")
return value
if __name__ == '__main__':
import doctest
doctest.testmod()