Files
web2py/gluon/storage.py
2012-09-01 07:01:38 -05:00

282 lines
7.5 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']`
"""
import cPickle
import portalocker
__all__ = ['List', 'Storage', 'Settings', 'Messages',
'StorageList', 'load_storage', 'save_storage']
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.
>>> 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
__repr__ = lambda self: '<Storage %s>' % dict.__repr__(self)
__getstate__ = dict
__setstate__ = dict.update
# def __getattr__(self, key):
# return dict.get(self, key, None)
# def __setattr__(self, key, value):
# self[key] = value
# def __getitem__(self, key):
# return dict.get(self, key, None)
# def __delattr__(self, key):
# del self[key]
# def __repr__(self):
# return '<Storage %s>' % dict.__repr__(self)
# def __getstate__(self):
# return dict(self)
# def __setstate__(self,values):
# self.update(values)
def getlist(self,key):
"""
Return 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,[])
return value if not value else \
value if isinstance(value,(list,tuple)) else [value]
def getfirst(self,key,default=None):
"""
Return the first or only value 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 or only single value 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
PICKABLE = (str,int,long,float,bool,list,dict,tuple,set)
class StorageList(Storage):
"""
like Storage but missing elements default to [] instead of None
"""
def __getitem__(self,key):
return self.__getattr__(key)
def __getattr__(self, key):
if key in self:
return getattr(self,key)
else:
r = []
setattr(self,key,r)
return r
def load_storage(filename):
fp = None
try:
fp = portalocker.LockedFile(filename, 'rb')
storage = cPickle.load(fp)
finally:
if fp: fp.close()
return Storage(storage)
def save_storage(storage, filename):
fp = None
try:
fp = portalocker.LockedFile(filename, 'wb')
cPickle.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 str(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 a[i] if i is out of bounds return None
instead of IndexOutOfBounds
"""
def __call__(self, i, default=None, cast=None, otherwise=None):
"""
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]
else:
value = default
if cast:
try:
value = cast(value)
except (ValueError, TypeError):
from 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()