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datastructures.py
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# -*- coding: utf-8 -*-
## This file is part of Invenio.
## Copyright (C) 2012, 2013 CERN.
##
## Invenio 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 2 of the
## License, or (at your option) any later version.
##
## Invenio 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 Invenio; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
"""
Invenio special data structures
"""
class LazyDict(object):
"""
Lazy dictionary that evaluates its content when it is first accessed.
Example of use:
def my_dict():
from werkzeug.utils import import_string
return {'foo': import_string('foo')}
lazy_dict = LazyDict(my_dict)
# at this point the internal dictionary is empty
lazy_dict['foo']
"""
def __init__(self, function=dict):
"""
:param function: it must return a dictionary like structure
"""
super(LazyDict, self).__init__()
self._cached_dict = None
self._function = function
def _evaluate_function(self):
self._cached_dict = self._function()
def __getitem__(self, key):
if self._cached_dict is None:
self._evaluate_function()
return self._cached_dict.__getitem__(key)
def __setitem__(self, key, value):
if self._cached_dict is None:
self._evaluate_function()
return self._cached_dict.__setitem__(key, value)
def __getattr__(self, key):
if self._cached_dict is None:
self._evaluate_function()
return getattr(self._cached_dict, key)
def __iter__(self):
if self._cached_dict is None:
self._evaluate_function()
return self._cached_dict.__iter__()
def iteritems(self):
if self._cached_dict is None:
self._evaluate_function()
return self._cached_dict.iteritems()
def iterkeys(self):
if self._cached_dict is None:
self._evaluate_function()
return self._cached_dict.iterkeys()
def itervalues(self):
if self._cached_dict is None:
self._evaluate_function()
return self._cached_dict.itervalues()
def expunge(self):
self._cached_dict = None
def get(self, key, default=None):
try:
return self.__getitem__(key)
except KeyError:
return default
class LaziestDict(LazyDict):
"""
Even lazier dictionary (maybe the laziest), it doesn't have content
and when a key is accessed it tries to evaluate only this key.
Example of use:
def reader_discover(key):
from werkzeug.utils import import_string
return import_string('invenio.jsonalchemy.jsonext.readers%sreader:reader' % (key))
laziest_dict = LaziestDict(reader_discover)
laziest_dict['json']
# It will give you the JsonReader class
"""
def __init__(self, function):
"""
@param function: it must accept one parameter (the key of the dictionary)
and returns the element which will be store that key.
"""
super(LaziestDict, self).__init__(function)
def _evaluate_function(self):
"""
It doesn't know how to create the full dictionary, in case
is really needed an empty dictionary is created.
"""
if self._cached_dict is None:
self._cached_dict = {}
def __getitem__(self, key):
if self._cached_dict is None:
self._evaluate_function()
if not key in self._cached_dict:
try:
self._cached_dict.__setitem__(key, self._function(key))
except:
raise KeyError(key)
return self._cached_dict.__getitem__(key)
def __contains__(self, key):
if self._cached_dict is None:
self._evaluate_function()
if not key in self._cached_dict:
try:
self.__getitem__(key)
except:
return False
return True
import re
class SmartDict(object):
"""
This dictionary allows to do some 'smart queries' to its content::
>>> d = SmartDict()
>>> d['foo'] = {'a': 'world', 'b':'hello'}
>>> d['a'] = [ {'b':1}, {'b':2}, {'b':3} ]
>>> d['a']
[ {'b':1}, {'b':2}, {'b':3} ]
>>> d['a[0]']
{'b':1}
>>> d['a.b']
[1,2,3]
>>> d['a[1:]']
[{'b':2}, {'b':3}]
"""
split_key_pattern = re.compile('\.|\[')
main_key_pattern = re.compile('\..*|\[.*')
def __init__(self, d=None):
self._dict = d if not d is None else dict()
def __getitem__(self, key):
"""
As in C{dict.__getitem__} but using 'smart queries'
NOTE: accessing one value in a normal way, meaning d['a'], is almost as
fast as accessing a regular dictionary. But using the special name
convention is a bit slower than using the regular access::
%timeit x = dd['a[0].b']
100000 loops, best of 3: 3.94 µs per loop
%timeit x = dd['a'][0]['b']
1000000 loops, best of 3: 598 ns per loop
"""
def getitem(k, v):
if isinstance(v, dict):
return v[k]
elif ']' in k:
k = k[:-1].replace('n', '-1')
#Work around for list indexes and slices
try:
return v[int(k)]
except ValueError:
return v[slice(*map(lambda x: int(x.strip()) if x.strip() else None, k.split(':')))]
else:
tmp = []
for inner_v in v:
tmp.append(getitem(k, inner_v))
return tmp
#Check if we are using python regular keys
try:
return self._dict[key]
except KeyError:
pass
keys = SmartDict.split_key_pattern.split(key)
value = self._dict
for k in keys:
value = getitem(k, value)
return value
def __setitem__(self, key, value, extend=False):
#TODO: Check repeatable fields
if '.' not in key and ']' not in key and not extend:
self._dict[key] = value
else:
keys = SmartDict.split_key_pattern.split(key)
self.__setitem(self._dict, keys[0], keys[1:], value, extend)
def __delitem__(self, key):
"""Note: It only works with first keys"""
del self._dict[key]
def __contains__(self, key):
if '.' not in key and '[' not in key:
return key in self._dict
try:
self[key]
except:
return False
return True
def __eq__(self, other):
return (isinstance(other, self.__class__)
and self._dict == other._dict)
def __iter__(self):
return iter(self._dict)
def __len__(self):
return len(self._dict)
def keys(self):
return self._dict.keys()
def items(self):
return self._dict.items()
def iteritems(self):
return self._dict.iteritems()
def iterkeys(self):
return self._dict.iterkeys()
def itervalues(self):
return self._dict.itervalues()
def has_key(self, key):
return key in self
def __repr__(self):
return repr(self._dict)
def __setitem(self, chunk, key, keys, value, extend=False):
""" Helper function to fill up the dictionary"""
def setitem(chunk):
if keys:
return self.__setitem(chunk, keys[0], keys[1:], value, extend)
else:
return value
if ']' in key: # list
key = int(key[:-1].replace('n', '-1'))
if extend:
if chunk is None:
chunk = [None, ]
else:
if not isinstance(chunk, list):
chunk = [chunk, ]
if key != -1:
chunk.insert(key, None)
else:
chunk.append(None)
else:
if chunk is None:
chunk = [None, ]
chunk[key] = setitem(chunk[key])
else: # dict
if extend:
if chunk is None:
chunk = {}
chunk[key] = None
chunk[key] = setitem(chunk[key])
elif not key in chunk:
chunk[key] = None
chunk[key] = setitem(chunk[key])
else:
if keys:
chunk[key] = setitem(chunk[key])
else:
if not isinstance(chunk[key], list):
chunk[key] = [chunk[key],]
chunk[key].append(None)
chunk[key][-1] = setitem(chunk[key][-1])
else:
if chunk is None:
chunk = {}
if key not in chunk:
chunk[key] = None
chunk[key] = setitem(chunk[key])
return chunk
def get(self, key, default=None):
try:
return self[key]
except:
return default
def set(self, key, value, extend=False):
self.__setitem__(key, value, extend)
def update(self, E, **F):
self._dict.update(E, **F)
def flatten_multidict(multidict):
return dict([(key, value if len(value) > 1 else value[0])
for (key, value) in multidict.iterlists()])

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