286 lines
8.4 KiB
Python
286 lines
8.4 KiB
Python
import copy
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from collections import OrderedDict
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from contextlib import suppress
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class OrderedSet:
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"""
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A set which keeps the ordering of the inserted items.
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Currently backs onto OrderedDict.
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"""
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def __init__(self, iterable=None):
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self.dict = OrderedDict(((x, None) for x in iterable) if iterable else [])
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def add(self, item):
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self.dict[item] = None
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def remove(self, item):
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del self.dict[item]
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def discard(self, item):
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with suppress(KeyError):
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self.remove(item)
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def __iter__(self):
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return iter(self.dict)
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def __contains__(self, item):
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return item in self.dict
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def __bool__(self):
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return bool(self.dict)
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def __len__(self):
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return len(self.dict)
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class MultiValueDictKeyError(KeyError):
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pass
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class MultiValueDict(dict):
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"""
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A subclass of dictionary customized to handle multiple values for the
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same key.
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>>> d = MultiValueDict({'name': ['Adrian', 'Simon'], 'position': ['Developer']})
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>>> d['name']
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'Simon'
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>>> d.getlist('name')
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['Adrian', 'Simon']
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>>> d.getlist('doesnotexist')
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[]
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>>> d.getlist('doesnotexist', ['Adrian', 'Simon'])
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['Adrian', 'Simon']
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>>> d.get('lastname', 'nonexistent')
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'nonexistent'
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>>> d.setlist('lastname', ['Holovaty', 'Willison'])
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This class exists to solve the irritating problem raised by cgi.parse_qs,
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which returns a list for every key, even though most Web forms submit
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single name-value pairs.
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"""
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def __init__(self, key_to_list_mapping=()):
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super().__init__(key_to_list_mapping)
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def __repr__(self):
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return "<%s: %s>" % (self.__class__.__name__, super().__repr__())
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def __getitem__(self, key):
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"""
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Return the last data value for this key, or [] if it's an empty list;
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raise KeyError if not found.
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"""
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try:
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list_ = super().__getitem__(key)
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except KeyError:
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raise MultiValueDictKeyError(key)
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try:
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return list_[-1]
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except IndexError:
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return []
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def __setitem__(self, key, value):
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super().__setitem__(key, [value])
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def __copy__(self):
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return self.__class__([
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(k, v[:])
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for k, v in self.lists()
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])
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def __deepcopy__(self, memo):
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result = self.__class__()
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memo[id(self)] = result
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for key, value in dict.items(self):
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dict.__setitem__(result, copy.deepcopy(key, memo),
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copy.deepcopy(value, memo))
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return result
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def __getstate__(self):
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obj_dict = self.__dict__.copy()
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obj_dict['_data'] = {k: self._getlist(k) for k in self}
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return obj_dict
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def __setstate__(self, obj_dict):
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data = obj_dict.pop('_data', {})
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for k, v in data.items():
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self.setlist(k, v)
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self.__dict__.update(obj_dict)
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def get(self, key, default=None):
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"""
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Return the last data value for the passed key. If key doesn't exist
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or value is an empty list, return `default`.
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"""
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try:
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val = self[key]
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except KeyError:
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return default
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if val == []:
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return default
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return val
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def _getlist(self, key, default=None, force_list=False):
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"""
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Return a list of values for the key.
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Used internally to manipulate values list. If force_list is True,
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return a new copy of values.
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"""
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try:
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values = super().__getitem__(key)
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except KeyError:
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if default is None:
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return []
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return default
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else:
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if force_list:
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values = list(values) if values is not None else None
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return values
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def getlist(self, key, default=None):
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"""
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Return the list of values for the key. If key doesn't exist, return a
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default value.
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"""
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return self._getlist(key, default, force_list=True)
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def setlist(self, key, list_):
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super().__setitem__(key, list_)
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def setdefault(self, key, default=None):
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if key not in self:
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self[key] = default
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# Do not return default here because __setitem__() may store
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# another value -- QueryDict.__setitem__() does. Look it up.
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return self[key]
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def setlistdefault(self, key, default_list=None):
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if key not in self:
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if default_list is None:
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default_list = []
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self.setlist(key, default_list)
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# Do not return default_list here because setlist() may store
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# another value -- QueryDict.setlist() does. Look it up.
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return self._getlist(key)
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def appendlist(self, key, value):
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"""Append an item to the internal list associated with key."""
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self.setlistdefault(key).append(value)
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def items(self):
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"""
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Yield (key, value) pairs, where value is the last item in the list
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associated with the key.
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"""
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for key in self:
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yield key, self[key]
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def lists(self):
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"""Yield (key, list) pairs."""
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return iter(super().items())
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def values(self):
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"""Yield the last value on every key list."""
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for key in self:
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yield self[key]
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def copy(self):
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"""Return a shallow copy of this object."""
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return copy.copy(self)
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def update(self, *args, **kwargs):
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"""Extend rather than replace existing key lists."""
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if len(args) > 1:
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raise TypeError("update expected at most 1 arguments, got %d" % len(args))
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if args:
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other_dict = args[0]
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if isinstance(other_dict, MultiValueDict):
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for key, value_list in other_dict.lists():
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self.setlistdefault(key).extend(value_list)
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else:
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try:
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for key, value in other_dict.items():
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self.setlistdefault(key).append(value)
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except TypeError:
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raise ValueError("MultiValueDict.update() takes either a MultiValueDict or dictionary")
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for key, value in kwargs.items():
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self.setlistdefault(key).append(value)
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def dict(self):
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"""Return current object as a dict with singular values."""
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return {key: self[key] for key in self}
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class ImmutableList(tuple):
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"""
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A tuple-like object that raises useful errors when it is asked to mutate.
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Example::
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>>> a = ImmutableList(range(5), warning="You cannot mutate this.")
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>>> a[3] = '4'
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Traceback (most recent call last):
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...
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AttributeError: You cannot mutate this.
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"""
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def __new__(cls, *args, warning='ImmutableList object is immutable.', **kwargs):
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self = tuple.__new__(cls, *args, **kwargs)
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self.warning = warning
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return self
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def complain(self, *wargs, **kwargs):
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if isinstance(self.warning, Exception):
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raise self.warning
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else:
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raise AttributeError(self.warning)
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# All list mutation functions complain.
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__delitem__ = complain
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__delslice__ = complain
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__iadd__ = complain
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__imul__ = complain
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__setitem__ = complain
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__setslice__ = complain
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append = complain
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extend = complain
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insert = complain
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pop = complain
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remove = complain
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sort = complain
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reverse = complain
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class DictWrapper(dict):
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"""
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Wrap accesses to a dictionary so that certain values (those starting with
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the specified prefix) are passed through a function before being returned.
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The prefix is removed before looking up the real value.
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Used by the SQL construction code to ensure that values are correctly
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quoted before being used.
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"""
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def __init__(self, data, func, prefix):
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super().__init__(data)
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self.func = func
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self.prefix = prefix
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def __getitem__(self, key):
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"""
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Retrieve the real value after stripping the prefix string (if
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present). If the prefix is present, pass the value through self.func
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before returning, otherwise return the raw value.
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"""
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if key.startswith(self.prefix):
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use_func = True
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key = key[len(self.prefix):]
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else:
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use_func = False
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value = super().__getitem__(key)
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if use_func:
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return self.func(value)
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return value
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