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from collections import Mapping, MutableMapping
try:
from threading import RLock
except ImportError: # Platform-specific: No threads available
class RLock:
def __enter__(self):
pass
def __exit__(self, exc_type, exc_value, traceback):
pass
try: # Python 2.7+
from collections import OrderedDict
except ImportError:
from .packages.ordered_dict import OrderedDict
from .packages.six import itervalues
__all__ = ['RecentlyUsedContainer', 'HTTPHeaderDict']
_Null = object()
class RecentlyUsedContainer(MutableMapping):
"""
Provides a thread-safe dict-like container which maintains up to
``maxsize`` keys while throwing away the least-recently-used keys beyond
``maxsize``.
:param maxsize:
Maximum number of recent elements to retain.
:param dispose_func:
Every time an item is evicted from the container,
``dispose_func(value)`` is called. Callback which will get called
"""
ContainerCls = OrderedDict
def __init__(self, maxsize=10, dispose_func=None):
self._maxsize = maxsize
self.dispose_func = dispose_func
self._container = self.ContainerCls()
self.lock = RLock()
def __getitem__(self, key):
# Re-insert the item, moving it to the end of the eviction line.
with self.lock:
item = self._container.pop(key)
self._container[key] = item
return item
def __setitem__(self, key, value):
evicted_value = _Null
with self.lock:
# Possibly evict the existing value of 'key'
evicted_value = self._container.get(key, _Null)
self._container[key] = value
# If we didn't evict an existing value, we might have to evict the
# least recently used item from the beginning of the container.
if len(self._container) > self._maxsize:
_key, evicted_value = self._container.popitem(last=False)
if self.dispose_func and evicted_value is not _Null:
self.dispose_func(evicted_value)
def __delitem__(self, key):
with self.lock:
value = self._container.pop(key)
if self.dispose_func:
self.dispose_func(value)
def __len__(self):
with self.lock:
return len(self._container)
def __iter__(self):
raise NotImplementedError('Iteration over this class is unlikely to be threadsafe.')
def clear(self):
with self.lock:
# Copy pointers to all values, then wipe the mapping
# under Python 2, this copies the list of values twice :-|
values = list(self._container.values())
self._container.clear()
if self.dispose_func:
for value in values:
self.dispose_func(value)
def keys(self):
with self.lock:
return self._container.keys()
class HTTPHeaderDict(MutableMapping):
"""
:param headers:
An iterable of field-value pairs. Must not contain multiple field names
when compared case-insensitively.
:param kwargs:
Additional field-value pairs to pass in to ``dict.update``.
A ``dict`` like container for storing HTTP Headers.
Field names are stored and compared case-insensitively in compliance with
RFC 7230. Iteration provides the first case-sensitive key seen for each
case-insensitive pair.
Using ``__setitem__`` syntax overwrites fields that compare equal
case-insensitively in order to maintain ``dict``'s api. For fields that
compare equal, instead create a new ``HTTPHeaderDict`` and use ``.add``
in a loop.
If multiple fields that are equal case-insensitively are passed to the
constructor or ``.update``, the behavior is undefined and some will be
lost.
>>> headers = HTTPHeaderDict()
>>> headers.add('Set-Cookie', 'foo=bar')
>>> headers.add('set-cookie', 'baz=quxx')
>>> headers['content-length'] = '7'
>>> headers['SET-cookie']
'foo=bar, baz=quxx'
>>> headers['Content-Length']
'7'
If you want to access the raw headers with their original casing
for debugging purposes you can access the private ``._data`` attribute
which is a normal python ``dict`` that maps the case-insensitive key to a
list of tuples stored as (case-sensitive-original-name, value). Using the
structure from above as our example:
>>> headers._data
{'set-cookie': [('Set-Cookie', 'foo=bar'), ('set-cookie', 'baz=quxx')],
'content-length': [('content-length', '7')]}
"""
def __init__(self, headers=None, **kwargs):
self._data = {}
if headers is None:
headers = {}
self.update(headers, **kwargs)
def add(self, key, value):
"""Adds a (name, value) pair, doesn't overwrite the value if it already
exists.
>>> headers = HTTPHeaderDict(foo='bar')
>>> headers.add('Foo', 'baz')
>>> headers['foo']
'bar, baz'
"""
self._data.setdefault(key.lower(), []).append((key, value))
def getlist(self, key):
"""Returns a list of all the values for the named field. Returns an
empty list if the key doesn't exist."""
return self[key].split(', ') if key in self else []
def copy(self):
h = HTTPHeaderDict()
for key in self._data:
for rawkey, value in self._data[key]:
h.add(rawkey, value)
return h
def __eq__(self, other):
if not isinstance(other, Mapping):
return False
other = HTTPHeaderDict(other)
return dict((k1, self[k1]) for k1 in self._data) == \
dict((k2, other[k2]) for k2 in other._data)
def __getitem__(self, key):
values = self._data[key.lower()]
return ', '.join(value[1] for value in values)
def __setitem__(self, key, value):
self._data[key.lower()] = [(key, value)]
def __delitem__(self, key):
del self._data[key.lower()]
def __len__(self):
return len(self._data)
def __iter__(self):
for headers in itervalues(self._data):
yield headers[0][0]
def __repr__(self):
return '%s(%r)' % (self.__class__.__name__, dict(self.items()))
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