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from threading import RLock
try:
from UserDict import DictMixin
except ImportError:
from collections import Mapping as DictMixin
# With lazy loading, we might end up with multiple threads triggering
# it at the same time. We need a lock.
_fill_lock = RLock()
class LazyDict(DictMixin):
"""Dictionary populated on first use."""
data = None
def __getitem__(self, key):
if self.data is None:
_fill_lock.acquire()
try:
if self.data is None:
self._fill()
finally:
_fill_lock.release()
return self.data[key.upper()]
def __contains__(self, key):
if self.data is None:
_fill_lock.acquire()
try:
if self.data is None:
self._fill()
finally:
_fill_lock.release()
return key in self.data
def __iter__(self):
if self.data is None:
_fill_lock.acquire()
try:
if self.data is None:
self._fill()
finally:
_fill_lock.release()
return iter(self.data)
def __len__(self):
if self.data is None:
_fill_lock.acquire()
try:
if self.data is None:
self._fill()
finally:
_fill_lock.release()
return len(self.data)
def keys(self):
if self.data is None:
_fill_lock.acquire()
try:
if self.data is None:
self._fill()
finally:
_fill_lock.release()
return self.data.keys()
class LazyList(list):
"""List populated on first use."""
_props = [
'__str__', '__repr__', '__unicode__',
'__hash__', '__sizeof__', '__cmp__',
'__lt__', '__le__', '__eq__', '__ne__', '__gt__', '__ge__',
'append', 'count', 'index', 'extend', 'insert', 'pop', 'remove',
'reverse', 'sort', '__add__', '__radd__', '__iadd__', '__mul__',
'__rmul__', '__imul__', '__contains__', '__len__', '__nonzero__',
'__getitem__', '__setitem__', '__delitem__', '__iter__',
'__reversed__', '__getslice__', '__setslice__', '__delslice__']
def __new__(cls, fill_iter=None):
if fill_iter is None:
return list()
# We need a new class as we will be dynamically messing with its
# methods.
class LazyList(list):
pass
fill_iter = [fill_iter]
def lazy(name):
def _lazy(self, *args, **kw):
_fill_lock.acquire()
try:
if len(fill_iter) > 0:
list.extend(self, fill_iter.pop())
for method_name in cls._props:
delattr(LazyList, method_name)
finally:
_fill_lock.release()
return getattr(list, name)(self, *args, **kw)
return _lazy
for name in cls._props:
setattr(LazyList, name, lazy(name))
new_list = LazyList()
return new_list
# Not all versions of Python declare the same magic methods.
# Filter out properties that don't exist in this version of Python
# from the list.
LazyList._props = [prop for prop in LazyList._props if hasattr(list, prop)]
class LazySet(set):
"""Set populated on first use."""
_props = (
'__str__', '__repr__', '__unicode__',
'__hash__', '__sizeof__', '__cmp__',
'__lt__', '__le__', '__eq__', '__ne__', '__gt__', '__ge__',
'__contains__', '__len__', '__nonzero__',
'__getitem__', '__setitem__', '__delitem__', '__iter__',
'__sub__', '__and__', '__xor__', '__or__',
'__rsub__', '__rand__', '__rxor__', '__ror__',
'__isub__', '__iand__', '__ixor__', '__ior__',
'add', 'clear', 'copy', 'difference', 'difference_update',
'discard', 'intersection', 'intersection_update', 'isdisjoint',
'issubset', 'issuperset', 'pop', 'remove',
'symmetric_difference', 'symmetric_difference_update',
'union', 'update')
def __new__(cls, fill_iter=None):
if fill_iter is None:
return set()
class LazySet(set):
pass
fill_iter = [fill_iter]
def lazy(name):
def _lazy(self, *args, **kw):
_fill_lock.acquire()
try:
if len(fill_iter) > 0:
for i in fill_iter.pop():
set.add(self, i)
for method_name in cls._props:
delattr(LazySet, method_name)
finally:
_fill_lock.release()
return getattr(set, name)(self, *args, **kw)
return _lazy
for name in cls._props:
setattr(LazySet, name, lazy(name))
new_set = LazySet()
return new_set
# Not all versions of Python declare the same magic methods.
# Filter out properties that don't exist in this version of Python
# from the list.
LazySet._props = [prop for prop in LazySet._props if hasattr(set, prop)]
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