jpayne@69: from threading import RLock
jpayne@69: try:
jpayne@69:     from collections.abc import Mapping as DictMixin
jpayne@69: except ImportError:  # Python < 3.3
jpayne@69:     try:
jpayne@69:         from UserDict import DictMixin  # Python 2
jpayne@69:     except ImportError:  # Python 3.0-3.3
jpayne@69:         from collections import Mapping as DictMixin
jpayne@69: 
jpayne@69: 
jpayne@69: # With lazy loading, we might end up with multiple threads triggering
jpayne@69: # it at the same time. We need a lock.
jpayne@69: _fill_lock = RLock()
jpayne@69: 
jpayne@69: 
jpayne@69: class LazyDict(DictMixin):
jpayne@69:     """Dictionary populated on first use."""
jpayne@69:     data = None
jpayne@69: 
jpayne@69:     def __getitem__(self, key):
jpayne@69:         if self.data is None:
jpayne@69:             _fill_lock.acquire()
jpayne@69:             try:
jpayne@69:                 if self.data is None:
jpayne@69:                     self._fill()
jpayne@69:             finally:
jpayne@69:                 _fill_lock.release()
jpayne@69:         return self.data[key.upper()]
jpayne@69: 
jpayne@69:     def __contains__(self, key):
jpayne@69:         if self.data is None:
jpayne@69:             _fill_lock.acquire()
jpayne@69:             try:
jpayne@69:                 if self.data is None:
jpayne@69:                     self._fill()
jpayne@69:             finally:
jpayne@69:                 _fill_lock.release()
jpayne@69:         return key in self.data
jpayne@69: 
jpayne@69:     def __iter__(self):
jpayne@69:         if self.data is None:
jpayne@69:             _fill_lock.acquire()
jpayne@69:             try:
jpayne@69:                 if self.data is None:
jpayne@69:                     self._fill()
jpayne@69:             finally:
jpayne@69:                 _fill_lock.release()
jpayne@69:         return iter(self.data)
jpayne@69: 
jpayne@69:     def __len__(self):
jpayne@69:         if self.data is None:
jpayne@69:             _fill_lock.acquire()
jpayne@69:             try:
jpayne@69:                 if self.data is None:
jpayne@69:                     self._fill()
jpayne@69:             finally:
jpayne@69:                 _fill_lock.release()
jpayne@69:         return len(self.data)
jpayne@69: 
jpayne@69:     def keys(self):
jpayne@69:         if self.data is None:
jpayne@69:             _fill_lock.acquire()
jpayne@69:             try:
jpayne@69:                 if self.data is None:
jpayne@69:                     self._fill()
jpayne@69:             finally:
jpayne@69:                 _fill_lock.release()
jpayne@69:         return self.data.keys()
jpayne@69: 
jpayne@69: 
jpayne@69: class LazyList(list):
jpayne@69:     """List populated on first use."""
jpayne@69: 
jpayne@69:     _props = [
jpayne@69:         '__str__', '__repr__', '__unicode__',
jpayne@69:         '__hash__', '__sizeof__', '__cmp__',
jpayne@69:         '__lt__', '__le__', '__eq__', '__ne__', '__gt__', '__ge__',
jpayne@69:         'append', 'count', 'index', 'extend', 'insert', 'pop', 'remove',
jpayne@69:         'reverse', 'sort', '__add__', '__radd__', '__iadd__', '__mul__',
jpayne@69:         '__rmul__', '__imul__', '__contains__', '__len__', '__nonzero__',
jpayne@69:         '__getitem__', '__setitem__', '__delitem__', '__iter__',
jpayne@69:         '__reversed__', '__getslice__', '__setslice__', '__delslice__']
jpayne@69: 
jpayne@69:     def __new__(cls, fill_iter=None):
jpayne@69: 
jpayne@69:         if fill_iter is None:
jpayne@69:             return list()
jpayne@69: 
jpayne@69:         # We need a new class as we will be dynamically messing with its
jpayne@69:         # methods.
jpayne@69:         class LazyList(list):
jpayne@69:             pass
jpayne@69: 
jpayne@69:         fill_iter = [fill_iter]
jpayne@69: 
jpayne@69:         def lazy(name):
jpayne@69:             def _lazy(self, *args, **kw):
jpayne@69:                 _fill_lock.acquire()
jpayne@69:                 try:
jpayne@69:                     if len(fill_iter) > 0:
jpayne@69:                         list.extend(self, fill_iter.pop())
jpayne@69:                         for method_name in cls._props:
jpayne@69:                             delattr(LazyList, method_name)
jpayne@69:                 finally:
jpayne@69:                     _fill_lock.release()
jpayne@69:                 return getattr(list, name)(self, *args, **kw)
jpayne@69:             return _lazy
jpayne@69: 
jpayne@69:         for name in cls._props:
jpayne@69:             setattr(LazyList, name, lazy(name))
jpayne@69: 
jpayne@69:         new_list = LazyList()
jpayne@69:         return new_list
jpayne@69: 
jpayne@69: # Not all versions of Python declare the same magic methods.
jpayne@69: # Filter out properties that don't exist in this version of Python
jpayne@69: # from the list.
jpayne@69: LazyList._props = [prop for prop in LazyList._props if hasattr(list, prop)]
jpayne@69: 
jpayne@69: 
jpayne@69: class LazySet(set):
jpayne@69:     """Set populated on first use."""
jpayne@69: 
jpayne@69:     _props = (
jpayne@69:         '__str__', '__repr__', '__unicode__',
jpayne@69:         '__hash__', '__sizeof__', '__cmp__',
jpayne@69:         '__lt__', '__le__', '__eq__', '__ne__', '__gt__', '__ge__',
jpayne@69:         '__contains__', '__len__', '__nonzero__',
jpayne@69:         '__getitem__', '__setitem__', '__delitem__', '__iter__',
jpayne@69:         '__sub__', '__and__', '__xor__', '__or__',
jpayne@69:         '__rsub__', '__rand__', '__rxor__', '__ror__',
jpayne@69:         '__isub__', '__iand__', '__ixor__', '__ior__',
jpayne@69:         'add', 'clear', 'copy', 'difference', 'difference_update',
jpayne@69:         'discard', 'intersection', 'intersection_update', 'isdisjoint',
jpayne@69:         'issubset', 'issuperset', 'pop', 'remove',
jpayne@69:         'symmetric_difference', 'symmetric_difference_update',
jpayne@69:         'union', 'update')
jpayne@69: 
jpayne@69:     def __new__(cls, fill_iter=None):
jpayne@69: 
jpayne@69:         if fill_iter is None:
jpayne@69:             return set()
jpayne@69: 
jpayne@69:         class LazySet(set):
jpayne@69:             pass
jpayne@69: 
jpayne@69:         fill_iter = [fill_iter]
jpayne@69: 
jpayne@69:         def lazy(name):
jpayne@69:             def _lazy(self, *args, **kw):
jpayne@69:                 _fill_lock.acquire()
jpayne@69:                 try:
jpayne@69:                     if len(fill_iter) > 0:
jpayne@69:                         for i in fill_iter.pop():
jpayne@69:                             set.add(self, i)
jpayne@69:                         for method_name in cls._props:
jpayne@69:                             delattr(LazySet, method_name)
jpayne@69:                 finally:
jpayne@69:                     _fill_lock.release()
jpayne@69:                 return getattr(set, name)(self, *args, **kw)
jpayne@69:             return _lazy
jpayne@69: 
jpayne@69:         for name in cls._props:
jpayne@69:             setattr(LazySet, name, lazy(name))
jpayne@69: 
jpayne@69:         new_set = LazySet()
jpayne@69:         return new_set
jpayne@69: 
jpayne@69: # Not all versions of Python declare the same magic methods.
jpayne@69: # Filter out properties that don't exist in this version of Python
jpayne@69: # from the list.
jpayne@69: LazySet._props = [prop for prop in LazySet._props if hasattr(set, prop)]