import weakref
import gc

builtin_types = (bool, float, int, str)

class MemoryStuff():
    id = 0

    def __init__(self):
        MemoryStuff.id += 1
        self.id = MemoryStuff.id

    def __repr__(self):
        return "{Memory#" + str(self.id) + "}"


class WeakDictBase:
    primdict = {}

    def keys(self):
        return self.objdict.keys() + self.primdict.keys()

    def __len__(self):
        return len(self.objdict) + len(self.primdict)


class WeakKeyDict(WeakDictBase):
    objdict = weakref.WeakKeyDictionary()

    def __getitem__(self, key):
        dict = self.primdict if type(key) in builtin_types else self.objdict

        return dict[key] if key in dict else "Not found"

    def __setitem__(self, key, val):
        if type(key) in builtin_types:
            self.primdict[key] = val
        else:
            self.objdict[key] = val

class WeakValueDict(WeakDictBase):
    objdict = weakref.WeakValueDictionary()

    def __getitem__(self, key):
        if key in self.primdict:
            return self.primdict[key]
        elif key in self.objdict:
            return self.objdict[key]

        return "Not found"

    def __setitem__(self, key, val):
        if type(val) in builtin_types:
            if key in self.objdict:
                del self.objdict[key]

            self.primdict[key] = val
        else:
            if key in self.primdict:
                del self.primdict[key]

            self.objdict[key] = val

class WeakKeyValueDict(dict):

    def __getitem__(self, key):
        val = dict.__getitem__(self, key)
        return val() if isinstance(val, weakref.ref) else val

    def __setitem__(self, key, val):
        k = key if type(key) in builtin_types else weakref.ref(key)
        v = val if type(val) in builtin_types else weakref.ref(val)

        return dict.__setitem__(self, k, v)

    def keys(self):
        return filter(lambda key: not isinstance(key, weakref.ref) or key() is not None, dict.keys(self))

print("--- Weak Keys ---")

a = WeakKeyDict()
a[10] = 100

x = MemoryStuff()
a[x] = 777

print("keys: ")
print(a.keys())
print(len(a))
print(a[x])

x = 555

print("-- gc --")
gc.collect()

print("keys: ")
print(a.keys())
print(len(a))
print(a[x])


print("--- Weak Values ---")

a = WeakValueDict()
a[10] = 100

x = MemoryStuff()
a[x] = 777

y = MemoryStuff()
a[10] = y

print("keys: ")
print(a.keys())
print(len(a))
print(a[x])

y = 20

print("-- gc --")
gc.collect()

print("keys: ")
print(a.keys())
print(len(a))
print(a[x])


print("--- Weak Keys & Values ---")

a = WeakKeyValueDict()
a[10] = 100
obj = MemoryStuff()
stuff = MemoryStuff()
a[obj] = 100
a[100] = obj
a[stuff] = obj

print("keys: ")
print(a.keys())
print(len(a))
print(a[10])
print(a[100])

obj = 10
stuff = 20
gc.collect()

print("keys: ")
print(a.keys())
print(len(a))
print(a[10])
print(a[100])