class SharedPointerPrinter:
    "Print a shared_ptr or weak_ptr"

    class _iterator:
        def __init__(self, sharedPointer):
            self.sharedPointer = sharedPointer
            self.managedValue = sharedPointer.val['_M_ptr']
            self.count = 0

        def __iter__(self):
            return self

        def next(self):
            if self.managedValue == 0:
                raise StopIteration
            self.count = self.count + 1
            if (self.count == 1):
                return ('Managed value', self.managedValue.cast(self.managedValue.dynamic_type).dereference())
               
            else:
                raise StopIteration

    def __init__ (self, typename, val):
        self.typename = typename
        self.val = val

    def children (self):
        return self._iterator(self)

    def to_string (self):
        state = 'empty'
        refcounts = self.val['_M_refcount']['_M_pi']
        if refcounts != 0:
            usecount = refcounts['_M_use_count']
            weakcount = refcounts['_M_weak_count']
            if usecount == 0:
                state = 'expired, weakcount %d' % weakcount
            else:
                state = 'usecount %d, weakcount %d' % (usecount, weakcount - 1)
        return '%s (%s) to %s' % (self.typename, state, self.val['_M_ptr'])