4:22
 ?÷     rbiter = rbiter
            self.count = 0
            self.type = type

        def __iter__(self):
            return self

        def __next__(self):
            item = next(self.rbiter)
            item = item.cast(self.type).dereference()['_M_value_field']
            # FIXME: this is weird ... what to do?
            # Maybe a 'set' display hint?
            result = ('[%d]' % self.count, item)
            self.count = self.count + 1
            return result

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

    def to_string (self):
        return '%s with %d elements' % (self.typename,
                                        len (RbtreeIterator (self.val)))

    def children (self):
        rep_type = find_type(self.val.type, '_Rep_type')
        node = find_type(rep_type, '_Link_type')
        node = node.strip_typedefs()
        return self._iter (RbtreeIterator (self.val), node)

class StdBitsetPrinter:
    "Print a std::bitset"

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

    def to_string (self):
        # If template_argument handled values, we could print the
        # size.  Or we could use a regexp on the type.
        return '%s' % (self.typename)

    def children (self):
        words = self.val['_M_w']
        wtype = words.type

        # The _M_w member can be either an unsigned long, or an
        # array.  This depends on the template specialization used.
        # If it is a single long, convert to a single element list.
        if wtype.code == gdb.TYPE_CODE_ARRAY:
            tsize = wtype.target ().sizeof
        else:
            words = [words]
            tsize = wtype.sizeof 

        nwords = wtype.sizeof / tsize
        result = []
        byte = 0
        while byte < nwords:
            w = words[byte]
            bit = 0
            while w != 0:
                if (w & 1) != 0:
                    # Another spot where we could use 'set'?
                    result.append(('[%d]' % (byte * tsize * 8 + bit), 1))
                bit = bit + 1
                w = w >> 1
            byte = byte + 1
        return result

class StdDequePrinter:
    "Print a std::deque"

    class _iter(Iterator):
        def __init__(self, node, start, end, last, buffer_size):
            self.node = node
            self.p = start
            self.end = end
            self.last = last
            self.buffer_size = buffer_size
            self.count = 0

        def __iter__(self):
            return self

        def __next__(self):
            if self.p == self.last:
                raise StopIteration

            result = ('[%d]' % self.count, self.p.dereference())
            self.count = self.count + 1

            # Advance the 'cur' pointer.
            self.p = self.p + 1
            if self.p == self.end:
                # If we got to the end of this bucket, move to the
                # next bucket.
                self.node = self.node + 1
                self.p = self.node[0]
                self.end = self.p + self.buffer_size

            return result

    def __init__(self, typename, val):
        self.typename = typename
        self.val = val
        self.elttype = val.type.template_argument(0)
        size = self.elttype.sizeof
        if size < 512:
            self.buffer_size = int (512 / size)
        else:
            self.buffer_size = 1

    def to_string(self):
        start = self.val['_M_impl']['_M_start']
        end = self.val['_M_impl']['_M_finish']

        delta_n = end['_M_node'] - start['_M_node'] - 1
        delta_s = start['_M_last'] - start['_M_cur']
        delta_e = end['_M_cur'] - end['_M_first']

        size = self.buffer_size * delta_n + delta_s + delta_e

        return '%s with %d elements' % (self.typename, long (size))

    def children(self):
        start = self.val['_M_impl']['_M_start']
        end = self.val['_M_impl']['_M_finish']
        return self._iter(start['_M_node'], start['_M_cur'], start['_M_last'],