Pretty printing boost :: unordered_map on gdb

Question

I recently started using the excellent boost :: unordered_map on my system, but got one drawback: I could not figure out how to check its contents. Printing on gdb gives me table_ and buckets_, but could not find where the elements are. Does anyone know about this?

Answer 1

For those who need a printer, I managed to create one. Here is the code:

class BoostUnorderedMapPrinter: "prints a boost::unordered_map" class _iterator: def __init__ (self, fields): type_1 = fields.val.type.template_argument(0) type_2 = fields.val.type.template_argument(1) self.buckets = fields.val['table_']['buckets_'] self.bucket_count = fields.val['table_']['bucket_count_'] self.current_bucket = 0 pair = "std::pair<%s const, %s>" % (type_1, type_2) self.pair_pointer = gdb.lookup_type(pair).pointer() self.base_pointer = gdb.lookup_type("boost::unordered_detail::value_base< %s >" % pair).pointer() self.node_pointer = gdb.lookup_type("boost::unordered_detail::hash_node<std::allocator< %s >, boost::unordered_detail::ungrouped>" % pair).pointer() self.node = self.buckets[self.current_bucket]['next_'] def __iter__(self): return self def next(self): while not self.node: self.current_bucket = self.current_bucket + 1 if self.current_bucket >= self.bucket_count: raise StopIteration self.node = self.buckets[self.current_bucket]['next_'] iterator = self.node.cast(self.node_pointer).cast(self.base_pointer).cast(self.pair_pointer).dereference() self.node = self.node['next_'] return ('%s' % iterator['first'], iterator['second']) def __init__(self, val): self.val = val def children(self): return self._iterator(self) def to_string(self): return "boost::unordered_map" 

Answer 2

In a typical hash table implementation, buckets contain a chapter in a linked list that actually contains values ​​corresponding to that particular hash. So I would bet on buckets_ .

Another option: now there are various python library libraries for gdb, and I think you can find one that works with C ++ 0x and check where it looks for values.