[boost] Graph: edge(u,v,g) isn't O(log(E/V)) as promised

From: Alan Stokes (alan_at_[hidden])
Date: 2004-01-30 06:25:26

For an adjaceny_list which uses sets for its edges, edge(u, v, g) is supposed to 
be O(log(E/V)), as you would expect for a lookup in a set. (See 
http://www.boost.org/libs/graph/doc/using_adjacency_list.html#sec:choosing-graph-type.)

But in fact it is linear in the number of out edges.

This is because in graph/detail/adjacency_list.hpp (line 1325 in revision 
1.113), in the edge_dispatch function that handles the 
disallow_parallel_edge_tag case, the code reads:
    i = std::find(g.out_edge_list(u).begin(),
                  g.out_edge_list(u).end(), StoredEdge(v)),
when it should probably be:
    i = g.out_edge_list(u).find(StoredEdge(v)),
as it was in revisions 1.59 and previous.

As an aside, it's not that obvious from the documentation that adjacency_list 
supports edge(u, v, g). AFAICT it's defined only in the AdjacencyMatrix concept, 
which adjacency_list is not documented as being a model of.

[This is a repost - the original was in message 31695 on the 21st of January. 
But I foolishly reported two different problems with the same subject & in the 
same thread, only one of which was addressed. I'm assuming the other one was 
overlooked and so repeating it. I apologise if this assumption is incorrect.]

- Alan