graphs: incidence_iterator

From: jsiek_at_[hidden]
Date: 2000-05-22 18:56:02

Hello,

A "bug" in GGCL has revealed a problem in the graph interface (or at
least how we had extended the graph interface to deal with in-edges).

The "bug" is that the source and target vertex appear reversed for
in-edges.  The fix is simply to flip them around. The problem with the
fix is that for efficiency the "flip" needs to be encoded in the
iterator type, but GGCL currently uses the
graph_traits<G>::incidence_iterator type for accessing out-edges as
well as in-edges in a bidirectional graph.  This brings me to the main
point:

I think there needs to be two separate incidence iterator types in the
graph_traits class, one for out-edges an one for in-edges.
Here are some ideas for naming the types:

1. out_edge_iterator
   in_edge_iterator

2. incidence_iterator (for out-edges, same as before)
   in_edge_iterator (for in-edges)

3. incidence_iterator (for out-edges, same as before)
   incident_to_iterator (for in-edges)

4. incident_from_iterator (for out-edges)
   incident_to_iterator (for in-edges)

Thoughts?

Jeremy

----------------------------------------------------------------------
 Jeremy Siek                        www: http://www.lsc.nd.edu/~jsiek/
 Ph.D. Candidate                  email: jsiek_at_[hidden]
 Univ. of Notre Dame         cell phone: [phone]   
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