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From: Jeremy Siek (jsiek_at_[hidden])
Date: 2001-06-01 08:49:08

On Fri, 1 Jun 2001, Vladimir Prus wrote:
ghost> I am very sceptical about this idea. After all, automaton
ghost> should do one thing -- perform transition, and do it fast,
ghost> whereas traversing adjacent vertices may be slow or not
ghost> supported. This is quite different from graph. Unless I'm
ghost> shown an implementation doing both tasks equally well, I
ghost> won't belive such can be written.

Perhaps you don't understand what I'm suggesting. When I was browsing
through the ASTL source code, I saw a function named astl_copy_breadth()
which includes code that looks like this:

// Iterating on from1 outgoing transitions:
DFA1::Edges edges = dfa1.delta2(from1);
for(trans_it = edges.begin(), trans_end = edges.end();
    trans_it != trans_end; ++trans_it)
  to1 = (*trans_it).second;

To me this looks exactly like traversing a graph... so it would make sense
to use the graph interface we have all agreed on. That way when people are
reading the code, they can see a familiar interface instead of trying to
learn a new one. I'm guessing, but converting to the BGL interface might
look like this:

for (tie(trans_it, trans_end) = out_edges(from1, dfa1);
     trans_it != trans_end; ++trans_it)
  to1 = target(*trans_it, dfa1);

Who knows, maybe the astl_copy_breadth() could even be implemented by the
copy_graph() function in the BGL.


 Jeremy Siek www:
 Ph.D. Candidate, IU B'ton email: jsiek_at_[hidden]
 Summer Manager, AT&T Research phone: (973) 360-8185

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