Reinhold Kainhofer <reinh...@kainhofer.com> writes: > Am Thursday, 15. September 2011, 01:50:34 schrieb David Kastrup: >> reinhold.kainho...@gmail.com writes: >> > On 2011/09/13 18:53:55, hanwenn wrote: >> >> have you thought of fixing this generically instead? >> >> >> >> You could the hare/tortoise algorithm to detect cycles in any markup, >> >> and could run that on the entry point (not the recursive function) >> >> for evaluating markups to stencils. >> > >> > Actually, I fail to see how I can use the algorithm to detect cycles in >> > markups. First, a markup is a tree and a recursive function rather tan a >> > chained function application, so the algorithm would have to run on each >> > branch. >> >> You traverse a tree in a certain order, and for the purpose of loop >> detection, you can consider the elements you reach as a list. > > The only problem is that we never get to the elements' values.
Who is interested in the values? They are not required for loop detection. > We never even really have a tree to traverse. The elements are only > created by interpret-markup, which will already cause the infinite > loop. I don't get your point. Whether the tree is explicit or implicit, the nodes are recognizable before evaluation. > Without running interpret-markup on a markup we don't know anything > about its contents (because the markup function might create anything > it wants), and as soon as we are running interpret-markup on a markup, > we might end up in a cycle. And the topic of this issue is detecting this cycle. > So, I wouldn't characterize this as a loop detection, but rather > determining whether an arbitrary recursion ever terminates... "cycle" and "loop" are two different names for the same thing. -- David Kastrup _______________________________________________ lilypond-devel mailing list lilypond-devel@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-devel
