# IRC log for #marpa, 2015-11-15

All times shown according to UTC.

Time Nick Message
00:34 Cheery now I tried an another..
00:35 Cheery what's the simplest method to turn an earley recognizer into a parser?
00:46 Idiosyncrat Begin with the completed start rule, and traverse the tree in the Earley sets in whatever is your preferred way.
00:46 Idiosyncrat Not all Earley items will necessarily be relevant to yoiur tree.
00:46 Idiosyncrat This ignores ambiguity.
00:47 Idiosyncrat The traversal will be easier if you store, with each Earley item as you create it, links to the other Earley items
00:47 Idiosyncrat from which it was created.
00:47 Idiosyncrat This is for traditional Earley items.  The method if you use LR(0) states is gruesomely hard.
00:49 Cheery yeah. sort of noticing that.
00:55 Cheery starting to remember.. the method I picked was the same I picked the last time.
01:25 Cheery in a way. the method I use is dividing with the topmost rule.
01:26 Cheery then I divide with sub rules.
01:26 Cheery but I'm noticing a problem.
01:27 Cheery this kind of division will be impacted badly by right recursion.
01:28 Cheery the recursion produces lot of bad-mannered branches.
01:29 Cheery but I may be able to handle it by denoting where each rule prediction begins, then take minimum when merging that detail.
01:34 Cheery may also manage it by being mad-mannered myself.
01:53 Idiosyncrat Just look up tree traversals and do one.
01:53 Idiosyncrat For using parses, it's good to be very fluent with tree traversals.
01:54 Idiosyncrat There's a method in Aho&Ullman, Vol. I, p. 328.
01:55 Idiosyncrat It's a straightforward recursion that does a rightmost derivation.
01:55 Idiosyncrat There's also one in one of Earley's papers, though I heard from somewhere that's there's some sort of bug in it.
01:57 Idiosyncrat But anyway, it's a straightforward tree traversal, except your tree is in a special kind of notation -- Earley items,
01:57 Idiosyncrat instead of something more convenient.
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17:34 JPGainsborough hi
17:36 JPGainsborough I heard recently that C++ reached an anniversary of some sort, 30 years. CFront was open source. I'll bet the parser for modern C++ is a horror
17:36 JPGainsborough CFront source has been released
17:38 Cheery now I've got a parser I should just dare to plug in.
17:41 Cheery because it's not using ordereddict of python, it should be couple times more efficient
17:41 Cheery but otherwise it's the exactly same as before
17:42 JPGainsborough interesting
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