_____________________________________________________________________________ Immediately - Lay down the law on the different kinds of Sequence productions and how they work. - switch maximal to not-followed-by (~/~) - should Union.add() be there? - should Atom.top() be there? - fix the location stuff, it's broken - decent/better error messages - write some grammars - Java grammar - TeX (math?) - URL (RFC) - RFC2822 (email message/headers) - Wiki grammar ______________________________________________________________________________ Soon - clean up the whole Walk situation - cleaner solution to "maximal"? - "lift" cases: - right now I can only lift the last child in a forest... begs the question of what the right representation for Forests is if we need to be able to do lift operations on it. - Parameterized LR - "Regular Right Part" grammars (NP Chapman, etc) - Attribute unification - serialization of parse tables - inference of rejections for literals - "prefer whitespace higher up" (?) - "ambiguity modulo dropped fragments"? - can this be checked statically? - eliminated statically? ______________________________________________________________________________ Later - Implement a k-token peek buffer (for each state, see if it "dead ends" during the next k Phases based solely on state -- ignoring result SPPF) - Arrange for the SPPF corresponding to dropped subtrees to never be generated (or merged, etc) - Is there any way we can avoid creating a GSS.Node instance for nodes which are transient in the sense that they have only one eligible reduction? - Implement "GLR syntactic predicates" -- the ability to do arbitrary lookahead (ie "followed-by" and "not-followed-by" for arbitrary patterns). This enables generalized longest-match and lets us drop the Maximal hack. - Re-read Rekers, particularly the stuff on optimal sharing - Isolate the Element objects from Parse.Table/GSS so we can move towards compilation. - consider allowing a Forest.Body to represent some other Tree whose Body's should be [recursively] considered part of this Forest. - perhaps not: right now we have a nice situation where Forest.Ref instances become immutable once iterator()ed. This also gives us a strong place to to culling with the certainty that we won't throw out a Body which would later be salvaged by some yet-to-be-added dependency. - Figure out if there is a way to: - allow unwrapping of children other than the very last one. - fold repetitions into an array form in Forest, before conversion to Tree. The major problem here is that multiple tree-arrays are possible, all of different lengths. Worse, even if they're all the same length, not all elements belong in the same "possibility vector" as all others. You essentially need a GSS to represent the array, which perhaps is what the unfolded form was in the first place. - Wikipedia grammar (needs to be both lexerless and boolean) - Boolean Parsing => Ordered Choice (";" operator) - bring back in parse-table phase resolution of precedence (just like associativity). This can be inferred from the use of ">" when the rules are in one of these special forms: E ::= E _ > _ E E ::= _ E > E _ E E ::= E _ E > E _ E where "_" is anything and "E" is the defining nonterminal. Essentially what we're looking for is the situation where the leftmost portion of one rule produces another rule, and the rightmost portion of the latter produces the former. I'm not 100% certain that this is as "strong" as the prefer/avoid form (try to prove this, you probably can), but it's "what people intend" most of the time. - implement Johnstone's algorithm for "reduced, resolved LR tables" to eliminate superfluous reductions on epsilon-transitions.