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4 - do Forest/Tree still need a Region?
5 - the unwrap bit in Forest makes it really hard to expose an API for forests
7 - evil problems with (x y? z /ws)
8 - ParseFailed, GSS, Walk, Parser, Sequence, Forest
12 - grammar highlighting?
13 - comment indentation vs block indentation?
15 - recursive { { foo } }
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20 - finalize metagrammar and rdp-op's
25 - RFC2822 (email message/headers)
26 - clean up the whole Walk situation (?)
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32 - serialization of parse tables
34 - "ambiguity modulo dropped fragments"?
35 - can this be checked statically?
36 - eliminated statically?
38 - substring parsing for better error messages
41 - "Regular Right Part" grammars (NP Chapman, etc)
42 - Attribute unification
44 - inference of rejections for literals
45 - "prefer whitespace higher up" (?)
47 - Labeled edges on trees (associate a label with each slot in the
48 child array in Forest.Body? might make equality tough) --
49 equivalent to Feature Structures. Colon-labeling.
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54 - Partly-Linear-PATR? (O(n^6) unification grammar)
56 - Implement a k-token peek buffer (for each state, see if it "dead
57 ends" during the next k Phases based solely on state -- ignoring
60 - Arrange for the SPPF corresponding to dropped subtrees to never be
61 generated (or merged, etc)
63 - Is there any way we can avoid creating a GSS.Node instance for
64 nodes which are transient in the sense that they have only one
67 - Re-read Rekers, particularly the stuff on optimal sharing
69 - Isolate the Element objects from Parse.Table/GSS so we can move
72 - consider allowing a Forest.Body to represent some other Tree whose
73 Body's should be [recursively] considered part of this Forest.
75 - perhaps not: right now we have a nice situation where
76 Forest.Ref instances become immutable once iterator()ed. This
77 also gives us a strong place to to culling with the certainty
78 that we won't throw out a Body which would later be salvaged
79 by some yet-to-be-added dependency.
81 - Figure out if there is a way to:
83 - allow unwrapping of children other than the very last one.
85 - fold repetitions into an array form in Forest, before
86 conversion to Tree. The major problem here is that multiple
87 tree-arrays are possible, all of different lengths. Worse,
88 even if they're all the same length, not all elements belong
89 in the same "possibility vector" as all others. You
90 essentially need a GSS to represent the array, which perhaps
91 is what the unfolded form was in the first place.
93 - Wikipedia grammar (needs to be both lexerless and boolean)
96 => Ordered Choice (";" operator)
98 - bring back in parse-table phase resolution of precedence (just
99 like associativity). This can be inferred from the use of ">"
100 when the rules are in one of these special forms:
111 where "_" is anything and "E" is the defining nonterminal.
112 Essentially what we're looking for is the situation where the
113 leftmost portion of one rule produces another rule, and the
114 rightmost portion of the latter produces the former.
116 I'm not 100% certain that this is as "strong" as the prefer/avoid
117 form (try to prove this, you probably can), but it's "what people
118 intend" most of the time.
120 - implement Johnstone's algorithm for "reduced, resolved LR
121 tables" to eliminate superfluous reductions on
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127 - Rekers & Koorn note that GLR Substring Parsing can be used to do
128 really elegant and generalized "autocompletion".
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134 - Incremental parse table construction
135 - "lazy GLR" and "lazy trees" -> language with first-class CF matching
136 - perhaps linear boolean grammars instead? (linear time, quad space)
137 - Forest parsing => chained parsers
138 - unification parsing, attributes, etc
140 - Take another stab at maximal-match? Nonterminal not-followed-by is
142 - Error recovery based on substring parsing