X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=TODO;h=ecaed945c686612e34587b500a92c5c35d62841b;hp=ed981e83321eb371782d03abf3cd29196827e34e;hb=92bbf1d8e58c7ed013ef802fa873486438967b03;hpb=e84029a8b861075d6d0ed5040f919b2e4da4c98f diff --git a/TODO b/TODO index ed981e8..ecaed94 100644 --- a/TODO +++ b/TODO @@ -1,122 +1,119 @@ _____________________________________________________________________________ Immediately - - comparison test is probably chewing up most of the time + - keywordification (ie globally reject from all productions? + - generalized follow-by?) - - Check if the only remaining stack is lame (hopeful/nothopeful) - - write a testcase for this - - circular gramars - s = A - A = A | "b" - - foo.add(x) - foo.add(y.andnot(x)) ==> this is broken - - Annotation Tutorial + - clean up util package - .................................................. + - currently we GC the doomed stack when the parent dies... but + [ideally] we should also GC the parent when the doomed stack dies + if it was a positive conjunct. - - serializable parse tables? - - Treewalker code compiler? + - single-tree-return assumption + - have a way to let question marks not be tagged? + - "flat" sequences (no subtrees contain "::"s?) -- stringifiable + - make it so that we can have multi-result nonterminals + so long as they always appear under double-colons? + auto-insert the unwrap? + + - get rid of Sequence.Singleton if possible + + - use 'a'-'z' or 'a-z' instead of [a-z]? + - de-genericize? + - foo.add(x) + foo.add(y.andnot(x)) ==> this is broken + - distinguish Conjunct from Sequence? + => !(Conjunct instanceof Reducible) + - avoid building the parts of the tree that end up getting dropped + - is it worth adding an additional class of states for these? + - or perhaps just a runtime node marker (hasNonDroppedParent) + - "ambiguity modulo dropped fragments"? + - this may conceal highly inefficient grammars... + - double-check all the region logic + - automatically collect time statistics and display ______________________________________________________________________________ v1.1 - - precedes restrictions ("<-") +- use regression/least-squares/trend-prof to look for reductions whose + behavior is O(n^2)? (ie performed a number of times proportional to + the input consumed so far). + +- Optimizations: + - (x &~ y) => (x & z) + - string lookahead + - don't form result forests for negated productions + - early kills: (a &~ ... b ...) -> once "... b" is seen, "a" is dead + - MUST HAVE BETTER ERROR MESSAGES - use for developing java15.g - - java15.g - - once this is ready, do big announcement - - broader regression testing (for stuff like error messages, etc) + - better ambiguity reporting + - colorized tree-diffs? + - graphviz? + - better toString() methods all around... + + - Treewalker code compiler? + - detect and reject circular gramars + - skeleton generator? + - precedes restrictions ("<-") - More topology untangling [later] - grammar highlighting? - - Forest needs a "manual access" API - - the unwrap bit in Forest makes it really hard to expose an API for forests - - - -______________________________________________________________________________ -v1.2 - - - finalize metagrammar and rdp-op's + - Forest needs a "manual access" API (lifting makes this hard) + - rewriting language? multiple passes? - write some grammars - - Java grammar + - Java grammar (java15.g) - TeX (math?) - - URL (RFC) - RFC2822 (email message/headers) - - clean up the whole Walk situation (?) + - Wikipedia grammar (needs to be both lexerless and boolean) ______________________________________________________________________________ -Soon - - - serialization of parse tables - - - "ambiguity modulo dropped fragments"? - - can this be checked statically? - - eliminated statically? +Features - - substring parsing for better error messages + - try harder to "fuse" states together along two dimensions: + - identical (equivalent) states, or states that subsume each other + - unnecessary intermediate states ("short cut" GLR) + - substring parsing + - better error messages + - Rekers & Koorn note that this can do really elegant and generalized "autocompletion". - Parameterized LR - "Regular Right Part" grammars (NP Chapman, etc) - Attribute unification + - Partly-Linear-PATR? (O(n^6) unification grammar) + + - optional "prefer whitespace higher up" disambiguation heuristic + + - Incremental parse table construction - - inference of rejections for literals - - "prefer whitespace higher up" (?) + - "lazy GLR" and "lazy trees" -> language with first-class CF matching + - perhaps linear boolean grammars instead? (linear time, quad space) - - Labeled edges on trees (associate a label with each slot in the - child array in Forest.Body? might make equality tough) -- - equivalent to Feature Structures. Colon-labeling. + - Followed-by and not-followed-by predicates of arbitrary length + - expands the grammar beyond Boolean LR... + - requires *very* smart garbage collection ______________________________________________________________________________ -Later +Optimizations - understand and implement the RNGLR "kernel state" optimization. The _Practical Early Parsing_ paper may help. - - Partly-Linear-PATR? (O(n^6) unification grammar) + - implement Johnstone's algorithm for "reduced, resolved LR + tables" to eliminate superfluous reductions on + epsilon-transitions. - 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? - 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: @@ -139,26 +136,3 @@ Later 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. - -______________________________________________________________________________ -Neat Ideas - - - Rekers & Koorn note that GLR Substring Parsing can be used to do - really elegant and generalized "autocompletion". - - -______________________________________________________________________________ -Ideas for the Future - -- Incremental parse table construction -- "lazy GLR" and "lazy trees" -> language with first-class CF matching - - perhaps linear boolean grammars instead? (linear time, quad space) -- Forest parsing => chained parsers -- unification parsing, attributes, etc -- RRP grammars? -- Take another stab at maximal-match? Nonterminal not-followed-by is - too strong. -- Error recovery based on substring parsing