X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=TODO;h=f8746d0b5f6ab9e0c92924920000dfbfbf798943;hp=1d628025dfb76a84c08b695ad58aacc26f7c6650;hb=9680415a3e36240dcac947b3d4d1ad6b312c4fce;hpb=d684010debf9069af108981d9451932c15b1ec75 diff --git a/TODO b/TODO index 1d62802..f8746d0 100644 --- a/TODO +++ b/TODO @@ -1,95 +1,116 @@ _____________________________________________________________________________ Immediately - - decent/better error messages - - fix the location stuff, it's broken - - - copyright notices - - - documentation + - 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. + + - 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 - - finalize metagrammar and rdp-op's +- 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 + - 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 (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 - - "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. + - 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) - - inference of rejections for literals - - "prefer whitespace higher up" (?) + - optional "prefer whitespace higher up" disambiguation heuristic + - Incremental parse table construction + + - "lazy GLR" and "lazy trees" -> language with first-class CF matching + - perhaps linear boolean grammars instead? (linear time, quad space) + + - 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: @@ -112,26 +133,3 @@ 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