That answers my question pretty well, thanks. On Thursday, February 6, 2014 11:20:42 PM UTC-8, Reid McKenzie wrote: > > Okay. So there's one big thing you're doing wrong here just from reading > your grammars: you are complecting the datastructures and valid _tokens_ > which make up the clojure language with the _meaing_ associated therewith > by the language. If you discard such things as destructuring as "part of > the grammar" and instead just provide the parse grammars for basic > datastructures like symbols, maps, keywords sets and soforth it's trivial > to produce a grammar which can _parse_ valid clojure code. _Reading_ > clojure code from such a parse tree is and should be an entirely seperate > concern, implemented as a pass over the generated parse structure. > > - Reid > > On Thursday, February 6, 2014 9:28:08 PM UTC-6, Travis Moy wrote: >> >> I'm trying to use instaparse to parse Clojure code so that I can reformat >> it, but I'm having an issue with how to handle special forms. Should I >> attempt to parse special forms such as let and defn into their own rules, >> or should I rely instead on the actual content of the terminal to determine >> what lists should be treated as special forms? >> >> For example, let's say I want to write a function which takes the parse >> tree returned by instaparse and arranges all the let bindings as >> recommended by the Clojure style guide ( >> https://github.com/bbatsov/clojure-style-guide#source-code-layout--organization). >> >> There are two approaches I could take: >> >> 1) Build the recognition into the grammar itself: >> >> S = Form* >>> >>> <Form> = !SpecialForm List | ReaderMacro | Literal | Vector | Map | >>> SpecialForm | !SpecialForm Symbol >>> >>> List = '(' Form* ')' >>> >>> ... >>> >>> <SpecialForm> = defn | let | try | JavaMemberAccess | JavaConstructor >>> defn = '(' "defn" Symbol String? MapMetadata? >>> VectorDestructuring Form* ')' >>> >>> <Destructuring> = VectorDestructuring | MapDestructuring >>> VectorDestructuring = '[' (Symbol | Destructuring)* ('&' (Symbol | >>> Destructuring))? ']' >>> MapDestructuring = Map >>> >> >> 2) Don't try to detect the let bindings in the grammar. Instead, search >> the resulting parse tree for lists with "let" content. >> >> Which of these is a better approach? I sadly didn't take compilers in >> college so I'm kind of playing this by ear; I'm sure if I had I'd have a >> better idea of what the best practice is here. >> >> Thanks! >> >> (Full code for my project is at >> https://github.com/MoyTW/clojure-toys/tree/master/formatter if needed) >> >>
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