https://github.com/hlian/jiffy

Parser combinators, for Swift
https://github.com/hlian/jiffy

Last synced: 21 days ago
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Parser combinators, for Swift

• Host: GitHub
• URL: https://github.com/hlian/jiffy
• Owner: hlian
• Created: 2014-06-06T21:17:44.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2015-11-22T06:00:33.000Z (almost 9 years ago)
• Last Synced: 2024-07-31T21:55:12.744Z (4 months ago)
• Language: Swift
• Size: 18.6 KB
• Stars: 65
• Watchers: 2
• Forks: 5
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-combinator-parsers - jiffy

README

        
# Jiffy?

*Jiffy* is a parser-combinator library written in Swift, heavily inspired by [FParsec](http://www.quanttec.com/fparsec/), which in turn originates from [Parsec](http://legacy.cs.uu.nl/daan/parsec.html). 

Included is a work-in-progress parser for the [Doge Serialized Object Notation](http://dogeon.org/), the premier textual data representation of our time. See: [DSON.swift](https://github.com/hlian/jiffy/blob/master/Jiffy/DSON.swift).

# Parser combinators?

Are fantastic, and you can read all about them here: ["Dive into parser combinators."](http://blog.fogcreek.com/fparsec/)    Whoever wrote that must be a pretty OK dude. Gist: you can quickly and easily write composable, readable parsers for complicated grammars. Here, for example, is a parser for floating-point numbers:

    let pdigit = oneOf(Array("01234567"))

    let pdigit1 = oneOf(Array("1234567"))

    let pceil = string("0") <|> (concat <%> (s <%> pdigit1) <*> manyChar(pdigit1))

    let pmantissa = concat <%> oneChar(".") <*> many1Char(pdigit)

    let pexponent = (string("very") <|> string("VERY")) *> (concat <%> oneCharOf(Array("+-")) <*> many1Char(pdigit))

    let pnumber = toNumber <%> opt(oneChar("-")) <*> pceil <*> opt(pmantissa) <*> opt(pexponent)

    

(If IEEE were to replace the `e` keyword with the DOGE `very` -- and I think we can all agree they should.)

If you allow for some leeway, I hope to convince you that the code is a trivial transcription of this diagram:

![DSON floating-point number diagram](http://i.imgur.com/bHhToCN.png)

# Swift?

[Swift](http://haskell.org/) is a new language with a compiler that crashes and hangs a lot.

Generics and typeclasses I mean protocols are ideal for something like parser combinators, don't you think? Having custom operators doesn't hurt either.

If you're coming from Haskell or F#, there's one slight change you should be aware of: `<$>` isn't a valid operator name in Swift, so I went with `<%>` instead. Mnemonic: they're right next to each other!

Yours,


Hao.