The rex package

[Tags:bsd3, library]

Provides a quasi-quoter for regular expressions which yields a tuple, of appropriate arity and types, representing the results of the captures. Allows the user to specify parsers for captures as inline Haskell. Can also be used to provide typeful pattern matching in function definitions and pattern matches. Also, it precompiles the regular expressions into a PCRE compiled byte-array representation, at compile time.


[Skip to Readme]

Properties

Versions 0.1, 0.2, 0.3, 0.3.1, 0.4.1, 0.4.2, 0.4.3, 0.5, 0.5.1, 0.5.2
Change log CHANGES.md
Dependencies base (>=3.0 && <6), bytestring, containers, ghc (>=7.0), haskell-src-meta (>=0.5), pcre-light, split, template-haskell (>=2.5.0.0) [details]
License BSD3
Copyright Michael Sloan 2011
Author Michael Sloan
Maintainer Michael Sloan <mgsloan at gmail>
Stability experimental
Category Control
Home page http://github.com/mgsloan/rex
Bug tracker http://github.com/mgsloan/rex/issues
Source repository head: git clone git://github.com/mgsloan/rex
Uploaded Tue Feb 5 07:27:35 UTC 2013 by MichaelSloan
Distributions NixOS:0.5.2
Downloads 2089 total (17 in the last 30 days)
Votes
0 []
Status Docs uploaded by user
Build status unknown [no reports yet]

Modules

[Index]

Downloads

Maintainer's Corner

For package maintainers and hackage trustees

Readme for rex

Readme for rex-0.4.2

http://hackage.haskell.org/package/rex

Provides a quasi-quoter for regular expressions which yields a tuple, of appropriate arity and types, representing the results of the captures. Allows the user to specify parsers for captures as inline Haskell. Can also be used to provide typeful pattern matching in function definitions and case patterns.

To build / install:

./Setup.hs configure --user
./Setup.hs build
./Setup.hs install

See the haddock or Text/Regex/PCRE/Rex.hs for documentation.

Some examples (verbatim from Test.hs):

math x = mathl x 0

mathl [] x = x
mathl [rex|^  \s*(?{ read -> y }\d+)\s*(?{ s }.*)$|] x = mathl s y
mathl [rex|^\+\s*(?{ read -> y }\d+)\s*(?{ s }.*)$|] x = mathl s $ x + y
mathl [rex|^ -\s*(?{ read -> y }\d+)\s*(?{ s }.*)$|] x = mathl s $ x - y
mathl [rex|^\*\s*(?{ read -> y }\d+)\s*(?{ s }.*)$|] x = mathl s $ x * y
mathl [rex|^ /\s*(?{ read -> y }\d+)\s*(?{ s }.*)$|] x = mathl s $ x / y
mathl str x = error str

-- math "1 + 3" == 4.0
-- math "3 * 2 + 100" == 106.0
-- math "20 / 3 + 100 * 2" == 213.33333333333334
peano :: String -> Maybe Int
peano = [rex|^(?{ length . filter (=='S') } \s* (?:S\s+)*Z)\s*$|]

--  peano "S Z" == Just 1
--  peano "S S S S Z" == Just 4
--  peano "S   S   Z" == Just 2
parsePair :: String -> Maybe (String, String)
parsePair = [rex|^<\s* (?{ }[^\s,>]+) \s*,\s* (?{ }[^\s,>]+) \s*>$|]

--  parsePair "<-1, 3>" == Just ("-1","3")
--  parsePair "<-4,3b0>" == Just ("-4","3b0")
--  parsePair "< a,  -30 >" == Just ("a","-30")
--  parsePair "< a,  other>" == Just ("a","other")
-- From http://www.regular-expressions.info/dates.html
parseDate :: String -> Maybe (Int, Int, Int)
parseDate [rex|^(?{ read -> y }(?:19|20)\d\d)[- /.]
                (?{ read -> m }0[1-9]|1[012])[- /.]
                (?{ read -> d }0[1-9]|[12][0-9]|3[01])$|]
  |  (d > 30 && (m `elem` [4, 6, 9, 11]))
  || (m == 2 &&
       (d ==29 && not (mod y 4 == 0 && (mod y 100 /= 0 || mod y 400 == 0)))
    || (d > 29)) = Nothing
  | otherwise = Just (y, m, d)
parseDate _ = Nothing

--  parseDate "1993.8.10" == Nothing
--  parseDate "1993.08.10" == Just (1993,8,10)
--  parseDate "2003.02.28" == Just (2003,2,28)
--  parseDate "2003.02.27" == Just (2003,2,27)
onNull a f [] = a
onNull _ f xs = f xs

nonNull = onNull Nothing

disjunct [rex| ^(?:(?{nonNull $ Just . head -> a} .)
             | (?{nonNull $ Just . head -> b} ..)
             | (?{nonNull $ Just . last -> c} ...))$|] =
  head $ catMaybes [a, b, c]

--  disjunct "a" == 'a'
--  disjunct "ab" == 'a'
--  disjunct "abc" == 'c'