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rex: A quasi-quoter for typeful results of regex captures.

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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.

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Properties

Versions 0.1, 0.2, 0.3, 0.3.1, 0.4.1, 0.4.2, 0.4.3, 0.4.3, 0.5, 0.5.1, 0.5.2, 0.6, 0.6.1, 0.6.2
Change log CHANGES.md
Dependencies base (>=3.0 && <6), bytestring, containers, haskell-src-exts (>=1.14), haskell-src-meta (>=0.5), pcre-light, template-haskell (>=2.5.0.0) [details]
License BSD-3-Clause
Copyright Michael Sloan 2011
Author Michael Sloan
Maintainer Michael Sloan <mgsloan at gmail>
Category Control
Home page http://github.com/mgsloan/rex
Bug tracker http://github.com/mgsloan/rex/issues
Source repo head: git clone git://github.com/mgsloan/rex
Uploaded by MichaelSloan at 2013-12-21T12:16:21Z

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Readme for rex-0.4.3

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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'