src/Hakyll/Core/Util/String.hs · hakyll

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1-- | Miscellaneous string manipulation functions.

2--

3module Hakyll.Core.Util.String

4 ( trim

5 , replaceAll

6 , splitAll

7 ) where

9import Data.Char (isSpace)

10import Data.Maybe (listToMaybe)

12import Text.Regex.PCRE ((=~~))

14-- | Trim a string (drop spaces, tabs and newlines at both sides).

16trim :: String -> String

17trim = reverse . trim' . reverse . trim'

18 where

19 trim' = dropWhile isSpace

21-- | A simple (but inefficient) regex replace funcion

23replaceAll :: String -- ^ Pattern

24 -> (String -> String) -- ^ Replacement (called on capture)

25 -> String -- ^ Source string

26 -> String -- ^ Result

27replaceAll pattern f source = replaceAll' source

28 where

29 replaceAll' src = case listToMaybe (src =~~ pattern) of

30 Nothing -> src

31 Just (o, l) ->

32 let (before, tmp) = splitAt o src

33 (capture, after) = splitAt l tmp

34 in before ++ f capture ++ replaceAll' after

36-- | A simple regex split function. The resulting list will contain no empty

37-- strings.

39splitAll :: String -- ^ Pattern

40 -> String -- ^ String to split

41 -> [String] -- ^ Result

42splitAll pattern = filter (not . null) . splitAll'

43 where

44 splitAll' src = case listToMaybe (src =~~ pattern) of

45 Nothing -> [src]

46 Just (o, l) ->

47 let (before, tmp) = splitAt o src

48 in before : splitAll' (drop l tmp)