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|
-- | Miscellaneous string manipulation functions.
--
module Hakyll.Web.Util.String
( trim
, replaceAll
, splitAll
, toUrl
, toSiteRoot
) where
import Data.Char (isSpace)
import Data.Maybe (listToMaybe)
import System.FilePath (splitPath, takeDirectory, joinPath)
import Text.Regex.PCRE ((=~~))
-- | Trim a string (drop spaces, tabs and newlines at both sides).
--
trim :: String -> String
trim = reverse . trim' . reverse . trim'
where
trim' = dropWhile isSpace
-- | A simple (but inefficient) regex replace funcion
--
replaceAll :: String -- ^ Pattern
-> (String -> String) -- ^ Replacement (called on capture)
-> String -- ^ Source string
-> String -- ^ Result
replaceAll pattern f source = replaceAll' source
where
replaceAll' src = case listToMaybe (src =~~ pattern) of
Nothing -> src
Just (o, l) ->
let (before, tmp) = splitAt o src
(capture, after) = splitAt l tmp
in before ++ f capture ++ replaceAll' after
-- | A simple regex split function. The resulting list will contain no empty
-- strings.
--
splitAll :: String -- ^ Pattern
-> String -- ^ String to split
-> [String] -- ^ Result
splitAll pattern = filter (not . null) . splitAll'
where
splitAll' src = case listToMaybe (src =~~ pattern) of
Nothing -> [src]
Just (o, l) ->
let (before, tmp) = splitAt o src
in before : splitAll' (drop l tmp)
-- | Convert a filepath to an URL starting from the site root
--
-- Example:
--
-- > toUrl "foo/bar.html"
--
-- Result:
--
-- > "/foo/bar.html"
--
toUrl :: FilePath -> String
toUrl = ('/' :)
-- | Get the relative url to the site root, for a given (absolute) url
--
toSiteRoot :: String -> String
toSiteRoot = emptyException . joinPath . map parent . splitPath . takeDirectory
where
parent = const ".."
emptyException [] = "."
emptyException x = x
|
