Test Text string escaping.

benchmark.hs

{-# LANGUAGE OverloadedStrings #-}
import qualified Data.Text as X
import Data.Text (Text)

import Criterion
import Criterion.Main

escapedChars :: String
escapedChars =  '"':'\\':"-!@~/()*[]="

escapeText1 :: Text -> Text
escapeText1 = X.concatMap (\x -> if x `elem` escapedChars
                                  then X.pack $ '\\':[x]
                                  else X.singleton x)

escapeText2 :: Text -> Text
escapeText2 = X.intercalate "\\" . breakBy (`elem` escapedChars)

escapeText3 :: Text -> Text
escapeText3 t | t == X.empty = t
              | otherwise   = let (untouched, broken) = X.break (`elem` escapedChars) t
                              in  untouched `X.append` ('\\' `X.cons` (if broken == X.empty then X.empty else X.head broken `X.cons` escapeText3 (X.tail broken)))

escapeText4 :: Text -> Text
escapeText4 t | t == X.empty = t
              | otherwise   = let (untouched, broken) = X.break (`elem` escapedChars) t
                              in  untouched `X.append` ('\\' `X.cons` X.take 1 broken `X.append` escapeText3 (X.drop 1 broken))

escapeText5 :: Text -> Text
escapeText5 t | t == X.empty = t
              | otherwise   = let (untouched, broken) = X.break (`elem` escapedChars) t
                              in  X.concat [untouched, "\\", X.take 1 broken, escapeText4 $ X.drop 1 broken]

breakBy = X.groupBy . const . fmap not

t1 = "abc\"\\-!@~/()*[]foobar"
t2 = "This is more natural text! It contains (only some) characters we *want* to escape, and it contains an email address: foo@bar.baz."

main = defaultMain
    [ bench "escapeText1-t1" $ whnf escapeText1 t1
    , bench "escapeText2-t1" $ whnf escapeText2 t1
    , bench "escapeText3-t1" $ whnf escapeText3 t1
    , bench "escapeText4-t1" $ whnf escapeText4 t1
    , bench "escapeText5-t1" $ whnf escapeText5 t1

    , bench "escapeText1-t2" $ whnf escapeText1 t2
    , bench "escapeText2-t2" $ whnf escapeText2 t2
    , bench "escapeText3-t2" $ whnf escapeText3 t2
    , bench "escapeText4-t2" $ whnf escapeText4 t2
    , bench "escapeText5-t2" $ whnf escapeText5 t2
    ]