Question

是否有任何Haskell PCRE库提供了一个函数来逃避字符串中的正则表达式元字符？即取一个像“[$ 100]”这样的字符串并将其变成“\ [\ $ 100 \]”的函数。

我正在寻找相当于Python的re.escape，这在regex-pcre中似乎找不到。

Answer 1

我不知道任何一个这样的功能 PCRE库，但取决于什么你正试图完成你可以使用 PCRE引用：

{-# LANGUAGE OverloadedStrings #-}

import qualified Data.ByteString.Char8 as B
import Text.Regex.PCRE


quotePCRE bs = B.concat [ "\\Q" , bs , "\\E" ]

-- Of course, this won't work if the
-- string to be quoted contains `\E` ,
-- but that would be much eaiser to fix
-- than writing a function taking into
-- account all the necessary escaping.

literal = "^[$100]$"

quoted = quotePCRE literal

main :: IO ()
main = do B.putStr "literal: " >> B.putStrLn literal

          -- literal: ^[$100]$

          B.putStr "quoted: "  >> B.putStrLn quoted

          -- quoted: \Q^[$100]$\E

          putStrLn "literal =~ literal :: Bool"
          print ( literal =~ literal :: Bool )

          -- literal =~ literal :: Bool
          -- False

          putStrLn "literal =~ quoted :: Bool"
          print ( literal =~ quoted :: Bool )

          -- literal =~ quoted :: Bool
          -- True

在Haskell中转义PCRE元字符

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