haskell - Haskell 中的转义 PCRE 元字符

Question

Haskell PCRE 库是否提供了转义字符串中正则表达式元字符的函数？ IE。一个函数，用于将“[$100]”这样的字符串转换为“\[\$100\]”。

我正在寻找Python的re.escape的等价物，我似乎无法在 regex-pcre 中找到它。

Answer 1

我不知道有这样的功能PCRE 库，但取决于什么你正在尝试完成你可以使用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