Haskell Posix中的多行匹配 [英] Multiline Matching in Haskell Posix

问题描述

我似乎无法找到关于haskell的POSIX实现的体面的文档。
特别是模块 Text.Regex.Posix 。

任何人都可以指向正确的方向在字符串上使用多行匹配？

这个好奇的代码片段：

 > extractToken body = body =〜< textarea [^>] * id = \wpTextbox1 \[^>] *>（。*）< / textarea> :: String 
  

我试图提取维基百科页面的源代码，涉及多条线时。

解决方案

您可能需要 import Text.Regex.Base.RegexLike 访问 makeRegexOpts 和朋友。

  extractToken body = match regex body其中
 regex = makeRegexOpts（defaultCompOpt-compNewline）defaultExecOpt 
< textarea [^>] * id = \wpTextbox1 \[^>] *>（。*）< ; / textarea的>中
  

好了，既然 Text.Regex.Posix ' defaultCompOpt = compExtended + compNewline ，这等效于

  extractToken body = match regex body where 
 regex = makeRegexOpts compExtended defaultExecOpt 
< textarea [^>] * id = \wpTextbox1 \[^>] *>（。* ）< / textarea的>中
  

要取出第一组，请使用 RegexLike 。一种可能性是：

  extractToken body = head groups其中
（preMatch，inMatch，postMatch，groups）= 
 match regex body ::（String，String，String，[String]）
 regex = makeRegexOpts compExtended defaultExecOpt 
< textarea [^>] * id = \wpTextbox1 \[ ^>] * GT;<（*）; / textarea的>中
  

I can't seem to find decent documentation on haskell's POSIX implementation. Specifically the module Text.Regex.Posix.

Can anyone point me in the right direction of using multiline matching on a string?

A snippet for the curious:

> extractToken body = body =~ "<textarea[^>]*id=\"wpTextbox1\"[^>]*>(.*)</textarea>" :: String

I'm trying to extract the source of wikipedia pages, however this method clearly falls over when more than one line is involved.

解决方案

You may need to import Text.Regex.Base.RegexLike for access to makeRegexOpts and friends.

extractToken body = match regex body where
    regex = makeRegexOpts (defaultCompOpt - compNewline) defaultExecOpt
              "<textarea[^>]*id=\"wpTextbox1\"[^>]*>(.*)</textarea>"

Well, since Text.Regex.Posix's defaultCompOpt = compExtended + compNewline, that works out equivalently as

extractToken body = match regex body where
    regex = makeRegexOpts compExtended defaultExecOpt
              "<textarea[^>]*id=\"wpTextbox1\"[^>]*>(.*)</textarea>"

To pull out just the first group, use one of the other instances of RegexLike. One possibility is

extractToken body = head groups where
    (preMatch, inMatch, postMatch, groups) =
        match regex body :: (String, String, String, [String])
    regex = makeRegexOpts compExtended defaultExecOpt
              "<textarea[^>]*id=\"wpTextbox1\"[^>]*>(.*)</textarea>"

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