正则表达式文字-文本跨度 [英] Regular expression literal-text span

问题描述

有什么方法可以向正则表达式指明要显式搜索的文本块吗?我问是因为我必须匹配一段非常长的文本，其中包含各种元字符(并且(并且必须完全匹配)，然后是一些灵活的东西(足以值得使用正则表达式)，然后是更多的文本必须完全匹配.

Is there any way to indicate to a regular expression a block of text that is to be searched for explicitly? I ask because I have to match a very very long piece of text which contains all sorts of metacharacters (and (and has to match exactly), followed by some flexible stuff (enough to merit the use of a regex), followed by more text that has to be matched exactly.

冲洗，重复.

不用说，我真的不想遍历整个事情并且不得不转义每个元字符.这只是让它读起来很不舒服.有没有办法包装这些部分，这样我就不必这样做了?

Needless to say, I don't really want to have to run through the entire thing and have to escape every metacharacter. That just makes it a bear to read. Is there a way to wrap those portions so that I don't have to do this?

具体来说，我正在使用 Tcl，并且通过元字符"，我的意思是有各种长字符串，例如**$^{*$%\)".我真的不想逃避这些.我的意思是，它会在字符串中添加数千个字符.Tcl regexp 是否有文字文本跨度元字符?

Specifically, I am using Tcl, and by "metacharacters", I mean that there's all sorts of long strings like "**$^{*$%\)". I would really not like to escape these. I mean, it would add thousands of characters to the string. Does Tcl regexp have a literal-text span metacharacter?

推荐答案

在 Tcl 中执行此操作的正常方法是使用帮助程序进行转义，如下所示:

The normal way of doing this in Tcl is to use a helper procedure to do the escaping, like this:

proc re_escape str {
    # Every non-word char gets a backslash put in front
    regsub -all {\W} $str {\\&}
}

set awkwardString "**$^{*$%\\)"
regexp "simpleWord *[re_escape $awkwardString] *simpleWord" $largeString

如果你有一个完整的文字字符串，你还有另外两个选择:

Where you have a whole literal string, you have two other alternatives:

regexp "***=$literal" $someString
regexp "(?q)$literal" $someString

然而，这两种模式都只允许纯文字模式；你不能那样混合模式和文字.

However, both of these only permit patterns that are pure literals; you can't mix patterns and literals that way.

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