我可以否定POSIX括号表达式吗? [英] Can I do a negation of a POSIX bracket expression?

问题描述

我知道我可以使用POSIX括号表达式[[:space:]]搜索与空格匹配的内容.我可以使用POSIX括号表达式搜索不匹配空格的内容吗?特别是，它应该匹配的字符包括字母和括号(().

I know I can search for something matching a space with the POSIX bracket expression [[:space:]]. Can I do a search for something not matching a space using a POSIX bracket expression? In particular, the characters it should match include letters, and parentheses (().

[[:graph:]]看起来有些模糊:

[[:graph:]]-非空白字符(不包括空格，控制字符等)

[[:graph:]] - Non-blank character (excludes spaces, control characters, and similar)

推荐答案

您在这里混淆了两件事:a 括号表达式和POSIX字符类.外部[...]是括号表达式，可以用紧跟在[之后的^取反. POSIX字符类是[: + name + :]构造，仅在括号表达式内有效.

You confuse two things here: a bracket expression and a POSIX character class. The outer [...] is a bracket expression, and it can be negated with a ^ that immediately follows [. A POSIX character class is a [:+name+:] construct that only works inside bracket expressions.

因此，在您的情况下，[[:space:]]模式是一个括号表达式，仅包含一个与空白匹配的POSIX字符类:

So, in your case, [[:space:]] pattern is a bracket expression containing just 1 POSIX character class that matches a whitespace:

• [-打开方括号表达式
  • [:space:]-空格的POSIX字符类
  • [ - opening a bracket expression
    • [:space:] - a POSIX character class for whitespace

    要否定它，只需像通常的NFA中那样添加^ 字符类 :[^[:space:]].

    To negate it, just add the ^ as in usual NFA character classes: [^[:space:]].

    请注意，由于POSIX和常见的NFA regex世界遵循不同的术语，因此我故意区分术语括号表达"，"POSIX字符类"和字符类".

    Note I deliberately differentiate the terms "bracket expression", "POSIX character class" and "character class" since POSIX and common NFA regex worlds adhere to different terminology.

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