Question

要匹配的行是

part1a_part1b__part1c_part1d_part3.extension
part1a_part1b__part1c_part1d__part3.extension
part1a_part1b__part1c_part1d_part2short_part3.extension
part1a_part1b__part1c_part1d_part2short__part3.extension
part1a_part1b__part1c_part1d_part2_part3.extension
part1a_part1b__part1c_part1d_part2__part3.extension
part1a_part1b__part1c_part1d_part2full_part3.extension
part1a_part1b__part1c_part1d_part2full__part3.extension
part1a_part1b__part1c_part1d_part2short-part3.extension
part1a_part1b__part1c_part1d_part2-part3.extension
part1a_part1b__part1c_part1d_part2full-part3.extension
part1a_part1b__part1c_part1d_part4.extension
part1a_part1b__part1c_part1d__part4.extension

对于除最后两行之外的所有上述行，所需匹配应准确part1a_part1b__part1c_part1d。也就是说，＆＃34;干＆＃34;具有part1，optional part2 (in limited forms)的任意数字，并且必须以part3.extension结尾。

现在，我只有

(?P<stem>[[:alnum:]_-]+)(?=(|part2short|part2|part2full))[_-]+part3\.extension

，匹配＆＃34;茎＆＃34;上面几行的值是

part1a_part1b__part1c_part1d
part1a_part1b__part1c_part1d_
part1a_part1b__part1c_part1d_part2short
part1a_part1b__part1c_part1d_part2short_
part1a_part1b__part1c_part1d_part2
part1a_part1b__part1c_part1d_part2_
part1a_part1b__part1c_part1d_part2full
part1a_part1b__part1c_part1d_part2full_
part1a_part1b__part1c_part1d_part2short
part1a_part1b__part1c_part1d_part2
part1a_part1b__part1c_part1d_part2full

如果有可能，你可以帮忙评论一下如何精确匹配除最后两行之外的所有上述行part1a_part1b__part1c_part1d吗？

Answer 1

你可以将前4个部分与文本和下划线匹配，并使用一个肯定的前瞻，断言字符串以part3.extension结尾：

^(?P<stem>[^_]+_[^_]+__[^_]+_[^_]+)(?=.*part3\.extension$)

匹配：

^                     # Begin of the string
(?P<stem>             # Named captured group stem
[^_]+_                # Match not _ one or more times, then _
[^_]+__               # Match not _ one or more times, then __
[^_]+_                # Match not _ one or more times, then _
[^_]+                 # # Match not _ one or more times
)                     # Close named capturing group
(?=                   # A positive lookahead that asserts what follows
  .*part3\.extension$ # Match part3.extension at the end of the string
)                     # Close lookahead

Answer 2

你可以使用这个正则表达式使用非贪婪的匹配，一个带有可选匹配的前瞻：

(?m)^(?P<stem>[[:alnum:]_-]+?)(?=(?:[_-]+part2(?:short|full)?)?[_-]+part3\.extension$)

RegEx Demo

(?=(?:[_-]+part2(?:short|full)?)?[_-]+part3\.extension$)是一个积极的先行者，断言行以[-_]part3.extension结尾，并带有可选的[-_]part2...字符串。

如何使用正面正则表达式前瞻匹配，但排除前瞻部分？

2 个答案: