这样的东西适用于没有属性的标签:
\[(b|i|u)(:[a-z0-9]+)?\](.*?)\[\/\1(?:\2)?\]
\[ -- matches literal "["
(b|i|u) -- matches b, i, or u, captures as backreference 1
(:[a-z0-9]+)? -- matches colon and then alphanumeric string, captures as backreference 2
-- the question mark allows the :string not to be present.
\] -- matches literal "]"
(.*?) -- matches anything*, as few times as required to finish the match, creates backreference 3.
\[ -- matches literal "["
\/ -- matches literal "/"
\1 -- invokes backreference 1 to make sure the opening/closing tags match
(?:\2)? -- invokes backreference 2 to further make sure it's the same tag
\] -- matches literal "]"
匹配像 url 这样的标签很容易
对于具有属性的标签,它们对属性执行不同的操作,因此将 URL 等标签与 IMG 等标签分开处理可能更容易。
\[(url)(?:\s*=\s*(.*?))?(:[a-z0-9]+)\](.*?)\[\/\1(?:\3)?\]
\[ -- matches literal "["
(url) -- matches literal "url", in parentheses so we can invoke backreference 1 later, easier for you to modify
(?: -- ?: signifies a non-capturing group, so it creates a group without creating a backreference, or altering the backreference count.
\s*=\s* -- matches literal "=", padded by any amount of whitespace on either side
(.*?) -- matches any character, as few times as possible, to complete the match, creates backreference 2
) -- closes the noncapturing group
(:[a-z0-9]+) -- matches the alphanumeric string as backreference 3.
\] -- matches literal "]"
(.*?) -- matches any character as few times as possible to complete the match, backreference 4
\[ -- matches literal "["
\/ -- matches literal "/"
\1 -- invokes backreference 1
(?:\3)? -- invokes backreference 3
\] -- matches literal "["
对于您的替换,标签的内容本身在反向引用中,因此您可以对 b/i/u 标签执行类似的操作。
<\1>\3</\1>
对于url标签,是这样的
<A href="\2">\4</A>
我说点/句点匹配多个位置的任何字符。它匹配除换行符以外的任何字符。您可以像这样使用"dotall" 修饰符s 来打开正则表达式中的换行修饰符
/(.*)<foo>/s