RE-flex | fast lexical analyzer generator for C++ with full Unicode | Regex library

Use !important in the following style. The styles of the dropdown are overriding your styles when dropdown is opened

It's really important to be absolutely clear about what you want to accept. Otherwise, you cannot write a regular expression to accept it, and neither can anyone trying to help you.

Please note: The (broken) URLs in the following paragraphs were deliberately typed like that so that Markdown's recognition algorithm would be evident.

Both http://www.domain.tld/foo/bar/. and http://www.domain.tld/foo/bar. are valid URLs. But it's common for URL recognizers to avoid matching the trailing . (as you can see, Markdown won't match it) because of the common practice of writing a URL at the end of a sentence, even like this http://www.domain.tld/foo? (But with http://www.domain.tld/foo?search, Markdown recognizes the ? as part of the URL.)

Parentheses and quotes are also tricky. Markdown, to continue the running example, will accept parentheses in a URL if they are balanced (http://foo.es/?q=(main())) but as you can see, it is still possible to put the URL inside of parentheses. This behaviour is not possible to emulate with a regular expression, since regular expressions can't count.

But let's keep it simple. We can just accept a URL, but exclude the last character if it is in a list of punctuation characters. So that might end up with something like this:

I don't know anything about RE-flex (although it looks cool) but assuming it really is compatible with flex, the same approach should work: forget about forward lookahead assertions (since the string matched will not include the lookahead pattern, and you want to match the whole string) and put the rule after all the other rules which might match the same thing.

The flex rule is:

• the pattern which has the longest match wins, but
• if two or more patterns both match the longest match, the first pattern in the file wins.

So, for example, say you have the patterns: