How to make regex matchers non-greedy?

Question

I am trying to use a regex for replacing text in a file (replace a full url with just protocol/domain/):

:%s/\(https\?:\/\/.*?\/\).*/\1/gc

Unfortunately .*? does not match the string, even trying to escape the ? quantifier? How should non-greedy quantifier be escaped in vim?

Answer 1

Vim's regex has special syntax for non-greedy versions of operators (it's kind of annoying, but you just have to memorize them): http://vimregex.com/#Non-Greedy

The non-greedy version of * is \{-}. So, simply replace .* with .\{-}:

:%s/\(https\?:\/\/.\{-}\/\).*/\1/gc

Answer 2

I prefer always breaking the problem into two steps:

/\v(https?):\/\/(.{-})\/.*        <-- Search
:%s,,Protocol:\1 - Domain:\2,g    <-- Substitution

Using very magic "\v" to avoid many backslashes, referencing the last search in substitution and changing substitution delimiter. All these changes make the code more readable.

Answer 3

You can also use the [^\]+/. to prevent greediness. [^/] means "match anything expect /, and + repeats that one or more times..

:%s!\v^(https?)\://([^/]+)/.*$!Protocol:\1 \t Domain:\2!g

If I have / in the regex, I will use ! as a separator so that I don't have to escape /.

Example

Let's suppose you have the following urls:

http://academy.mises.org/courses/econgd/
http://academy.mises.org/moodle/course/view.php?id=172
http://acmsel.safaribooksonline.com/book/-/9781449358204?bookview=overview
http://acmsel.safaribooksonline.com/home
http://acordes.lacuerda.net/bebo__cigala/lagrimas_negras-2.shtml
http://acordes.lacuerda.net/jose_antonio_labordeta/albada.shtml
http://anarchitext.wordpress.com/category/new-middle-east/
https://courses.edx.org/courses/course-v1%3ADelftX%2BFP101x%2B3T2015/wiki/DelftX.FP101x.3T2015/resources-and-links/
https://cseweb.ucsd.edu/classes/wi11/cse230/lectures.html
https://developer.mozilla.org/en-US/docs/CSS
https://developers.google.com/edu/python
https://developers.google.com/structured-data/testing-tool/

Applying the substitution you would get that :

Protocol:http    Domain:academy.mises.org
Protocol:http    Domain:academy.mises.org
Protocol:http    Domain:acmsel.safaribooksonline.com
Protocol:http    Domain:acmsel.safaribooksonline.com
Protocol:http    Domain:acordes.lacuerda.net
Protocol:http    Domain:acordes.lacuerda.net
Protocol:http    Domain:anarchitext.wordpress.com
Protocol:https   Domain:courses.edx.org
Protocol:https   Domain:cseweb.ucsd.edu
Protocol:https   Domain:developer.mozilla.org
Protocol:https   Domain:developers.google.com
Protocol:https   Domain:developers.google.com