Match pattern and grab argument value using elisp regex returns nil

Question

This is my code statement

var myStr = require('ssh2')

and my elisp regex must return the arg value iff the statement has a require func invocation.

 (let ((s "var myStr = require('ssh2')"))
   (if (string-match "'require(\\([^']+\\)'" s)
       (match-string 1 s)))

this returns nil, however? what makes my regex a mess, someone?

Community · Accepted Answer · 2017-05-23 12:20:43Z

2

How about?:

"require\(\\(?:'\\(.*\\)'\\)\)"

If you haven't already played around with M-x re-builder RET, you'll enjoy it.

Here is a link to one of my favorite threads regarding a noncapturing group:

What is a non-capturing group? What does a question mark followed by a colon (?:) mean?

edited May 23, 2017 at 12:20

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answered Jan 18, 2015 at 4:42

lawlist

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2 Comments

user2879704 Over a year ago

it worked... but this pattern, "require\(\(?:'\(.*\)'\))" returned nil... the change i have made is put double slashes in the place of single slashes because somewhere i read in elisp, all escapes must be done twice...

lawlist Over a year ago

I believe literal parentheses are single-escaped. Re-builder will fail if literal parentheses are double-escaped. Parentheses that are for grouping, are double-escaped. Your example contains an opening literal parentheses and a closing literal parentheses.

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