Convert between String and Regexp

Question

I need to convert back and forth between the string representation of a Regexp and the Regexp itself.

Something like this:
> Regexp.new "\bword\b|other
=> /\bword\b|other/

However, doing so results in /\x08word\x08|other/

Is there some way to accomplish this?

I'd like \b to match a word boundary. e.g. "sword" would not match /\bword\b/ but "word" would. — yek
– yek, Commented Apr 9, 2018 at 20:00
You need to escape the backslashes so they are treated as characters, as opposed to escaping the following character: Regexp.new "\\bword\\b|other" #=> /\bword\b|other/. — Cary Swoveland
– Cary Swoveland, Commented Apr 9, 2018 at 20:10
It's probably easier to start with a regex and use to_s / source to get its string representation. — Stefan
– Stefan, Commented Apr 10, 2018 at 7:13

steenslag · Accepted Answer · 2018-04-09 21:49:56Z

2

Use single quotes, or escape the backslashes.

p re = Regexp.new('\bword\b|other') # => /\bword\b|other/
p re = Regexp.new("\\bword\\b|other")  # => /\bword\b|other/

p re.to_s  # => "(?-mix:\\bword\\b|other)"
p re.inspect # => "/\\bword\\b|other/"

The resulting string of to_s can be used as argument for Regexp.new (as can the regular expression itself).

edited Apr 9, 2018 at 21:49

answered Apr 9, 2018 at 20:20

steenslag

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1 Comment

Frederik Spang Over a year ago

Also worth mentioning %r(#{str}) for interpolated regex.

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