How do I tell my regex to pick from an array of strings?

Question

I'm using Rails 5. I want to replace occurrences in a string of an arbitrary amount of numbers, an optional number of spaces, a token from an array of strings, an optinal number of spaces, and an arbitrary amount of numbers. So for example, this would match my pattern ....

123 / 2221111

or this

 102849/222

so I thought my regular expression should be

re = /\d+[[:space:]]*[#{Regexp.union(TOKENS)}][[:space:]]*\d+/

but the following is matching something that does not fit the criteria ...

2.4.0 :015 > re = /\d+[[:space:]]*[#{Regexp.union(TOKENS)}][[:space:]]*\d+/
 => /\d+[[:space:]]*[(?-mix:of|\/)][[:space:]]*\d+/
2.4.0 :016 > TOKENS
 => ["of", "/"]
2.4.0 :017 > name = "10F 2017"
 => "10F 2017"
2.4.0 :018 > name.gsub!(re, '#')
 => "#"

The string "10F 2017" does not contain any of the strings from my TOKENS array so right there things should fail. How do I rewrite my regex so that it only matches what I want?

Dave, [(?-mix:of|\/)] matches a single char: (, a range from ? to m (i.e. a lot of letters, all ASCII uppercase ones), i. etc. Delete the [ and ]. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Aug 11, 2017 at 18:15

Wiktor Stribiżew · Accepted Answer · 2017-08-11 18:24:55Z

2

By enclosing the #{Regexp.union(TOKENS)} into a character class, [(?-mix:of|\/)], you made it match a single char: (, characters ranging from ? to m, i, etc. The range between ? and m matches:

And see what parts of the string each part of your regex matches:

So, [(?-mix:of|\/)] matched F in your input string.

You need to remove [ and ]:

re = /\d+[[:space:]]*#{Regexp.union(TOKENS)}[[:space:]]*\d+/

See the Ruby demo

answered Aug 11, 2017 at 18:24

Wiktor Stribiżew

631k41 gold badges502 silver badges633 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How do I tell my regex to pick from an array of strings?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related