Finding a regex match from an array of regexes

Question

def match_line regex
    @line.match(regex) if !regex.is_a?(Array)
    regex.each {|rgx| 
        results = @line.match(rgx) 
        return results if !results.nil? 
    }
    return nil
end

This looks like something that could be done in a one line idiomatic way, and I'm just not seeing how.

Your question isn't clear. Do you want to see if one of the regex patterns in the array matches something? Or, do you want to find out which of the regex patterns matched? — the Tin Man
– the Tin Man, Commented Apr 16, 2011 at 19:23
You meant to put return before the second line, I suppose. — sawa
– sawa, Commented Apr 16, 2011 at 19:46

Rein Henrichs · Accepted Answer · 2011-04-16 19:10:55Z

5

[*regex].map{ |re| @line.match re }.compact.first

or

Array(regex).map{ |re| @line.match re }.compact.first

answered Apr 16, 2011 at 19:10

Rein Henrichs

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3 Comments

Jeremy Smith Over a year ago

Thank you, that is great. Does the Array() turn a variable into an array if it isn't already one? Also, I assume all of the regexes are matched and there isn't a way to jump out after the first match?

Jeremy Smith Over a year ago

nm on Array().. that's a very useful function.

Rein Henrichs Over a year ago

That's correct, it will iterate over all regexes in regex, but assuming there are relatively few this won't be a big deal. You could do a custom each that short-circuits but I doubt the performance gain would be worth the loss in readability.

Mike Lewis · Accepted Answer · 2011-04-16 19:09:55Z

1

 [*regex].find{|r| @line.match(r)}
 return $~ #will return the last MatchedData returned, otherwise nil.

$~ will return the last MatchedData returned, otherwise nil.

answered Apr 16, 2011 at 19:09

Mike Lewis

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2 Comments

Rein Henrichs Over a year ago

:( perlish magic global variables are unreadable, as indicated by your explaining comment.

Mike Lewis Over a year ago

Having a comment associated with that line seems like no issue to me, especially because it is literally one line that is in question.

DigitalRoss · Accepted Answer · 2011-04-16 19:43:58Z

0

def match_line regex
  [*regex].each { |r| return r if (r = @line.match r) }
end

answered Apr 16, 2011 at 19:43

DigitalRoss

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Comments

sawa · Accepted Answer · 2011-04-16 19:52:07Z

0

It is a preferred, established practice to pass arguments in this case like

match_line(regex1, regex2, ...)

or

match_line(*array_of_regexes)

rather than

match_line([regex1, regex2, ...])

or

match_lines(array_of_regexes)

so your conditioning regarding array-ness is unnecessary.

def match_line *regex
  regex.detect{|r| @line =~ r}
  Regexp.last_match
end

answered Apr 16, 2011 at 19:52

sawa

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