How do I match a string up to the first comma (if present) with a Ruby regexp

I'm struggling to get a regexp (in Ruby) that will provide the following

"one, two" -> "one"
"one, two, three" -> "one"
"one two three" -> "one two three"

I want to match any characters up until the first comma in a string. If there are no commas I want the entire string to be matched. My best effort so far is

/.*(?=,)?/

This produces the following output from the above examples

"one, two" -> "one"
"one, two, three" -> "one, two"
"one two three" -> "one two three"

Close but no cigar. Can an开发者_如何转开发yone help?

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I'm wondering if it can't be simpler:

/([^,]+)/

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Does it have to be a regex? Another solution:

text.split(',').first

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Would matching only non commas from the beginning work? e.g.:

/^[^,]+/

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How about /.*?(?=,|$)/ That way it either reads to the end or to a comma.