Regex to pick characters outside of pair of quotes

Question

I would like to find a regex that will pick out all commas that fall outside quote sets.

For example:

'foo' => 'bar', 'foofoo' => 'bar,bar' 

This would pick out the single comma on line 1, after 'bar',

I don't really care about single vs double quotes.

Has anyone got any thoughts? I feel like this should be possible with readaheads, but my regex fu is too weak.

Answer 1

This will match any string up to and including the first non-quoted ",". Is that what you are wanting?

/^([^"]|"[^"]*")*?(,)/ 

If you want all of them (and as a counter-example to the guy who said it wasn't possible) you could write:

/(,)(?=(?:[^"]|"[^"]*")*$)/ 

which will match all of them. Thus

'test, a "comma,", bob, ",sam,",here'.gsub(/(,)(?=(?:[^"]|"[^"]*")*$)/,';') 

replaces all the commas not inside quotes with semicolons, and produces:

'test; a "comma,"; bob; ",sam,";here' 

If you need it to work across line breaks just add the m (multiline) flag.

Answer 2

The below regexes would match all the comma's which are present outside the double quotes,

,(?=(?:[^"]*"[^"]*")*[^"]*$) 

DEMO

OR(PCRE only)

"[^"]*"(*SKIP)(*F)|, 

"[^"]*" matches all the double quoted block. That is, in this buz,"bar,foo" input, this regex would match "bar,foo" only. Now the following (*SKIP)(*F) makes the match to fail. Then it moves on to the pattern which was next to | symbol and tries to match characters from the remaining string. That is, in our output , next to pattern | will match only the comma which was just after to buz . Note that this won't match the comma which was present inside double quotes, because we already make the double quoted part to skip.

DEMO

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The below regex would match all the comma's which are present inside the double quotes,

,(?!(?:[^"]*"[^"]*")*[^"]*$) 

DEMO