this should handle single and double quotes and escaping

  DB<145> p $s3=q{ "no" yo \\' yo ' no \\\\\\' no ' yo } 
 "no" yo \' yo ' no \\\' no ' yo

  DB<146> $_=$s3;  s/ ( \\. | ' (?: \\.|[^'] )* ' | " (?: \\.|[^"] )* 
+" ) | o /  $1 or 'O' /xge ; 
 => 6

  DB<147> p $_
 "no" yO \' yO ' no \\\' no ' yO
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If escapes outside of quotes should be ignored depends on the use-case, otherwise just skip the first or-case.

of course both quote-cases can be joined:

  DB<148> $_=$s3;  s/ ( \\. | (['"]) (?: \\.|[^\2] )* \2 ) | o /  $1 o
+r 'O' /xge ; 
 => 6

  DB<149> p $_
 "no" yO \' yO ' no \\\' no ' yO
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I think it's a good example to show how the regex engine does backtracking! =)

update

maybe easier to reuse with non-greedy quantifier

  DB<110> $_=$s3;  s/ ( \\. | (['"]) (?: \\.|. )*? \2 ) | o /  $1 or '
+O' /xge ; print ; ()
 "no'" yO \' yO ' no \\\' no ' yO
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