c# - Can Regex be used for this particular string manipulation?

Question

I need to replace character (say) x with character (say) P in a string, but only if it is contained in a quoted substring. An example makes it clearer:

axbx'cxdxe'fxgh'ixj'k  -> axbx'cPdPe'fxgh'iPj'k

Let's assume, for the sake of simplicity, that quotes always come in pairs.

The obvious way is to just process the string one character at a time (a simple state machine approach);
however, I'm wondering if regular expressions can be used to do all the processing in one go.

My target language is C#, but I guess my question pertains to any language having builtin or library support for regular expressions.

Answer 1

I converted Greg Hewgill's python code to C# and it worked!

[Test]
public void ReplaceTextInQuotes()
{
  Assert.AreEqual("axbx'cPdPe'fxgh'iPj'k", 
    Regex.Replace("axbx'cxdxe'fxgh'ixj'k",
      @"x(?=[^']*'([^']|'[^']*')*$)", "P"));
}

That test passed.