Comment by penteract

I think the author has underestimated the power of the substitution rules - it looks like it should be possible to drag a state machine along, hence recognise any regular language. Something like the following should handle quoted strings (untested and needs every character to be listed out in the definitions of @Char, @CharQuoted and @NonQuoteQuoted):

    sub Quote @Char' by @CharQuoted;
    sub Backslash.quoted Backslash' by Backslash.quoted2;
    sub Backslash.quoted Quote' by Quote.escaped;
    sub [@NonQuoteQuoted Quote.escaped Backslash.quoted2] @Char' by @CharQuoted;

I don't know if context can be carried between different lines.