_Coroutine StringLiteral {
	char ch;							// character passed by cocaller
	// YOU ADD MEMBERS HERE
	void main();						// coroutine main
  public:
	enum Encoding { C, Wide /* u */, Integer /* U or L */, UTF8 /* u8 */ };
	_Exception Match {					// last character match
	  public:
		Encoding prefix;				// string encoding
		unsigned int length;			// string length
		std::string & str;				// string value
		Match( Encoding prefix, unsigned int length, std::string & str )
			: prefix{prefix}, length{length}, str{str} {}
	};
	_Exception Error {};				// last character invalid
	void next( char c ) {
		ch = c;							// communication input
		resume();						// activate
	}
};

/*
Test data

""
"a\n"
"abc"
"xyz\012"
"xyz\x000c"
L"www"
"abc"xyz

"
"a
ab"
"\\\"
"\9"
l"www"
*/