Boost spirit library does not seem to work properly with wide strings .

struct add_1000
	{
		add_1000(unsigned& r_) : r(r_) {}
		void operator()(wchar_t) const { r += 1000; }
		unsigned& r;
	};
	
	struct add_roman
	{
		add_roman(unsigned& r_) : r(r_) {}
		void operator()(unsigned n) const { r += n; }
		unsigned& r;
	};
	
	///////////////////////////////////////////////////////////////////////////////
	//
	//  roman (numerals) grammar
	//
	///////////////////////////////////////////////////////////////////////////////
	struct roman : public grammar<roman>
	{
		template <typename scannert="">
		struct definition
		{
			definition(roman const& self)
			{
				first
				=   +ch_p(L'M')  [add_1000(self.r)]
				||  hundreds_p  [add_roman(self.r)]
				||  tens_p      [add_roman(self.r)]
				||  ones_p      [add_roman(self.r)];
				
				//  Note the use of the || operator. The expression
				//  a || b reads match a or b and in sequence. Try
				//  defining the roman numerals grammar in YACC or
				//  PCCTS. Spirit rules! :-)
			}
			
			rule<scannert> first;
			rule<scannert> const&
			start() const { return first; }
		};
		
		roman(unsigned& r_) : r(r_) {}
		unsigned& r;
	};
BOOST_SPIRIT_CLASSIC_NAMESPACE_END
}}

<pre lang="cs">int
RomanNumeralConversion::
RomanToInt(const std::wstring& romanNumeral)
{
    std::wstring upperRoman(romanNumeral);
    FDStringUtils::ToUpper(upperRoman.begin(), upperRoman.end());
    unsigned int result = 0;
    BOOST_SPIRIT_CLASSIC_NS::roman roman_p(result);
    if (parse(upperRoman.c_str(), roman_p).full)
        return result;
    return -1;
}