//  Copyright (c) 2001, Joel de Guzman and Dan Nuffer
//  Permission is granted to use this code without restriction as
//  long as this copyright notice appears in all source files.

template <typename DerivedT>
struct parser
{
    DerivedT&
    derived()
    { return *static_cast<DerivedT*>(this); }

    DerivedT const&
    derived() const
    { return *static_cast<DerivedT const*>(this); }
};

template <typename DerivedT>
struct char_parser : public parser<DerivedT>
{
    template <typename IteratorT>
    match
    parse(IteratorT& first, IteratorT const& last) const
    {
        if (first != last)
            if (bool r = this->derived().test(*first))
            {
                ++first;
                return match(1);
            }
        return match();
    }
    ...
};

template <typename CharT = char>
class chlit : public char_parser<chlit<CharT> >
{
public:
    ...
    template <typename T>
    bool test(T ch_) const
    { return T(ch) == ch_; }

private:

    CharT  ch;
};