DouKaku?

#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <iterator>
#include <ctype.h> // isalpha()

struct is_alpha : public std::unary_function<char, bool>
{
    bool operator()(char c) const
    {
        return isalpha(c);
    }
};

bool option(
    std::string::const_iterator beg,
    std::string::const_iterator& it,
    const std::string& name,
    std::string& ret)
{
    const std::string s = "-" + name;

    if (std::distance(beg, it) >= s.size() && std::equal(it - s.size(), it, s.begin()))
    {
        it -= s.size();

        ret = name;

        return true;
    }
    else
    {
        return false;
    }
}

void extract(const std::string& s)
{
    std::string::const_iterator it = s.begin();

    while ((it = std::find(it, s.end(), '.')) != s.end())
    {
        std::string::const_iterator it2;

        it2 = std::find_if(it + 1, s.end(), std::not1(is_alpha()));

        const std::string ext(it + 1, it2);

        std::string size, hidden;

        it2 = it;

        option(s.begin(), it2, "big", size) || option(s.begin(), it2, "small", size);

        option(s.begin(), it2, "hidden", hidden);

        std::string name(
            std::find_if(
                std::string::const_reverse_iterator(it2),
                s.rend(),
                std::not1(is_alpha())
            ).base(), it2
        );

        if (name.empty())
        {
            if (!hidden.empty())
            {
                name.swap(hidden);
            }
            else if (!size.empty())
            {
                name.swap(size);
            }
        }

        if (size.empty())
        {
            size = "normal";
        }

        std::cout
            << "name:'" << name << "', "
            << "ext:'" << ext << "', "
            << "size: " << size << " "
            << "hidden: " << (!hidden.empty())
            << std::endl;

        ++it;
    }
}

int main()
{
    std::boolalpha(std::cout);

    extract(
        "aaa abc-hidden.png>hoge-big.jpeg\n"
        "---foo-hidden-small.gif|^_^a.bmp\n"
        "--hiddena-hoge.png<=not hidden~~\n"
        "--small.jpg<=not small(^_^)\n"
        "normal-small-big.hoge\n"
    );
}