使用STD :: MAP时错误

在以下代码中，我试图了解地图查找如何与用户定义的数据一起用作键。

#include <iostream>
#include <map>
#include <boost/tuple/tuple.hpp>
#include <boost/tuple/tuple_io.hpp>
#include "unicode/coll.h"
using namespace std;
using namespace icu;
class mystring {
public:
    std::string s;
    bool operator==(const mystring &s1) const;
    bool operator!=(const mystring &s) const;
    bool operator<(const mystring &s1) const;
    bool operator>(const mystring &s1) const;
    bool operator<=(const mystring &s1) const;
    bool operator>=(const mystring &s1) const;
};
int caseCompare(UnicodeString& str1, int32_t len1, UnicodeString& str2, int32_t len2)
{
    int ret;
    ret = str1.caseCompare(0, len1, str2, 0, len2, 0);
    cout << "caseCompare: " << ret << endl;
    return ret;
}
bool mystring::operator==(const mystring &s1) const
{
    cout << "== operator" << "n";
    cout << s << "t" << s1.s << "n";
    UnicodeString us1(s.c_str(), s.length());
    UnicodeString us2(s1.s.c_str(), s1.s.length());
    if(caseCompare(us1, s.length(), us2, s1.s.length() != 0)) {
        return 0;
    }
    return 1;
}
bool mystring::operator<(const mystring &s1) const
{
    UnicodeString us1(s.c_str(), s.length());
    UnicodeString us2(s1.s.c_str(), s1.s.length());
    int ret;
    cout << "< operator" << "n";
    cout << s << "t" << s1.s << "n";
    size_t smaller_size;
    if (s.size() < s1.s.size()) {
        smaller_size = s.size();
    } else {
        smaller_size = s1.s.size();
    }
    ret = caseCompare(us1, s.length(), us2, s1.s.length() != 0);
    if(ret != 0) {
        if (ret < 0) {
            return 1;
        } else {
            return 0;
        }
    }
    if ((s.size() == s1.s.size()) || (s.size() > s1.s.size())) {
        return 0;
    } else {
        return 1;
    }
}
bool mystring::operator!=(const mystring &s1) const
{
    cout << "!= operator" << "n";
    cout << s << "t" << s1.s << "n";
    if (!(*this == s1)) {
        return 1;
    } else {
        return 0;
    }
}
bool mystring::operator>(const mystring &s1) const
{
    cout << "> operator" << "n";
    cout << s << "t" << s1.s << "n";
    if ((!(*this < s1)) && (!(*this == s1))) {
        return 1;
    } else {
        return 0;
    }
}
bool mystring::operator<=(const mystring &s1) const
{
    cout << "<= operator" << "n";
    cout << s << "t" << s1.s << "n";
    if ((*this < s1) || (*this == s1)) {
        return 1;
    } else {
        return 0;
    }
}
bool mystring::operator>=(const mystring &s1) const
{
    cout << ">= operator" << "n";
    cout << s << "t" << s1.s << "n";
    if ((*this > s1) || (*this == s1)) {
        return 1;
    } else {
        return 0;
    }
}
typedef boost::tuple<class mystring, class mystring> Key;
int data = 100;
typedef std::map<Key, int, std::less<Key> > Testmap;
Testmap map1;
int main(void)
{
    mystring str1;
    mystring str2;
    string str3, str4;
    cout << "String1: " << endl;
    cin >> str3;
    cout << "String2: " << endl;
    cin >> str4;
    str1.s = str3;
    str2.s = str4;
    Key fk = boost::make_tuple(str1, str2);
    map1.insert(std::make_pair(fk, data));
    cout << "String1: " << endl;
    cin >> str3;
    cout << "String2: " << endl;
    cin >> str4;
    str1.s = str3;
    str2.s = str4;
    fk = boost::make_tuple(str1, str2);
    Testmap::iterator itr = map1.find(fk);
    if (itr != map1.end()) {
        cout << itr->second << "n";
    } else {
        cout << "Not found";
    }
    return 0;
}

编译此代码时，我会收到此错误：

$ g++ map_test.cc -licuuc -licui18n
In file included from /usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/string:50,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/bits/locale_classes.h:42,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/bits/ios_base.h:43,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/ios:43,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/ostream:40,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/iostream:40,
                 from map_test.cc:1:
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/bits/stl_function.h: In member function ‘bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>]’:
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/bits/stl_tree.h:1170:   instantiated from ‘std::pair<typename std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator, bool> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_insert_unique(const _Val&) [with _Key = boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>, _Val = std::pair<const boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>, int>, _KeyOfValue = std::_Select1st<std::pair<const boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>, int> >, _Compare = std::less<boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >, _Alloc = std::allocator<std::pair<const boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>, int> >]’
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/bits/stl_map.h:500:   instantiated from ‘std::pair<typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator, bool> std::map<_Key, _Tp, _Compare, _Alloc>::insert(const std::pair<const _Key, _Tp>&) [with _Key = boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>, _Tp = int, _Compare = std::less<boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >, _Alloc = std::allocator<std::pair<const boost::tuples::tuple<mystring, mystring, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>, int> >]’
map_test.cc:146:   instantiated from here
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/bits/stl_function.h:230: error: no match for ‘operator<’ in ‘__x < __y’

我想它找不到<运算符，但这是在class mystring中定义的。还是抱怨缺乏分配方法？

谢谢！