// tuple_comparison.hpp ----------------------------------------------------- // // Copyright (C) 2001 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi) // Copyright (C) 2001 Gary Powell (gary.powell@sierra.com) // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // // For more information, see http://www.boost.org // // (The idea and first impl. of comparison operators was from Doug Gregor) // ----------------------------------------------------------------- #ifndef BOOST_TUPLE_COMPARISON_HPP #define BOOST_TUPLE_COMPARISON_HPP #include "boost/tuple/tuple.hpp" // ------------------------------------------------------------- // equality and comparison operators // // == and != compare tuples elementwise // <, >, <= and >= use lexicographical ordering // // Any operator between tuples of different length fails at compile time // No dependencies between operators are assumed // (i.e. !(a<b) does not imply a>=b, a!=b does not imply a==b etc. // so any weirdnesses of elementary operators are respected). // // ------------------------------------------------------------- namespace boost { namespace tuples { inline bool operator==(const null_type&, const null_type&) { return true; } inline bool operator>=(const null_type&, const null_type&) { return true; } inline bool operator<=(const null_type&, const null_type&) { return true; } inline bool operator!=(const null_type&, const null_type&) { return false; } inline bool operator<(const null_type&, const null_type&) { return false; } inline bool operator>(const null_type&, const null_type&) { return false; } namespace detail { // comparison operators check statically the length of its operands and // delegate the comparing task to the following functions. Hence // the static check is only made once (should help the compiler). // These functions assume tuples to be of the same length. template<class T1, class T2> inline bool eq(const T1& lhs, const T2& rhs) { return lhs.get_head() == rhs.get_head() && eq(lhs.get_tail(), rhs.get_tail()); } template<> inline bool eq<null_type,null_type>(const null_type&, const null_type&) { return true; } template<class T1, class T2> inline bool neq(const T1& lhs, const T2& rhs) { return lhs.get_head() != rhs.get_head() || neq(lhs.get_tail(), rhs.get_tail()); } template<> inline bool neq<null_type,null_type>(const null_type&, const null_type&) { return false; } template<class T1, class T2> inline bool lt(const T1& lhs, const T2& rhs) { return lhs.get_head() < rhs.get_head() || ( !(rhs.get_head() < lhs.get_head()) && lt(lhs.get_tail(), rhs.get_tail())); } template<> inline bool lt<null_type,null_type>(const null_type&, const null_type&) { return false; } template<class T1, class T2> inline bool gt(const T1& lhs, const T2& rhs) { return lhs.get_head() > rhs.get_head() || ( !(rhs.get_head() > lhs.get_head()) && gt(lhs.get_tail(), rhs.get_tail())); } template<> inline bool gt<null_type,null_type>(const null_type&, const null_type&) { return false; } template<class T1, class T2> inline bool lte(const T1& lhs, const T2& rhs) { return lhs.get_head() <= rhs.get_head() && ( !(rhs.get_head() <= lhs.get_head()) || lte(lhs.get_tail(), rhs.get_tail())); } template<> inline bool lte<null_type,null_type>(const null_type&, const null_type&) { return true; } template<class T1, class T2> inline bool gte(const T1& lhs, const T2& rhs) { return lhs.get_head() >= rhs.get_head() && ( !(rhs.get_head() >= lhs.get_head()) || gte(lhs.get_tail(), rhs.get_tail())); } template<> inline bool gte<null_type,null_type>(const null_type&, const null_type&) { return true; } } // end of namespace detail // equal ---- template<class T1, class T2, class S1, class S2> inline bool operator==(const cons<T1, T2>& lhs, const cons<S1, S2>& rhs) { // check that tuple lengths are equal BOOST_STATIC_ASSERT(length<T2>::value == length<S2>::value); return detail::eq(lhs, rhs); } // not equal ----- template<class T1, class T2, class S1, class S2> inline bool operator!=(const cons<T1, T2>& lhs, const cons<S1, S2>& rhs) { // check that tuple lengths are equal BOOST_STATIC_ASSERT(length<T2>::value == length<S2>::value); return detail::neq(lhs, rhs); } // < template<class T1, class T2, class S1, class S2> inline bool operator<(const cons<T1, T2>& lhs, const cons<S1, S2>& rhs) { // check that tuple lengths are equal BOOST_STATIC_ASSERT(length<T2>::value == length<S2>::value); return detail::lt(lhs, rhs); } // > template<class T1, class T2, class S1, class S2> inline bool operator>(const cons<T1, T2>& lhs, const cons<S1, S2>& rhs) { // check that tuple lengths are equal BOOST_STATIC_ASSERT(length<T2>::value == length<S2>::value); return detail::gt(lhs, rhs); } // <= template<class T1, class T2, class S1, class S2> inline bool operator<=(const cons<T1, T2>& lhs, const cons<S1, S2>& rhs) { // check that tuple lengths are equal BOOST_STATIC_ASSERT(length<T2>::value == length<S2>::value); return detail::lte(lhs, rhs); } // >= template<class T1, class T2, class S1, class S2> inline bool operator>=(const cons<T1, T2>& lhs, const cons<S1, S2>& rhs) { // check that tuple lengths are equal BOOST_STATIC_ASSERT(length<T2>::value == length<S2>::value); return detail::gte(lhs, rhs); } } // end of namespace tuples } // end of namespace boost #endif // BOOST_TUPLE_COMPARISON_HPP