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