forked from boostorg/utility
110 lines
3.0 KiB
C++
110 lines
3.0 KiB
C++
// (C) 2003, Jan Langer (jan@langernetz.de).
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//
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// This material is provided "as is", with absolutely no warranty expressed
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// or implied. Any use is at your own risk.
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//
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// Permission to use or copy this software for any purpose is hereby granted
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// without fee, provided the above notices are retained on all copies.
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// Permission to modify the code and to distribute modified code is granted,
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// provided the above notices are retained, and a notice that the code was
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// modified is included with the above copyright notice.
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#ifndef BOOST_UTILITY_LEXICOGRAPHIC_HPP
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#define BOOST_UTILITY_LEXICOGRAPHIC_HPP
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namespace boost
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{
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class lexicographic
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{
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public:
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enum result_type { minus = -1, equivalent = 0, plus = +1 };
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private:
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typedef void (lexicographic::*unspecified_bool_type) ();
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void safe_bool_conversion () {}
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template <typename T1, typename T2>
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result_type do_compare (T1 const &a, T2 const &b) const
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{
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if (a < b)
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return minus;
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else if (b < a)
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return plus;
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else
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return equivalent;
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}
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template <typename T1, typename T2, typename Cmp>
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result_type do_compare (T1 const &a, T2 const &b, Cmp cmp) const
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{
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if (cmp (a, b))
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return minus;
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else if (cmp (b, a))
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return plus;
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else
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return equivalent;
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}
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public:
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lexicographic () : m_value (equivalent) {}
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template <typename T1, typename T2>
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lexicographic (T1 const &a, T2 const &b)
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: m_value (do_compare (a, b))
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{}
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template <typename T1, typename T2, typename Cmp>
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lexicographic (T1 const &a, T2 const &b, Cmp cmp)
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: m_value (do_compare (a, b, cmp))
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{}
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template <typename T1, typename T2>
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lexicographic &operator () (T1 const &a, T2 const &b)
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{
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if (m_value == equivalent)
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m_value = do_compare (a, b);
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return *this;
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}
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template <typename T1, typename T2, typename Cmp>
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lexicographic &operator () (T1 const &a, T2 const &b, Cmp cmp)
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{
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if (m_value == equivalent)
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m_value = do_compare (a, b, cmp);
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return *this;
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}
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result_type result () const
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{
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return m_value;
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}
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operator unspecified_bool_type () const
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{
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return (m_value == minus)
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? &lexicographic::safe_bool_conversion
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: 0;
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}
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// somehow only needed old compilers
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bool operator ! () const
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{
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return m_value != minus;
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}
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private:
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result_type m_value;
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};
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bool operator == (lexicographic l1, lexicographic l2)
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{
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return l1.result () == l2.result ();
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}
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bool operator != (lexicographic l1, lexicographic l2)
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{
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return l1.result () != l2.result ();
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}
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} // namespace boost
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#endif // BOOST_UTILITY_LEXICOGRAPHIC_HPP
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