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/*
Copyright (c) Marshall Clow 2017-2017.
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
*/
#include <new> // for placement new
#include <iostream>
#include <cstddef> // for NULL, std::size_t, std::ptrdiff_t
#include <cstring> // for std::strchr and std::strcmp
#include <cstdlib> // for std::malloc and std::free
#include <cstdio> // for EOF
#include <boost/config.hpp>
#include <boost/utility/string_view.hpp>
#if __cplusplus >= 201402L
struct constexpr_char_traits
{
typedef char char_type;
typedef int int_type;
typedef std::streamoff off_type;
typedef std::streampos pos_type;
typedef std::mbstate_t state_type;
static void assign(char_type& c1, const char_type& c2) noexcept { c1 = c2; }
static constexpr bool eq(char_type c1, char_type c2) noexcept { return c1 == c2; }
static constexpr bool lt(char_type c1, char_type c2) noexcept { return c1 < c2; }
static constexpr int compare(const char_type* s1, const char_type* s2, std::size_t n) noexcept;
static constexpr std::size_t length(const char_type* s) noexcept;
static constexpr const char_type* find(const char_type* s, std::size_t n, const char_type& a) noexcept;
static constexpr char_type* move(char_type* s1, const char_type* s2, std::size_t n) noexcept;
static constexpr char_type* copy(char_type* s1, const char_type* s2, std::size_t n) noexcept;
static constexpr char_type* assign(char_type* s, std::size_t n, char_type a) noexcept;
static constexpr int_type not_eof(int_type c) noexcept { return eq_int_type(c, eof()) ? ~eof() : c; }
static constexpr char_type to_char_type(int_type c) noexcept { return char_type(c); }
static constexpr int_type to_int_type(char_type c) noexcept { return int_type(c); }
static constexpr bool eq_int_type(int_type c1, int_type c2) noexcept { return c1 == c2; }
static constexpr int_type eof() noexcept { return EOF; }
};
// yields:
// 0 if for each i in [0,n), X::eq(s1[i],s2[i]) is true;
// else, a negative value if, for some j in [0,n), X::lt(s1[j],s2[j]) is true and
// for each i in [0,j) X::eq(s2[i],s2[i]) is true;
// else a positive value.
constexpr int constexpr_char_traits::compare(const char_type* s1, const char_type* s2, std::size_t n) noexcept
{
for (; n != 0; --n, ++s1, ++s2)
{
if (lt(*s1, *s2))
return -1;
if (lt(*s2, *s1))
return 1;
}
return 0;
}
// yields: the smallest i such that X::eq(s[i],charT()) is true.
constexpr std::size_t constexpr_char_traits::length(const char_type* s) noexcept
{
std::size_t len = 0;
for (; !eq(*s, char_type(0)); ++s)
++len;
return len;
}
typedef boost::basic_string_view<char, constexpr_char_traits> string_view;
int main()
{
constexpr string_view sv1;
constexpr string_view sv2{"abc", 3}; // ptr, len
constexpr string_view sv3{"def"}; // ptr
constexpr const char *s1 = "";
constexpr const char *s2 = "abc";
static_assert( (sv1 == sv1), "" );
static_assert(!(sv1 == sv2), "" );
static_assert( (sv1 != sv2), "" );
static_assert( (sv1 < sv2), "" );
static_assert( (sv1 <= sv2), "" );
static_assert(!(sv1 > sv2), "" );
static_assert(!(sv1 >= sv2), "" );
static_assert(!(s1 == sv2), "" );
static_assert( (s1 != sv2), "" );
static_assert( (s1 < sv2), "" );
static_assert( (s1 <= sv2), "" );
static_assert(!(s1 > sv2), "" );
static_assert(!(s1 >= sv2), "" );
static_assert(!(sv1 == s2), "" );
static_assert( (sv1 != s2), "" );
static_assert( (sv1 < s2), "" );
static_assert( (sv1 <= s2), "" );
static_assert(!(sv1 > s2), "" );
static_assert(!(sv1 >= s2), "" );
static_assert( sv1.compare(sv2) < 0, "" );
static_assert( sv1.compare(sv1) == 0, "" );
static_assert( sv3.compare(sv1) > 0, "" );
static_assert( sv1.compare(s2) < 0, "" );
static_assert( sv1.compare(s1) == 0, "" );
static_assert( sv3.compare(s1) > 0, "" );
}
#endif
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