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https://github.com/boostorg/utility.git
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c63d36cf5b
These methods were added in C++23. Also updated string_view/ref tests: - Added tests for string_view::contains. - Added missing includes. - Added missing std:: qualification. - Removed tabs. - Fixed misleading indentation (fixes gcc warnings). - Fixed decrementing pointer before beginning of the string. Closes https://github.com/boostorg/utility/issues/93.
116 lines
4.2 KiB
C++
116 lines
4.2 KiB
C++
/*
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Copyright (c) Marshall Clow 2017-2017.
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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For more information, see http://www.boost.org
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*/
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#include <new> // for placement new
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#include <iostream>
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#include <cstddef> // for NULL, std::size_t, std::ptrdiff_t
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#include <cstring> // for std::strchr and std::strcmp
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#include <cstdlib> // for std::malloc and std::free
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#include <cstdio> // for EOF
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#include <boost/config.hpp>
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#include <boost/utility/string_view.hpp>
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#if __cplusplus >= 201402L
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struct constexpr_char_traits
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{
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typedef char char_type;
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typedef int int_type;
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typedef std::streamoff off_type;
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typedef std::streampos pos_type;
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typedef std::mbstate_t state_type;
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static void assign(char_type& c1, const char_type& c2) noexcept { c1 = c2; }
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static constexpr bool eq(char_type c1, char_type c2) noexcept { return c1 == c2; }
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static constexpr bool lt(char_type c1, char_type c2) noexcept { return c1 < c2; }
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static constexpr int compare(const char_type* s1, const char_type* s2, std::size_t n) noexcept;
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static constexpr std::size_t length(const char_type* s) noexcept;
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static constexpr const char_type* find(const char_type* s, std::size_t n, const char_type& a) noexcept;
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static constexpr char_type* move(char_type* s1, const char_type* s2, std::size_t n) noexcept;
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static constexpr char_type* copy(char_type* s1, const char_type* s2, std::size_t n) noexcept;
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static constexpr char_type* assign(char_type* s, std::size_t n, char_type a) noexcept;
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static constexpr int_type not_eof(int_type c) noexcept { return eq_int_type(c, eof()) ? ~eof() : c; }
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static constexpr char_type to_char_type(int_type c) noexcept { return char_type(c); }
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static constexpr int_type to_int_type(char_type c) noexcept { return int_type(c); }
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static constexpr bool eq_int_type(int_type c1, int_type c2) noexcept { return c1 == c2; }
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static constexpr int_type eof() noexcept { return EOF; }
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};
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// yields:
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// 0 if for each i in [0,n), X::eq(s1[i],s2[i]) is true;
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// else, a negative value if, for some j in [0,n), X::lt(s1[j],s2[j]) is true and
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// for each i in [0,j) X::eq(s2[i],s2[i]) is true;
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// else a positive value.
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constexpr int constexpr_char_traits::compare(const char_type* s1, const char_type* s2, std::size_t n) noexcept
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{
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for (; n != 0; --n, ++s1, ++s2)
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{
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if (lt(*s1, *s2))
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return -1;
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if (lt(*s2, *s1))
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return 1;
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}
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return 0;
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}
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// yields: the smallest i such that X::eq(s[i],charT()) is true.
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constexpr std::size_t constexpr_char_traits::length(const char_type* s) noexcept
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{
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std::size_t len = 0;
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for (; !eq(*s, char_type(0)); ++s)
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++len;
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return len;
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}
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typedef boost::basic_string_view<char, constexpr_char_traits> string_view;
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int main()
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{
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constexpr string_view sv1;
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constexpr string_view sv2{"abc", 3}; // ptr, len
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constexpr string_view sv3{"def"}; // ptr
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constexpr const char *s1 = "";
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constexpr const char *s2 = "abc";
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static_assert( (sv1 == sv1), "" );
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static_assert(!(sv1 == sv2), "" );
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static_assert( (sv1 != sv2), "" );
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static_assert( (sv1 < sv2), "" );
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static_assert( (sv1 <= sv2), "" );
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static_assert(!(sv1 > sv2), "" );
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static_assert(!(sv1 >= sv2), "" );
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static_assert(!(s1 == sv2), "" );
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static_assert( (s1 != sv2), "" );
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static_assert( (s1 < sv2), "" );
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static_assert( (s1 <= sv2), "" );
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static_assert(!(s1 > sv2), "" );
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static_assert(!(s1 >= sv2), "" );
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static_assert(!(sv1 == s2), "" );
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static_assert( (sv1 != s2), "" );
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static_assert( (sv1 < s2), "" );
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static_assert( (sv1 <= s2), "" );
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static_assert(!(sv1 > s2), "" );
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static_assert(!(sv1 >= s2), "" );
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static_assert( sv1.compare(sv2) < 0, "" );
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static_assert( sv1.compare(sv1) == 0, "" );
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static_assert( sv3.compare(sv1) > 0, "" );
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static_assert( sv1.compare(s2) < 0, "" );
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static_assert( sv1.compare(s1) == 0, "" );
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static_assert( sv3.compare(s1) > 0, "" );
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}
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#endif
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