C++程序  |  70行  |  1.49 KB

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//


// <string_view>

// constexpr basic_string_view(const _CharT* _s)
//    : __data (_s), __size(_Traits::length(_s)) {}


#include <string_view>
#include <string>
#include <cassert>

#include "test_macros.h"
#include "constexpr_char_traits.hpp"

template<typename CharT>
size_t StrLen ( const CharT *s ) {
    size_t retVal = 0;
    while ( *s != 0 ) { ++retVal; ++s; }
    return retVal;
    }

template<typename CharT>
void test ( const CharT *s ) {
    typedef std::basic_string_view<CharT> SV;
//  I'd love to do this, but it would require traits::length() to be noexcept
//  LIBCPP_ASSERT_NOEXCEPT(SV(s));

    SV sv1 ( s );
    assert ( sv1.size() == StrLen( s ));
    assert ( sv1.data() == s );
    }


int main () {

    test ( "QBCDE" );
    test ( "A" );
    test ( "" );

    test ( L"QBCDE" );
    test ( L"A" );
    test ( L"" );

#if TEST_STD_VER >= 11
    test ( u"QBCDE" );
    test ( u"A" );
    test ( u"" );

    test ( U"QBCDE" );
    test ( U"A" );
    test ( U"" );
#endif

#if TEST_STD_VER > 11
    {
    constexpr std::basic_string_view<char, constexpr_char_traits<char>> sv1 ( "ABCDE" );
    static_assert ( sv1.size() == 5, "");
    }
#endif
}