test/std/strings/string.view/string.view.ops/substr.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: !stdlib=libc++ && (c++03 || c++11 || c++14)

// <string_view>

// constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;

// Throws: out_of_range if pos > size().
// Effects: Determines the effective length rlen of the string to reference as the smaller of n and size() - pos.
// Returns: basic_string_view(data()+pos, rlen).

#include <string_view>
#include <algorithm>
#include <stdexcept>
#include <cassert>

#include "test_macros.h"

template <typename CharT>
void test1(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
  std::basic_string_view<CharT> sv1;
#ifdef TEST_HAS_NO_EXCEPTIONS
  if (pos > sv.size())
    return; // would throw if exceptions were enabled
  sv1 = sv.substr(pos, n);
#else
  try {
    sv1 = sv.substr(pos, n);
    assert(pos <= sv.size());
  } catch (const std::out_of_range&) {
    assert(pos > sv.size());
    return;
  }
#endif
  const std::size_t rlen = std::min(n, sv.size() - pos);
  assert(sv1.size() == rlen);
  for (std::size_t i = 0; i < rlen; ++i)
    assert(sv[pos + i] == sv1[i]);
}

template <typename CharT>
void test(const CharT* s) {
  typedef std::basic_string_view<CharT> string_view_t;

  string_view_t sv1(s);

  test1(sv1, 0, 0);
  test1(sv1, 1, 0);
  test1(sv1, 20, 0);
  test1(sv1, sv1.size(), 0);

  test1(sv1, 0, 3);
  test1(sv1, 2, 3);
  test1(sv1, 100, 3);

  test1(sv1, 0, string_view_t::npos);
  test1(sv1, 2, string_view_t::npos);
  test1(sv1, sv1.size(), string_view_t::npos);

  test1(sv1, sv1.size() + 1, 0);
  test1(sv1, sv1.size() + 1, 1);
  test1(sv1, sv1.size() + 1, string_view_t::npos);
}

int main(int, char**) {
  test("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
  test("ABCDE");
  test("a");
  test("");

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
  test(L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
  test(L"ABCDE");
  test(L"a");
  test(L"");
#endif

#if TEST_STD_VER >= 11
  test(u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
  test(u"ABCDE");
  test(u"a");
  test(u"");

  test(U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
  test(U"ABCDE");
  test(U"a");
  test(U"");
#endif

#if TEST_STD_VER > 11
  {
    constexpr std::string_view sv1{"ABCDE", 5};

    {
      constexpr std::string_view sv2 = sv1.substr(0, 3);
      static_assert(sv2.size() == 3, "");
      static_assert(sv2[0] == 'A', "");
      static_assert(sv2[1] == 'B', "");
      static_assert(sv2[2] == 'C', "");
    }

    {
      constexpr std::string_view sv2 = sv1.substr(3, 0);
      static_assert(sv2.size() == 0, "");
    }

    {
      constexpr std::string_view sv2 = sv1.substr(3, 3);
      static_assert(sv2.size() == 2, "");
      static_assert(sv2[0] == 'D', "");
      static_assert(sv2[1] == 'E', "");
    }
  }
#endif

  return 0;
}