libstdc++-v3/testsuite/std/ranges/adaptors/conditionally_borrowed.cc

   1 // Copyright (C) 2020-2021 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a" }
  19 // { dg-do run { target c++2a } }
  20
  21 #include <ranges>
  22 #include <algorithm>
  23 #include <string>
  24 #include <cctype>
  25 #include <testsuite_hooks.h>
  26
  27 namespace ranges = std::ranges;
  28 namespace views = std::views;
  29 using namespace std::literals;
  30
  31 // P2017R1 "Conditionally borrowed ranges"
  32 auto trim(std::string const& s) {
  33     auto isalpha = [](unsigned char c){ return std::isalpha(c); };
  34     auto b = ranges::find_if(s, isalpha);
  35     auto e = ranges::find_if(s | views::reverse, isalpha).base();
  36     return ranges::subrange(b, e);
  37 }
  38
  39 void
  40 test01()
  41 {
  42   VERIFY( ranges::equal( trim("  abc    "), "abc"sv ) );
  43
  44   std::string s = "0123456789";
  45   auto odd = [](char c){ return (c - '0') % 2; };
  46   using namespace std::views;
  47   auto pos = ranges::find(s | take(5) | drop(1) | drop_while(odd), '2');
  48   VERIFY( *pos == '2' );
  49
  50   static_assert( ranges::borrowed_range<decltype(s | reverse)> );
  51   static_assert( ranges::borrowed_range<decltype(s | take(1))> );
  52   static_assert( ranges::borrowed_range<decltype(s | drop(1))> );
  53   static_assert( ranges::borrowed_range<decltype(s | drop_while(odd))> );
  54
  55   ranges::subrange r(s.begin(), s.cend());
  56   static_assert( !ranges::common_range<decltype(r)> );
  57   auto pos2 = ranges::find(r | views::common, '2');
  58   VERIFY( *pos2 == '2' );
  59 }
  60
  61 void
  62 test02()
  63 {
  64   std::pair<int, std::string_view> a[2]{ {1,"two"}, {3,"four"}};
  65   auto pos = ranges::find(a | views::values, "four");
  66   VERIFY( *pos == "four" );
  67
  68   static_assert( ranges::borrowed_range<decltype(a | views::keys)> );
  69 }
  70
  71 int main()
  72 {
  73   test01();
  74   test02();
  75 }