1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10 // UNSUPPORTED: libcpp-no-concepts
11 // UNSUPPORTED: gcc-10
12 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
13 
14 // Some basic examples of how transform_view might be used in the wild. This is a general
15 // collection of sample algorithms and functions that try to mock general usage of
16 // this view.
17 
18 #include <ranges>
19 
20 #include <cctype>
21 #include <functional>
22 #include <list>
23 #include <numeric>
24 #include <string>
25 #include <vector>
26 
27 #include <cassert>
28 #include "test_macros.h"
29 #include "test_iterators.h"
30 #include "types.h"
31 
32 template<std::ranges::range R>
33 auto toUpper(R range) {
34   return std::ranges::transform_view(range, [](char c) { return std::toupper(c); });
35 }
36 
37 unsigned badRandom() { return 42; }
38 
39 template<std::ranges::range R, class Fn = std::plus<std::iter_value_t<R>>>
40 auto withRandom(R&& range, Fn func = Fn()) {
41   return std::ranges::transform_view(range, std::bind_front(func, badRandom()));
42 }
43 
44 template<class E1, class E2, size_t N, class Join = std::plus<E1>>
45 auto joinArrays(E1 (&a)[N], E2 (&b)[N], Join join = Join()) {
46   return std::ranges::transform_view(a, [&a, &b, join](auto& x) {
47     auto idx = (&x) - a;
48     return join(x, b[idx]);
49   });
50 }
51 
52 int main(int, char**) {
53   {
54     std::vector vec = {1, 2, 3, 4};
55     auto sortOfRandom = withRandom(vec);
56     std::vector check = {43, 44, 45, 46};
57     assert(std::equal(sortOfRandom.begin(), sortOfRandom.end(), check.begin(), check.end()));
58   }
59 
60   {
61     int a[4] = {1, 2, 3, 4};
62     int b[4] = {4, 3, 2, 1};
63     auto out = joinArrays(a, b);
64     int check[4] = {5, 5, 5, 5};
65     assert(std::equal(out.begin(), out.end(), check));
66   }
67 
68   {
69     std::string_view str = "Hello, World.";
70     auto upp = toUpper(str);
71     std::string_view check = "HELLO, WORLD.";
72     assert(std::equal(upp.begin(), upp.end(), check.begin(), check.end()));
73   }
74 
75   return 0;
76 }
77