1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
//===----------------------------------------------------------------------===//
//
// 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: c++03, c++11, c++14, c++17
// Some basic examples of how transform_view might be used in the wild. This is a general
// collection of sample algorithms and functions that try to mock general usage of
// this view.
#include <ranges>
#include <cctype>
#include <functional>
#include <list>
#include <numeric>
#include <string>
#include <vector>
#include <cassert>
#include "MoveOnly.h"
#include "test_macros.h"
#include "test_iterators.h"
#include "types.h"
template<class T, class F>
concept ValidTransformView = requires { typename std::ranges::transform_view<T, F>; };
struct BadFunction { };
static_assert( ValidTransformView<MoveOnlyView, PlusOne>);
static_assert(!ValidTransformView<Range, PlusOne>);
static_assert(!ValidTransformView<MoveOnlyView, BadFunction>);
template<std::ranges::range R>
auto toUpper(R range) {
return std::ranges::transform_view(range, [](char c) { return std::toupper(c); });
}
template<class E1, class E2, std::size_t N, class Join = std::plus<E1>>
auto joinArrays(E1 (&a)[N], E2 (&b)[N], Join join = Join()) {
return std::ranges::transform_view(a, [&a, &b, join](auto& x) {
auto idx = (&x) - a;
return join(x, b[idx]);
});
}
#if _LIBCPP_STD_VER >= 23
struct MoveOnlyFunction : public MoveOnly {
template <class T>
constexpr T operator()(T x) const {
return x + 42;
}
};
#endif
struct NonConstView : std::ranges::view_base {
explicit NonConstView(int *b, int *e) : b_(b), e_(e) {}
const int *begin() { return b_; } // deliberately non-const
const int *end() { return e_; } // deliberately non-const
const int *b_;
const int *e_;
};
int main(int, char**) {
{
std::vector<int> vec = {1, 2, 3, 4};
auto transformed = std::ranges::transform_view(vec, [](int x) { return x + 42; });
int expected[] = {43, 44, 45, 46};
assert(std::equal(transformed.begin(), transformed.end(), expected, expected + 4));
const auto& ct = transformed;
assert(std::equal(ct.begin(), ct.end(), expected, expected + 4));
}
{
// Test a view type that is not const-iterable.
int a[] = {1, 2, 3, 4};
auto transformed = NonConstView(a, a + 4) | std::views::transform([](int x) { return x + 42; });
int expected[4] = {43, 44, 45, 46};
assert(std::equal(transformed.begin(), transformed.end(), expected, expected + 4));
}
{
int a[4] = {1, 2, 3, 4};
int b[4] = {4, 3, 2, 1};
auto out = joinArrays(a, b);
int check[4] = {5, 5, 5, 5};
assert(std::equal(out.begin(), out.end(), check, check + 4));
}
{
std::string_view str = "Hello, World.";
auto upp = toUpper(str);
std::string_view check = "HELLO, WORLD.";
assert(std::equal(upp.begin(), upp.end(), check.begin(), check.end()));
}
#if _LIBCPP_STD_VER >= 23
// [P2494R2] Relaxing range adaptors to allow for move only types.
// Test transform_view is valid when the function object is a move only type.
{
int a[] = {1, 2, 3, 4};
auto transformed = NonConstView(a, a + 4) | std::views::transform(MoveOnlyFunction());
int expected[] = {43, 44, 45, 46};
assert(std::equal(transformed.begin(), transformed.end(), expected, expected + 4));
}
#endif
// GH issue #70506
// movable_box::operator= overwrites underlying view
{
auto f = [l = 0.0L, b = false](int i) {
(void)l;
(void)b;
return i;
};
auto v1 = std::vector{1, 2, 3, 4} | std::views::transform(f);
auto v2 = std::vector{1, 2, 3, 4} | std::views::transform(f);
v1 = std::move(v2);
int expected[] = {1, 2, 3, 4};
assert(std::equal(v1.begin(), v1.end(), expected, expected + 4));
}
return 0;
}
|
