//===----------------------------------------------------------------------===//
//
// 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
// template<forward_iterator I, sentinel_for<I> S, class T, class Proj = identity,
// indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
// constexpr I ranges::lower_bound(I first, S last, const T& value, Comp comp = {},
// Proj proj = {});
// template<forward_range R, class T, class Proj = identity,
// indirect_strict_weak_order<const T*, projected<iterator_t<R>, Proj>> Comp =
// ranges::less>
// constexpr borrowed_iterator_t<R>
// ranges::lower_bound(R&& r, const T& value, Comp comp = {}, Proj proj = {});
#include <algorithm>
#include <array>
#include <cassert>
#include <functional>
#include <ranges>
#include "almost_satisfies_types.h"
#include "test_iterators.h"
struct NotLessThanComparable {};
template <class It, class Sent = It>
concept HasLowerBoundIt = requires(It it, Sent sent) { std::ranges::lower_bound(it, sent, 1); };
static_assert(HasLowerBoundIt<int*>);
static_assert(!HasLowerBoundIt<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>);
static_assert(!HasLowerBoundIt<ForwardIteratorNotDerivedFrom>);
static_assert(!HasLowerBoundIt<ForwardIteratorNotIncrementable>);
static_assert(!HasLowerBoundIt<NotLessThanComparable*>);
template <class Range>
concept HasLowerBoundR = requires(Range range) { std::ranges::lower_bound(range, 1); };
static_assert(HasLowerBoundR<std::array<int, 1>>);
static_assert(!HasLowerBoundR<ForwardRangeNotDerivedFrom>);
static_assert(!HasLowerBoundR<ForwardRangeNotIncrementable>);
static_assert(!HasLowerBoundR<UncheckedRange<NotLessThanComparable*>>);
template <class Pred>
concept HasLowerBoundPred = requires(int* it, Pred pred) {std::ranges::lower_bound(it, it, 1, pred); };
static_assert(HasLowerBoundPred<std::ranges::less>);
static_assert(!HasLowerBoundPred<IndirectUnaryPredicateNotCopyConstructible>);
static_assert(!HasLowerBoundPred<IndirectUnaryPredicateNotPredicate>);
template <class It>
constexpr void test_iterators() {
{ // simple test
{
int a[] = {1, 2, 3, 4, 5, 6};
std::same_as<It> auto ret = std::ranges::lower_bound(It(a), It(a + 6), 3);
assert(base(ret) == a + 2);
}
{
int a[] = {1, 2, 3, 4, 5, 6};
auto range = std::ranges::subrange(It(a), It(a + 6));
std::same_as<It> auto ret = std::ranges::lower_bound(range, 3);
assert(base(ret) == a + 2);
}
}
{ // check that the predicate is used
{
int a[] = {6, 5, 4, 3, 2, 1};
auto ret = std::ranges::lower_bound(It(a), It(a + 6), 2, std::ranges::greater{});
assert(base(ret) == a + 4);
}
{
int a[] = {6, 5, 4, 3, 2, 1};
auto range = std::ranges::subrange(It(a), It(a + 6));
auto ret = std::ranges::lower_bound(range, 2, std::ranges::greater{});
assert(base(ret) == a + 4);
}
}
{ // check that the projection is used
{
int a[] = {1, 2, 3, 4, 5, 6};
auto ret = std::ranges::lower_bound(It(a), It(a + 6), 0, {}, [](int i) { return i - 3; });
assert(base(ret) == a + 2);
}
{
int a[] = {1, 2, 3, 4, 5, 6};
auto range = std::ranges::subrange(It(a), It(a + 6));
auto ret = std::ranges::lower_bound(range, 0, {}, [](int i) { return i - 3; });
assert(base(ret) == a + 2);
}
}
{ // check that the last lower bound is returned
{
int a[] = {1, 2, 2, 2, 3};
auto ret = std::ranges::lower_bound(It(a), It(a + 5), 2);
assert(base(ret) == a + 1);
}
{
int a[] = {1, 2, 2, 2, 3};
auto range = std::ranges::subrange(It(a), It(a + 5));
auto ret = std::ranges::lower_bound(range, 2);
assert(base(ret) == a + 1);
}
}
{ // check that end is returned if all elements compare less than
{
int a[] = {1, 2, 3, 4};
auto ret = std::ranges::lower_bound(It(a), It(a + 4), 5);
assert(base(ret) == a + 4);
}
{
int a[] = {1, 2, 3, 4};
auto range = std::ranges::subrange(It(a), It(a + 4));
auto ret = std::ranges::lower_bound(range, 5);
assert(base(ret) == a + 4);
}
}
{ // check that the first element is returned if no element compares less than
{
int a[] = {1, 2, 3, 4};
auto ret = std::ranges::lower_bound(It(a), It(a + 4), 0);
assert(base(ret) == a);
}
{
int a[] = {1, 2, 3, 4};
auto range = std::ranges::subrange(It(a), It(a + 4));
auto ret = std::ranges::lower_bound(range, 0);
assert(base(ret) == a);
}
}
{ // check that a single element works
{
int a[] = {1};
auto ret = std::ranges::lower_bound(It(a), It(a + 1), 1);
assert(base(ret) == a);
}
{
int a[] = {1};
auto range = std::ranges::subrange(It(a), It(a + 1));
auto ret = std::ranges::lower_bound(range, 1);
assert(base(ret) == a);
}
}
{ // check that an even number of elements works
{
int a[] = {1, 3, 6, 6, 7, 8};
auto ret = std::ranges::lower_bound(It(a), It(a + 6), 6);
assert(base(ret) == a + 2);
}
{
int a[] = {1, 3, 6, 6, 7, 8};
auto range = std::ranges::subrange(It(a), It(a + 6));
auto ret = std::ranges::lower_bound(range, 6);
assert(base(ret) == a + 2);
}
}
{ // check that an odd number of elements works
{
int a[] = {1, 3, 6, 6, 7};
auto ret = std::ranges::lower_bound(It(a), It(a + 5), 6);
assert(base(ret) == a + 2);
}
{
int a[] = {1, 3, 6, 6, 7};
auto range = std::ranges::subrange(It(a), It(a + 5));
auto ret = std::ranges::lower_bound(range, 6);
assert(base(ret) == a + 2);
}
}
{ // check that it works when all but the searched for element are equal
{
int a[] = {1, 6, 6, 6, 6, 6};
auto ret = std::ranges::lower_bound(It(a), It(a + 6), 1);
assert(base(ret) == a);
}
{
int a[] = {1, 6, 6, 6, 6, 6};
auto range = std::ranges::subrange(It(a), It(a + 6));
auto ret = std::ranges::lower_bound(range, 1);
assert(base(ret) == a);
}
}
{ // check that the middle of a range is returned when there are smaller and larger elements
{
int a[] = {1, 2, 3, 4, 6, 7, 8};
auto ret = std::ranges::lower_bound(It(a), It(a + 7), 5);
assert(base(ret) == a + 4);
assert(*ret == 6);
}
{
int a[] = {1, 2, 3, 4, 6, 7, 8};
auto range = std::ranges::subrange(It(a), It(a + 7));
auto ret = std::ranges::lower_bound(range, 5);
assert(base(ret) == a + 4);
assert(*ret == 6);
}
}
}
constexpr bool test() {
test_iterators<int*>();
test_iterators<forward_iterator<int*>>();
test_iterators<bidirectional_iterator<int*>>();
test_iterators<random_access_iterator<int*>>();
test_iterators<contiguous_iterator<int*>>();
{ // check that std::invoke is used for the projections
{
struct S { int check; int other; };
S a[] = {{1, 6}, {2, 5}, {3, 4}, {4, 3}, {5, 2}, {6, 1}};
auto ret = std::ranges::lower_bound(a, a + 6, 4, {}, &S::check);
assert(ret == a + 3);
}
{
struct S { int check; int other; };
S a[] = {{1, 6}, {2, 5}, {3, 4}, {4, 3}, {5, 2}, {6, 1}};
auto ret = std::ranges::lower_bound(a, 4, {}, &S::check);
assert(ret == a + 3);
}
}
{ // check that std::invoke is used for the predicate
struct S {
int check;
int other;
constexpr bool compare(const S& s) const {
return check < s.check;
}
};
{
S a[] = {{1, 6}, {2, 5}, {3, 4}, {4, 3}, {5, 2}, {6, 1}};
auto ret = std::ranges::lower_bound(a, a + 6, S{4, 0}, &S::compare);
assert(ret == a + 3);
}
{
S a[] = {{1, 6}, {2, 5}, {3, 4}, {4, 3}, {5, 2}, {6, 1}};
auto ret = std::ranges::lower_bound(a, S{4, 0}, &S::compare);
assert(ret == a + 3);
}
}
{ // check that an empty range works
{
std::array<int, 0> a;
auto ret = std::ranges::lower_bound(a.begin(), a.end(), 1);
assert(ret == a.end());
}
{
std::array<int, 0> a;
auto ret = std::ranges::lower_bound(a, 1);
assert(ret == a.end());
}
}
{ // check that ranges::dangling is returned
[[maybe_unused]] std::same_as<std::ranges::dangling> auto ret = std::ranges::lower_bound(std::array{1, 2}, 1);
}
{ // check that an iterator is returned with a borrowing range
int a[] = {1, 2, 3};
std::same_as<int*> auto ret = std::ranges::lower_bound(std::views::all(a), 1);
assert(ret == a);
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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