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// Range v3 library
//
// Copyright Eric Niebler 2014-present
//
// Use, modification and distribution is subject to the
// Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ericniebler/range-v3
#include <range/v3/core.hpp>
#include <range/v3/view/generate.hpp>
#include <range/v3/view/drop_exactly.hpp>
#include <range/v3/view/take_exactly.hpp>
#include "../simple_test.hpp"
#include "../test_utils.hpp"
namespace views = ranges::views;
int main()
{
// Test for constant generator functions
{
int i = 0, j = 1;
auto fib = views::generate([&]()->int{int tmp = i; i += j; std::swap(i, j); return tmp;});
CPP_assert(ranges::input_range<decltype(fib)> && ranges::view_<decltype(fib)>);
check_equal(fib | views::take_exactly(10), {0,1,1,2,3,5,8,13,21,34});
}
// Test for mutable-only generator functions
{
int i = 0, j = 1;
auto fib = views::generate([=]()mutable->int{int tmp = i; i += j; std::swap(i, j); return tmp;});
CPP_assert(ranges::input_range<decltype(fib)> && ranges::view_<decltype(fib)>);
check_equal(fib | views::take_exactly(10), {0,1,1,2,3,5,8,13,21,34});
// The generator cannot be called when it's const-qualified, so "fib const"
// does not model View.
CPP_assert(!ranges::view_<decltype(fib) const>);
}
// Test for generator functions that return move-only types
// https://github.com/ericniebler/range-v3/issues/905
{
char str[] = "gi";
auto rng = views::generate([&]{str[0]++; return MoveOnlyString{str};}) | views::take_exactly(2);
auto i = rng.begin();
CHECK(bool(*i == MoveOnlyString{"hi"}));
CHECK(bool(*i == MoveOnlyString{"hi"}));
CHECK(bool(*rng.begin() == MoveOnlyString{"hi"}));
CHECK(bool(*rng.begin() == MoveOnlyString{"hi"}));
CPP_assert(ranges::input_range<decltype(rng)> && ranges::view_<decltype(rng)>);
check_equal(rng, {MoveOnlyString{"hi"}, MoveOnlyString{"ii"}});
static_assert(std::is_same<ranges::range_reference_t<decltype(rng)>, MoveOnlyString &&>::value, "");
}
// Test for generator functions that return internal references
// https://github.com/ericniebler/range-v3/issues/807
{
int i = 42;
auto rng = views::generate([i]{return &i;});
auto rng2 = std::move(rng);
auto it = rng2.begin();
auto p = *it;
auto p2 = *++it;
CHECK(p == p2);
}
// Test that we only call the function once for each dereferenceable position
// https://github.com/ericniebler/range-v3/issues/819
{
int i = 0;
auto rng = views::generate([&i]{return ++i;});
auto rng2 = std::move(rng);
auto it = rng2.begin();
CHECK(i == 0);
CHECK(*it == 1);
CHECK(i == 1);
++it;
CHECK(i == 1);
CHECK(*it == 2);
CHECK(i == 2);
}
// Test that skipping past positions works correctly
// https://github.com/ericniebler/range-v3/issues/1258
{
auto fib = [p = std::make_pair(0, 1)]() mutable -> int {
auto a = p.first;
p = {p.second, p.first + p.second};
return a;
};
auto rng = ranges::views::generate(fib)
| ranges::views::drop_exactly(3)
| ranges::views::take_exactly(5);
check_equal(rng, {2,3,5,8,13});
}
return test_result();
}
|
