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