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102 lines
2.5 KiB
C++
102 lines
2.5 KiB
C++
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// Copyright 2017 Daniel James.
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// clang-format off
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#include "../helpers/prefix.hpp"
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#include <boost/unordered_map.hpp>
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#include <boost/unordered_set.hpp>
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#include "../helpers/postfix.hpp"
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// clang-format on
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#include "../helpers/test.hpp"
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#include <map>
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// Pretty inefficient, but the test is fast enough.
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// Might be too slow if we had larger primes?
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bool is_prime(std::size_t x)
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{
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if (x == 2) {
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return true;
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} else if (x == 1 || x % 2 == 0) {
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return false;
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} else {
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// y*y <= x had rounding errors, so instead use y <= (x/y).
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for (std::size_t y = 3; y <= (x / y); y += 2) {
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if (x % y == 0) {
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return false;
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break;
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}
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}
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return true;
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}
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}
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void test_next_prime(std::size_t value)
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{
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std::size_t x = boost::unordered::detail::next_prime(value);
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BOOST_TEST(is_prime(x));
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BOOST_TEST(x >= value);
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}
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void test_prev_prime(std::size_t value)
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{
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std::size_t x = boost::unordered::detail::prev_prime(value);
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BOOST_TEST(is_prime(x));
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BOOST_TEST(x <= value);
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if (x > value) {
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BOOST_LIGHTWEIGHT_TEST_OSTREAM << x << "," << value << std::endl;
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}
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}
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UNORDERED_AUTO_TEST (next_prime_test) {
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BOOST_TEST(!is_prime(0));
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BOOST_TEST(!is_prime(1));
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BOOST_TEST(is_prime(2));
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BOOST_TEST(is_prime(3));
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BOOST_TEST(is_prime(13));
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BOOST_TEST(!is_prime(4));
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BOOST_TEST(!is_prime(100));
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BOOST_TEST(boost::unordered::detail::next_prime(0) > 0);
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// test_prev_prime doesn't work for values less than 17.
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// Which should be okay, unless an allocator has a really tiny
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// max_size?
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const std::size_t min_prime = 17;
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// test_next_prime doesn't work for values greater than this,
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// which might be a problem if you've got terrabytes of memory?
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// I seriously doubt the container would work well at such sizes
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// regardless.
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const std::size_t max_prime = 4294967291ul;
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std::size_t i;
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BOOST_TEST(is_prime(min_prime));
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BOOST_TEST(is_prime(max_prime));
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for (i = 0; i < 10000; ++i) {
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if (i < min_prime) {
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BOOST_TEST(boost::unordered::detail::prev_prime(i) == min_prime);
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} else {
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test_prev_prime(i);
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}
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test_next_prime(i);
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}
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std::size_t last = i - 1;
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for (; i > last; last = i, i += i / 5) {
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if (i > max_prime) {
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BOOST_TEST(boost::unordered::detail::next_prime(i) == max_prime);
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} else {
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test_next_prime(i);
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}
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test_prev_prime(i);
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}
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}
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RUN_TESTS()
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