libcruft-util/test/algo/sort.cpp
Danny Robson 1ad3e0bde0 algo/sort: add SOA sorting helper
sort::soa applies a permutation to multiple value arrays such that the
first value array is sorted
2017-05-18 18:24:48 +10:00

121 lines
3.3 KiB
C++

#include "algo/sort.hpp"
#include "tap.hpp"
#include <iterator>
void
reorder (std::vector<int> &values, std::vector<int> &indices)
{
CHECK_EQ (values.size (), indices.size ());
if (indices.size () <= 1)
return;
for (size_t i = 0; i < indices.size () - 1; ++i) {
// check if this item is in the correct slot
while ((int)i != indices[i]) {
auto alt = indices[i];
// swap this item with the one that's occupying its intended slot
std::swap (values[i], values[alt]);
//std::swap (*(values... + i), *)
std::swap (indices[i], indices[alt]);
}
}
}
int
main (int, char**)
{
util::TAP::logger tap;
// Check that reorder works with a single value array
{
std::array<int,3> indices { 2, 0, 1 };
std::array<int,3> values { 3, 4, 5 };
const std::array<int,3> expected = { 4, 5, 3 };
cruft::util::sort::reorder (
std::begin (indices), std::end (indices),
std::begin (values)
);
tap.expect_eq (expected, values, "reorder with one array");
}
// Check that reorder works with multiple value arrays
{
std::array<int,3> indices { 2, 0, 1 };
std::array<int,3> values[] = {
{ 3, 4, 5 },
{ 8, 7, 6 },
{ 11, 9, 10 },
};
const std::array<int,3> expected[] = {
{ 4, 5, 3 },
{ 7, 6, 8 },
{ 9, 10, 11 },
};
cruft::util::sort::reorder (
std::begin (indices), std::end (indices),
std::begin (values[0]),
std::begin (values[1]),
std::begin (values[2])
);
tap.expect (values[0] == expected[0] &&
values[1] == expected[1] &&
values[2] == expected[2],
"reorder with three arrays"
);
}
// Check that SOA sort works with a single value array
static struct {
std::vector<int> values;
const char *msg;
} TESTS[] = {
{ { 0 }, "single value, single array" },
{ { 1, 0 }, "two values, single array" },
{ { 5, 0, 4, 1, 2, 3 }, "many values, single array" },
};
for (auto &t: TESTS) {
cruft::util::sort::soa (
std::begin (t.values), std::end (t.values),
[] (int a, int b) { return a < b; }
);
tap.expect (std::is_sorted (std::cbegin (t.values), std::cend (t.values)), "%s", t.msg);
}
// Check that SOA sort works with multiple value arrays
{
std::array<unsigned, 3> value_i { 2, 0, 1 };
std::array<char, 3> value_c { 'a', 'b', 'c' };
std::array<float,3> value_f { 0.f, 1.f, 2.f };
const std::array<unsigned,3> expected_i { 0, 1, 2 };
const std::array<char,3> expected_c { 'b', 'c', 'a' };
const std::array<float,3> expected_f { 1.f, 2.f, 0.f };
cruft::util::sort::soa (
std::begin (value_i), std::end (value_i),
[] (const auto &i, const auto &j) { return i < j; },
std::begin (value_c),
std::begin (value_f)
);
tap.expect (
value_i == expected_i &&
value_c == expected_c &&
value_f == expected_f,
"SOA sort with 3 arrays"
);
}
return tap.status ();
}