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Fix, MSVC's std::sort fails on Zip2Iterator

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This commit is contained in:
Benjamin Doherty
2021-07-09 12:16:38 -07:00
committed by Mathias Agopian
parent 62787de97b
commit 26c9732b4e
2 changed files with 49 additions and 7 deletions
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49
libs/utils/test/test_Zip2Iterator.cpp
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@@ -17,6 +17,7 @@
#include <gtest/gtest.h>
#include <utils/Zip2Iterator.h>
#include <utils/StructureOfArrays.h>
#include <algorithm>
#include <array>
@@ -37,12 +38,56 @@ TEST(Zip2IteratorTest, sort) {
EXPECT_FALSE(std::is_sorted(keys.begin(), keys.end()));
EXPECT_FALSE(std::is_sorted(values.begin(), values.end()));
#if !defined(WIN32)
Zip2Iterator<Array::iterator, Array::iterator> b = { values.begin(), keys.begin() };
Zip2Iterator<Array::iterator, Array::iterator> e = b + values.size();
std::sort(b, e, [](auto const& lhs, auto const& rhs) { return lhs.second < rhs.second; });
EXPECT_TRUE(std::is_sorted(keys.begin(), keys.end()));
EXPECT_TRUE(std::is_sorted(values.begin(), values.end()));
#endif
}
enum {
LIGHT_INSTANCE,
};
using LightSoa = utils::StructureOfArrays<
int
>;
TEST(Zip2IteratorTest, soa) {
LightSoa lightData;
lightData.push_back(3);
lightData.push_back(2);
lightData.push_back(1);
float distances[3] = {1.00f, 0.5f, 0.25f};
EXPECT_EQ(lightData.size(), 3);
Zip2Iterator<LightSoa::iterator, float*> z = { lightData.begin(), distances };
// To sort lightData by distance, we just need to swap the first and third elements.
// MSVC's std::sort does something akin to the following:
// using _BidIt = Zip2Iterator<LightSoa::iterator, float*>;
// const _BidIt _First = z;
// const _BidIt _Last = z + 2;
// std::iter_value_t<_BidIt> _Val = std::move(*_First);
// *_First = std::move(*_Last);
// *_Last = std::move(_Val);
std::sort(z, z + lightData.size(),
[](auto const& lhs, auto const& rhs) { return lhs.second < rhs.second; });
auto const* instances = lightData.data<LIGHT_INSTANCE>();
EXPECT_EQ(distances[0], 0.25f);
EXPECT_EQ(distances[1], 0.5f);
EXPECT_EQ(distances[2], 1.0f);
EXPECT_EQ(instances[0], 1);
EXPECT_EQ(instances[1], 2);
EXPECT_EQ(instances[2], 3);
}