三方比較演算子と一貫比較。これはらくちん。

three-way.cpp

#include "pch.h"

#include <compare>
#include <iostream>

// https://cpprefjp.github.io/lang/cpp20/consistent_comparison.html

struct Hoge
{
	int a, b;

	auto operator<=>(const Hoge &) const = default;

	friend std::ostream & operator<<(std::ostream & out, const Hoge & hoge)
	{
		return out << "a=" << hoge.a << ", b=" << hoge.b;
	}
};


TEST(ThreeWayComparison, Hoge)
{
	Hoge hogeA{ 1,2 };
	Hoge hogeB{ 1,2 };
	Hoge hogeC{ 1,3 };

	EXPECT_EQ(hogeA, hogeB);
	EXPECT_NE(hogeA, hogeC);

	EXPECT_LT(hogeA, hogeC);
	EXPECT_GT(hogeC, hogeA);

	EXPECT_LE(hogeA, hogeB);
	EXPECT_GE(hogeB, hogeA);
}