From f0824fdebc79fbf3843c2053522107c33e3ce2a3 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Mon, 7 Mar 2022 20:20:18 +0100
Subject: refactor: move directions to vector2 & make vector2 hashable

---
 src/util/hash.hpp | 10 ++++++++++
 src/util/hash.tpp | 22 ++++++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 src/util/hash.hpp
 create mode 100644 src/util/hash.tpp

(limited to 'src/util')

diff --git a/src/util/hash.hpp b/src/util/hash.hpp
new file mode 100644
index 0000000..72e9b82
--- /dev/null
+++ b/src/util/hash.hpp
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <cstddef>
+
+constexpr auto GOLDEN_RATIO = 0x9e3779b9;
+
+template <typename Value>
+void hash_combine(std::size_t &seed, const Value &value) noexcept;
+
+#include "hash.tpp"
diff --git a/src/util/hash.tpp b/src/util/hash.tpp
new file mode 100644
index 0000000..146cfa0
--- /dev/null
+++ b/src/util/hash.tpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "hash.hpp"
+
+#include <cstdint>
+#include <functional>
+
+/**
+ * Combines the hash 'seed' with the hash of 'value'.
+ *
+ * @param seed A hash that will be mutated
+ * @param value A hashable value
+ */
+template <typename Value>
+void hash_combine(std::size_t &seed, const Value &value) noexcept
+{
+	constexpr uint32_t shift_left = 6;
+	constexpr uint32_t shift_right = 2;
+
+	seed ^= std::hash<Value>()(value) + GOLDEN_RATIO + (seed << shift_left) +
+			(seed >> shift_right);
+}
-- 
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