[core] don't use <boost/functional/hash.hpp> to avoid <locale> include

1 files changed, 23 insertions, 0 deletions

diff --git a/src/mbgl/util/hash.hpp b/src/mbgl/util/hash.hpp
new file mode 100644
index 0000000000..987a8bd8dc
--- /dev/null
+++ b/src/mbgl/util/hash.hpp
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <mbgl/util/ignore.hpp>
+
+#include <functional>
+
+namespace mbgl {
+namespace util {
+
+template <class T>
+inline void hash_combine(std::size_t& seed, const T& v) {
+    seed ^= std::hash<T>()(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+}
+
+template <class... Args>
+inline std::size_t hash(Args&&... args) {
+    std::size_t seed = 0;
+    ignore({ (hash_combine(seed, args), 0)... });
+    return seed;
+}
+
+} // namespace util
+} // namespace mbgl