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

2 files changed, 29 insertions, 2 deletions

diff --git a/src/mbgl/util/font_stack.cpp b/src/mbgl/util/font_stack.cpp
index fb1b716fb6..4093a21793 100644
--- a/src/mbgl/util/font_stack.cpp
+++ b/src/mbgl/util/font_stack.cpp
@@ -1,8 +1,8 @@
 #include <mbgl/util/font_stack.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/style/layers/symbol_layer_impl.hpp>
+#include <mbgl/util/hash.hpp>
 
-#include <boost/functional/hash.hpp>
 #include <boost/algorithm/string/join.hpp>
 
 namespace mbgl {
@@ -14,7 +14,11 @@ std::string fontStackToString(const FontStack& fontStack) {
 }
 
 FontStackHash FontStackHasher::operator()(const FontStack& fontStack) const {
-    return boost::hash_range(fontStack.begin(), fontStack.end());
+    std::size_t seed = 0;
+    for (const auto& font : fontStack) {
+        util::hash_combine(seed, font);
+    }
+    return seed;
 }
 
 std::set<FontStack> fontStacks(const std::vector<Immutable<style::Layer::Impl>>& layers) {
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