1 files changed, 53 insertions, 0 deletions
diff --git a/include/mbgl/style/expression/value.hpp b/include/mbgl/style/expression/value.hpp
new file mode 100644
index 0000000000..0cac50c6ab
--- /dev/null
+++ b/include/mbgl/style/expression/value.hpp
@@ -0,0 +1,53 @@
+#pragma once
+
+#include <mbgl/util/variant.hpp>
+#include <mbgl/util/feature.hpp>
+#include <mbgl/style/expression/type.hpp>
+
+namespace mbgl {
+namespace style {
+namespace expression {
+
+struct Value;
+using ValueBase = variant<
+    NullValue,
+    float,
+    std::string,
+    mbgl::Color,
+    mapbox::util::recursive_wrapper<std::vector<Value>>,
+    mapbox::util::recursive_wrapper<std::unordered_map<std::string, Value>>>;
+struct Value : ValueBase {
+    using ValueBase::ValueBase;
+};
+
+constexpr NullValue Null = NullValue();
+
+type::Type typeOf(const Value& value) {
+    return value.match(
+        [&](float) -> type::Type { return type::Primitive::Number; },
+        [&](const std::string&) -> type::Type { return type::Primitive::String; },
+        [&](const mbgl::Color&) -> type::Type { return type::Primitive::Color; },
+        [&](const NullValue&) -> type::Type { return type::Primitive::Null; },
+        [&](const std::unordered_map<std::string, Value>&) -> type::Type { return type::Primitive::Object; },
+        [&](const std::vector<Value>& arr) -> type::Type {
+            optional<type::Type> itemType;
+            for (const auto& item : arr) {
+                const auto& t = typeOf(item);
+                if (!itemType) {
+                    itemType = {t};
+                } else if (type::toString(*itemType) == type::toString(t)) {
+                    continue;
+                } else {
+                    itemType = {type::Primitive::Value};
+                    break;
+                }
+            }
+
+            return type::Array(type::Primitive::Value, arr.size());
+        }
+    );
+}
+
+} // namespace expression
+} // namespace style
+} // namespace mbgl