[core] Split up and clean up conversion.hpp

1 files changed, 69 insertions, 0 deletions

diff --git a/include/mbgl/style/conversion/function.hpp b/include/mbgl/style/conversion/function.hpp
new file mode 100644
index 0000000000..f14b5089be
--- /dev/null
+++ b/include/mbgl/style/conversion/function.hpp
@@ -0,0 +1,69 @@
+#pragma once
+
+#include <mbgl/style/function.hpp>
+#include <mbgl/style/conversion.hpp>
+#include <mbgl/style/conversion/constant.hpp>
+
+namespace mbgl {
+namespace style {
+namespace conversion {
+
+template <class T>
+struct Converter<Function<T>> {
+    template <class V>
+    Result<Function<T>> operator()(const V& value) const {
+        if (!isObject(value)) {
+            return Error { "function must be an object" };
+        }
+
+        auto stopsValue = objectMember(value, "stops");
+        if (!stopsValue) {
+            return Error { "function value must specify stops" };
+        }
+
+        if (!isArray(*stopsValue)) {
+            return Error { "function stops must be an array" };
+        }
+
+        std::vector<std::pair<float, T>> stops;
+        for (std::size_t i = 0; i < arrayLength(*stopsValue); ++i) {
+            const auto& stopValue = arrayMember(*stopsValue, i);
+
+            if (!isArray(stopValue)) {
+                return Error { "function stop must be an array" };
+            }
+
+            if (arrayLength(stopValue) != 2) {
+                return Error { "function stop must have two elements" };
+            }
+
+            optional<float> z = toNumber(arrayMember(stopValue, 0));
+            if (!z) {
+                return Error { "function stop zoom level must be a number" };
+            }
+
+            Result<T> v = convert<T>(arrayMember(stopValue, 1));
+            if (!v) {
+                return v.error();
+            }
+
+            stops.emplace_back(*z, *v);
+        }
+
+        auto baseValue = objectMember(value, "base");
+        if (!baseValue) {
+            return Function<T>(stops, 1.0f);
+        }
+
+        optional<float> base = toNumber(*baseValue);
+        if (!base) {
+            return Error { "function base must be a number"};
+        }
+
+        return Function<T>(stops, *base);
+    }
+};
+
+} // namespace conversion
+} // namespace style
+} // namespace mbgl