[core] Use mbgl::style::conversion in node bindings

platform/node/src/node_conversion.hpp

@@ -0,0 +1,73 @@
+#pragma once
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wshadow"
+#include <nan.h>
+#pragma GCC diagnostic pop
+
+#include <mbgl/util/optional.hpp>
+
+namespace mbgl {
+namespace style {
+namespace conversion {
+
+inline bool isArray(v8::Local<v8::Value> value) {
+    Nan::HandleScope scope;
+    return value->IsArray();
+}
+
+inline std::size_t arrayLength(v8::Local<v8::Value> value) {
+    Nan::HandleScope scope;
+    return value.As<v8::Array>()->Length();
+}
+
+inline v8::Local<v8::Value> arrayMember(v8::Local<v8::Value> value, std::size_t i) {
+    Nan::EscapableHandleScope scope;
+    return scope.Escape(Nan::Get(value.As<v8::Array>(), i).ToLocalChecked());
+}
+
+inline bool isObject(v8::Local<v8::Value> value) {
+    Nan::HandleScope scope;
+    return value->IsObject();
+}
+
+inline optional<v8::Local<v8::Value>> objectMember(v8::Local<v8::Value> value, const char * name) {
+    Nan::EscapableHandleScope scope;
+    if (!Nan::Has(value.As<v8::Array>(), Nan::New(name).ToLocalChecked()).FromJust()) {
+        return {};
+    }
+    Nan::MaybeLocal<v8::Value> result = Nan::Get(value.As<v8::Array>(), Nan::New(name).ToLocalChecked());
+    if (result.IsEmpty()) {
+        return {};
+    }
+    return scope.Escape(result.ToLocalChecked());
+}
+
+inline optional<bool> toBool(v8::Local<v8::Value> value) {
+    Nan::HandleScope scope;
+    if (!value->IsBoolean()) {
+        return {};
+    }
+    return value->BooleanValue();
+}
+
+inline optional<float> toNumber(v8::Local<v8::Value> value) {
+    Nan::HandleScope scope;
+    if (!value->IsNumber()) {
+        return {};
+    }
+    return value->NumberValue();
+}
+
+inline optional<std::string> toString(v8::Local<v8::Value> value) {
+    Nan::HandleScope scope;
+    if (!value->IsString()) {
+        return {};
+    }
+    return std::string(*Nan::Utf8String(value));
+}
+
+} // namespace conversion
+} // namespace style
+} // namespace mbgl