Introducing `ConcreteShadowNode`

Summary: ConcreteShadowNode defines a template which connects typed Props and typed ShadowNode.

Reviewed By: fkgozali

Differential Revision: D7230667

fbshipit-source-id: be28314d6846d69960e921da852f01232951f965

ReactCommon/fabric/core/shadownode/ConcreteShadowNode.h

@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <fabric/core/Props.h>
+#include <fabric/core/ShadowNode.h>
+
+namespace facebook {
+namespace react {
+
+/*
+ * Base templace class for all `ShadowNode`s which connects exact `ShadowNode`
+ * type with exact `Props` type.
+ * `ConcreteShadowNode` is a default implementation of `ShadowNode` interface
+ * with many handy features.
+ */
+template <typename PropsT>
+class ConcreteShadowNode: public ShadowNode {
+  static_assert(std::is_base_of<Props, PropsT>::value, "PropsT must be a descendant of Props");
+
+public:
+  using ConcreteProps = PropsT;
+  using SharedConcreteProps = std::shared_ptr<const PropsT>;
+  using SharedConcreteShadowNode = std::shared_ptr<const ConcreteShadowNode>;
+
+  static const SharedConcreteProps Props(const RawProps &rawProps, const SharedProps &baseProps = nullptr) {
+    if (!baseProps) {
+      auto props = std::make_shared<PropsT>();
+      props->apply(rawProps);
+      return props;
+    }
+
+    auto concreteBaseProps = std::dynamic_pointer_cast<const PropsT>(baseProps);
+    auto props = std::make_shared<PropsT>(*concreteBaseProps);
+    props->apply(rawProps);
+    return props;
+  }
+
+  static const SharedConcreteProps defaultSharedProps() {
+    static const SharedConcreteProps defaultSharedProps = std::make_shared<PropsT>();
+    return defaultSharedProps;
+  }
+
+  ConcreteShadowNode(
+    const Tag &tag,
+    const Tag &rootTag,
+    const InstanceHandle &instanceHandle,
+    const SharedConcreteProps &props = ConcreteShadowNode::defaultSharedProps(),
+    const SharedShadowNodeSharedList &children = ShadowNode::emptySharedShadowNodeSharedList()
+  ):
+    ShadowNode(
+      tag,
+      rootTag,
+      instanceHandle,
+      (SharedProps)props,
+      children
+    ) {};
+
+  ConcreteShadowNode(
+    const SharedConcreteShadowNode &shadowNode,
+    const SharedProps &props = nullptr,
+    const SharedShadowNodeSharedList &children = nullptr
+  ):
+    ShadowNode(
+      shadowNode,
+      (SharedProps)props,
+      children
+    ) {}
+
+  virtual ComponentHandle getComponentHandle() const {
+    return typeid(*this).hash_code();
+  }
+
+  const SharedConcreteProps &getProps() const {
+    return std::static_pointer_cast<const PropsT>(props_);
+  }
+
+};
+
+} // namespace react
+} // namespace facebook