159 lines
4.2 KiB
C++
159 lines
4.2 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <functional>
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#include <memory>
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#include <react/renderer/core/ShadowNode.h>
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#include <react/renderer/element/ElementFragment.h>
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namespace facebook {
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namespace react {
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/*
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* `Element<>` is an abstraction layer that allows describing component
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* hierarchy in a declarative way. Creating `Element`s themself does not create
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* a component tree (aka `ShadowNode` tree) but describes some hierarchical
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* structure that might be used to build an actual component tree (similar to
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* XML Elements).
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* `Element` provides some basic type-safety guarantees: all modifications
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* of element objects require using objects (such as Props or State) of
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* compatible type.
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*/
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template <typename ShadowNodeT>
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class Element final {
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public:
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using ConcreteProps = typename ShadowNodeT::ConcreteProps;
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using SharedConcreteProps = std::shared_ptr<ConcreteProps const>;
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using ConcreteState = typename ShadowNodeT::ConcreteState;
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using ConcreteStateData = typename ShadowNodeT::ConcreteStateData;
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using SharedConcreteState = std::shared_ptr<ConcreteState const>;
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using ConcreteShadowNode = ShadowNodeT;
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using ConcreteUnsharedShadowNode = std::shared_ptr<ConcreteShadowNode>;
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using ConcreteReferenceCallback =
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std::function<void(std::shared_ptr<ShadowNodeT const> const &shadowNode)>;
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/*
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* Constructs an `Element`.
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*/
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Element() {
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fragment_.componentHandle = ShadowNodeT::Handle();
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fragment_.componentName = ShadowNodeT::Name();
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fragment_.props = ShadowNodeT::defaultSharedProps();
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}
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/*
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* Converts to `ElementFragment` object.
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*/
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operator ElementFragment() {
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return fragment_;
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}
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/*
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* Sets `tag`.
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*/
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Element &tag(Tag tag) {
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fragment_.tag = tag;
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return *this;
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}
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/*
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* Sets `surfaceId`.
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*/
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Element &surfaceId(SurfaceId surfaceId) {
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fragment_.surfaceId = surfaceId;
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return *this;
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}
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/*
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* Sets `props`.
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*/
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Element &props(SharedConcreteProps props) {
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fragment_.props = props;
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return *this;
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}
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/*
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* Sets `props` using callback.
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*/
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Element &props(std::function<SharedConcreteProps()> callback) {
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fragment_.props = callback();
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return *this;
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}
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/*
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* Sets `state` using callback.
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*/
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Element &stateData(std::function<void(ConcreteStateData &)> callback) {
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fragment_.stateCallback = [callback =
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std::move(callback)]() -> StateData::Shared {
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auto stateData = ConcreteStateData();
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callback(stateData);
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return std::make_shared<ConcreteStateData>(stateData);
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};
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return *this;
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}
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/*
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* Sets children.
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*/
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Element &children(std::vector<ElementFragment> children) {
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auto fragments = ElementFragment::List{};
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fragments.reserve(children.size());
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for (auto const &child : children) {
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fragments.push_back(child);
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}
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fragment_.children = fragments;
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return *this;
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}
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/*
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* Calls the callback during component construction with a pointer to the
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* component which is being constructed.
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*/
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Element &reference(
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std::function<void(ConcreteUnsharedShadowNode const &shadowNode)>
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callback) {
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fragment_.referenceCallback = callback;
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return *this;
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}
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/*
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* During component construction, assigns a given pointer to a component
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* that is being constructed.
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*/
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Element &reference(ConcreteUnsharedShadowNode &outShadowNode) {
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fragment_.referenceCallback = [&](ShadowNode::Shared const &shadowNode) {
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outShadowNode = std::const_pointer_cast<ConcreteShadowNode>(
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std::static_pointer_cast<ConcreteShadowNode const>(shadowNode));
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};
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return *this;
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}
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/*
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* Calls the callback with a reference to a just constructed component.
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*/
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Element &finalize(
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std::function<void(ConcreteShadowNode &shadowNode)> finalizeCallback) {
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fragment_.finalizeCallback = [=](ShadowNode &shadowNode) {
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return finalizeCallback(static_cast<ConcreteShadowNode &>(shadowNode));
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};
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return *this;
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}
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private:
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friend class ComponentBuilder;
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ElementFragment fragment_;
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};
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} // namespace react
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} // namespace facebook
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