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Added Ref<T> wrapper template. StateVars always contain elements by-value, but for State it might be convenient to use pointers/references, especially when dealing with class types. Use CreateRef for State<T> -> State<Ref<T>> binding. Semantically, it's the same as using State<T*>, but avoids the null check. The State<Ref<T>> changes when the referenced state changes.
1 parent 5467003 commit 76be2a9

3 files changed

Lines changed: 71 additions & 13 deletions

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‎include/react/api.h‎

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,7 @@
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#pragma once
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#include <type_traits>
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#include <vector>
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#include "react/detail/defs.h"
@@ -93,6 +94,26 @@ using EventValueSink = std::back_insert_iterator<std::vector<E>>;
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// Observer
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class Observer;
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// Ref
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template <typename T>
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using Ref = std::reference_wrapper<const T>;
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template <typename T>
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bool HasChanged(const T& a, const T& b)
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{ return !(a == b); }
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template <typename T>
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bool HasChanged(const Ref<T>& a, const Ref<T>& b)
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{ return true; }
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template <typename T, typename V>
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void ListInsert(T& list, V&& value)
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{ list.push_back(std::forward<V>(value)); }
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template <typename T, typename V>
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void MapInsert(T& map, V&& value)
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{ map.insert(std::forward<V>(value)); }
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/******************************************/ REACT_END /******************************************/
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#endif // REACT_TYPETRAITS_H_INCLUDED

‎include/react/detail/state_nodes.h‎

Lines changed: 36 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -171,22 +171,19 @@ class StateFuncNode : public StateNode<S>
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}
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virtual UpdateResult Update(TurnId turnId) noexcept override
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{
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bool changed = false;
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{
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S newValue = apply([this] (const auto& ... deps)
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{ return this->func_(GetInternals(deps).Value() ...); }, depHolder_);
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if (! (this->Value() == newValue))
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if (HasChanged(this->Value(), newValue))
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{
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this->Value() = std::move(newValue);
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changed = true;
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}
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if (changed)
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return UpdateResult::changed;
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}
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else
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{
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return UpdateResult::unchanged;
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}
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}
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private:
@@ -439,6 +436,37 @@ class StateInternals
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std::shared_ptr<StateNode<S>> nodePtr_;
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};
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/// StateRefNode
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///////////////////////////////////////////////////////////////////////////////////////////////////
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template <typename S>
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class StateRefNode : public StateNode<Ref<S>>
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{
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public:
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StateRefNode(const Group& group, const State<S>& input) :
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StateRefNode::StateNode( group, std::cref(GetInternals(input).Value()) ),
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input_( input )
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{
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this->RegisterMe();
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this->AttachToMe(GetInternals(input).GetNodeId());
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}
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~StateRefNode()
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{
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this->DetachFromMe(GetInternals(input_).GetNodeId());
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this->UnregisterMe();
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}
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virtual UpdateResult Update(TurnId turnId) noexcept override
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{
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this->Value() = std::cref(GetInternals(input_).Value());
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return UpdateResult::changed;
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}
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private:
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State<S> input_;
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};
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/// SameGroupOrLink
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///////////////////////////////////////////////////////////////////////////////////////////////////

‎include/react/state.h‎

Lines changed: 14 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -202,10 +202,7 @@ class StateSlot : public State<S>
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StateSlot& operator=(StateSlot&&) = default;
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void Set(const State<S>& newInput)
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{ SetInput(newInput); }
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void operator<<=(const State<S>& newInput)
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{ SetInput(newInput); }
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{ SetSlotInput(newInput); }
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protected:
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StateSlot(std::shared_ptr<REACT_IMPL::StateNode<S>>&& nodePtr) :
@@ -221,7 +218,7 @@ class StateSlot : public State<S>
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return std::make_shared<StateSlotNode<S>>(group, SameGroupOrLink(group, input));
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}
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void SetInput(const State<S>& newInput)
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void SetSlotInput(const State<S>& newInput)
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{
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using REACT_IMPL::NodeId;
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using REACT_IMPL::StateSlotNode;
@@ -282,6 +279,18 @@ class StateLink : public State<S>
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}
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};
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/// CreateRef
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///////////////////////////////////////////////////////////////////////////////////////////////////
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template <typename S>
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auto CreateRef(const State<S>& state) -> State<Ref<S>>
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{
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using REACT_IMPL::StateRefNode;
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using REACT_IMPL::CreateWrappedNode;
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return CreateWrappedNode<State<Ref<S>>, StateRefNode<S>>(state.GetGroup(), state);
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}
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/// ObjectContext
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///////////////////////////////////////////////////////////////////////////////////////////////////

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