binding.h

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/*
  This file is part of KDBindings.
 
  SPDX-FileCopyrightText: 2021-2023 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
  Author: Sean Harmer <sean.harmer@kdab.com>
 
  SPDX-License-Identifier: MIT
 
  Contact KDAB at <info@kdab.com> for commercial licensing options.
*/
 
#pragma once
 
#include <kdbindings/node.h>
#include <kdbindings/node_operators.h>
#include <kdbindings/node_functions.h>
#include <kdbindings/make_node.h>
#include <kdbindings/binding_evaluator.h>
#include <kdbindings/property_updater.h>
 
namespace KDBindings {
 
template<typename T, typename EvaluatorT = BindingEvaluator>
class Binding : public PropertyUpdater<T>, public Private::Dirtyable
{
    static_assert(
            std::is_base_of<BindingEvaluator, EvaluatorT>::value,
            "The EvaluatorT type must inherit from BindingEvaluator.");
 
public:
    explicit Binding(Private::Node<T> &&rootNode, EvaluatorT const &evaluator)
        : m_rootNode{ std::move(rootNode) }
        , m_evaluator{ evaluator }
    {
        m_bindingId = m_evaluator.insert(this);
        m_rootNode.setParent(this);
    }
 
    ~Binding() override
    {
        m_evaluator.remove(m_bindingId);
    }
 
    Binding() = delete;
 
    Binding(Binding const &other) = delete;
    Binding &operator=(Binding const &other) = delete;
 
    // Move construction would invalidate the this pointer passed to the evaluator
    // in the constructor
    Binding(Binding &&other) = delete;
    Binding &operator=(Binding &&other) = delete;
 
    void setUpdateFunction(std::function<void(T &&)> const &updateFunction) override
    {
        m_propertyUpdateFunction = updateFunction;
    }
 
    T get() const override { return m_rootNode.evaluate(); }
 
    void evaluate()
    {
        T value = m_rootNode.evaluate();
 
        // Use this to update any associated property via the PropertyUpdater's update function
        m_propertyUpdateFunction(std::move(value));
    }
 
protected:
    Private::Dirtyable **parentVariable() override { return nullptr; }
    const bool *dirtyVariable() const override { return nullptr; }
 
    Private::Node<T> m_rootNode;
    EvaluatorT m_evaluator;
    std::function<void(T &&)> m_propertyUpdateFunction = [](T &&) {};
    int m_bindingId = -1;
};
 
template<typename T, typename EvaluatorT>
inline std::unique_ptr<Binding<T, EvaluatorT>> makeBinding(EvaluatorT &evaluator, Property<T> &property)
{
    return std::make_unique<Binding<T, EvaluatorT>>(Private::makeNode(property), evaluator);
}
 
template<typename T, typename EvaluatorT>
inline std::unique_ptr<Binding<T, EvaluatorT>> makeBinding(EvaluatorT &evaluator, Private::Node<T> &&rootNode)
{
    return std::make_unique<Binding<T, EvaluatorT>>(std::move(rootNode), evaluator);
}
 
template<typename EvaluatorT, typename Func, typename... Args, typename = std::enable_if_t<sizeof...(Args) != 0>, typename ResultType = Private::operator_node_result_t<Func, Args...>>
inline std::unique_ptr<Binding<ResultType, EvaluatorT>> makeBinding(EvaluatorT &evaluator, Func &&func, Args &&...args)
{
    return std::make_unique<Binding<ResultType, EvaluatorT>>(Private::makeNode(std::forward<Func>(func), std::forward<Args>(args)...), evaluator);
}
 
template<typename T>
class Binding<T, ImmediateBindingEvaluator> : public Binding<T, BindingEvaluator>
{
public:
    explicit Binding(Private::Node<T> &&rootNode)
        : Binding<T, BindingEvaluator>(std::move(rootNode), ImmediateBindingEvaluator::instance())
    {
    }
 
    Binding() = delete;
 
    virtual ~Binding() = default;
 
    Binding(Binding const &other) = delete;
    Binding &operator=(Binding const &other) = delete;
 
    Binding(Binding &&other) = delete;
    Binding &operator=(Binding &&other) = delete;
 
    void markDirty() override
    {
        Binding::evaluate();
    }
};
 
template<typename T>
inline std::unique_ptr<Binding<T, ImmediateBindingEvaluator>> makeBinding(Property<T> &property)
{
    return std::make_unique<Binding<T, ImmediateBindingEvaluator>>(Private::makeNode(property));
}
 
template<typename T>
inline std::unique_ptr<Binding<T, ImmediateBindingEvaluator>> makeBinding(Private::Node<T> &&rootNode)
{
    return std::make_unique<Binding<T, ImmediateBindingEvaluator>>(std::move(rootNode));
}
 
template<typename Func, typename... Args, typename = std::enable_if_t<sizeof...(Args) != 0>, typename ResultType = Private::operator_node_result_t<Func, Args...>>
inline std::unique_ptr<Binding<ResultType, ImmediateBindingEvaluator>> makeBinding(Func &&func, Args &&...args)
{
    return std::make_unique<Binding<ResultType, ImmediateBindingEvaluator>>(Private::makeNode(std::forward<Func>(func), std::forward<Args>(args)...));
}
 
template<typename... T>
inline auto makeBoundProperty(T &&...args)
{
    auto binding = makeBinding(std::forward<T>(args)...);
    return Property<decltype(binding->get())>(std::move(binding));
}
 
} // namespace KDBindings