437 lines
13 KiB
C++
437 lines
13 KiB
C++
// Copyright (c) 2012-2021 Wojciech Figat. All rights reserved.
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#pragma once
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#include "Engine/Core/Memory/Allocation.h"
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template<typename>
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class Function;
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template<typename... Params>
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class Delegate;
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/// <summary>
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/// The function object.
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/// </summary>
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template<typename ReturnType, typename... Params>
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class Function<ReturnType(Params ...)>
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{
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friend Delegate<Params...>;
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public:
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/// <summary>
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/// Signature of the function to call.
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/// </summary>
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typedef ReturnType (*Signature)(Params ...);
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private:
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typedef ReturnType (*StubSignature)(void*, Params ...);
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template<ReturnType(*Method)(Params ...)>
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static ReturnType StaticMethodStub(void*, Params ... params)
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{
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return (Method)(Forward<Params>(params)...);
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}
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static ReturnType StaticPointerMethodStub(void* callee, Params ... params)
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{
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return reinterpret_cast<Signature>(callee)(Forward<Params>(params)...);
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}
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template<class T, ReturnType(T::*Method)(Params ...)>
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static ReturnType ClassMethodStub(void* callee, Params ... params)
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{
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return (reinterpret_cast<T*>(callee)->*Method)(Forward<Params>(params)...);
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}
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template<class T, ReturnType(T::*Method)(Params ...) const>
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static ReturnType ClassMethodStub(void* callee, Params ... params)
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{
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return (reinterpret_cast<T*>(callee)->*Method)(Forward<Params>(params)...);
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}
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void* _callee;
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StubSignature _function;
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public:
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/// <summary>
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/// Initializes a new instance of the <see cref="Function"/> class.
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/// </summary>
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Function()
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{
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_callee = nullptr;
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_function = nullptr;
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="Function"/> class.
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/// </summary>
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Function(Signature method)
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{
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ASSERT(method);
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_callee = (void*)method;
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_function = &StaticPointerMethodStub;
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}
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public:
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/// <summary>
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/// Binds a static function.
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/// </summary>
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template<ReturnType (*Method)(Params ...)>
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void Bind()
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{
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_callee = nullptr;
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_function = &StaticMethodStub<Method>;
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}
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/// <summary>
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/// Binds a member function.
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/// </summary>
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/// <param name="callee">The object instance.</param>
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template<class T, ReturnType(T::*Method)(Params ...)>
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void Bind(T* callee)
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{
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_callee = callee;
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_function = &ClassMethodStub<T, Method>;
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}
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/// <summary>
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/// Binds a function.
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/// </summary>
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/// <param name="method">The method.</param>
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void Bind(Signature method)
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{
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_callee = (void*)method;
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_function = &StaticPointerMethodStub;
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}
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/// <summary>
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/// Unbinds the function.
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/// </summary>
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void Unbind()
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{
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_callee = nullptr;
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_function = nullptr;
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}
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public:
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/// <summary>
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/// Returns true if any function has been binded.
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/// </summary>
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/// <returns>True if any function has been binded, otherwise false.</returns>
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FORCE_INLINE bool IsBinded() const
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{
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return _function != nullptr;
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}
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/// <summary>
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/// Calls the binded function if any has been assigned.
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/// </summary>
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/// <param name="params">A list of parameters for the function invocation.</param>
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/// <returns>Function result</returns>
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void TryCall(Params ... params) const
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{
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if (_function)
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_function(_callee, Forward<Params>(params)...);
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}
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/// <summary>
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/// Calls the binded function (it must be assigned).
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/// </summary>
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/// <param name="params">A list of parameters for the function invocation.</param>
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/// <returns>Function result</returns>
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ReturnType operator()(Params ... params) const
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{
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ASSERT(_function);
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return _function(_callee, Forward<Params>(params)...);
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}
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FORCE_INLINE bool operator==(const Function& other) const
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{
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return _function == other._function && _callee == other._callee;
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}
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FORCE_INLINE bool operator!=(const Function& other) const
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{
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return _function != other._function || _callee != other._callee;
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}
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};
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/// <summary>
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/// Delegate object that can be used to bind and call multiply functions. Thread-safe to register/unregister during the call.
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/// </summary>
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template<typename... Params>
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class Delegate
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{
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public:
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/// <summary>
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/// Signature of the function to call.
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/// </summary>
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typedef void (*Signature)(Params ...);
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/// <summary>
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/// Template for the function.
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/// </summary>
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using FunctionType = Function<void(Params ...)>;
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protected:
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// Single allocation for list of binded functions. Thread-safe access via atomic operations. Removing binded function simply clears the entry to handle function unregister during invocation.
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intptr volatile _ptr = 0;
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intptr volatile _size = 0;
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typedef void (*StubSignature)(void*, Params ...);
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public:
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NON_COPYABLE(Delegate);
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Delegate()
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{
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}
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~Delegate()
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{
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Allocator::Free((void*)_ptr);
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}
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public:
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/// <summary>
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/// Binds a static function.
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/// </summary>
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template<void(*Method)(Params ...)>
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void Bind()
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{
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FunctionType f;
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f.template Bind<Method>();
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Bind(f);
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}
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/// <summary>
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/// Binds a member function.
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/// </summary>
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/// <param name="callee">The object instance.</param>
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template<class T, void(T::*Method)(Params ...)>
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void Bind(T* callee)
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{
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ASSERT(callee);
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FunctionType f;
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f.template Bind<T, Method>(callee);
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Bind(f);
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}
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/// <summary>
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/// Binds a function.
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/// </summary>
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/// <param name="method">The method.</param>
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void Bind(Signature method)
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{
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FunctionType f(method);
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Bind(f);
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}
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/// <summary>
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/// Binds a function.
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/// </summary>
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/// <param name="f">The function to bind.</param>
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void Bind(const FunctionType& f)
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{
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const intptr size = Platform::AtomicRead(&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead(&_ptr);
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if (bindings)
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{
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// Find a first free slot
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for (intptr i = 0; i < size; i++)
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{
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if (Platform::InterlockedCompareExchange((intptr volatile*)&bindings[i]._function, (intptr)f._function, 0) == 0)
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{
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Platform::AtomicStore((intptr volatile*)&bindings[i]._callee, (intptr)f._callee);
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return;
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}
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}
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}
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// Failed to find an empty slot in the list (empty or too small) so perform reallocation
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const intptr newSize = size ? size * 2 : 32;
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auto newBindings = (FunctionType*)Allocator::Allocate(newSize * sizeof(FunctionType));
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Platform::MemoryCopy(newBindings, bindings, size * sizeof(FunctionType));
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Platform::MemoryClear(newBindings + size, (newSize - size) * sizeof(FunctionType));
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// Insert function into a first slot after the old list
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newBindings[size] = f;
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// Set the new list
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auto oldBindings = (FunctionType*)Platform::InterlockedCompareExchange(&_ptr, (intptr)newBindings, (intptr)bindings);
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if (oldBindings != bindings)
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{
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// Other thread already set the new list so free this list and try again
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Allocator::Free(newBindings);
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Bind(f);
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}
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else
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{
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// Free previous bindings and update list size
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Platform::AtomicStore(&_size, newSize);
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// TODO: what is someone read this value before and is using the old table?
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Allocator::Free(bindings);
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}
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}
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/// <summary>
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/// Unbinds a static function.
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/// </summary>
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template<void(*Method)(Params ...)>
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void Unbind()
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{
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FunctionType f;
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f.template Bind<Method>();
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Unbind(f);
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}
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/// <summary>
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/// Unbinds a member function.
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/// </summary>
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/// <param name="callee">The object instance.</param>
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template<class T, void(T::*Method)(Params ...)>
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void Unbind(T* callee)
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{
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ASSERT(callee);
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FunctionType f;
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f.template Bind<T, Method>(callee);
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Unbind(f);
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}
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/// <summary>
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/// Unbinds the specified function.
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/// </summary>
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/// <param name="method">The method.</param>
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void Unbind(Signature method)
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{
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FunctionType f(method);
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Unbind(f);
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}
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/// <summary>
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/// Unbinds the specified function.
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/// </summary>
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/// <param name="f">The function to unbind.</param>
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void Unbind(FunctionType& f)
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{
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// Find slot with that function
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const intptr size = Platform::AtomicRead(&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead(&_ptr);
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for (intptr i = 0; i < size; i++)
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{
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if (Platform::AtomicRead((intptr volatile*)&bindings[i]._callee) == (intptr)f._callee && Platform::AtomicRead((intptr volatile*)&bindings[i]._function) == (intptr)f._function)
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{
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Platform::AtomicStore((intptr volatile*)&bindings[i]._callee, 0);
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Platform::AtomicStore((intptr volatile*)&bindings[i]._function, 0);
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break;
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}
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}
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if ((FunctionType*)Platform::AtomicRead(&_ptr) != bindings)
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{
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// Someone changed the bindings list so retry unbind from the new one
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Unbind(f);
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}
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}
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/// <summary>
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/// Unbinds all the functions.
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/// </summary>
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void UnbindAll()
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{
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const intptr size = Platform::AtomicRead(&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead(&_ptr);
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for (intptr i = 0; i < size; i++)
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{
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Platform::AtomicStore((intptr volatile*)&bindings[i]._function, 0);
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Platform::AtomicStore((intptr volatile*)&bindings[i]._callee, 0);
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}
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}
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/// <summary>
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/// Counts the amount of binded functions.
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/// </summary>
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/// <returns>The binded functions count.</returns>
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int32 Count() const
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{
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int32 count = 0;
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const intptr size = Platform::AtomicRead((intptr volatile*)&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead((intptr volatile*)&_ptr);
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for (intptr i = 0; i < size; i++)
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{
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if (Platform::AtomicRead((intptr volatile*)&bindings[i]._function) != 0)
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count++;
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}
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return count;
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}
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/// <summary>
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/// Determines whether any function is binded.
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/// </summary>
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/// <returns><c>true</c> if any function is binded; otherwise, <c>false</c>.</returns>
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bool IsBinded() const
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{
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const intptr size = Platform::AtomicRead((intptr volatile*)&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead((intptr volatile*)&_ptr);
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for (intptr i = 0; i < size; i++)
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{
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if (Platform::AtomicRead((intptr volatile*)&bindings[i]._function) != 0)
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return true;
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}
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return false;
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}
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/// <summary>
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/// Gets all the binded functions.
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/// </summary>
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/// <param name="buffer">The result bindings functions memory.</param>
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/// <param name="bufferSize">The result bindings functions memory size.</param>
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/// <returns>The amount of written items into the output bindings buffer. Can be equal or less than input bindingsCount capacity.</returns>
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int32 GetBindings(FunctionType* buffer, int32 bufferSize) const
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{
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int32 count = 0;
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const intptr size = Platform::AtomicRead((intptr volatile*)&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead((intptr volatile*)&_ptr);
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for (intptr i = 0; i < size && i < bufferSize; i++)
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{
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buffer[count]._function = (StubSignature)Platform::AtomicRead((intptr volatile*)&bindings[i]._function);
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if (buffer[count]._function != nullptr)
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{
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buffer[count]._callee = (void*)Platform::AtomicRead((intptr volatile*)&bindings[i]._callee);
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count++;
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}
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}
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return count;
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}
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/// <summary>
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/// Calls all the binded functions. Supports unbinding of the called functions during invocation.
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/// </summary>
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/// <param name="params">A list of parameters for the function invocation.</param>
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void operator()(Params ... params) const
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{
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const intptr size = Platform::AtomicRead((intptr volatile*)&_size);
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FunctionType* bindings = (FunctionType*)Platform::AtomicRead((intptr volatile*)&_ptr);
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for (intptr i = 0; i < size; i++)
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{
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FunctionType f;
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f._function = (StubSignature)Platform::AtomicRead((intptr volatile*)&bindings[i]._function);
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if (f._function != nullptr)
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{
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f._callee = (void*)Platform::AtomicRead((intptr volatile*)&bindings[i]._callee);
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f._function(f._callee, Forward<Params>(params)...);
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}
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}
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}
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};
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/// <summary>
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/// Action delegate.
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/// </summary>
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typedef Delegate<> Action;
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