ObjectLinker.hpp

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#pragma once
 
#include "AstGlobal.h"
#include "AstUtil/Object.hpp"
#include "AstUtil/WeakPtr.hpp"
#include <type_traits>
 
AST_NAMESPACE_BEGIN
 
class ObjectLinker
{
public:
    ObjectLinker(Object* object)
        : object_(object)
    {
    }
 
    virtual ~ObjectLinker() = default;
 
    virtual errc_t resolve() = 0;
 
    Object* object() const {return object_.get();}
private:
    WeakPtr<Object> object_;
};
 
 
template <typename Func>
class ObjectLinkerGeneric : public ObjectLinker
{
    Func func_;
 
    // 非 void 版本
    template <typename F>
    static errc_t invoke(F& f,
        typename std::enable_if<!std::is_void<
            decltype(std::declval<F>()())>::value>::type* = nullptr)
    {
        return f();
    }
 
    // void 版本
    template <typename F>
    static errc_t invoke(F& f,
        typename std::enable_if<std::is_void<
            decltype(std::declval<F>()())>::value>::type* = nullptr)
    {
        f();
        return 0;   
    }
 
public:
    ObjectLinkerGeneric(Object* object, Func func)
        : ObjectLinker(object), func_(func)
    {
    }
 
    virtual errc_t resolve() override
    {
        return invoke(func_);
    }
};
 
 
 
AST_UTIL_CAPI void aAddObjectLinker(ObjectLinker* linker);
 
 
AST_UTIL_CAPI errc_t aObject_ResolveLinks(Object* object);
 
 
AST_UTIL_CAPI errc_t aResolveAllLinks();
 
 
template <typename Func>
inline void aObject_AddDelayedLink(Object* object, Func func)
{
    aAddObjectLinker(new ObjectLinkerGeneric<Func>(object, func));
}
 
 
// object methods
 
template<typename Func>
inline void Object::addDelayedLink(Func &&link)
{
    aObject_AddDelayedLink(this, std::forward<Func>(link));
}
 
template<typename Func>
inline void Object::addDelayedLinkIfFailed(Func &&link)
{
    errc_t rc = link();
    if(rc != eNoError)
        aObject_AddDelayedLink(this, std::forward<Func>(link));
}
 
 
A_ALWAYS_INLINE void Object::resolveLinks()
{
    aObject_ResolveLinks(this);
}
 
 
AST_NAMESPACE_END