ScopeExit.hpp

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#pragma once
 
#include "AstGlobal.h"
#include "AstUtil/TypeTraits.hpp"
#include <utility>          // std::move, std::forward
#include <type_traits>      // std::decay, std::is_nothrow_move_constructible
 
AST_NAMESPACE_BEGIN
 
template <typename F>
class ScopeExit
{
    static_assert(is_callable<F&>::value, "type F must be callable with no arguments");
public:
    explicit ScopeExit(const F& fn)
        : fn_(fn), active_(true)
    {}
 
    explicit ScopeExit(F&& fn)
        : fn_(std::move(fn)), active_(true)
    {}
 
    ScopeExit(ScopeExit&& other) noexcept(std::is_nothrow_move_constructible<F>::value)
        : fn_(std::move(other.fn_)), active_(other.active_)
    {
        other.active_ = false;
    }
 
    ~ScopeExit()
    {
        invoke();
    }
 
    A_DISABLE_COPY(ScopeExit);
 
    void invoke()
    {
        if (active_) {
            active_ = false;
            fn_();
        }
    }
 
    void release() noexcept
    {
        active_ = false;
    }
 
    bool isActive() const noexcept { return active_; }
 
    operator bool() const noexcept { return isActive(); }
 
protected:
    F fn_;               
    bool active_{true};  
};
 
 
template <typename F>
A_NODISCARD A_ALWAYS_INLINE ScopeExit<typename std::decay<F>::type> aScopeExit(F&& fn)
{
    return ScopeExit<typename std::decay<F>::type>(std::forward<F>(fn));
}
 
AST_NAMESPACE_END