tweak.hpp

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#pragma once
 
#include "memlite/binder/binder.hpp"
#include "memlite/binder/weakTactic.hpp"
 
namespace by {
 
    class origin;
 
    template <typename T, typename TACTIC = weakTactic> class tweak: public binder {
        BY_ME(tweak, binder)
        BY_INIT_META(me)
        friend class bindTag;
 
    public:
        tweak();
        tweak(const type& subtype);
        tweak(const T& it);
        tweak(const T* it);
        tweak(const tmedium<T>& it);
        tweak(const me& rhs);
        explicit tweak(const binder& rhs);
 
    public:
        T* operator->();
        T& operator*();
        const T* operator->() const BY_CONST_FUNC(operator->())
        const T& operator*() const BY_CONST_FUNC(operator*())
        me& operator=(const binder& rhs);
        me& operator=(const me& rhs);
 
    public:
        using super::get;
        T* get();
        const T* get() const BY_CONST_FUNC(get())
 
        using super::bind;
        nbool bind(const T& new1);
    };
 
    // extension for OR macro:
    template <typename T, typename F> tmedium<T> operator|(tweak<T>& t, F&& f) {
        f(t);
        // this returns null-reference but take it easy.
        // it'll never be used.
        return t.get();
    }
 
    template <typename T, typename F> tmedium<T> operator|(const tweak<T>& t, F&& f) {
        f(t);
        // this returns null-reference but take it easy.
        // it'll never be used.
        return t.get();
    }
 
    template <typename T, typename F> tweak<T> operator|(tweak<T>&& t, F&& f) {
        f(t);
        // this returns null-reference but take it easy.
        // it'll never be used.
        return t;
    }
 
    // extension for typeTrait:
    template <typename T> struct typeTrait<tweak<T>> {
        typedef tweak<T> Org;
        typedef tweak<T>& Ref;
        typedef tweak<T>* Ptr;
 
        static tweak<T> ret() { return tweak<T>{}; } // return default value
 
        static nbool isNul(const tweak<T>& it) { return !it.isBind(); }
 
        static constexpr nbool is_ptr = false;
        static constexpr nbool is_ref = false;
        static constexpr nbool is_like_ptr = true;
    };
 
    template <typename T> struct typeTrait<tweak<T>*> {
        typedef tweak<T> Org;
        typedef tweak<T>& Ref;
        typedef tweak<T>* Ptr;
 
        static tweak<T>* ret() { return nullptr; }
 
        static nbool isNul(const tweak<T>* it) { return !it || !it->isBind(); }
 
        static constexpr nbool is_ptr = true;
        static constexpr nbool is_ref = false;
        static constexpr nbool is_like_ptr = is_ptr;
    };
 
    template <typename T> struct typeTrait<tweak<T>&> {
        typedef tweak<T> Org;
        typedef tweak<T>& Ref;
        typedef tweak<T>* Ptr;
 
        static nbool isNul(const tweak<T>& it) { return !it.isBind(); }
 
        static tweak<T>& ret() {
            static tweak<T> dummy;
            return dummy;
        }
 
        static constexpr nbool is_ptr = false;
        static constexpr nbool is_ref = true;
        static constexpr nbool is_like_ptr = true;
    };
 
    // extension for TO macro:
    template <typename T, typename F>
    auto operator->*(tweak<T>& t, F&& f) -> decltype(typeTrait<decltype(f(*t))>::ret()) {
        return t ? f(*t) : typeTrait<decltype(f(*t))>::ret();
    }
 
    template <typename T, typename F>
    auto operator->*(const tweak<T>& t, F&& f) -> decltype(typeTrait<decltype(f(*t))>::ret()) {
        return t ? f(*t) : typeTrait<decltype(f(*t))>::ret();
    }
 
    template <typename T, typename F>
    auto operator->*(tweak<T>&& t, F&& f) -> decltype(typeTrait<decltype(f(*t))>::ret()) {
        return t ? f(*t) : typeTrait<decltype(f(*t))>::ret();
    }
 
} // namespace by