pocketpy/include/pocketpy/bindings.h

#pragma once

#include "cffi.h"

namespace pkpy{

struct NativeProxyFuncCBase {
    virtual PyObject* operator()(VM* vm, ArgsView args) = 0;
};

template<typename Ret, typename... Params>
struct NativeProxyFuncC final: NativeProxyFuncCBase {
    static constexpr int N = sizeof...(Params);
    using _Fp = Ret(*)(Params...);
    _Fp func;
    NativeProxyFuncC(_Fp func) : func(func) {}

    PyObject* operator()(VM* vm, ArgsView args) override {
        PK_ASSERT(args.size() == N);
        return call<Ret>(vm, args, std::make_index_sequence<N>());
    }

    template<typename __Ret, size_t... Is>
    PyObject* call(VM* vm, ArgsView args, std::index_sequence<Is...>){
        if constexpr(std::is_void_v<__Ret>){
            func(py_cast<Params>(vm, args[Is])...);
            return vm->None;
        }else{
            __Ret ret = func(py_cast<Params>(vm, args[Is])...);
            return VAR(std::move(ret));
        }
    }
};

template<typename Ret, typename T, typename... Params>
struct NativeProxyMethodC final: NativeProxyFuncCBase {
    static constexpr int N = sizeof...(Params);
    using _Fp = Ret(T::*)(Params...);
    _Fp func;
    NativeProxyMethodC(_Fp func) : func(func) {}

    PyObject* operator()(VM* vm, ArgsView args) override {
        PK_ASSERT(args.size() == N+1);
        return call<Ret>(vm, args, std::make_index_sequence<N>());
    }

    template<typename __Ret, size_t... Is>
    PyObject* call(VM* vm, ArgsView args, std::index_sequence<Is...>){
        T& self = py_cast<T&>(vm, args[0]);
        if constexpr(std::is_void_v<__Ret>){
            (self.*func)(py_cast<Params>(vm, args[Is+1])...);
            return vm->None;
        }else{
            __Ret ret = (self.*func)(py_cast<Params>(vm, args[Is+1])...);
            return VAR(std::move(ret));
        }
    }
};

inline PyObject* proxy_wrapper(VM* vm, ArgsView args){
    NativeProxyFuncCBase* pf = lambda_get_userdata<NativeProxyFuncCBase*>(args.begin());
    return (*pf)(vm, args);
}

template<typename Ret, typename... Params>
void _bind(VM* vm, PyObject* obj, const char* sig, Ret(*func)(Params...)){
    auto proxy = new NativeProxyFuncC<Ret, Params...>(func);
    vm->bind(obj, sig, proxy_wrapper, proxy);
}

template<typename Ret, typename T, typename... Params>
void _bind(VM* vm, PyObject* obj, const char* sig, Ret(T::*func)(Params...)){
    auto proxy = new NativeProxyMethodC<Ret, T, Params...>(func);
    vm->bind(obj, sig, proxy_wrapper, proxy);
}
/*****************************************************************/
#define PY_FIELD(T, NAME, REF, EXPR)       \
        vm->bind_property(type, NAME,               \
            [](VM* vm, ArgsView args){              \
                T& self = PK_OBJ_GET(T, args[0]);   \
                return VAR(self.REF()->EXPR);       \
            },                                      \
            [](VM* vm, ArgsView args){              \
                T& self = PK_OBJ_GET(T, args[0]);   \
                self.REF()->EXPR = CAST(decltype(self.REF()->EXPR), args[1]);       \
                return vm->None;                                                    \
            });

#define PY_FIELD_P(T, NAME, EXPR)                   \
        vm->bind_property(type, NAME,               \
            [](VM* vm, ArgsView args){              \
                VoidP& self = PK_OBJ_GET(VoidP, args[0]);   \
                T* tgt = reinterpret_cast<T*>(self.ptr);    \
                return VAR(tgt->EXPR);                      \
            },                                      \
            [](VM* vm, ArgsView args){              \
                VoidP& self = PK_OBJ_GET(VoidP, args[0]);   \
                T* tgt = reinterpret_cast<T*>(self.ptr);    \
                tgt->EXPR = CAST(decltype(tgt->EXPR), args[1]);       \
                return vm->None;                                      \
            });

#define PY_READONLY_FIELD(T, NAME, REF, EXPR)          \
        vm->bind_property(type, NAME,                  \
            [](VM* vm, ArgsView args){              \
                T& self = PK_OBJ_GET(T, args[0]);   \
                return VAR(self.REF()->EXPR);       \
            });

#define PY_READONLY_FIELD_P(T, NAME, EXPR)          \
        vm->bind_property(type, NAME,                  \
            [](VM* vm, ArgsView args){              \
                VoidP& self = PK_OBJ_GET(VoidP, args[0]);   \
                T* tgt = reinterpret_cast<T*>(self.ptr);    \
                return VAR(tgt->EXPR);                      \
            });

#define PY_PROPERTY(T, NAME, REF, FGET, FSET)  \
        vm->bind_property(type, NAME,                   \
            [](VM* vm, ArgsView args){                  \
                T& self = PK_OBJ_GET(T, args[0]);       \
                return VAR(self.REF()->FGET());         \
            },                                          \
            [](VM* vm, ArgsView args){                  \
                T& self = _CAST(T&, args[0]);           \
                using __NT = decltype(self.REF()->FGET());   \
                self.REF()->FSET(CAST(__NT, args[1]));       \
                return vm->None;                            \
            });

#define PY_READONLY_PROPERTY(T, NAME, REF, FGET)  \
        vm->bind_property(type, NAME,                   \
            [](VM* vm, ArgsView args){                  \
                T& self = PK_OBJ_GET(T, args[0]);       \
                return VAR(self.REF()->FGET());         \
            });

#define PY_STRUCT_LIKE(wT)   \
        using vT = std::remove_pointer_t<decltype(std::declval<wT>()._())>;         \
        static_assert(std::is_trivially_copyable<vT>::value);                       \
        type->attr().set("__struct__", vm->True);                                   \
        vm->bind_func<1>(type, "from_struct", [](VM* vm, ArgsView args){            \
            C99Struct& s = CAST(C99Struct&, args[0]);                               \
            if(s.size != sizeof(vT)) vm->ValueError("size mismatch");               \
            PyObject* obj = vm->heap.gcnew<wT>(wT::_type(vm));                      \
            memcpy(_CAST(wT&, obj)._(), s.p, sizeof(vT));                           \
            return obj;                                                             \
        }, {}, BindType::STATICMETHOD);                                             \
        vm->bind_method<0>(type, "to_struct", [](VM* vm, ArgsView args){            \
            wT& self = _CAST(wT&, args[0]);                                         \
            return VAR_T(C99Struct, self._(), sizeof(vT));                          \
        });                                                                         \
        vm->bind_method<0>(type, "addr", [](VM* vm, ArgsView args){                 \
            wT& self = _CAST(wT&, args[0]);                                         \
            return VAR_T(VoidP, self._());                                          \
        });                                                                         \
        vm->bind_method<0>(type, "copy", [](VM* vm, ArgsView args){                 \
            wT& self = _CAST(wT&, args[0]);                                         \
            return VAR_T(wT, *self._());                                            \
        });                                                                         \
        vm->bind_method<0>(type, "sizeof", [](VM* vm, ArgsView args){               \
            return VAR(sizeof(vT));                                                 \
        });                                                                         \
        vm->bind__eq__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* _0, PyObject* _1){  \
            wT& self = _CAST(wT&, _0);                                              \
            if(!vm->isinstance(_1, wT::_type(vm))) return vm->NotImplemented;       \
            wT& other = _CAST(wT&, _1);                                             \
            return VAR(self == other);                                              \
        });                                                                         \

#define PY_POINTER_SETGETITEM(T) \
        vm->bind__getitem__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* _0, PyObject* _1){  \
            VoidP& self = PK_OBJ_GET(VoidP, _0);                                       \
            i64 i = CAST(i64, _1);                                                      \
            T* tgt = reinterpret_cast<T*>(self.ptr);                                    \
            return VAR(tgt[i]);                                                         \
        });                                                                             \
        vm->bind__setitem__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* _0, PyObject* _1, PyObject* _2){  \
            VoidP& self = PK_OBJ_GET(VoidP, _0);                                       \
            i64 i = CAST(i64, _1);                                                      \
            T* tgt = reinterpret_cast<T*>(self.ptr);                                    \
            tgt[i] = CAST(T, _2);                                                       \
        });                                                                         \

}   // namespace pkpy