jerryscript/src/include/Jerryscript/Function.h

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/****
 * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
 * Created 2015 by Skurydin Alexey
 * http://github.com/SmingHub/Sming
 * All files of the Sming Core are provided under the LGPL v3 license.
 *
 * Function.h
 *
 * @author: Dec 2021 - Mikee47 <mike@sillyhouse.net>
 *
 */

#pragma once

#include "Types.h"

namespace JS
{
using namespace Jerryscript;
}

// get number of arguments with JS_NARG
// https://newbedev.com/overloading-macro-on-number-of-arguments
// https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html
#define JS_NARG(...) JS_NARG_I(_0 __VA_OPT__(, ) __VA_ARGS__, JS_RSEQ_N)
#define JS_NARG_I(...) JS_ARG_N(__VA_ARGS__)
#define JS_ARG_N(_0, _1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
#define JS_RSEQ_N 8, 7, 6, 5, 4, 3, 2, 1, 0
static_assert(JS_NARG() == 0 && JS_NARG(!, !) == 2, "JS_NARG broken");

#define JS_CONCAT_(x, y) x##y
#define JS_CONCAT(x, y) JS_CONCAT_(x, y)

#define JS_ARGS_0
#define JS_ARGS_1 JS_ARGS_0, &args[0]
#define JS_ARGS_2 JS_ARGS_1, &args[1]
#define JS_ARGS_3 JS_ARGS_2, &args[2]
#define JS_ARGS_4 JS_ARGS_3, &args[3]
#define JS_ARGS_5 JS_ARGS_4, &args[4]
#define JS_ARGS_6 JS_ARGS_5, &args[5]
#define JS_ARGS_7 JS_ARGS_6, &args[6]
#define JS_ARGS_8 JS_ARGS_7, &args[7]

#define JS_DEFINE_FUNCTION(func, ...)                                                                                  \
    JS::Value js_##func(const JS::CallInfo& callInfo, ##__VA_ARGS__);                                                  \
    jerry_value_t func(const jerry_call_info_t* call_info_p, const jerry_value_t args[],                               \
                       const jerry_length_t args_count)                                                                \
    {                                                                                                                  \
        using Function = JS::Value (*)(const jerry_call_info_t*, ...);                                                 \
        if(JS_NARG(__VA_ARGS__) != args_count) {                                                                       \
            return JS::create_arg_count_error(__FUNCTION__);                                                           \
        }                                                                                                              \
        auto res = Function(js_##func)(call_info_p JS_CONCAT(JS_ARGS_, JS_NARG(__VA_ARGS__)));                         \
        return res.release();                                                                                          \
    }                                                                                                                  \
    JS::Value js_##func(const Jerryscript::CallInfo& callInfo, ##__VA_ARGS__)

#define JS_DEFINE_FUNCTION_VAR(func)                                                                                   \
    JS::Value js_##func(const JS::CallInfo& callInfo, JS::Value[], unsigned);                                          \
    jerry_value_t func(const jerry_call_info_t* call_info_p, const jerry_value_t args[],                               \
                       const jerry_length_t args_count)                                                                \
    {                                                                                                                  \
        using Function = JS::Value (*)(const jerry_call_info_t*, JS::Value[], unsigned);                               \
        auto res = Function(js_##func)(call_info_p, (JS::Value*)args, args_count);                                     \
        return res.release();                                                                                          \
    }                                                                                                                  \
    JS::Value js_##func(const JS::CallInfo& callInfo, JS::Value args[], unsigned argCount)

#define JS_DECLARE_FUNCTION(func)                                                                                      \
    jerry_value_t func(const jerry_call_info_t*, const jerry_value_t[], const jerry_length_t);

namespace Jerryscript
{
struct CallInfo {
    Value function;   
    Value this_value; 
    Value new_target; 
};

// Internal helper function used by JS_DEFINE_FUNCTION
jerry_value_t create_arg_count_error(const char* functionName);

} // namespace Jerryscript