sjlj_exc.cpp

struct ExceptionPad {
    jmp_buf retaddr;
    Exception exc;

    void invoke(const Exception &exc) {
        this->exc = exc;
        longjmp(retaddr, 1);
    }
};

#define SCOPES_TRY() \
    ExceptionPad exc_pad; \
    ExceptionPad *_last_exc_pad = _exc_pad; \
    _exc_pad = &exc_pad; \
    if (!setjmp(exc_pad.retaddr)) {

#define SCOPES_CATCH(EXCNAME) \
        _exc_pad = _last_exc_pad; \
    } else { \
        _exc_pad = _last_exc_pad; \
        auto &&EXCNAME = exc_pad.exc;

#define SCOPES_TRY_END() \
    }

static ExceptionPad *_exc_pad = nullptr;