//
int rpn_if(branch& myobj)
{
	// myobj.arg1 = 'if' condition evaluation value
	MIN_ARGUMENTS_RET(1, -1);
	ARG_IS_OF_TYPE_RET(0, cmd_number, -1);
	myobj.arg1 = ((getf() != 0) ? 1 : 0);
	return -1;
}

int rpn_then(branch& myobj)
{
	// myobj.arg1 = index of then + 1
	// myobj.arg2 = index of else + 1 or end + 1
	// myobj.arg3 = index of if
	// if condition is true -> arg1 (= jump to then + 1)
	// else -> arg2 (= jump to else + 1 or end + 1)
	branch* if_cmd = (branch*)seq_obj(myobj.arg3);
	if (if_cmd->arg1 == 1)
		return myobj.arg1;
	else
		return myobj.arg2;
}

int rpn_else(branch& myobj)
{
	// myobj.arg1 = index of else + 1
	// myobj.arg2 = index of end + 1
	// myobj.arg3 = index of if
	// if condition was false -> arg1 (= jump to else + 1)
	// if condition was true -> arg2 (= jump to end + 1)
	branch* if_cmd = (branch*)seq_obj(myobj.arg3);
	if (if_cmd->arg1 == 1)
		return myobj.arg2;
	else
		return myobj.arg1;
}

void rpn_end(void)
{
	// nothing
}

int rpn_start(branch& myobj)
{
	MIN_ARGUMENTS_RET(2, 1);
	ARG_IS_OF_TYPE_RET(0, cmd_number, -1);
	ARG_IS_OF_TYPE_RET(1, cmd_number, -1);

	// farg1 = first value of start command
	// farg2 = last value of start command
	myobj.farg2 = getf();
	myobj.farg1 = getf();
	return -1;
}

int rpn_for(branch& myobj)
{
	MIN_ARGUMENTS_RET(2, 1);
	ARG_IS_OF_TYPE_RET(0, cmd_number, -1);
	ARG_IS_OF_TYPE_RET(1, cmd_number, -1);

	symbol* sym = ((symbol*)seq_obj(myobj.arg1));

	// farg1 = first value of for command
	// farg2 = last value of for command
	// arg1 = index of symbol to increase
	myobj.farg2 = getf();
	myobj.farg1 = getf();
	
	// store symbol with first value
	_heap->add(sym->_name, &number(myobj.farg1), sizeof(number), cmd_number);

	return myobj.arg1 + 1;
}

int rpn_next(branch& myobj)
{
	// arg1 = index of start or for command in program
	// farg1 = current count
	branch* start_or_for = (branch*)seq_obj(myobj.arg1);
	if (! myobj.arg_bool)
	{
		myobj.arg_bool = true;
		myobj.farg1 = start_or_for->farg1;
	}

	// increment then test
	myobj.farg1++;
	
	// for command: increment symbol too
	if (start_or_for->arg1 != -1)
	{
		void* obj;
		unsigned int size;
		int type;
		symbol* var = (symbol*)seq_obj(start_or_for->arg1);
		// check symbol variable is a number, then increase
		if (_heap->get(var->_name, obj, size, type) && (type == cmd_number))
			((number*)obj)->_value = myobj.farg1;
	}

	//test value
	if (myobj.farg1 > start_or_for->farg2)
	{
		// end of loop
		myobj.arg_bool = false;// init again next time
		return -1;
	}
	else
	{
		// for command: next instruction will be after symbol variable
		if (start_or_for->arg1 != -1)
			return start_or_for->arg1 + 1;
		// start command: next instruction will be after start command
		else
			return myobj.arg1 + 1;
	}
}

int rpn_step(branch& myobj)
{
	// arg1 = index of start or for command in program
	// farg1 = current count
	floating_t step = getf();
	branch* start_or_for = (branch*)seq_obj(myobj.arg1);
	if (! myobj.arg_bool)
	{
		myobj.arg_bool = true;
		myobj.farg1 = start_or_for->farg1;
	}

	// increment then test
	myobj.farg1 += step;

	// for command: increment symbol too
	if (start_or_for->arg1 != -1)
	{
		void* obj;
		unsigned int size;
		int type;
		symbol* var = (symbol*)seq_obj(start_or_for->arg1);
		// check symbol variable is a number, then increase
		if (_heap->get(var->_name, obj, size, type) && (type == cmd_number))
			((number*)obj)->_value = myobj.farg1;
	}

	//test value
	if (((step>0) && (myobj.farg1 > start_or_for->farg2))
	   || ((step<0) && (myobj.farg1 < start_or_for->farg2)))
	{
		// end of loop
		myobj.arg_bool = false;// init again next time
		return -1;
	}
	else
	{
		// for command: next instruction will be after symbol variable
		if (start_or_for->arg1 != -1)
			return start_or_for->arg1 + 1;
		// start command: next instruction will be after start command
		else
			return myobj.arg1 + 1;
	}
}