Method TV_AddModifyDelete

source/script2.cpp:16033–16305

ResultType GuiControlType::TV_AddModifyDelete(ResultToken &aResultToken, int aID, int aFlags, ExprTokenType *aParam[], int aParamCount)
// TV.Add():
// Returns the HTREEITEM of the item on success, zero on failure.
// Parameters:
//    1: Text/name of item.
//    2: Parent of item.
//    3: Options.
// TV.Modify():
// Returns the HTREEITEM of the item on success (to allow nested calls in script, zero on failure or partial failure.
// Parameters:
//    1: ID of item to modify.
//    2: Options.
//    3: New name.
// Parameters for TV.Delete():
//    1: ID of item to delete (if omitted, all items are deleted).
{
	GuiControlType &control = *this;
	auto mode = BuiltInFunctionID(aID);
	LPTSTR buf = _f_number_buf; // Resolve macro early for maintainability.

	if (mode == FID_TV_Delete)
	{
		// If param #1 is present but is zero, for safety it seems best not to do a delete-all (in case a
		// script bug is so rare that it is never caught until the script is distributed).  Another reason
		// is that a script might do something like TV.Delete(TV.GetSelection()), which would be desired
		// to fail not delete-all if there's ever any way for there to be no selection.
		_o_return(SendMessage(control.hwnd, TVM_DELETEITEM, 0
			, ParamIndexIsOmitted(0) ? NULL : (LPARAM)ParamIndexToInt64(0)));
	}

	// Since above didn't return, this is TV.Add() or TV.Modify().
	TVINSERTSTRUCT tvi; // It contains a TVITEMEX, which is okay even if MSIE pre-4.0 on Win95/NT because those OSes will simply never access the new/bottommost item in the struct.
	bool add_mode = (mode == FID_TV_Add); // For readability & maint.
	HTREEITEM retval;
	
	// Suppress any events raised by the changes made below:
	control.attrib |= GUI_CONTROL_ATTRIB_SUPPRESS_EVENTS;

	LPTSTR options;
	if (add_mode) // TV.Add()
	{
		tvi.hParent = ParamIndexIsOmitted(1) ? NULL : (HTREEITEM)ParamIndexToInt64(1);
		tvi.hInsertAfter = TVI_LAST; // i.e. default is to insert the new item underneath the bottommost sibling.
		options = ParamIndexToOptionalString(2, buf);
		retval = 0; // Set default return value.
	}
	else // TV.Modify()
	{
		// NOTE: Must allow hitem==0 for TV.Modify, at least for the Sort option, because otherwise there would
		// be no way to sort the root-level items.
		tvi.item.hItem = (HTREEITEM)ParamIndexToInt64(0); // Load-time validation has ensured there is a first parameter for TV.Modify().
		// For modify-mode, set default return value to be "success" from this point forward.  Note that
		// in the case of sorting the root-level items, this will set it to zero, but since that almost
		// always succeeds and the script rarely cares whether it succeeds or not, adding code size for that
		// doesn't seem worth it:
		retval = tvi.item.hItem; // Set default return value.
		if (aParamCount < 2) // In one-parameter mode, simply select the item.
		{