Stacks.pas

unit stacks;

interface
 
 const
	maxBoardSize = 8;

 type
	TCell = (cQueen, cUnderAttack, cFree);
	TBoard = array[1..maxBoardSize, 1..maxBoardSize] of TCell;
	PStack= ^TStack;	
	TStack = record
       x: byte;
       CurrAbsBoardPos: integer; //òåêóùåå ïîëîæåíèå ôåðçÿ â ñòðîêå ïðèìåíèòåëüíî ê îòðèñîâêå
       board: TBoard;
       next: PStack;
	end;
	
	procedure CreateStack (var top:pStack);
  procedure ClearStack (var top: PStack);
	procedure PushStack (var top: pStack; x: byte; board: TBoard; CurrAbsBoardPos: integer);
  procedure PopStack (var top: pStack; var x: byte; var board: TBoard; var CurrAbsBoardPos: integer);
	//function StackElements (var top: pStack): integer;

implementation
	
	procedure CreateStack (var top: pStack);
	{ñîçäàíèå ïóñòîãî ñòåêà}
	begin
    if top <> nil then
      ClearStack (top)
    else
  		top:= nil;
	end;
	
	procedure PushStack (var top: pStack; x: byte; board: TBoard; CurrAbsBoardPos: integer);
	{äîáàâëåíèå ýëåìåíòà â âåðõ ñòåêà}
	var
		temp: pStack;
	begin
		new (temp);				{âûäåëÿåì ïàìÿòü äëÿ íîâîãî ýëåìåíòà}
		temp^.x:= x;		{ïðèñâàèâàåì ýëåìåíòó èíôîðìàöèþ}
		temp^.board:= board;
    temp^.CurrAbsBoardPos:= CurrAbsBoardPos;
		temp^.next:= top;		{"ñòàâèì" íîâûé ýëåìåíò â âåðõ ñòåêà}
		top:= temp;					{ñîõðàíÿåì ñòåê ñ íîâûì ýëåìåíòîì}
	end;
		
	procedure PopStack (var top: pStack; var x: byte; var board: TBoard; var CurrAbsBoardPos: integer);
	{èçúÿòèå ýëåìåíòà èç âåðøèíû ñòåêà}
	var
		temp: pStack;
	begin
		if top <> nil then			{åñëè ñòåê íå ïóñò, òî}
		begin
			temp:= top^.next;	{ñîõðàíÿåì ñòåê, íà÷èíàÿ ñî âòîðîãî ýëåìåíòà îò âåðøèíû}
			x:= top^.x;				{ñ÷èòûâàåì èíôîðìàöèþ}
      CurrAbsBoardPos:= top^.CurrAbsBoardPos;
			board:= top^.board;
			dispose (top);			{î÷èùàåì ïàìÿòü îò ïåðâîãî ýëåìåíòà}
			top:= temp;				{çàïèñûâàåì íîâûé ñòåê â top}
		end;
	end;

  procedure ClearStack (var top: PStack);
  var
    temp: PStack;
  begin
    while top <> nil do
    begin
      temp:= top;
      top:= top^.next;
      dispose (temp);
    end;
  end;

	
end.