Курсовой проект Задача о трёх телах / Runge / Unit5

unit Unit5;

interface
  uses SysUtils;
  type
    ExceptArrClass = class(Exception)
    end;

    PDynElem = ^TDynElem;
    TDynElem = record
      val: double;
      next: PDynElem;
      pred: PDynElem;
      ind: integer;
    end;

    TDynArr = class
    private
      start: PDynElem;
      this: PDynElem;
      last, first:PDynElem;
      maxLen: integer;
      function GetArr(index: integer): double;
      procedure SetArr(index: integer; const Value: Double);
      function GetPred: PDynElem;
      function GetNext: PDynElem;
    public
//      procedure Delete(index: integer);
      function Length:integer;
      function High:integer;
      function low:integer;
      property Arr[index: integer]: double read GetArr write SetArr; Default;
      constructor Create;
  end;

implementation
constructor TDynArr.Create;
begin
  start:=nil;
  last:=start;
  first:=start;
  maxLen:=1500;
end;

function TDynArr.GetArr(index: integer): double;
  procedure rec(Base: PDynElem; ind: integer);
  begin
    if ind = 0 then begin
      result:=base.val;
      this :=base;
    end else if ind > 0 then
      rec(base.next, ind -1)
    else if ind < 0 then
      rec(base.pred, ind +1)
  end;
begin
  if (last = nil) or (first = nil )then
    raise ExceptArrClass.Create('Неверный индекс ' + inttostr(index))
  else if index > last.ind then
    raise ExceptArrClass.Create('Неверный индекс ' + inttostr(index))
  else if index < first.ind then
    raise ExceptArrClass.Create('Неверный индекс ' + inttostr(index))
  else if index = last.ind then
    Result:=last.val
  else if index = first.ind then
    Result:=first.val
  else
    if abs(index - this.ind) < abs(index - start.ind) then
      rec(this, index-this.ind)
    else
      rec(start, index-start.ind);

end;

function TDynArr.GetNext: PDynElem;
begin
  result:= start;
  while result.next <> nil do
  begin
    Result:=Result.next;
  end;
end;

function TDynArr.GetPred: PDynElem;
begin
  result := start;
  while result.pred <> nil do
  begin
    Result:=Result.pred;
  end;
end;

function TDynArr.High: integer;
begin
  result:=last.ind;

end;

function TDynArr.Length: integer;
begin
  result:=last.ind-first.ind;
end;

function TDynArr.low: integer;
begin
  result:=first.ind;
end;

procedure TDynArr.SetArr(index: integer; const Value: double);
  procedure rec(Base: PDynElem; ind: integer);
  begin
    if ind = 0 then begin
      base.val:=value;
      this :=base;
    end else if ind > 0 then
      rec(base.next, ind-1)
    else
      rec(base.pred, ind+1)
  end;
begin
  if start = nil then begin
    new(start);
    start.val:=Value;
    start.next:=nil;
    start.pred:=nil;
    start.ind:=index;
    first:=start;
    last:=start;
    this :=start;
  end else if index > last.ind+1 then
    raise ExceptArrClass.Create('Неверный индекс ' + inttostr(index))
  else if index < first.ind-1 then
    raise ExceptArrClass.Create('Неверный индекс ' + inttostr(index))
  else if index = last.ind+1 then begin
    new(last.next);
    last.next.pred:=last;
    last.next.next:=nil;
    last.next.val:=Value;
    last:=last.next;
    last.ind:=index;
    this :=last;
    if last.ind - first.ind >= maxLen then begin
      first:=first.next;
      if start = first.pred then  start:=first;
      dispose(first.pred);
      first.pred:=nil;

    end
  end else if index = first.ind-1 then begin
    new(first.pred);
    first.pred.next:=first;
    first.pred.pred:=nil;
    first.pred.val:=Value;
    first:=first.pred;
    first.ind:=index;
    this :=first;
    if last.ind - first.ind >= maxLen then begin
      last:=last.pred;
      if start = last.next then  start:=last;
      dispose(last.next);
      last.next:=nil;
    end
  end else
    if abs(this.ind - index) < abs(start.ind-index) then
      rec(this, index-this.ind)
    else
      rec(start, index-start.ind);
end;

end.