DimsaMathParser/uConstantGroup.pas at master · dimsa/DimsaMathParser · GitHub

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unit uConstantGroup;

interface

uses
  System.SysUtils,
  uParserValue, uTextProc;

type
  // Íåñ÷èòàåìîå çíà÷åíèå, ïåðåìåííàÿ èëè êîíñòàíòà
  TConstantValue = class(TValue)
  public
    constructor Create(const AValue: String); reintroduce; virtual;
  end;

  TVariable = class(TConstantValue)
  strict private
    FPlacedValue: Double;
    FPlaced: Boolean;
    FValueStack: TValueStack;
    function GetName: string;
    procedure PlaceValue(const AValue: Double);// Ïðîñòî âûäàåò Text
  public
    property Name: string read GetName; // Íàçâàíèå ýòî ïî ñóòè òåêñò ïåðåìåííîé
    property ValueStack: TValueStack read FValueStack write FValueStack;
//    procedure PlaceValue(const AValue: Double);
    function Value: Double; override;
    constructor Create(const AValue: String); override;
  end;

  TDouble = class(TConstantValue)
  public
    function Value: Double; override;
  end;

implementation

{ TVariable }

constructor TVariable.Create(const AValue: String);
begin
  inherited;
  Text := AValue;
  FPlaced := False;
  Self.BoundLeft := 1;
  Self.BoundRight := Length(AValue)
end;

function TVariable.GetName: string;
begin
  Result := Self.Text;
end;

procedure TVariable.PlaceValue(const AValue: Double);
begin
  FPlaced := True;
  FPlacedValue := AValue;
end;

function TVariable.Value: Double;
begin
  if FValueStack = Nil then
    raise Exception.Create('Íà çàäàí ñòåê çíà÷åíèé äëÿ ìàòåìàòè÷åñêîãî âûðàæåíèÿ.');

  if FValueStack.IsHere(Name) then
  begin
    Result := FValueStack[Name];
  end else
    raise Exception.Create('Íà çàäàíî çíà÷åíèå ïåðåìåííîé «' + Name + '»');
{ Âàðèàíò êîäà äëÿ äðóãîé àðõèòåêòóðû. Íî îí íå íóæåí.
  if FPlaced then
    Result := FPlacedValue
  else
    raise Exception.Create('Íà çàäàíî çíà÷åíèå ïåðåìåííîé «' + Name + '»');}
end;

{ TDouble }

function TDouble.Value: Double;
var
  vA: Double;
  vErr: Integer;
begin
  Val(Text, vA, vErr);

  if vErr = 0 then
    Result := vA
  else
    raise Exception.Create('Îøèáêà êîíñòàíòîâîãî çíà÷åíèÿ, íåâîçìîæíî ïåðåâåñòè â ÷èñëî ñ ïëàâàþùåé òî÷êîé «' + Text + '»');
end;

{ TConstantValue }

constructor TConstantValue.Create(const AValue: String);
begin
  Text := AValue;
end;

end.