unit jsbase;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils;

Type
  TJSType = (jstUNDEFINED,jstNull,jstBoolean,jstNumber,jstString,jstObject,jstReference,JSTCompletion);

  TJSString = WideString;
  TJSNumber = Double;

  { TJSValue }

  TJSValue = Class(TObject)
  private
    FValueType: TJSType;
    FValue : Record
      Case Integer of
      0 : (P : Pointer);
      1 : (F : TJSNumber);
      2 : (I : Integer);
    end;
    procedure ClearValue(ANewValue: TJSType);
    function GetAsBoolean: Boolean;
    function GetAsCompletion: TObject;
    function GetAsNumber: TJSNumber;
    function GetAsObject: TObject;
    function GetAsReference: TObject;
    function GetAsString: TJSString;
    function GetIsNull: Boolean;
    function GetIsUndefined: Boolean;
    procedure SetAsBoolean(const AValue: Boolean);
    procedure SetAsCompletion(const AValue: TObject);
    procedure SetAsNumber(const AValue: TJSNumber);
    procedure SetAsObject(const AValue: TObject);
    procedure SetAsReference(const AValue: TObject);
    procedure SetAsString(const AValue: TJSString);
    procedure SetIsNull(const AValue: Boolean);
    procedure SetIsUndefined(const AValue: Boolean);
  Public
    Destructor Destroy; override;
    Property ValueType : TJSType Read FValueType;
    Property IsUndefined : Boolean Read GetIsUndefined Write SetIsUndefined;
    Property IsNull : Boolean Read GetIsNull Write SetIsNull;
    Property AsNumber : TJSNumber Read GetAsNumber Write SetAsNumber;
    Property AsBoolean : Boolean Read GetAsBoolean Write SetAsBoolean;
    Property AsObject : TObject Read GetAsObject Write SetAsObject;
    Property AsString : TJSString Read GetAsString Write SetAsString;
    Property AsReference : TObject Read GetAsReference Write SetAsReference;
    Property AsCompletion : TObject Read GetAsCompletion Write SetAsCompletion;
  end;

implementation

{ TJSValue }


function TJSValue.GetAsBoolean: Boolean;
begin
  If (ValueType=jstBoolean) then
    Result:=(FValue.I<>0)
  else
    Result:=False;
end;

function TJSValue.GetAsCompletion: TObject;
begin
  Result:=TObject(FValue.P);
end;

function TJSValue.GetAsNumber: TJSNumber;
begin
  If (ValueType=jstNumber) then
    Result:=FValue.F;
end;

function TJSValue.GetAsObject: TObject;
begin
  If (ValueType=jstObject) then
    Result:=TObject(FValue.P);
end;

function TJSValue.GetAsReference: TObject;
begin
  If (ValueType=jstReference) then
    Result:=TObject(FValue.P);
end;

function TJSValue.GetAsString: TJSString;
begin
  If (ValueType=jstString) then
    Result:=String(FValue.P);
end;

function TJSValue.GetIsNull: Boolean;
begin
  Result:=(ValueType=jstNull);
end;

function TJSValue.GetIsUndefined: Boolean;
begin
  Result:=(fValueType=jstUndefined);
end;

procedure TJSValue.ClearValue(ANewValue : TJSType);

begin
  Case FValueType of
    jstString : String(FValue.P):='';
    jstNumber : FValue.F:=0;
  else
    FValue.I:=0;
  end;
  FValueType:=ANewValue;
end;

procedure TJSValue.SetAsBoolean(const AValue: Boolean);
begin
  ClearValue(jstBoolean);
  FValue.I:=Ord(AValue);
end;

procedure TJSValue.SetAsCompletion(const AValue: TObject);
begin
  ClearValue(jstBoolean);
  FValue.P:=AValue;
end;

procedure TJSValue.SetAsNumber(const AValue: TJSNumber);
begin
  ClearValue(jstNumber);
  FValue.F:=AValue;
end;

procedure TJSValue.SetAsObject(const AValue: TObject);
begin
  ClearValue(jstObject);
  FValue.P:=AVAlue;
end;

procedure TJSValue.SetAsReference(const AValue: TObject);
begin
  ClearValue(jstReference);
  FValue.P:=AVAlue;
end;

procedure TJSValue.SetAsString(const AValue: TJSString);
begin
  ClearValue(jstString);
  String(FValue.P):=AValue;
end;

procedure TJSValue.SetIsNull(const AValue: Boolean);
begin
  ClearValue(jstNull);
end;

procedure TJSValue.SetIsUndefined(const AValue: Boolean);
begin
  ClearValue(jstUndefined);
end;

destructor TJSValue.Destroy;
begin
  ClearValue(jstUndefined);
  inherited Destroy;
end;


end.