Chip 2000 February/Chip_2000-02_cd.bin/zkuste/Delphi/navody/tt/objvm.exe/UNITS/LangValue.pas

Pascal/Delphi Source File | 1998-06-27 | 6KB | 152 lines

{contains TLangValue - Value for macro language}
unit LangValue;
interface
uses
    LangValMessages,Classes;

type ILangValue=class;
       {IValueOwner is interface of something that can contain ILangValue }
     IValueOwner=class(TComponent)
     public
       procedure AddValue(const s:string;Value:ILangValue);virtual;abstract;
       procedure RemoveValue(Value:ILangValue);virtual;abstract;
     end;
       {IValStack is an interface to stack of ILangValue. Implementaton }
       {see in ValStack unit }
     IValStack=class
     protected
       function rdFrameValues(No:integer):ILangValue;virtual;abstract;
     public
           {Pops a value from top of stack}
       function Pop:ILangValue;virtual;abstract;
           {Pushes a value to stack}
       procedure Push(a:ILangValue);virtual;abstract;
           {Removes a procedure call frame from top of stack}
       procedure DropFrame;virtual;abstract;
           {Provides access to topmost frame values}
       property  FrameValues[No:Integer]:ILangValue read rdFrameValues;
           {Counts values in frame}
       function  FrameCount:integer;virtual;abstract;
    end;
       {ILangValue is a class providing all language objects functionality.  }
       {Variables,Values,Procedures,Objects are implementation of ILangValue.}
       {}
     ILangValue=class(IValueOwner)
     protected
        function rdAsString:string;virtual;
        procedure wrAsString(a:string);virtual;
        function rdAsInteger:integer;virtual;
        procedure wrAsInteger(a:integer);virtual;
        function rdAsBoolean:boolean;virtual;
        procedure wrAsBoolean(a:boolean);virtual;
        function rdAsVariant:variant;virtual;
        procedure wrAsVariant(a:variant);virtual;
        function rdAsFloat:Extended;virtual;
        procedure wrAsFloat(a:Extended);virtual;
        function  rdValues(const s:string):ILangValue;virtual;
     public
          {Returns integer representation of ILangValue if posible otherwise raises exception}
        property AsInteger:Integer read rdAsInteger write wrAsInteger;
          {Returns string representation of ILangValue if posible otherwise raises exception}
        property AsString:STring read rdAsSTring write wrAsString;
          {Returns boolean representation of ILangValue if posible otherwise raises exception}
        property AsBoolean:Boolean read rdAsBoolean write wrAsBoolean;
          {Returns Variant representation of ILangValue if posible otherwise raises exception}
        property AsVariant:Variant read rdAsVariant write wrAsVariant;
          {Returns float representation of ILangValue if posible otherwise raises exception}
        property AsFloat:Extended read rdAsFloat write wrAsFloat;
           {Execute value on given stack. if MustReturn is set to true }
           {method have to leave one value to stack. It is expected that }
           {Exec clears stack by DropFrame method. }
        procedure Exec(S:IValStack;MustReturn:boolean);virtual;
           {If this value has value named s returns true.}
        function  HasValue(const s:string):boolean;virtual;
           {Accessor for holded values}
        property  Values[const s:string]:ILangValue read rdValues;
            {Creates value equal to itself }
        function  CreateEqu:ILangValue;virtual;abstract;
            {Returns value placed inside. For example for variable}
        function  GetValue:ILangValue;
            {Sets value to given }
        procedure SetValue(a:ILangValue);
     end;
implementation
uses ValStack,VarLangValue;
function  ILangValue.rdAsString;
          begin
            CantBeString;
          end;
procedure ILangValue.wrAsString;
          begin
            CantBeString;
          end;
function  ILangValue.rdAsInteger;
          begin
            CantBeInteger;
          end;
procedure ILangValue.wrAsInteger;
          begin
            CantBeInteger;
          end;
function  ILangValue.rdAsBoolean;
          begin
            CantBeBoolean;
          end;
procedure ILangValue.wrAsBoolean;
          begin
            CantBeBoolean;
          end;
function  ILangValue.rdAsVariant;
          begin
            CantBeVariant;
          end;
procedure ILangValue.wrAsVariant;
          begin
            CantBeVariant;
          end;
function  ILangValue.rdAsFloat;
          begin
            CantBeFloat;
          end;
procedure ILangValue.wrAsFloat;
          begin
            CantBeFloat;
          end;
function  ILangValue.rdValues;
          begin
            ContainsNoValues;
          end;
procedure ILangValue.Exec;
          begin
            NotExecutable;
          end;
function  ILangValue.HasValue;
          begin
            Result:=false;
          end;
function  ILangValue.GetValue;
          Var s:TValStack;
              v:TVarLangValue;
          begin
            v:=TVarLangValue.Create(nil);            v.AsInteger:=0;
            s:=TValStack.Create;
            s.Push(v);
            Exec(s,true);
            Result:=s.Pop;
            s.Free;
          end;
procedure ILangValue.SetValue;
          Var s:TValStack;
              v:TVarLangValue;
          begin
            v:=TVarLangValue.Create(nil);
            v.AsInteger:=1;
            s:=TValStack.Create;
            s.Push(a);
            s.Push(v);
            Exec(s,false);
            s.Free;
          end;

end.