TPaxInvoke component for Delphi and Borland C++ Builder.

The TPaxInvoke component allows you to dynamically invoke both script-defined (created with paxCompiler) and host-defined methods and global functions. The supported calling conventions are: register (Borland fastcall), cdecl, stdcall, safecall, pascal and msfastcall (Microsoft fastcall).

Methods
Properties

The TPaxInvoke is a part of paxCompiler package, but you can also use it as a stand alone component to call any host-defined or dll-defined function. In particular, the component gives you a flexible way to invoke functions with msfastcall convention.

Demos.

Invoke a host-defined function.

type
  TCharRec = record
    X, Y: Char;
  end;

function MyHostFunc(const U, V: TCharRec): String; stdcall;
begin
  result := U.X + V.Y;
end;

var
  R: TCharRec;
  S: String;
begin
  R.X := 'a';
  R.Y := 'b';

  PaxInvoke1.Address := @ MyHostFunc;
  PaxInvoke1.This := nil; // this is not a method
  PaxInvoke1.ClearArguments;
  PaxInvoke1.AddArgAsRecord(R, SizeOf(R));
  PaxInvoke1.AddArgAsRecord(R, SizeOf(R));
  PaxInvoke1.SetResultAsAnsiString;
  PaxInvoke1.CallConv := _ccSTDCALL;
  PaxInvoke1.CallHost; // call host-defined function
  S := String(PaxInvoke1.GetResultPtr^);
  ShowMessage(S);

  PaxInvoke1.ClearResult;

Invoke a host-defined method.

function TForm1.MyHostMethod(const X, Y: ShortString; Z: Integer): String;
begin
  result := X + Y + IntToStr(Z);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  PaxInvoke1.Address := @ TForm1.MyHostMethod;
  PaxInvoke1.This := Self; // we call a method
  PaxInvoke1.ClearArguments;
  PaxInvoke1.AddArgAsShortString('xyz');
  PaxInvoke1.AddArgAsShortString('uv');
  PaxInvoke1.AddArgAsInteger(8);
  PaxInvoke1.SetResultAsAnsiString;
  PaxInvoke1.CallConv := _ccREGISTER;
  PaxInvoke1.CallHost; 
  ShowMessage(String(PaxInvoke1.GetResultPtr^));

  PaxInvoke1.ClearResult;
end;

Invoke a dll-defined function.

// Point  __msfastcall ret_struct(int x, int y, int z);

type
  TMyPoint = record
    x, y, z: Integer;
  end;
var
  r: TMyPoint;
begin
  PaxInvoke1.This := nil; // this is not a method
  PaxInvoke1.CallConv := _ccMSFASTCALL;

  PaxInvoke1.LoadAddress('CppDll.dll', 'ret_struct');
  PaxInvoke1.ClearArguments;
  PaxInvoke1.AddArgAsInteger(2);
  PaxInvoke1.AddArgAsInteger(3);
  PaxInvoke1.AddArgAsInteger(5);
  PaxInvoke1.SetResultAsRecord(SizeOf(TMyPoint));
  PaxInvoke1.CallHost; // call dll-defined function
  r := TMyPoint(PaxInvoke1.GetResultPtr^);
  ShowMessage(IntToStr(r.x) + ' ' + IntToStr(r.y) + ' ' + IntToStr(r.z));
end;

Invoke a script-defined function.

uses
  IMPORT_SysUtils;

procedure Print(const S: String);
begin
  ShowMessage(S);
end;

var
  H_MyFunc: Integer;
  I: Integer;
  P: Pointer;
begin
{$O-}
  PaxCompiler1.Reset;
  PaxCompiler1.RegisterLanguage(PaxPascalLanguage1);
  PaxCompiler1.RegisterHeader(0, 'procedure Print(const S: String);', @Print);

  PaxCompiler1.AddModule('1', PaxPascalLanguage1.LanguageName);
  PaxCompiler1.AddCode('1', 'uses SysUtils;');
  PaxCompiler1.AddCode('1', 'function MyFunc(U, V: Integer): Currency; cdecl;');
  PaxCompiler1.AddCode('1', 'begin');
  PaxCompiler1.AddCode('1', '  try');
  PaxCompiler1.AddCode('1', '    result := U / V;');
  PaxCompiler1.AddCode('1', '  except');
  PaxCompiler1.AddCode('1', '    on E: Exception do');
  PaxCompiler1.AddCode('1', '    begin');
  PaxCompiler1.AddCode('1', '      print(E.Message);');
  PaxCompiler1.AddCode('1', '      result := 7;');
  PaxCompiler1.AddCode('1', '    end;');
  PaxCompiler1.AddCode('1', '  end;');
  PaxCompiler1.AddCode('1', 'end;');
  PaxCompiler1.AddCode('1', 'begin');
  PaxCompiler1.AddCode('1', 'end.');

  if PaxCompiler1.Compile(PaxProgram1) then
  begin
    H_MyFunc := PaxCompiler1.GetHandle(0, 'MyFunc', true);

    P := PaxProgram1.GetAddress(H_MyFunc); // get address of script-defined function

    PaxInvoke1.Address := P;
    PaxInvoke1.This := nil; // this is not a method, but global function.
    PaxInvoke1.ClearArguments;
    PaxInvoke1.AddArgAsInteger(8);
    PaxInvoke1.AddArgAsInteger(2); 
    PaxInvoke1.SetResultAsCurrency;
    PaxInvoke1.CallConv := _ccCDECL;

    PaxProgram1.SetEntryPoint(PaxInvoke1);
    PaxProgram1.Run;

    ShowMessage(CurrToStr(Currency(PaxInvoke1.GetResultPtr^)));
  end
  else
    for I:=0 to PaxCompiler1.ErrorCount do
      ShowMessage(PaxCompiler1.ErrorMessage[I]);
end;