有两种方法在执行DWScript时保留变量值吗？

Question

我正在处理的应用程序允许将脚本sinppets嵌入到文档中.例如:

SomeText
<* PrintLn("This line is generated by a script"); *>
Some other text
<* PrintLn("This line is generated by a script, too"); *>
Some more lines

结果

SomeText
This line is generated by a script
Some other text
This line is generated by a script, too
Some more lines

我正在使用DWScript.在内部编译和执行第一个脚本片段.比下一个是RecompiledInContext并执行等等.在片段中声明的函数/变量/ etc在所有后续片段中都可用.但是,片段之间的变量值会丢失.例如:

SomeText
<* var x: Integer = 5; *>
Some other text
<* PrintLn(x); *>
Some more lines

生成文档后:

SomeText
Some other text
0  <-- I would like this to be 5
Some more lines

这是一个说明问题的示例应用程序:

program POC.Variable;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  dwsExprs,
  dwsComp,
  dwsCompiler; 

var
  FDelphiWebScript: TDelphiWebScript;
  FProgram: IdwsProgram;
  FExecutionResult: IdwsProgramExecution;

begin
  FDelphiWebScript := TDelphiWebScript.Create(nil);
  try
    FProgram := FDelphiWebScript.Compile('var x: Integer = 2;');
    FProgram.Execute;

    FDelphiWebScript.RecompileInContext(FProgram, 'PrintLn(x);');

    FExecutionResult := FProgram.Execute;
    // The next line fails, Result[1] is '0'
    Assert(FExecutionResult.Result.ToString[1] = '2');
  finally
    FDelphiWebScript.Free;
  end
end.

有没有办法在执行之间"转移"或"保留"变量值？

这是Andrew的答案的更新代码,它不起作用:

begin
  FDelphiWebScript := TDelphiWebScript.Create(nil);
  try
    FProgram := FDelphiWebScript.Compile('PrintLn("Hello");');

    FExecution:= FProgram.BeginNewExecution();

    FDelphiWebScript.RecompileInContext(FProgram, 'var x: Integer;');
    FExecution.RunProgram(0);
    WriteLn('Compile Result:');
    WriteLn(FExecution.Result.ToString);

    FDelphiWebScript.RecompileInContext(FProgram, 'x := 2; PrintLn(x);');
    FExecution.RunProgram(0); // <-- Access violation
    WriteLn('Compile Result:');
    WriteLn(FExecution.Result.ToString);

    FExecution.EndProgram();
    ReadLn;
  finally
    FDelphiWebScript.Free;
  end
end;

Answer 1

您可以尝试使用BeginNewExecution/ RunProgram/ EndProgram阻塞(在DWScript 2.2上测试):

begin
  FDelphiWebScript := TDelphiWebScript.Create(nil);
  try
    FProgram := FDelphiWebScript.Compile('var x: Integer;');

    FExecution:= FProgram.BeginNewExecution();

    FDelphiWebScript.RecompileInContext(FProgram, 'x := 2; PrintLn(x);');
    FExecution.RunProgram(0);
    WriteLn('Compile Result:');
    WriteLn(FExecution.Result.ToString);

    FDelphiWebScript.RecompileInContext(FProgram, 'x := x + 3; PrintLn(x);');
    FExecution.RunProgram(0);
    WriteLn('Recompile Result: ');
    WriteLn(FExecution.Result.ToString);

    FExecution.EndProgram();

    ReadLn;
  finally
    FDelphiWebScript.Free;
  end
end.

Answer 2

问题是，当 RecompileInContext() 添加新的全局变量时，它们没有分配空间，因为空间分配是由 BeginNewExecution 执行的，但如果变量预先存在，或者如果在函数中添加新变量，那么它应该可以工作是局部变量，而不是全局变量）。

因此，如果您将“更新的代码”更改为类似这样的内容，它将起作用

FProgram := DelphiWebScript1.Compile( 'PrintLn("Hello");'
                                     +'var x: Integer;');

FExecution:= FProgram.BeginNewExecution();

FExecution.RunProgram(0);
SynEdit1.Lines.Add('Compile Result:');
SynEdit1.Lines.Add(FExecution.Result.ToString);

DelphiWebScript1.RecompileInContext(FProgram, 'x := 2; PrintLn(x);');
FExecution.RunProgram(0); // <-- Access violation
SynEdit1.Lines.Add('Compile Result:');
SynEdit1.Lines.Add(FExecution.Result.ToString);

FExecution.EndProgram();

编辑：现在已由DWScript SVN中的 r1513 修复。