// BaseFrameStream is an abstract base class for encapsulating the VM-side

// implementation of the StackWalker API.  There are two concrete subclasses:

// - JavaFrameStream:

//     -based on vframeStream; used in most instances

// - LiveFrameStream:

//     -based on javaVFrame; used for retrieving locals/monitors/operands for

//      LiveStackFrame

class BaseFrameStream : public StackObj {

protected:

  void fill_stackframe(Handle stackFrame, const methodHandle& method);

  BaseFrameStream(JavaThread* thread) : _thread(thread), _anchor(0L) {}

  virtual void    next()=0;

  virtual bool    at_end()=0;

  virtual Method* method()=0;

  virtual int     bci()=0;

  virtual void    fill_frame(int index, objArrayHandle  frames_array,

                             const methodHandle& method, TRAPS)=0;

  static BaseFrameStream* from_current(JavaThread* thread, jlong magic, objArrayHandle frames_array);

};

class JavaFrameStream : public BaseFrameStream {

private:

  vframeStream          _vfst;

  bool                  _need_method_info;

public:

  JavaFrameStream(JavaThread* thread, int mode);

  void next()      { _vfst.next();}

  bool at_end()    { return _vfst.at_end(); }

  Method* method() { return _vfst.method(); }

  int bci()        { return _vfst.bci(); }

  void fill_frame(int index, objArrayHandle  frames_array,

                  const methodHandle& method, TRAPS);

};

class LiveFrameStream : public BaseFrameStream {

private:

  javaVFrame*           _jvf;

  void fill_live_stackframe(Handle stackFrame, const methodHandle& method, TRAPS);

  static oop create_primitive_value_instance(StackValueCollection* values,

                                             int i, TRAPS);

  static objArrayHandle monitors_to_object_array(GrowableArray<MonitorInfo*>* monitors,

                                                 TRAPS);

  static objArrayHandle values_to_object_array(StackValueCollection* values, TRAPS);

public:

  LiveFrameStream(JavaThread* thread, RegisterMap* rm) : BaseFrameStream(thread) {

    _jvf = thread->last_java_vframe(rm);

  }

  void next()      { _jvf = _jvf->java_sender(); }

  bool at_end()    { return _jvf == NULL; }

  Method* method() { return _jvf->method(); }

  int bci()        { return _jvf->bci(); }

  void fill_frame(int index, objArrayHandle  frames_array,

                  const methodHandle& method, TRAPS);

  static int fill_in_frames(jlong mode, BaseFrameStream& stream,

  static inline bool need_method_info(int mode) {

    return (mode & JVM_STACKWALK_FILL_CLASS_REFS_ONLY) == 0;

  }

  static oop fetchFirstBatch(BaseFrameStream& stream, Handle stackStream,

                             jlong mode, int skip_frames, int frame_count,

                             int start_index, objArrayHandle frames_array, TRAPS);

  static jint fetchNextBatch(Handle stackStream, jlong mode, jlong magic,

                             int frame_count, int start_index,

                             objArrayHandle frames_array, TRAPS);