StepRequestor.java

package jetbrains.mps.debugger.java.runtime.engine.requests;

/*Generated by MPS */

import org.apache.log4j.Logger;
import org.apache.log4j.LogManager;
import jetbrains.mps.debug.api.IDebuggableFramesSelector;
import com.sun.jdi.ThreadReference;
import com.sun.jdi.StackFrame;
import com.sun.jdi.IncompatibleThreadStateException;
import com.sun.jdi.AbsentInformationException;
import com.sun.jdi.event.StepEvent;
import com.sun.jdi.request.StepRequest;
import org.jetbrains.annotations.NotNull;
import com.sun.jdi.Location;

public class StepRequestor implements Requestor {
  public static final int STOP = 0;
  private static final Logger LOG = LogManager.getLogger(StepRequestor.class);
  private final int myStepType;
  private String myDeclaringType;
  private int myLineNumber;
  private int myFrameCount;
  private String mySourceName;
  private final IDebuggableFramesSelector myFramesSelector;
  public StepRequestor(ThreadReference thread, int stepType, IDebuggableFramesSelector framesSelector) {
    myStepType = stepType;
    myFramesSelector = framesSelector;
    try {
      if (thread != null) {
        myFrameCount = thread.frameCount();
        StackFrame frame = thread.frame(0);
        if (frame != null) {
          myDeclaringType = frame.location().declaringType().name();
          myLineNumber = frame.location().lineNumber();
          mySourceName = frame.location().sourceName();
        }
      }
    } catch (IncompatibleThreadStateException e) {
      LOG.error(null, e);
    } catch (AbsentInformationException e) {
      LOG.error(null, e);
    }
  }
  public int nextStep(StepEvent event) {
    ThreadReference thread = event.thread();
    if (thread == null) {
      return defaultStepType();
    }
    try {
      if (thread.frameCount() == 0) {
        return defaultStepType();
      }
      StackFrame frame = thread.frame(0);
      return nextStep(thread, frame);
    } catch (IncompatibleThreadStateException e) {
      return defaultStepType();
    }
  }
  private int defaultStepType() {
    if (myStepType == StepRequest.STEP_OVER || myStepType == StepRequest.STEP_INTO) {
      return myStepType;
    }
    return STOP;
  }
  private int nextStep(@NotNull ThreadReference thread, @NotNull StackFrame frame) {
    // decides whether we need to step again; depends on whether our current line in generated java class has been changed. 
    if (myStepType == StepRequest.STEP_OVER || myStepType == StepRequest.STEP_INTO) {
      int frameCount = -1;
      Location location = frame.location();
      String sourceName = "";
      try {
        frameCount = thread.frameCount();
        sourceName = location.sourceName();
      } catch (IncompatibleThreadStateException e) {
        LOG.error(null, e);
      } catch (AbsentInformationException e) {
        LOG.error(null, e);
      }
      //  if we are not in debuggable position we step again 
      //  TODO this place may lead (and does lead) to bad performance (see MPS-8725) 
      if (!(sourceName.isEmpty()) && !(myFramesSelector.isDebuggablePosition(location.declaringType().name(), sourceName, location.lineNumber()))) {
        return myStepType;
      }
      boolean filesEqual = myDeclaringType.equals(location.declaringType().name());
      //  if we are on the same place we should step again 
      if (myFramesSelector.isSamePosition(myDeclaringType, mySourceName, myLineNumber, myFrameCount, location.declaringType().name(), sourceName, location.lineNumber(), frameCount)) {
        return myStepType;
      }
    }
    return STOP;
  }
}