Better single stepping in VM debugger

runtime/vm/debugger.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_DEBUGGER_H_
 #define VM_DEBUGGER_H_
 
 #include "include/dart_debugger_api.h"
 
 #include "vm/object.h"
@@ skipping 248 matching lines @@
 
   // Set breakpoint at closest location to function entry.
   SourceBreakpoint* SetBreakpointAtEntry(const Function& target_function);
   SourceBreakpoint* SetBreakpointAtLine(const String& script_url,
                                         intptr_t line_number);
   void OneTimeBreakAtEntry(const Function& target_function);
 
   void RemoveBreakpoint(intptr_t bp_id);
   SourceBreakpoint* GetBreakpointById(intptr_t id);
 
-  void SetStepOver() { resume_action_ = kStepOver; }
-  void SetStepInto() { resume_action_ = kStepInto; }
-  void SetStepOut() { resume_action_ = kStepOut; }
+  void SetStepOver();
+  void SetSingleStep();
+  void SetStepOut();
+  bool IsStepping() const { return resume_action_ != kContinue; }
 
   void SetExceptionPauseInfo(Dart_ExceptionPauseInfo pause_info);
   Dart_ExceptionPauseInfo GetExceptionPauseInfo();
 
   void VisitObjectPointers(ObjectPointerVisitor* visitor);
 
   // Called from Runtime when a breakpoint in Dart code is reached.
   void BreakpointCallback();
 
   // Returns true if there is at least one breakpoint set in func.
   // Checks for both user-defined and internal temporary breakpoints.
   bool HasBreakpoint(const Function& func);
 
-  DebuggerStackTrace* StackTrace() const { return stack_trace_; }
+  DebuggerStackTrace* StackTrace();
 
   RawArray* GetInstanceFields(const Instance& obj);
   RawArray* GetStaticFields(const Class& cls);
   RawArray* GetLibraryFields(const Library& lib);
   RawArray* GetGlobalFields(const Library& lib);
 
   intptr_t CacheObject(const Object& obj);
   RawObject* GetCachedObject(intptr_t obj_id);
   bool IsValidObjectId(intptr_t obj_id);
 
   Dart_Port GetIsolateId() { return isolate_id_; }
 
   static void SetEventHandler(EventHandler* handler);
 
   // Utility functions.
   static const char* QualifiedFunctionName(const Function& func);
 
   RawObject* GetInstanceField(const Class& cls,
                               const String& field_name,
                               const Instance& object);
   RawObject* GetStaticField(const Class& cls,
                             const String& field_name);
 
   void SignalBpReached();
+  void SingleStepCallback();
+
   void SignalExceptionThrown(const Instance& exc);
   static void SignalIsolateEvent(EventType type);
 
   uword GetPatchedStubAddress(uword breakpoint_address);
 
  private:
   enum ResumeAction {
     kContinue,
     kStepOver,
-    kStepInto,
-    kStepOut
+    kStepOut,
+    kSingleStep
   };
 
   intptr_t ResolveBreakpointPos(const Function& func,
                                 intptr_t first_token_pos,
                                 intptr_t last_token_pos);
   void DeoptimizeWorld();
   void InstrumentForStepping(const Function& target_function);
   SourceBreakpoint* SetBreakpoint(const Function& target_function,
                                   intptr_t first_token_pos,
                                   intptr_t last_token_pos);
   void RemoveInternalBreakpoints();
   void UnlinkCodeBreakpoints(SourceBreakpoint* src_bpt);
   void RegisterSourceBreakpoint(SourceBreakpoint* bpt);
   void RegisterCodeBreakpoint(CodeBreakpoint* bpt);
   SourceBreakpoint* GetSourceBreakpoint(const Function& func,
                                         intptr_t token_pos);
   void MakeCodeBreakpointsAt(const Function& func,
                              intptr_t token_pos,
                              SourceBreakpoint* bpt);
   // Returns NULL if no breakpoint exists for the given address.
   CodeBreakpoint* GetCodeBreakpoint(uword breakpoint_address);
 
   void SyncBreakpoint(SourceBreakpoint* bpt);
 
+  ActivationFrame* TopDartFrame() const;
   static DebuggerStackTrace* CollectStackTrace();
   void SignalBpResolved(SourceBreakpoint *bpt);
+  void SignalPausedEvent(ActivationFrame* top_frame);
 
   bool IsDebuggable(const Function& func);
 
   intptr_t nextId() { return next_id_++; }
 
   bool ShouldPauseOnException(DebuggerStackTrace* stack_trace,
                               const Instance& exc);
 
   void CollectLibraryFields(const GrowableObjectArray& field_list,
                             const Library& lib,
@@ skipping 16 matching lines @@
   CodeBreakpoint* code_breakpoints_;
 
   // Tells debugger what to do when resuming execution after a breakpoint.
   ResumeAction resume_action_;
 
   // Do not call back to breakpoint handler if this flag is set.
   // Effectively this means ignoring breakpoints. Set when Dart code may
   // be run as a side effect of getting values of fields.
   bool ignore_breakpoints_;
 
+  // True while debugger calls event_handler_. Used to prevent recursive
+  // debugger events.
+  bool in_event_notification_;
+
   Dart_ExceptionPauseInfo exc_pause_info_;
 
-  static BreakpointHandler* bp_handler_;
   static EventHandler* event_handler_;
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_