Handle all debugger stepping with the isolate single step flag

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 344 matching lines @@
   // 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 DebuggerStepCallback();
 
   void SignalExceptionThrown(const Instance& exc);
   static void SignalIsolateEvent(EventType type);
 
   uword GetPatchedStubAddress(uword breakpoint_address);
 
   void PrintBreakpointsToJSONArray(JSONArray* jsarr) const;
 
   static bool IsDebuggable(const Function& func);
 
  private:
   enum ResumeAction {
     kContinue,
     kStepOver,
     kStepOut,
     kSingleStep
   };
 
   void FindEquivalentFunctions(const Script& script,
                                intptr_t start_pos,
                                intptr_t end_pos,
                                GrowableObjectArray* function_list);
   RawFunction* FindBestFit(const Script& script, intptr_t token_pos);
   RawFunction* FindInnermostClosure(const Function& function,
                                     intptr_t token_pos);
   intptr_t ResolveBreakpointPos(const Function& func,
                                 intptr_t requested_token_pos);
   void DeoptimizeWorld();
-  void InstrumentForStepping(const Function& target_function);
+  void SetInternalBreakpoints(const Function& target_function);
   SourceBreakpoint* SetBreakpoint(const Script& script, intptr_t token_pos);
   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 Script& script,
                                         intptr_t token_pos);
@@ skipping 59 matching lines @@
   // paused for breakpoints, isolate interruption, and (sometimes)
   // exceptions.
   DebuggerEvent* pause_event_;
 
   // An id -> object map.  Valid only while IsPaused().
   RemoteObjectCache* obj_cache_;
 
   // Current stack trace. Valid only while IsPaused().
   DebuggerStackTrace* stack_trace_;
 
+  // When stepping through code, only pause the program if the top
+  // frame corresponds to this fp value, or if the top frame is
+  // lower on the stack.
+  uword stepping_fp_;
+
   Dart_ExceptionPauseInfo exc_pause_info_;
 
   static EventHandler* event_handler_;
 
   friend class Isolate;
   friend class SourceBreakpoint;
   DISALLOW_COPY_AND_ASSIGN(Debugger);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DEBUGGER_H_