[debugger] Refactor LiveEdit function info collection

src/debug/liveedit.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_DEBUG_LIVEEDIT_H_
 #define V8_DEBUG_LIVEEDIT_H_
 
 
 // Live Edit feature implementation.
 // User should be able to change script on already running VM. This feature
@@ skipping 14 matching lines @@
 // instantiate newly compiled functions.
 
 
 #include "src/allocation.h"
 #include "src/compiler.h"
 
 namespace v8 {
 namespace internal {
 
 // This class collects some specific information on structure of functions
-// in a particular script. It gets called from compiler all the time, but
-// actually records any data only when liveedit operation is in process;
-// in any other time this class is very cheap.
+// in a particular script.
 //
 // The primary interest of the Tracker is to record function scope structures
-// in order to analyze whether function code maybe safely patched (with new
+// in order to analyze whether function code may be safely patched (with new
 // code successfully reading existing data from function scopes). The Tracker
 // also collects compiled function codes.
-class LiveEditFunctionTracker {
+class LiveEditFunctionTracker : public AstTraversalVisitor {
  public:
-  explicit LiveEditFunctionTracker(Isolate* isolate, FunctionLiteral* fun);
-  ~LiveEditFunctionTracker();
-  void RecordFunctionInfo(Handle<SharedFunctionInfo> info,
-                          FunctionLiteral* lit, Zone* zone);
+  // Traverses the entire AST, and records information about all
+  // FunctionLiterals for further use by LiveEdit code patching. The collected
+  // information is returned as a serialized array.
+  static Handle<JSArray> Collect(FunctionLiteral* node, Handle<Script> script,
+                                 Zone* zone, Isolate* isolate);
 
-  static bool IsActive(Isolate* isolate);
+  virtual ~LiveEditFunctionTracker() {}
+  void VisitFunctionLiteral(FunctionLiteral* node) override;
 
  private:
+  LiveEditFunctionTracker(Handle<Script> script, Zone* zone, Isolate* isolate);
+
+  void FunctionStarted(FunctionLiteral* fun);
+  void FunctionDone(Handle<SharedFunctionInfo> shared, Scope* scope);
+  Handle<Object> SerializeFunctionScope(Scope* scope);
+
+  Handle<Script> script_;
+  Zone* zone_;
   Isolate* isolate_;
+
+  Handle<JSArray> result_;
+  int len_;
+  int current_parent_index_;
+
+  DISALLOW_COPY_AND_ASSIGN(LiveEditFunctionTracker);
 };
 
 
 class LiveEdit : AllStatic {
  public:
   // Describes how exactly a frame has been dropped from stack.
   enum FrameDropMode {
     // No frame has been dropped.
     FRAMES_UNTOUCHED,
     // The top JS frame had been calling debug break slot stub. Patch the
@@ skipping 292 matching lines @@
   static const int kSharedInfoOffset_ = 3;
   static const int kSize_ = 4;
 
   friend class JSArrayBasedStruct<SharedInfoWrapper>;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif /* V8_DEBUG_LIVEEDIT_H_ */