// Copyright 2010 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
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//
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#ifndef V8_LIVEEDIT_H_
#define V8_LIVEEDIT_H_


// Live Edit feature implementation.
// User should be able to change script on already running VM. This feature
// matches hot swap features in other frameworks.
//
// The basic use-case is when user spots some mistake in function body
// from debugger and wishes to change the algorithm without restart.
//
// A single change always has a form of a simple replacement (in pseudo-code):
//   script.source[positions, positions+length] = new_string;
// Implementation first determines, which function's body includes this
// change area. Then both old and new versions of script are fully compiled
// in order to analyze, whether the function changed its outer scope
// expectations (or number of parameters). If it didn't, function's code is
// patched with a newly compiled code. If it did change, enclosing function
// gets patched. All inner functions are left untouched, whatever happened
// to them in a new script version. However, new version of code will
// instantiate newly compiled functions.


#include "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.
//
// The primary interest of the Tracker is to record function scope structures
// in order to analyze whether function code maybe safely patched (with new
// code successfully reading existing data from function scopes). The Tracker
// also collects compiled function codes.
class LiveEditFunctionTracker {
 public:
  explicit LiveEditFunctionTracker(FunctionLiteral* fun);
  ~LiveEditFunctionTracker();
  void RecordFunctionCode(Handle<Code> code);
  void RecordFunctionScope(Scope* scope);

  static bool IsActive();
};

#ifdef ENABLE_DEBUGGER_SUPPORT

class LiveEdit : AllStatic {
 public:
  static JSArray* GatherCompileInfo(Handle<Script> script,
                                    Handle<String> source);

  static void WrapSharedFunctionInfos(Handle<JSArray> array);

  static void ReplaceFunctionCode(Handle<JSArray> new_compile_info_array,
                                  Handle<JSArray> shared_info_array);

  static void RelinkFunctionToScript(Handle<JSArray> shared_info_array,
                                     Handle<Script> script_handle);

  static void PatchFunctionPositions(Handle<JSArray> shared_info_array,
                                     Handle<JSArray> position_change_array);

  // A copy of this is in liveedit-delay.js.
  enum FunctionPatchabilityStatus {
    FUNCTION_AVAILABLE_FOR_PATCH = 0,
    FUNCTION_BLOCKED_ON_STACK = 1
  };
};

#endif  // ENABLE_DEBUGGER_SUPPORT


} }  // namespace v8::internal

#endif /* V*_LIVEEDIT_H_ */