v8/src/func-name-inferrer.h

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#ifndef V8_FUNC_NAME_INFERRER_H_
#define V8_FUNC_NAME_INFERRER_H_

namespace v8 {
namespace internal {

// FuncNameInferrer is a stateful class that is used to perform name
// inference for anonymous functions during static analysis of source code.
// Inference is performed in cases when an anonymous function is assigned
// to a variable or a property (see test-func-name-inference.cc for examples.)
//
// The basic idea is that during AST traversal LHSs of expressions are
// always visited before RHSs. Thus, during visiting the LHS, a name can be
// collected, and during visiting the RHS, a function literal can be collected.
// Inference is performed while leaving the assignment node.
class FuncNameInferrer BASE_EMBEDDED {
 public:
  FuncNameInferrer()
      : entries_stack_(10),
        names_stack_(5),
        funcs_to_infer_(4),
        dot_(Factory::NewStringFromAscii(CStrVector("."))) {
  }

  // Returns whether we have entered name collection state.
  bool IsOpen() const { return !entries_stack_.is_empty(); }

  // Pushes an enclosing the name of enclosing function onto names stack.
  void PushEnclosingName(Handle<String> name);

  // Enters name collection state.
  void Enter() {
    entries_stack_.Add(names_stack_.length());
  }

  // Pushes an encountered name onto names stack when in collection state.
  void PushName(Handle<String> name) {
    if (IsOpen()) {
      names_stack_.Add(name);
    }
  }

  // Adds a function to infer name for.
  void AddFunction(FunctionLiteral* func_to_infer) {
    if (IsOpen()) {
      funcs_to_infer_.Add(func_to_infer);
    }
  }

  // Infers a function name and leaves names collection state.
  void InferAndLeave() {
    ASSERT(IsOpen());
    if (!funcs_to_infer_.is_empty()) {
      InferFunctionsNames();
    }
    names_stack_.Rewind(entries_stack_.RemoveLast());
  }

 private:
  // Constructs a full name in dotted notation from gathered names.
  Handle<String> MakeNameFromStack();

  // A helper function for MakeNameFromStack.
  Handle<String> MakeNameFromStackHelper(int pos, Handle<String> prev);

  // Performs name inferring for added functions.
  void InferFunctionsNames();

  ZoneList<int> entries_stack_;
  ZoneList<Handle<String> > names_stack_;
  ZoneList<FunctionLiteral*> funcs_to_infer_;
  Handle<String> dot_;

  DISALLOW_COPY_AND_ASSIGN(FuncNameInferrer);
};


// A wrapper class that automatically calls InferAndLeave when
// leaving scope.
class ScopedFuncNameInferrer BASE_EMBEDDED {
 public:
  explicit ScopedFuncNameInferrer(FuncNameInferrer* inferrer)
      : inferrer_(inferrer),
        is_entered_(false) {}

  ~ScopedFuncNameInferrer() {
    if (is_entered_) {
      inferrer_->InferAndLeave();
    }
  }

  // Triggers the wrapped inferrer into name collection state.
  void Enter() {
    inferrer_->Enter();
    is_entered_ = true;
  }

 private:
  FuncNameInferrer* inferrer_;
  bool is_entered_;

  DISALLOW_COPY_AND_ASSIGN(ScopedFuncNameInferrer);
};


} }  // namespace v8::internal

#endif  // V8_FUNC_NAME_INFERRER_H_