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      1 // Copyright 2006-2009 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_FUNC_NAME_INFERRER_H_
     29 #define V8_FUNC_NAME_INFERRER_H_
     30 
     31 namespace v8 {
     32 namespace internal {
     33 
     34 // FuncNameInferrer is a stateful class that is used to perform name
     35 // inference for anonymous functions during static analysis of source code.
     36 // Inference is performed in cases when an anonymous function is assigned
     37 // to a variable or a property (see test-func-name-inference.cc for examples.)
     38 //
     39 // The basic idea is that during AST traversal LHSs of expressions are
     40 // always visited before RHSs. Thus, during visiting the LHS, a name can be
     41 // collected, and during visiting the RHS, a function literal can be collected.
     42 // Inference is performed while leaving the assignment node.
     43 class FuncNameInferrer BASE_EMBEDDED {
     44  public:
     45   FuncNameInferrer()
     46       : entries_stack_(10),
     47         names_stack_(5),
     48         funcs_to_infer_(4),
     49         dot_(Factory::NewStringFromAscii(CStrVector("."))) {
     50   }
     51 
     52   // Returns whether we have entered name collection state.
     53   bool IsOpen() const { return !entries_stack_.is_empty(); }
     54 
     55   // Pushes an enclosing the name of enclosing function onto names stack.
     56   void PushEnclosingName(Handle<String> name);
     57 
     58   // Enters name collection state.
     59   void Enter() {
     60     entries_stack_.Add(names_stack_.length());
     61   }
     62 
     63   // Pushes an encountered name onto names stack when in collection state.
     64   void PushName(Handle<String> name) {
     65     if (IsOpen()) {
     66       names_stack_.Add(name);
     67     }
     68   }
     69 
     70   // Adds a function to infer name for.
     71   void AddFunction(FunctionLiteral* func_to_infer) {
     72     if (IsOpen()) {
     73       funcs_to_infer_.Add(func_to_infer);
     74     }
     75   }
     76 
     77   // Infers a function name and leaves names collection state.
     78   void InferAndLeave() {
     79     ASSERT(IsOpen());
     80     if (!funcs_to_infer_.is_empty()) {
     81       InferFunctionsNames();
     82     }
     83     names_stack_.Rewind(entries_stack_.RemoveLast());
     84   }
     85 
     86  private:
     87   // Constructs a full name in dotted notation from gathered names.
     88   Handle<String> MakeNameFromStack();
     89 
     90   // A helper function for MakeNameFromStack.
     91   Handle<String> MakeNameFromStackHelper(int pos, Handle<String> prev);
     92 
     93   // Performs name inferring for added functions.
     94   void InferFunctionsNames();
     95 
     96   ZoneList<int> entries_stack_;
     97   ZoneList<Handle<String> > names_stack_;
     98   ZoneList<FunctionLiteral*> funcs_to_infer_;
     99   Handle<String> dot_;
    100 
    101   DISALLOW_COPY_AND_ASSIGN(FuncNameInferrer);
    102 };
    103 
    104 
    105 // A wrapper class that automatically calls InferAndLeave when
    106 // leaving scope.
    107 class ScopedFuncNameInferrer BASE_EMBEDDED {
    108  public:
    109   explicit ScopedFuncNameInferrer(FuncNameInferrer* inferrer)
    110       : inferrer_(inferrer),
    111         is_entered_(false) {}
    112 
    113   ~ScopedFuncNameInferrer() {
    114     if (is_entered_) {
    115       inferrer_->InferAndLeave();
    116     }
    117   }
    118 
    119   // Triggers the wrapped inferrer into name collection state.
    120   void Enter() {
    121     inferrer_->Enter();
    122     is_entered_ = true;
    123   }
    124 
    125  private:
    126   FuncNameInferrer* inferrer_;
    127   bool is_entered_;
    128 
    129   DISALLOW_COPY_AND_ASSIGN(ScopedFuncNameInferrer);
    130 };
    131 
    132 
    133 } }  // namespace v8::internal
    134 
    135 #endif  // V8_FUNC_NAME_INFERRER_H_
    136