1 // Copyright 2006-2009 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef V8_PARSING_FUNC_NAME_INFERRER_H_
6 #define V8_PARSING_FUNC_NAME_INFERRER_H_
7 
8 #include "src/handles.h"
9 #include "src/zone/zone.h"
10 
11 namespace v8 {
12 namespace internal {
13 
14 class AstRawString;
15 class AstString;
16 class AstValueFactory;
17 class FunctionLiteral;
18 
19 enum class InferName { kYes, kNo };
20 
21 // FuncNameInferrer is a stateful class that is used to perform name
22 // inference for anonymous functions during static analysis of source code.
23 // Inference is performed in cases when an anonymous function is assigned
24 // to a variable or a property (see test-func-name-inference.cc for examples.)
25 //
26 // The basic idea is that during parsing of LHSs of certain expressions
27 // (assignments, declarations, object literals) we collect name strings,
28 // and during parsing of the RHS, a function literal can be collected. After
29 // parsing the RHS we can infer a name for function literals that do not have
30 // a name.
31 class FuncNameInferrer : public ZoneObject {
32  public:
33   FuncNameInferrer(AstValueFactory* ast_value_factory, Zone* zone);
34 
35   // To enter function name inference state, put a FuncNameInferrer::State
36   // on the stack.
37   class State {
38    public:
State(FuncNameInferrer * fni)39     explicit State(FuncNameInferrer* fni) : fni_(fni) {
40       if (fni_ != nullptr) fni_->Enter();
41     }
~State()42     ~State() {
43       if (fni_ != nullptr) fni_->Leave();
44     }
45 
46    private:
47     FuncNameInferrer* fni_;
48 
49     DISALLOW_COPY_AND_ASSIGN(State);
50   };
51 
52   // Returns whether we have entered name collection state.
IsOpen()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(const AstRawString* name);
57 
58   // Pushes an encountered name onto names stack when in collection state.
59   void PushLiteralName(const AstRawString* name);
60 
61   void PushVariableName(const AstRawString* name);
62 
63   // Adds a function to infer name for.
AddFunction(FunctionLiteral * func_to_infer)64   void AddFunction(FunctionLiteral* func_to_infer) {
65     if (IsOpen()) {
66       funcs_to_infer_.Add(func_to_infer, zone());
67     }
68   }
69 
RemoveLastFunction()70   void RemoveLastFunction() {
71     if (IsOpen() && !funcs_to_infer_.is_empty()) {
72       funcs_to_infer_.RemoveLast();
73     }
74   }
75 
76   void RemoveAsyncKeywordFromEnd();
77 
78   // Infers a function name and leaves names collection state.
Infer()79   void Infer() {
80     DCHECK(IsOpen());
81     if (!funcs_to_infer_.is_empty()) {
82       InferFunctionsNames();
83     }
84   }
85 
86  private:
87   enum NameType {
88     kEnclosingConstructorName,
89     kLiteralName,
90     kVariableName
91   };
92   struct Name {
NameName93     Name(const AstRawString* name, NameType type) : name(name), type(type) {}
94     const AstRawString* name;
95     NameType type;
96   };
97 
Enter()98   void Enter() { entries_stack_.Add(names_stack_.length(), zone()); }
99 
Leave()100   void Leave() {
101     DCHECK(IsOpen());
102     names_stack_.Rewind(entries_stack_.RemoveLast());
103     if (entries_stack_.is_empty()) funcs_to_infer_.Clear();
104   }
105 
zone()106   Zone* zone() const { return zone_; }
107 
108   // Constructs a full name in dotted notation from gathered names.
109   const AstString* MakeNameFromStack();
110 
111   // A helper function for MakeNameFromStack.
112   const AstString* MakeNameFromStackHelper(int pos,
113                                                const AstString* prev);
114 
115   // Performs name inferring for added functions.
116   void InferFunctionsNames();
117 
118   AstValueFactory* ast_value_factory_;
119   ZoneList<int> entries_stack_;
120   ZoneList<Name> names_stack_;
121   ZoneList<FunctionLiteral*> funcs_to_infer_;
122   Zone* zone_;
123 
124   DISALLOW_COPY_AND_ASSIGN(FuncNameInferrer);
125 };
126 
127 
128 }  // namespace internal
129 }  // namespace v8
130 
131 #endif  // V8_PARSING_FUNC_NAME_INFERRER_H_
132