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_FUNC_NAME_INFERRER_H_
6 #define V8_FUNC_NAME_INFERRER_H_
7 
8 #include "src/handles.h"
9 #include "src/zone.h"
10 
11 namespace v8 {
12 namespace internal {
13 
14 class AstRawString;
15 class AstString;
16 class AstValueFactory;
17 class FunctionLiteral;
18 
19 // FuncNameInferrer is a stateful class that is used to perform name
20 // inference for anonymous functions during static analysis of source code.
21 // Inference is performed in cases when an anonymous function is assigned
22 // to a variable or a property (see test-func-name-inference.cc for examples.)
23 //
24 // The basic idea is that during parsing of LHSs of certain expressions
25 // (assignments, declarations, object literals) we collect name strings,
26 // and during parsing of the RHS, a function literal can be collected. After
27 // parsing the RHS we can infer a name for function literals that do not have
28 // a name.
29 class FuncNameInferrer : public ZoneObject {
30  public:
31   FuncNameInferrer(AstValueFactory* ast_value_factory, Zone* zone);
32 
33   // Returns whether we have entered name collection state.
IsOpen()34   bool IsOpen() const { return !entries_stack_.is_empty(); }
35 
36   // Pushes an enclosing the name of enclosing function onto names stack.
37   void PushEnclosingName(const AstRawString* name);
38 
39   // Enters name collection state.
Enter()40   void Enter() {
41     entries_stack_.Add(names_stack_.length(), zone());
42   }
43 
44   // Pushes an encountered name onto names stack when in collection state.
45   void PushLiteralName(const AstRawString* name);
46 
47   void PushVariableName(const AstRawString* name);
48 
49   // Adds a function to infer name for.
AddFunction(FunctionLiteral * func_to_infer)50   void AddFunction(FunctionLiteral* func_to_infer) {
51     if (IsOpen()) {
52       funcs_to_infer_.Add(func_to_infer, zone());
53     }
54   }
55 
RemoveLastFunction()56   void RemoveLastFunction() {
57     if (IsOpen() && !funcs_to_infer_.is_empty()) {
58       funcs_to_infer_.RemoveLast();
59     }
60   }
61 
62   // Infers a function name and leaves names collection state.
Infer()63   void Infer() {
64     DCHECK(IsOpen());
65     if (!funcs_to_infer_.is_empty()) {
66       InferFunctionsNames();
67     }
68   }
69 
70   // Leaves names collection state.
Leave()71   void Leave() {
72     DCHECK(IsOpen());
73     names_stack_.Rewind(entries_stack_.RemoveLast());
74     if (entries_stack_.is_empty())
75       funcs_to_infer_.Clear();
76   }
77 
78  private:
79   enum NameType {
80     kEnclosingConstructorName,
81     kLiteralName,
82     kVariableName
83   };
84   struct Name {
NameName85     Name(const AstRawString* name, NameType type) : name(name), type(type) {}
86     const AstRawString* name;
87     NameType type;
88   };
89 
zone()90   Zone* zone() const { return zone_; }
91 
92   // Constructs a full name in dotted notation from gathered names.
93   const AstString* MakeNameFromStack();
94 
95   // A helper function for MakeNameFromStack.
96   const AstString* MakeNameFromStackHelper(int pos,
97                                                const AstString* prev);
98 
99   // Performs name inferring for added functions.
100   void InferFunctionsNames();
101 
102   AstValueFactory* ast_value_factory_;
103   ZoneList<int> entries_stack_;
104   ZoneList<Name> names_stack_;
105   ZoneList<FunctionLiteral*> funcs_to_infer_;
106   Zone* zone_;
107 
108   DISALLOW_COPY_AND_ASSIGN(FuncNameInferrer);
109 };
110 
111 
112 } }  // namespace v8::internal
113 
114 #endif  // V8_FUNC_NAME_INFERRER_H_
115