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1 // Copyright 2011 the V8 project authors. All rights reserved. | 1 // Copyright 2011 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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33 namespace v8 { | 33 namespace v8 { |
34 namespace internal { | 34 namespace internal { |
35 | 35 |
36 // The AST refers to variables via VariableProxies - placeholders for the actual | 36 // The AST refers to variables via VariableProxies - placeholders for the actual |
37 // variables. Variables themselves are never directly referred to from the AST, | 37 // variables. Variables themselves are never directly referred to from the AST, |
38 // they are maintained by scopes, and referred to from VariableProxies and Slots | 38 // they are maintained by scopes, and referred to from VariableProxies and Slots |
39 // after binding and variable allocation. | 39 // after binding and variable allocation. |
40 | 40 |
41 class Variable: public ZoneObject { | 41 class Variable: public ZoneObject { |
42 public: | 42 public: |
43 enum Mode { | |
44 // User declared variables: | |
45 VAR, // declared via 'var', and 'function' declarations | |
46 | |
47 CONST, // declared via 'const' declarations | |
48 | |
49 LET, // declared via 'let' declarations | |
50 | |
51 // Variables introduced by the compiler: | |
52 DYNAMIC, // always require dynamic lookup (we don't know | |
53 // the declaration) | |
54 | |
55 DYNAMIC_GLOBAL, // requires dynamic lookup, but we know that the | |
56 // variable is global unless it has been shadowed | |
57 // by an eval-introduced variable | |
58 | |
59 DYNAMIC_LOCAL, // requires dynamic lookup, but we know that the | |
60 // variable is local and where it is unless it | |
61 // has been shadowed by an eval-introduced | |
62 // variable | |
63 | |
64 INTERNAL, // like VAR, but not user-visible (may or may not | |
65 // be in a context) | |
66 | |
67 TEMPORARY // temporary variables (not user-visible), never | |
68 // in a context | |
69 }; | |
70 | |
71 enum Kind { | 43 enum Kind { |
72 NORMAL, | 44 NORMAL, |
73 THIS, | 45 THIS, |
74 ARGUMENTS | 46 ARGUMENTS |
75 }; | 47 }; |
76 | 48 |
77 enum Location { | 49 enum Location { |
78 // Before and during variable allocation, a variable whose location is | 50 // Before and during variable allocation, a variable whose location is |
79 // not yet determined. After allocation, a variable looked up as a | 51 // not yet determined. After allocation, a variable looked up as a |
80 // property on the global object (and possibly absent). name() is the | 52 // property on the global object (and possibly absent). name() is the |
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96 CONTEXT, | 68 CONTEXT, |
97 | 69 |
98 // A named slot in a heap context. name() is the variable name in the | 70 // A named slot in a heap context. name() is the variable name in the |
99 // context object on the heap, with lookup starting at the current | 71 // context object on the heap, with lookup starting at the current |
100 // context. index() is invalid. | 72 // context. index() is invalid. |
101 LOOKUP | 73 LOOKUP |
102 }; | 74 }; |
103 | 75 |
104 Variable(Scope* scope, | 76 Variable(Scope* scope, |
105 Handle<String> name, | 77 Handle<String> name, |
106 Mode mode, | 78 VariableMode mode, |
107 bool is_valid_lhs, | 79 bool is_valid_lhs, |
108 Kind kind); | 80 Kind kind); |
109 | 81 |
110 // Printing support | 82 // Printing support |
111 static const char* Mode2String(Mode mode); | 83 static const char* Mode2String(VariableMode mode); |
112 | 84 |
113 bool IsValidLeftHandSide() { return is_valid_LHS_; } | 85 bool IsValidLeftHandSide() { return is_valid_LHS_; } |
114 | 86 |
115 // The source code for an eval() call may refer to a variable that is | 87 // The source code for an eval() call may refer to a variable that is |
116 // in an outer scope about which we don't know anything (it may not | 88 // in an outer scope about which we don't know anything (it may not |
117 // be the global scope). scope() is NULL in that case. Currently the | 89 // be the global scope). scope() is NULL in that case. Currently the |
118 // scope is only used to follow the context chain length. | 90 // scope is only used to follow the context chain length. |
119 Scope* scope() const { return scope_; } | 91 Scope* scope() const { return scope_; } |
120 | 92 |
121 Handle<String> name() const { return name_; } | 93 Handle<String> name() const { return name_; } |
122 Mode mode() const { return mode_; } | 94 VariableMode mode() const { return mode_; } |
123 bool is_accessed_from_inner_scope() const { | 95 bool is_accessed_from_inner_scope() const { |
124 return is_accessed_from_inner_scope_; | 96 return is_accessed_from_inner_scope_; |
125 } | 97 } |
126 void MarkAsAccessedFromInnerScope() { | 98 void MarkAsAccessedFromInnerScope() { |
127 ASSERT(mode_ != TEMPORARY); | 99 ASSERT(mode_ != TEMPORARY); |
128 is_accessed_from_inner_scope_ = true; | 100 is_accessed_from_inner_scope_ = true; |
129 } | 101 } |
130 bool is_used() { return is_used_; } | 102 bool is_used() { return is_used_; } |
131 void set_is_used(bool flag) { is_used_ = flag; } | 103 void set_is_used(bool flag) { is_used_ = flag; } |
132 | 104 |
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170 int index() const { return index_; } | 142 int index() const { return index_; } |
171 | 143 |
172 void AllocateTo(Location location, int index) { | 144 void AllocateTo(Location location, int index) { |
173 location_ = location; | 145 location_ = location; |
174 index_ = index; | 146 index_ = index; |
175 } | 147 } |
176 | 148 |
177 private: | 149 private: |
178 Scope* scope_; | 150 Scope* scope_; |
179 Handle<String> name_; | 151 Handle<String> name_; |
180 Mode mode_; | 152 VariableMode mode_; |
181 Kind kind_; | 153 Kind kind_; |
182 Location location_; | 154 Location location_; |
183 int index_; | 155 int index_; |
184 | 156 |
185 Variable* local_if_not_shadowed_; | 157 Variable* local_if_not_shadowed_; |
186 | 158 |
187 // Valid as a LHS? (const and this are not valid LHS, for example) | 159 // Valid as a LHS? (const and this are not valid LHS, for example) |
188 bool is_valid_LHS_; | 160 bool is_valid_LHS_; |
189 | 161 |
190 // Usage info. | 162 // Usage info. |
191 bool is_accessed_from_inner_scope_; // set by variable resolver | 163 bool is_accessed_from_inner_scope_; // set by variable resolver |
192 bool is_used_; | 164 bool is_used_; |
193 }; | 165 }; |
194 | 166 |
195 | 167 |
196 } } // namespace v8::internal | 168 } } // namespace v8::internal |
197 | 169 |
198 #endif // V8_VARIABLES_H_ | 170 #endif // V8_VARIABLES_H_ |
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