1 // Copyright 2011 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_VARIABLES_H_ 6 #define V8_VARIABLES_H_ 7 8 #include "src/ast-value-factory.h" 9 #include "src/interface.h" 10 #include "src/zone.h" 11 12 namespace v8 { 13 namespace internal { 14 15 // The AST refers to variables via VariableProxies - placeholders for the actual 16 // variables. Variables themselves are never directly referred to from the AST, 17 // they are maintained by scopes, and referred to from VariableProxies and Slots 18 // after binding and variable allocation. 19 20 class Variable: public ZoneObject { 21 public: 22 enum Kind { 23 NORMAL, 24 THIS, 25 ARGUMENTS 26 }; 27 28 enum Location { 29 // Before and during variable allocation, a variable whose location is 30 // not yet determined. After allocation, a variable looked up as a 31 // property on the global object (and possibly absent). name() is the 32 // variable name, index() is invalid. 33 UNALLOCATED, 34 35 // A slot in the parameter section on the stack. index() is the 36 // parameter index, counting left-to-right. The receiver is index -1; 37 // the first parameter is index 0. 38 PARAMETER, 39 40 // A slot in the local section on the stack. index() is the variable 41 // index in the stack frame, starting at 0. 42 LOCAL, 43 44 // An indexed slot in a heap context. index() is the variable index in 45 // the context object on the heap, starting at 0. scope() is the 46 // corresponding scope. 47 CONTEXT, 48 49 // A named slot in a heap context. name() is the variable name in the 50 // context object on the heap, with lookup starting at the current 51 // context. index() is invalid. 52 LOOKUP 53 }; 54 55 Variable(Scope* scope, const AstRawString* name, VariableMode mode, 56 bool is_valid_ref, Kind kind, InitializationFlag initialization_flag, 57 MaybeAssignedFlag maybe_assigned_flag = kNotAssigned, 58 Interface* interface = Interface::NewValue()); 59 60 // Printing support 61 static const char* Mode2String(VariableMode mode); 62 63 bool IsValidReference() { return is_valid_ref_; } 64 65 // The source code for an eval() call may refer to a variable that is 66 // in an outer scope about which we don't know anything (it may not 67 // be the global scope). scope() is NULL in that case. Currently the 68 // scope is only used to follow the context chain length. 69 Scope* scope() const { return scope_; } 70 71 Handle<String> name() const { return name_->string(); } 72 const AstRawString* raw_name() const { return name_; } 73 VariableMode mode() const { return mode_; } 74 bool has_forced_context_allocation() const { 75 return force_context_allocation_; 76 } 77 void ForceContextAllocation() { 78 DCHECK(mode_ != TEMPORARY); 79 force_context_allocation_ = true; 80 } 81 bool is_used() { return is_used_; } 82 void set_is_used() { is_used_ = true; } 83 MaybeAssignedFlag maybe_assigned() const { return maybe_assigned_; } 84 void set_maybe_assigned() { maybe_assigned_ = kMaybeAssigned; } 85 86 int initializer_position() { return initializer_position_; } 87 void set_initializer_position(int pos) { initializer_position_ = pos; } 88 89 bool IsVariable(Handle<String> n) const { 90 return !is_this() && name().is_identical_to(n); 91 } 92 93 bool IsUnallocated() const { return location_ == UNALLOCATED; } 94 bool IsParameter() const { return location_ == PARAMETER; } 95 bool IsStackLocal() const { return location_ == LOCAL; } 96 bool IsStackAllocated() const { return IsParameter() || IsStackLocal(); } 97 bool IsContextSlot() const { return location_ == CONTEXT; } 98 bool IsLookupSlot() const { return location_ == LOOKUP; } 99 bool IsGlobalObjectProperty() const; 100 101 bool is_dynamic() const { return IsDynamicVariableMode(mode_); } 102 bool is_const_mode() const { return IsImmutableVariableMode(mode_); } 103 bool binding_needs_init() const { 104 return initialization_flag_ == kNeedsInitialization; 105 } 106 107 bool is_this() const { return kind_ == THIS; } 108 bool is_arguments() const { return kind_ == ARGUMENTS; } 109 110 // True if the variable is named eval and not known to be shadowed. 111 bool is_possibly_eval(Isolate* isolate) const { 112 return IsVariable(isolate->factory()->eval_string()); 113 } 114 115 Variable* local_if_not_shadowed() const { 116 DCHECK(mode_ == DYNAMIC_LOCAL && local_if_not_shadowed_ != NULL); 117 return local_if_not_shadowed_; 118 } 119 120 void set_local_if_not_shadowed(Variable* local) { 121 local_if_not_shadowed_ = local; 122 } 123 124 Location location() const { return location_; } 125 int index() const { return index_; } 126 InitializationFlag initialization_flag() const { 127 return initialization_flag_; 128 } 129 Interface* interface() const { return interface_; } 130 131 void AllocateTo(Location location, int index) { 132 location_ = location; 133 index_ = index; 134 } 135 136 static int CompareIndex(Variable* const* v, Variable* const* w); 137 138 private: 139 Scope* scope_; 140 const AstRawString* name_; 141 VariableMode mode_; 142 Kind kind_; 143 Location location_; 144 int index_; 145 int initializer_position_; 146 147 // If this field is set, this variable references the stored locally bound 148 // variable, but it might be shadowed by variable bindings introduced by 149 // sloppy 'eval' calls between the reference scope (inclusive) and the 150 // binding scope (exclusive). 151 Variable* local_if_not_shadowed_; 152 153 // Valid as a reference? (const and this are not valid, for example) 154 bool is_valid_ref_; 155 156 // Usage info. 157 bool force_context_allocation_; // set by variable resolver 158 bool is_used_; 159 InitializationFlag initialization_flag_; 160 MaybeAssignedFlag maybe_assigned_; 161 162 // Module type info. 163 Interface* interface_; 164 }; 165 166 167 } } // namespace v8::internal 168 169 #endif // V8_VARIABLES_H_ 170
