1 // Copyright 2011 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_VARIABLES_H_ 29 #define V8_VARIABLES_H_ 30 31 #include "zone.h" 32 #include "interface.h" 33 34 namespace v8 { 35 namespace internal { 36 37 // The AST refers to variables via VariableProxies - placeholders for the actual 38 // variables. Variables themselves are never directly referred to from the AST, 39 // they are maintained by scopes, and referred to from VariableProxies and Slots 40 // after binding and variable allocation. 41 42 class Variable: public ZoneObject { 43 public: 44 enum Kind { 45 NORMAL, 46 THIS, 47 ARGUMENTS 48 }; 49 50 enum Location { 51 // Before and during variable allocation, a variable whose location is 52 // not yet determined. After allocation, a variable looked up as a 53 // property on the global object (and possibly absent). name() is the 54 // variable name, index() is invalid. 55 UNALLOCATED, 56 57 // A slot in the parameter section on the stack. index() is the 58 // parameter index, counting left-to-right. The receiver is index -1; 59 // the first parameter is index 0. 60 PARAMETER, 61 62 // A slot in the local section on the stack. index() is the variable 63 // index in the stack frame, starting at 0. 64 LOCAL, 65 66 // An indexed slot in a heap context. index() is the variable index in 67 // the context object on the heap, starting at 0. scope() is the 68 // corresponding scope. 69 CONTEXT, 70 71 // A named slot in a heap context. name() is the variable name in the 72 // context object on the heap, with lookup starting at the current 73 // context. index() is invalid. 74 LOOKUP 75 }; 76 77 Variable(Scope* scope, 78 Handle<String> name, 79 VariableMode mode, 80 bool is_valid_lhs, 81 Kind kind, 82 InitializationFlag initialization_flag, 83 Interface* interface = Interface::NewValue()); 84 85 // Printing support 86 static const char* Mode2String(VariableMode mode); 87 88 bool IsValidLeftHandSide() { return is_valid_LHS_; } 89 90 // The source code for an eval() call may refer to a variable that is 91 // in an outer scope about which we don't know anything (it may not 92 // be the global scope). scope() is NULL in that case. Currently the 93 // scope is only used to follow the context chain length. 94 Scope* scope() const { return scope_; } 95 96 Handle<String> name() const { return name_; } 97 VariableMode mode() const { return mode_; } 98 bool has_forced_context_allocation() const { 99 return force_context_allocation_; 100 } 101 void ForceContextAllocation() { 102 ASSERT(mode_ != TEMPORARY); 103 force_context_allocation_ = true; 104 } 105 bool is_used() { return is_used_; } 106 void set_is_used(bool flag) { is_used_ = flag; } 107 108 int initializer_position() { return initializer_position_; } 109 void set_initializer_position(int pos) { initializer_position_ = pos; } 110 111 bool IsVariable(Handle<String> n) const { 112 return !is_this() && name().is_identical_to(n); 113 } 114 115 bool IsUnallocated() const { return location_ == UNALLOCATED; } 116 bool IsParameter() const { return location_ == PARAMETER; } 117 bool IsStackLocal() const { return location_ == LOCAL; } 118 bool IsStackAllocated() const { return IsParameter() || IsStackLocal(); } 119 bool IsContextSlot() const { return location_ == CONTEXT; } 120 bool IsLookupSlot() const { return location_ == LOOKUP; } 121 bool IsGlobalObjectProperty() const; 122 123 bool is_dynamic() const { return IsDynamicVariableMode(mode_); } 124 bool is_const_mode() const { return IsImmutableVariableMode(mode_); } 125 bool binding_needs_init() const { 126 return initialization_flag_ == kNeedsInitialization; 127 } 128 129 bool is_this() const { return kind_ == THIS; } 130 bool is_arguments() const { return kind_ == ARGUMENTS; } 131 132 // True if the variable is named eval and not known to be shadowed. 133 bool is_possibly_eval(Isolate* isolate) const { 134 return IsVariable(isolate->factory()->eval_string()); 135 } 136 137 Variable* local_if_not_shadowed() const { 138 ASSERT(mode_ == DYNAMIC_LOCAL && local_if_not_shadowed_ != NULL); 139 return local_if_not_shadowed_; 140 } 141 142 void set_local_if_not_shadowed(Variable* local) { 143 local_if_not_shadowed_ = local; 144 } 145 146 Location location() const { return location_; } 147 int index() const { return index_; } 148 InitializationFlag initialization_flag() const { 149 return initialization_flag_; 150 } 151 Interface* interface() const { return interface_; } 152 153 void AllocateTo(Location location, int index) { 154 location_ = location; 155 index_ = index; 156 } 157 158 static int CompareIndex(Variable* const* v, Variable* const* w); 159 160 private: 161 Scope* scope_; 162 Handle<String> name_; 163 VariableMode mode_; 164 Kind kind_; 165 Location location_; 166 int index_; 167 int initializer_position_; 168 169 // If this field is set, this variable references the stored locally bound 170 // variable, but it might be shadowed by variable bindings introduced by 171 // non-strict 'eval' calls between the reference scope (inclusive) and the 172 // binding scope (exclusive). 173 Variable* local_if_not_shadowed_; 174 175 // Valid as a LHS? (const and this are not valid LHS, for example) 176 bool is_valid_LHS_; 177 178 // Usage info. 179 bool force_context_allocation_; // set by variable resolver 180 bool is_used_; 181 InitializationFlag initialization_flag_; 182 183 // Module type info. 184 Interface* interface_; 185 }; 186 187 188 } } // namespace v8::internal 189 190 #endif // V8_VARIABLES_H_ 191
