Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 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_AST_VARIABLES_H_ |
| 6 | #define V8_AST_VARIABLES_H_ |
| 7 | |
| 8 | #include "src/ast/ast-value-factory.h" |
| 9 | #include "src/zone.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | // The AST refers to variables via VariableProxies - placeholders for the actual |
| 15 | // variables. Variables themselves are never directly referred to from the AST, |
| 16 | // they are maintained by scopes, and referred to from VariableProxies and Slots |
| 17 | // after binding and variable allocation. |
| 18 | |
| 19 | class ClassVariable; |
| 20 | |
| 21 | class Variable: public ZoneObject { |
| 22 | public: |
| 23 | enum Kind { NORMAL, FUNCTION, CLASS, THIS, ARGUMENTS }; |
| 24 | |
| 25 | Variable(Scope* scope, const AstRawString* name, VariableMode mode, Kind kind, |
| 26 | InitializationFlag initialization_flag, |
| 27 | MaybeAssignedFlag maybe_assigned_flag = kNotAssigned); |
| 28 | |
| 29 | virtual ~Variable() {} |
| 30 | |
| 31 | // Printing support |
| 32 | static const char* Mode2String(VariableMode mode); |
| 33 | |
| 34 | // The source code for an eval() call may refer to a variable that is |
| 35 | // in an outer scope about which we don't know anything (it may not |
| 36 | // be the script scope). scope() is NULL in that case. Currently the |
| 37 | // scope is only used to follow the context chain length. |
| 38 | Scope* scope() const { return scope_; } |
| 39 | |
| 40 | // This is for adjusting the scope of temporaries used when desugaring |
| 41 | // parameter initializers. |
| 42 | void set_scope(Scope* scope) { scope_ = scope; } |
| 43 | |
| 44 | Handle<String> name() const { return name_->string(); } |
| 45 | const AstRawString* raw_name() const { return name_; } |
| 46 | VariableMode mode() const { return mode_; } |
| 47 | bool has_forced_context_allocation() const { |
| 48 | return force_context_allocation_; |
| 49 | } |
| 50 | void ForceContextAllocation() { |
| 51 | force_context_allocation_ = true; |
| 52 | } |
| 53 | bool is_used() { return is_used_; } |
| 54 | void set_is_used() { is_used_ = true; } |
| 55 | MaybeAssignedFlag maybe_assigned() const { return maybe_assigned_; } |
| 56 | void set_maybe_assigned() { maybe_assigned_ = kMaybeAssigned; } |
| 57 | |
| 58 | int initializer_position() { return initializer_position_; } |
| 59 | void set_initializer_position(int pos) { initializer_position_ = pos; } |
| 60 | |
| 61 | bool IsVariable(Handle<String> n) const { |
| 62 | return !is_this() && name().is_identical_to(n); |
| 63 | } |
| 64 | |
| 65 | bool IsUnallocated() const { |
| 66 | return location_ == VariableLocation::UNALLOCATED; |
| 67 | } |
| 68 | bool IsParameter() const { return location_ == VariableLocation::PARAMETER; } |
| 69 | bool IsStackLocal() const { return location_ == VariableLocation::LOCAL; } |
| 70 | bool IsStackAllocated() const { return IsParameter() || IsStackLocal(); } |
| 71 | bool IsContextSlot() const { return location_ == VariableLocation::CONTEXT; } |
| 72 | bool IsGlobalSlot() const { return location_ == VariableLocation::GLOBAL; } |
| 73 | bool IsUnallocatedOrGlobalSlot() const { |
| 74 | return IsUnallocated() || IsGlobalSlot(); |
| 75 | } |
| 76 | bool IsLookupSlot() const { return location_ == VariableLocation::LOOKUP; } |
| 77 | bool IsGlobalObjectProperty() const; |
| 78 | bool IsStaticGlobalObjectProperty() const; |
| 79 | |
| 80 | bool is_dynamic() const { return IsDynamicVariableMode(mode_); } |
| 81 | bool is_const_mode() const { return IsImmutableVariableMode(mode_); } |
| 82 | bool binding_needs_init() const { |
| 83 | return initialization_flag_ == kNeedsInitialization; |
| 84 | } |
| 85 | |
| 86 | bool is_function() const { return kind_ == FUNCTION; } |
| 87 | bool is_class() const { return kind_ == CLASS; } |
| 88 | bool is_this() const { return kind_ == THIS; } |
| 89 | bool is_arguments() const { return kind_ == ARGUMENTS; } |
| 90 | |
| 91 | // For script scopes, the "this" binding is provided by a ScriptContext added |
| 92 | // to the global's ScriptContextTable. This binding might not statically |
| 93 | // resolve to a Variable::THIS binding, instead being DYNAMIC_LOCAL. However |
| 94 | // any variable named "this" does indeed refer to a Variable::THIS binding; |
| 95 | // the grammar ensures this to be the case. So wherever a "this" binding |
| 96 | // might be provided by the global, use HasThisName instead of is_this(). |
| 97 | bool HasThisName(Isolate* isolate) const { |
| 98 | return is_this() || *name() == *isolate->factory()->this_string(); |
| 99 | } |
| 100 | |
| 101 | ClassVariable* AsClassVariable() { |
| 102 | DCHECK(is_class()); |
| 103 | return reinterpret_cast<ClassVariable*>(this); |
| 104 | } |
| 105 | |
| 106 | // True if the variable is named eval and not known to be shadowed. |
| 107 | bool is_possibly_eval(Isolate* isolate) const { |
| 108 | return IsVariable(isolate->factory()->eval_string()); |
| 109 | } |
| 110 | |
| 111 | Variable* local_if_not_shadowed() const { |
| 112 | DCHECK(mode_ == DYNAMIC_LOCAL && local_if_not_shadowed_ != NULL); |
| 113 | return local_if_not_shadowed_; |
| 114 | } |
| 115 | |
| 116 | void set_local_if_not_shadowed(Variable* local) { |
| 117 | local_if_not_shadowed_ = local; |
| 118 | } |
| 119 | |
| 120 | VariableLocation location() const { return location_; } |
| 121 | int index() const { return index_; } |
| 122 | InitializationFlag initialization_flag() const { |
| 123 | return initialization_flag_; |
| 124 | } |
| 125 | |
| 126 | void AllocateTo(VariableLocation location, int index) { |
| 127 | location_ = location; |
| 128 | index_ = index; |
| 129 | } |
| 130 | |
| 131 | void SetFromEval() { is_from_eval_ = true; } |
| 132 | |
| 133 | static int CompareIndex(Variable* const* v, Variable* const* w); |
| 134 | |
| 135 | void RecordStrongModeReference(int start_position, int end_position) { |
| 136 | // Record the earliest reference to the variable. Used in error messages for |
| 137 | // strong mode references to undeclared variables. |
| 138 | if (has_strong_mode_reference_ && |
| 139 | strong_mode_reference_start_position_ < start_position) |
| 140 | return; |
| 141 | has_strong_mode_reference_ = true; |
| 142 | strong_mode_reference_start_position_ = start_position; |
| 143 | strong_mode_reference_end_position_ = end_position; |
| 144 | } |
| 145 | |
| 146 | bool has_strong_mode_reference() const { return has_strong_mode_reference_; } |
| 147 | int strong_mode_reference_start_position() const { |
| 148 | return strong_mode_reference_start_position_; |
| 149 | } |
| 150 | int strong_mode_reference_end_position() const { |
| 151 | return strong_mode_reference_end_position_; |
| 152 | } |
| 153 | PropertyAttributes DeclarationPropertyAttributes() const { |
| 154 | int property_attributes = NONE; |
| 155 | if (IsImmutableVariableMode(mode_)) { |
| 156 | property_attributes |= READ_ONLY; |
| 157 | } |
| 158 | if (is_from_eval_) { |
| 159 | property_attributes |= EVAL_DECLARED; |
| 160 | } |
| 161 | return static_cast<PropertyAttributes>(property_attributes); |
| 162 | } |
| 163 | |
| 164 | private: |
| 165 | Scope* scope_; |
| 166 | const AstRawString* name_; |
| 167 | VariableMode mode_; |
| 168 | Kind kind_; |
| 169 | VariableLocation location_; |
| 170 | int index_; |
| 171 | int initializer_position_; |
| 172 | // Tracks whether the variable is bound to a VariableProxy which is in strong |
| 173 | // mode, and if yes, the source location of the reference. |
| 174 | bool has_strong_mode_reference_; |
| 175 | int strong_mode_reference_start_position_; |
| 176 | int strong_mode_reference_end_position_; |
| 177 | |
| 178 | // If this field is set, this variable references the stored locally bound |
| 179 | // variable, but it might be shadowed by variable bindings introduced by |
| 180 | // sloppy 'eval' calls between the reference scope (inclusive) and the |
| 181 | // binding scope (exclusive). |
| 182 | Variable* local_if_not_shadowed_; |
| 183 | |
| 184 | // True if this variable is introduced by a sloppy eval |
| 185 | bool is_from_eval_; |
| 186 | |
| 187 | // Usage info. |
| 188 | bool force_context_allocation_; // set by variable resolver |
| 189 | bool is_used_; |
| 190 | InitializationFlag initialization_flag_; |
| 191 | MaybeAssignedFlag maybe_assigned_; |
| 192 | }; |
| 193 | |
| 194 | class ClassVariable : public Variable { |
| 195 | public: |
| 196 | ClassVariable(Scope* scope, const AstRawString* name, VariableMode mode, |
| 197 | InitializationFlag initialization_flag, |
| 198 | MaybeAssignedFlag maybe_assigned_flag = kNotAssigned, |
| 199 | int declaration_group_start = -1) |
| 200 | : Variable(scope, name, mode, Variable::CLASS, initialization_flag, |
| 201 | maybe_assigned_flag), |
| 202 | declaration_group_start_(declaration_group_start) {} |
| 203 | |
| 204 | int declaration_group_start() const { return declaration_group_start_; } |
| 205 | void set_declaration_group_start(int declaration_group_start) { |
| 206 | declaration_group_start_ = declaration_group_start; |
| 207 | } |
| 208 | |
| 209 | private: |
| 210 | // For classes we keep track of consecutive groups of delcarations. They are |
| 211 | // needed for strong mode scoping checks. TODO(marja, rossberg): Implement |
| 212 | // checks for functions too. |
| 213 | int declaration_group_start_; |
| 214 | }; |
| 215 | } // namespace internal |
| 216 | } // namespace v8 |
| 217 | |
| 218 | #endif // V8_AST_VARIABLES_H_ |