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// Copyright 2011 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_VARIABLES_H_
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#define V8_VARIABLES_H_
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#include "src/ast-value-factory.h"
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#include "src/zone.h"
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namespace v8 {
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namespace internal {
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// The AST refers to variables via VariableProxies - placeholders for the actual
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// variables. Variables themselves are never directly referred to from the AST,
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// they are maintained by scopes, and referred to from VariableProxies and Slots
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// after binding and variable allocation.
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class Variable: public ZoneObject {
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public:
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enum Kind { NORMAL, FUNCTION, THIS, NEW_TARGET, ARGUMENTS };
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enum Location {
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// Before and during variable allocation, a variable whose location is
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// not yet determined. After allocation, a variable looked up as a
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// property on the global object (and possibly absent). name() is the
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// variable name, index() is invalid.
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UNALLOCATED,
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// A slot in the parameter section on the stack. index() is the
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// parameter index, counting left-to-right. The receiver is index -1;
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// the first parameter is index 0.
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PARAMETER,
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// A slot in the local section on the stack. index() is the variable
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// index in the stack frame, starting at 0.
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LOCAL,
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// An indexed slot in a heap context. index() is the variable index in
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// the context object on the heap, starting at 0. scope() is the
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// corresponding scope.
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CONTEXT,
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// A named slot in a heap context. name() is the variable name in the
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// context object on the heap, with lookup starting at the current
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// context. index() is invalid.
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LOOKUP
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};
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Variable(Scope* scope, const AstRawString* name, VariableMode mode, Kind kind,
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InitializationFlag initialization_flag,
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MaybeAssignedFlag maybe_assigned_flag = kNotAssigned);
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// Printing support
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static const char* Mode2String(VariableMode mode);
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// The source code for an eval() call may refer to a variable that is
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// in an outer scope about which we don't know anything (it may not
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// be the script scope). scope() is NULL in that case. Currently the
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// scope is only used to follow the context chain length.
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Scope* scope() const { return scope_; }
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Handle<String> name() const { return name_->string(); }
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const AstRawString* raw_name() const { return name_; }
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VariableMode mode() const { return mode_; }
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bool has_forced_context_allocation() const {
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return force_context_allocation_;
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}
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void ForceContextAllocation() {
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DCHECK(mode_ != TEMPORARY);
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force_context_allocation_ = true;
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}
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bool is_used() { return is_used_; }
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void set_is_used() { is_used_ = true; }
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MaybeAssignedFlag maybe_assigned() const { return maybe_assigned_; }
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void set_maybe_assigned() { maybe_assigned_ = kMaybeAssigned; }
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int initializer_position() { return initializer_position_; }
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void set_initializer_position(int pos) { initializer_position_ = pos; }
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bool IsVariable(Handle<String> n) const {
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return !is_this() && name().is_identical_to(n);
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}
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bool IsUnallocated() const { return location_ == UNALLOCATED; }
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bool IsParameter() const { return location_ == PARAMETER; }
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bool IsStackLocal() const { return location_ == LOCAL; }
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bool IsStackAllocated() const { return IsParameter() || IsStackLocal(); }
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bool IsContextSlot() const { return location_ == CONTEXT; }
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bool IsLookupSlot() const { return location_ == LOOKUP; }
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bool IsGlobalObjectProperty() const;
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bool is_dynamic() const { return IsDynamicVariableMode(mode_); }
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bool is_const_mode() const { return IsImmutableVariableMode(mode_); }
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bool binding_needs_init() const {
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return initialization_flag_ == kNeedsInitialization;
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}
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bool is_function() const { return kind_ == FUNCTION; }
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bool is_this() const { return kind_ == THIS; }
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bool is_new_target() const { return kind_ == NEW_TARGET; }
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bool is_arguments() const { return kind_ == ARGUMENTS; }
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// True if the variable is named eval and not known to be shadowed.
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bool is_possibly_eval(Isolate* isolate) const {
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return IsVariable(isolate->factory()->eval_string());
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}
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Variable* local_if_not_shadowed() const {
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DCHECK(mode_ == DYNAMIC_LOCAL && local_if_not_shadowed_ != NULL);
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return local_if_not_shadowed_;
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}
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void set_local_if_not_shadowed(Variable* local) {
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local_if_not_shadowed_ = local;
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}
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Location location() const { return location_; }
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int index() const { return index_; }
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InitializationFlag initialization_flag() const {
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return initialization_flag_;
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}
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void AllocateTo(Location location, int index) {
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location_ = location;
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index_ = index;
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}
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static int CompareIndex(Variable* const* v, Variable* const* w);
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void RecordStrongModeReference(int start_position, int end_position) {
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// Record the earliest reference to the variable. Used in error messages for
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// strong mode references to undeclared variables.
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if (has_strong_mode_reference_ &&
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strong_mode_reference_start_position_ < start_position)
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return;
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has_strong_mode_reference_ = true;
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strong_mode_reference_start_position_ = start_position;
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strong_mode_reference_end_position_ = end_position;
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}
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bool has_strong_mode_reference() const { return has_strong_mode_reference_; }
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int strong_mode_reference_start_position() const {
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return strong_mode_reference_start_position_;
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}
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int strong_mode_reference_end_position() const {
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return strong_mode_reference_end_position_;
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}
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private:
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Scope* scope_;
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const AstRawString* name_;
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VariableMode mode_;
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Kind kind_;
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Location location_;
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int index_;
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int initializer_position_;
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// Tracks whether the variable is bound to a VariableProxy which is in strong
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// mode, and if yes, the source location of the reference.
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bool has_strong_mode_reference_;
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int strong_mode_reference_start_position_;
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int strong_mode_reference_end_position_;
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// If this field is set, this variable references the stored locally bound
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// variable, but it might be shadowed by variable bindings introduced by
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// sloppy 'eval' calls between the reference scope (inclusive) and the
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// binding scope (exclusive).
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Variable* local_if_not_shadowed_;
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// Usage info.
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bool force_context_allocation_; // set by variable resolver
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bool is_used_;
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InitializationFlag initialization_flag_;
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MaybeAssignedFlag maybe_assigned_;
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};
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} } // namespace v8::internal
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#endif // V8_VARIABLES_H_
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