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// Copyright 2011 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_AST_VARIABLES_H_
#define V8_AST_VARIABLES_H_
#include "src/ast/ast-value-factory.h"
#include "src/zone.h"
namespace v8 {
namespace internal {
// The AST refers to variables via VariableProxies - placeholders for the actual
// variables. Variables themselves are never directly referred to from the AST,
// they are maintained by scopes, and referred to from VariableProxies and Slots
// after binding and variable allocation.
class Variable: public ZoneObject {
public:
enum Kind { NORMAL, FUNCTION, THIS, ARGUMENTS };
Variable(Scope* scope, const AstRawString* name, VariableMode mode, Kind kind,
InitializationFlag initialization_flag,
MaybeAssignedFlag maybe_assigned_flag = kNotAssigned);
virtual ~Variable() {}
// Printing support
static const char* Mode2String(VariableMode mode);
// The source code for an eval() call may refer to a variable that is
// in an outer scope about which we don't know anything (it may not
// be the script scope). scope() is NULL in that case. Currently the
// scope is only used to follow the context chain length.
Scope* scope() const { return scope_; }
// This is for adjusting the scope of temporaries used when desugaring
// parameter initializers.
void set_scope(Scope* scope) { scope_ = scope; }
Handle<String> name() const { return name_->string(); }
const AstRawString* raw_name() const { return name_; }
VariableMode mode() const { return mode_; }
bool has_forced_context_allocation() const {
return force_context_allocation_;
}
void ForceContextAllocation() {
force_context_allocation_ = true;
}
bool is_used() { return is_used_; }
void set_is_used() { is_used_ = true; }
MaybeAssignedFlag maybe_assigned() const { return maybe_assigned_; }
void set_maybe_assigned() { maybe_assigned_ = kMaybeAssigned; }
int initializer_position() { return initializer_position_; }
void set_initializer_position(int pos) { initializer_position_ = pos; }
bool IsVariable(Handle<String> n) const {
return !is_this() && name().is_identical_to(n);
}
bool IsUnallocated() const {
return location_ == VariableLocation::UNALLOCATED;
}
bool IsParameter() const { return location_ == VariableLocation::PARAMETER; }
bool IsStackLocal() const { return location_ == VariableLocation::LOCAL; }
bool IsStackAllocated() const { return IsParameter() || IsStackLocal(); }
bool IsContextSlot() const { return location_ == VariableLocation::CONTEXT; }
bool IsGlobalSlot() const { return location_ == VariableLocation::GLOBAL; }
bool IsUnallocatedOrGlobalSlot() const {
return IsUnallocated() || IsGlobalSlot();
}
bool IsLookupSlot() const { return location_ == VariableLocation::LOOKUP; }
bool IsGlobalObjectProperty() const;
bool IsStaticGlobalObjectProperty() const;
bool is_dynamic() const { return IsDynamicVariableMode(mode_); }
bool is_const_mode() const { return IsImmutableVariableMode(mode_); }
bool binding_needs_init() const {
return initialization_flag_ == kNeedsInitialization;
}
bool is_function() const { return kind_ == FUNCTION; }
bool is_this() const { return kind_ == THIS; }
bool is_arguments() const { return kind_ == ARGUMENTS; }
// For script scopes, the "this" binding is provided by a ScriptContext added
// to the global's ScriptContextTable. This binding might not statically
// resolve to a Variable::THIS binding, instead being DYNAMIC_LOCAL. However
// any variable named "this" does indeed refer to a Variable::THIS binding;
// the grammar ensures this to be the case. So wherever a "this" binding
// might be provided by the global, use HasThisName instead of is_this().
bool HasThisName(Isolate* isolate) const {
return is_this() || *name() == *isolate->factory()->this_string();
}
// True if the variable is named eval and not known to be shadowed.
bool is_possibly_eval(Isolate* isolate) const {
return IsVariable(isolate->factory()->eval_string());
}
Variable* local_if_not_shadowed() const {
DCHECK(mode_ == DYNAMIC_LOCAL && local_if_not_shadowed_ != NULL);
return local_if_not_shadowed_;
}
void set_local_if_not_shadowed(Variable* local) {
local_if_not_shadowed_ = local;
}
VariableLocation location() const { return location_; }
int index() const { return index_; }
InitializationFlag initialization_flag() const {
return initialization_flag_;
}
void AllocateTo(VariableLocation location, int index) {
location_ = location;
index_ = index;
}
void SetFromEval() { is_from_eval_ = true; }
static int CompareIndex(Variable* const* v, Variable* const* w);
PropertyAttributes DeclarationPropertyAttributes() const {
int property_attributes = NONE;
if (IsImmutableVariableMode(mode_)) {
property_attributes |= READ_ONLY;
}
if (is_from_eval_) {
property_attributes |= EVAL_DECLARED;
}
return static_cast<PropertyAttributes>(property_attributes);
}
private:
Scope* scope_;
const AstRawString* name_;
VariableMode mode_;
Kind kind_;
VariableLocation location_;
int index_;
int initializer_position_;
// If this field is set, this variable references the stored locally bound
// variable, but it might be shadowed by variable bindings introduced by
// sloppy 'eval' calls between the reference scope (inclusive) and the
// binding scope (exclusive).
Variable* local_if_not_shadowed_;
// True if this variable is introduced by a sloppy eval
bool is_from_eval_;
// Usage info.
bool force_context_allocation_; // set by variable resolver
bool is_used_;
InitializationFlag initialization_flag_;
MaybeAssignedFlag maybe_assigned_;
};
} // namespace internal
} // namespace v8
#endif // V8_AST_VARIABLES_H_
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