ast.h.svn-base

Google浏览器V8内核代码

  Expression* expression_;
};


class WithExitStatement: public Statement {
 public:
  WithExitStatement() { }

  virtual void Accept(Visitor* v);
};


class CaseClause: public ZoneObject {
 public:
  CaseClause(Expression* label, ZoneList<Statement*>* statements)
      : label_(label), statements_(statements) { }

  bool is_default() const  { return label_ == NULL; }
  Expression* label() const  {
    CHECK(!is_default());
    return label_;
  }
  ZoneList<Statement*>* statements() const  { return statements_; }

 private:
  Expression* label_;
  ZoneList<Statement*>* statements_;
};


class SwitchStatement: public BreakableStatement {
 public:
  explicit SwitchStatement(ZoneStringList* labels)
      : BreakableStatement(labels, TARGET_FOR_ANONYMOUS),
        tag_(NULL), cases_(NULL) { }

  void Initialize(Expression* tag, ZoneList<CaseClause*>* cases) {
    tag_ = tag;
    cases_ = cases;
  }

  virtual void Accept(Visitor* v);

  Expression* tag() const  { return tag_; }
  ZoneList<CaseClause*>* cases() const  { return cases_; }

 private:
  Expression* tag_;
  ZoneList<CaseClause*>* cases_;
};


// If-statements always have non-null references to their then- and
// else-parts. When parsing if-statements with no explicit else-part,
// the parser implicitly creates an empty statement. Use the
// HasThenStatement() and HasElseStatement() functions to check if a
// given if-statement has a then- or an else-part containing code.
class IfStatement: public Statement {
 public:
  IfStatement(Expression* condition,
              Statement* then_statement,
              Statement* else_statement)
      : condition_(condition),
        then_statement_(then_statement),
        else_statement_(else_statement) { }

  virtual void Accept(Visitor* v);

  bool HasThenStatement() const { return !then_statement()->IsEmpty(); }
  bool HasElseStatement() const { return !else_statement()->IsEmpty(); }

  Expression* condition() const { return condition_; }
  Statement* then_statement() const { return then_statement_; }
  Statement* else_statement() const { return else_statement_; }

 private:
  Expression* condition_;
  Statement* then_statement_;
  Statement* else_statement_;
};


// NOTE: LabelCollectors are represented as nodes to fit in the target
// stack in the compiler; this should probably be reworked.
class LabelCollector: public Node {
 public:
  explicit LabelCollector(ZoneList<Label*>* labels) : labels_(labels) { }

  // Adds a label to the collector. The collector stores a pointer not
  // a copy of the label to make binding work, so make sure not to
  // pass in references to something on the stack.
  void AddLabel(Label* label);

  // Virtual behaviour. LabelCollectors are never part of the AST.
  virtual void Accept(Visitor* v) { UNREACHABLE(); }
  virtual LabelCollector* AsLabelCollector() { return this; }

  ZoneList<Label*>* labels() { return labels_; }

 private:
  ZoneList<Label*>* labels_;
};


class TryStatement: public Statement {
 public:
  explicit TryStatement(Block* try_block)
      : try_block_(try_block), escaping_labels_(NULL) { }

  void set_escaping_labels(ZoneList<Label*>* labels) {
    escaping_labels_ = labels;
  }

  Block* try_block() const { return try_block_; }
  ZoneList<Label*>* escaping_labels() const { return escaping_labels_; }

 private:
  Block* try_block_;
  ZoneList<Label*>* escaping_labels_;
};


class TryCatch: public TryStatement {
 public:
  TryCatch(Block* try_block, Expression* catch_var, Block* catch_block)
      : TryStatement(try_block),
        catch_var_(catch_var),
        catch_block_(catch_block) {
    ASSERT(catch_var->AsVariableProxy() != NULL);
  }

  virtual void Accept(Visitor* v);

  Expression* catch_var() const  { return catch_var_; }
  Block* catch_block() const  { return catch_block_; }

 private:
  Expression* catch_var_;
  Block* catch_block_;
};


class TryFinally: public TryStatement {
 public:
  TryFinally(Block* try_block, Expression* finally_var, Block* finally_block)
      : TryStatement(try_block),
        finally_var_(finally_var),
        finally_block_(finally_block) { }

  virtual void Accept(Visitor* v);

  // If the finally block is non-trivial it may be problematic to have
  // extra stuff on the expression stack while evaluating it. The
  // finally variable is used to hold the state instead of storing it
  // on the stack. It may be NULL in which case the state is stored on
  // the stack.
  Expression* finally_var() const { return finally_var_; }

  Block* finally_block() const { return finally_block_; }

 private:
  Expression* finally_var_;
  Block* finally_block_;
};


class DebuggerStatement: public Statement {
 public:
  virtual void Accept(Visitor* v);
};


class EmptyStatement: public Statement {
 public:
  virtual void Accept(Visitor* v);

  // Type testing & conversion.
  virtual EmptyStatement* AsEmptyStatement() { return this; }
};


class Literal: public Expression {
 public:
  explicit Literal(Handle<Object> handle) : handle_(handle) { }

  virtual void Accept(Visitor* v);

  // Type testing & conversion.
  virtual Literal* AsLiteral() { return this; }

  // Check if this literal is identical to the other literal.
  bool IsIdenticalTo(const Literal* other) const {
    return handle_.is_identical_to(other->handle_);
  }

  // Identity testers.
  bool IsNull() const { return handle_.is_identical_to(Factory::null_value()); }
  bool IsTrue() const { return handle_.is_identical_to(Factory::true_value()); }
  bool IsFalse() const {
    return handle_.is_identical_to(Factory::false_value());
  }

  Handle<Object> handle() const { return handle_; }

 private:
  Handle<Object> handle_;
};


// Base class for literals that needs space in the corresponding JSFunction.
class MaterializedLiteral: public Expression {
 public:
  explicit MaterializedLiteral(int literal_index)
      : literal_index_(literal_index) {}
  int literal_index() { return literal_index_; }
 private:
  int literal_index_;
};


// An object literal has a boilerplate object that is used
// for minimizing the work when constructing it at runtime.
class ObjectLiteral: public MaterializedLiteral {
 public:
  // Property is used for passing information
  // about an object literal's properties from the parser
  // to the code generator.
  class Property: public ZoneObject {
   public:

    enum Kind {
      CONSTANT,       // Property with constant value (at compile time).
      COMPUTED,       // Property with computed value (at execution time).
      GETTER, SETTER,  // Property is an accessor function.
      PROTOTYPE       // Property is __proto__.
    };

    Property(Literal* key, Expression* value);
    Property(bool is_getter, FunctionLiteral* value);

    Literal* key() { return key_; }
    Expression* value() { return value_; }
    Kind kind() { return kind_; }

   private:
    Literal* key_;
    Expression* value_;
    Kind kind_;
  };

  ObjectLiteral(Handle<FixedArray> constant_properties,
                ZoneList<Property*>* properties,
                int literal_index)
      : MaterializedLiteral(literal_index),
        constant_properties_(constant_properties),
        properties_(properties) {
  }

  virtual void Accept(Visitor* v);

  Handle<FixedArray> constant_properties() const {
    return constant_properties_;
  }
  ZoneList<Property*>* properties() const { return properties_; }

 private:
  Handle<FixedArray> constant_properties_;
  ZoneList<Property*>* properties_;
};


// Node for capturing a regexp literal.
class RegExpLiteral: public MaterializedLiteral {
 public:
  RegExpLiteral(Handle<String> pattern,
                Handle<String> flags,
                int literal_index)
      : MaterializedLiteral(literal_index),
        pattern_(pattern),
        flags_(flags) {}

  virtual void Accept(Visitor* v);

  Handle<String> pattern() const { return pattern_; }
  Handle<String> flags() const { return flags_; }

 private:
  Handle<String> pattern_;
  Handle<String> flags_;
};

// An array literal has a literals object that is used
// used for minimizing the work when contructing it at runtime.
class ArrayLiteral: public Expression {
 public:
  ArrayLiteral(Handle<FixedArray> literals,
               ZoneList<Expression*>* values)
      : literals_(literals), values_(values) {
  }

  virtual void Accept(Visitor* v);

  Handle<FixedArray> literals() const { return literals_; }
  ZoneList<Expression*>* values() const { return values_; }

 private:
  Handle<FixedArray> literals_;
  ZoneList<Expression*>* values_;
};


class VariableProxy: public Expression {
 public:
  virtual void Accept(Visitor* v);

  // Type testing & conversion
  virtual Property* AsProperty() {
    return var_ == NULL ? NULL : var_->AsProperty();
  }
  virtual VariableProxy* AsVariableProxy()  { return this; }

  Variable* AsVariable() {
    return this == NULL || var_ == NULL ? NULL : var_->AsVariable();
  }
  virtual bool IsValidLeftHandSide() {
    return var_ == NULL ? true : var_->IsValidLeftHandSide();
  }
  bool IsVariable(Handle<String> n) {
    return !is_this() && name().is_identical_to(n);
  }

  // If this assertion fails it means that some code has tried to
  // treat the special "this" variable as an ordinary variable with
  // the name "this".
  Handle<String> name() const  { return name_; }
  Variable* var() const  { return var_; }
  UseCount* var_uses()  { return &var_uses_; }
  UseCount* obj_uses()  { return &obj_uses_; }
  bool is_this() const  { return is_this_; }
  bool inside_with() const  { return inside_with_; }

  // Bind this proxy to the variable var.
  void BindTo(Variable* var);

  // Generate code to store into an expression evaluated as the left-hand
  // side of an assignment.  The code will expect the stored value on top of
  // the expression stack, and a reference containing the expression
  // immediately below that.
  virtual void GenerateStoreCode(MacroAssembler* masm,
                                 Scope* scope,
                                 Reference* ref,
                                 InitState init_state);
 protected:
  Handle<String> name_;
  Variable* var_;  // resolved variable, or NULL
  bool is_this_;
  bool inside_with_;

  // VariableProxy usage info.
  UseCount var_uses_;  // uses of the variable value
  UseCount obj_uses_;  // uses of the object the variable points to

  VariableProxy(Handle<String> name, bool is_this, bool inside_with);
  explicit VariableProxy(bool is_this);

  friend class Scope;
};


class VariableProxySentinel: public VariableProxy {
 public:
  virtual bool IsValidLeftHandSide() { return !is_this(); }
  static VariableProxySentinel* this_proxy() { return &this_proxy_; }
  static VariableProxySentinel* identifier_proxy() {
    return &identifier_proxy_;
  }

 private:
  explicit VariableProxySentinel(bool is_this) : VariableProxy(is_this) { }
  static VariableProxySentinel this_proxy_;
  static VariableProxySentinel identifier_proxy_;
};


class Slot: public Expression {
 public:
  enum Type {
    // A slot in the parameter section on the stack. index() is
    // the parameter index, counting left-to-right, starting at 0.
    PARAMETER,

    // A slot in the local section on the stack. index() is
    // the variable index in the stack frame, starting at 0.
    LOCAL,

    // An indexed slot in a heap context. index() is the
    // variable index in the context object on the heap,
    // starting at 0. var()->scope() is the corresponding
    // scope.
    CONTEXT,

    // A named slot in a heap context. var()->name() is the
    // variable name in the context object on the heap,
    // with lookup starting at the current context. index()
    // is invalid.
    LOOKUP,

    // A property in the global object. var()->name() is
    // the property name.
    GLOBAL
  };

  Slot(Variable* var, Type type, int index)
    : var_(var), type_(type), index_(index) {
    ASSERT(var != NULL);
  }

  virtual void Accept(Visitor* v);

  // Type testing & conversion
  virtual Slot* AsSlot()  { return this; }

  // Accessors
  Variable* var() const  { return var_; }
  Type type() const  { return type_; }
  int index() const  { return index_; }