ast.h.svn-base

Google浏览器V8内核代码

// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_AST_H_
#define V8_AST_H_

#include "execution.h"
#include "factory.h"
#include "runtime.h"
#include "token.h"
#include "variables.h"
#include "macro-assembler.h"

namespace v8 { namespace internal {

// The abstract syntax tree is an intermediate, light-weight
// representation of the parsed JavaScript code suitable for
// compilation to native code.

// Nodes are allocated in a separate zone, which allows faster
// allocation and constant-time deallocation of the entire syntax
// tree.


// ----------------------------------------------------------------------------
// Nodes of the abstract syntax tree. Only concrete classes are
// enumerated here.

#define NODE_LIST(V)                            \
  V(Block)                                      \
  V(Declaration)                                \
  V(ExpressionStatement)                        \
  V(EmptyStatement)                             \
  V(IfStatement)                                \
  V(ContinueStatement)                          \
  V(BreakStatement)                             \
  V(ReturnStatement)                            \
  V(WithEnterStatement)                         \
  V(WithExitStatement)                          \
  V(SwitchStatement)                            \
  V(LoopStatement)                              \
  V(ForInStatement)                             \
  V(TryCatch)                                   \
  V(TryFinally)                                 \
  V(DebuggerStatement)                          \
  V(FunctionLiteral)                            \
  V(FunctionBoilerplateLiteral)                 \
  V(Conditional)                                \
  V(Slot)                                       \
  V(VariableProxy)                              \
  V(Literal)                                    \
  V(RegExpLiteral)                              \
  V(ObjectLiteral)                              \
  V(ArrayLiteral)                               \
  V(Assignment)                                 \
  V(Throw)                                      \
  V(Property)                                   \
  V(Call)                                       \
  V(CallNew)                                    \
  V(CallRuntime)                                \
  V(UnaryOperation)                             \
  V(CountOperation)                             \
  V(BinaryOperation)                            \
  V(CompareOperation)                           \
  V(ThisFunction)


#define DEF_FORWARD_DECLARATION(type) class type;
NODE_LIST(DEF_FORWARD_DECLARATION)
#undef DEF_FORWARD_DECLARATION


// Typedef only introduced to avoid unreadable code.
// Please do appreciate the required space in "> >".
typedef ZoneList<Handle<String> > ZoneStringList;


class Node: public ZoneObject {
 public:
  Node(): statement_pos_(RelocInfo::kNoPosition) { }
  virtual ~Node() { }
  virtual void Accept(Visitor* v) = 0;

  // Type testing & conversion.
  virtual Statement* AsStatement() { return NULL; }
  virtual ExpressionStatement* AsExpressionStatement() { return NULL; }
  virtual EmptyStatement* AsEmptyStatement() { return NULL; }
  virtual Expression* AsExpression() { return NULL; }
  virtual Literal* AsLiteral() { return NULL; }
  virtual Slot* AsSlot() { return NULL; }
  virtual VariableProxy* AsVariableProxy() { return NULL; }
  virtual Property* AsProperty() { return NULL; }
  virtual Call* AsCall() { return NULL; }
  virtual LabelCollector* AsLabelCollector() { return NULL; }
  virtual BreakableStatement* AsBreakableStatement() { return NULL; }
  virtual IterationStatement* AsIterationStatement() { return NULL; }
  virtual UnaryOperation* AsUnaryOperation() { return NULL; }
  virtual BinaryOperation* AsBinaryOperation() { return NULL; }
  virtual Assignment* AsAssignment() { return NULL; }
  virtual FunctionLiteral* AsFunctionLiteral() { return NULL; }

  void set_statement_pos(int statement_pos) { statement_pos_ = statement_pos; }
  int statement_pos() const { return statement_pos_; }

 private:
  int statement_pos_;
};


class Statement: public Node {
 public:
  virtual Statement* AsStatement()  { return this; }
  virtual ReturnStatement* AsReturnStatement() { return NULL; }

  bool IsEmpty() { return AsEmptyStatement() != NULL; }
};


class Reference;
enum InitState { CONST_INIT, NOT_CONST_INIT };

class Expression: public Node {
 public:
  virtual Expression* AsExpression()  { return this; }

  virtual bool IsValidLeftHandSide() { return false; }

  // Mark the expression as being compiled as an expression
  // statement. This is used to transform postfix increments to
  // (faster) prefix increments.
  virtual void MarkAsStatement() { /* do nothing */ }

  // 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.  This function is overridden for expression
  // types that can be stored into.
  virtual void GenerateStoreCode(MacroAssembler* masm,
                                 Scope* scope,
                                 Reference* ref,
                                 InitState init_state) {
    UNREACHABLE();
  }
};


/**
 * A sentinel used during pre parsing that represents some expression
 * that is a valid left hand side without having to actually build
 * the expression.
 */
class ValidLeftHandSideSentinel: public Expression {
 public:
  virtual bool IsValidLeftHandSide() { return true; }
  virtual void Accept(Visitor* v) { UNREACHABLE(); }
  static ValidLeftHandSideSentinel* instance() { return &instance_; }
 private:
  static ValidLeftHandSideSentinel instance_;
};


class BreakableStatement: public Statement {
 public:
  enum Type {
    TARGET_FOR_ANONYMOUS,
    TARGET_FOR_NAMED_ONLY
  };

  // The labels associated with this statement. May be NULL;
  // if it is != NULL, guaranteed to contain at least one entry.
  ZoneStringList* labels() const { return labels_; }

  // Type testing & conversion.
  virtual BreakableStatement* AsBreakableStatement() { return this; }

  // Code generation
  Label* break_target() { return &break_target_; }

  // Used during code generation for restoring the stack when a
  // break/continue crosses a statement that keeps stuff on the stack.
  int break_stack_height() { return break_stack_height_; }
  void set_break_stack_height(int height) { break_stack_height_ = height; }

  // Testers.
  bool is_target_for_anonymous() const { return type_ == TARGET_FOR_ANONYMOUS; }

 protected:
  BreakableStatement(ZoneStringList* labels, Type type)
      : labels_(labels), type_(type) {
    ASSERT(labels == NULL || labels->length() > 0);
  }

 private:
  ZoneStringList* labels_;
  Type type_;
  Label break_target_;
  int break_stack_height_;
};


class Block: public BreakableStatement {
 public:
  Block(ZoneStringList* labels, int capacity, bool is_initializer_block)
      : BreakableStatement(labels, TARGET_FOR_NAMED_ONLY),
        statements_(capacity),
        is_initializer_block_(is_initializer_block) { }

  virtual void Accept(Visitor* v);

  void AddStatement(Statement* statement) { statements_.Add(statement); }

  ZoneList<Statement*>* statements() { return &statements_; }
  bool is_initializer_block() const  { return is_initializer_block_; }

 private:
  ZoneList<Statement*> statements_;
  bool is_initializer_block_;
};


class Declaration: public Node {
 public:
  Declaration(VariableProxy* proxy, Variable::Mode mode, FunctionLiteral* fun)
    : proxy_(proxy),
      mode_(mode),
      fun_(fun) {
    ASSERT(mode == Variable::VAR || mode == Variable::CONST);
    // At the moment there are no "const functions"'s in JavaScript...
    ASSERT(fun == NULL || mode == Variable::VAR);
  }

  virtual void Accept(Visitor* v);

  VariableProxy* proxy() const  { return proxy_; }
  Variable::Mode mode() const  { return mode_; }
  FunctionLiteral* fun() const  { return fun_; }  // may be NULL

 private:
  VariableProxy* proxy_;
  Variable::Mode mode_;
  FunctionLiteral* fun_;
};


class IterationStatement: public BreakableStatement {
 public:
  // Type testing & conversion.
  virtual IterationStatement* AsIterationStatement() { return this; }

  Statement* body() const { return body_; }

  // Code generation
  Label* continue_target()  { return &continue_target_; }

 protected:
  explicit IterationStatement(ZoneStringList* labels)
    : BreakableStatement(labels, TARGET_FOR_ANONYMOUS), body_(NULL) { }

  void Initialize(Statement* body) {
    body_ = body;
  }

 private:
  Statement* body_;
  Label continue_target_;
};


class LoopStatement: public IterationStatement {
 public:
  enum Type { DO_LOOP, FOR_LOOP, WHILE_LOOP };

  LoopStatement(ZoneStringList* labels, Type type)
      : IterationStatement(labels), type_(type), init_(NULL),
        cond_(NULL), next_(NULL) { }

  void Initialize(Statement* init,
                  Expression* cond,
                  Statement* next,
                  Statement* body) {
    ASSERT(init == NULL || type_ == FOR_LOOP);
    ASSERT(next == NULL || type_ == FOR_LOOP);
    IterationStatement::Initialize(body);
    init_ = init;
    cond_ = cond;
    next_ = next;
  }

  virtual void Accept(Visitor* v);

  Type type() const  { return type_; }
  Statement* init() const  { return init_; }
  Expression* cond() const  { return cond_; }
  Statement* next() const  { return next_; }

#ifdef DEBUG
  const char* OperatorString() const;
#endif

 private:
  Type type_;
  Statement* init_;
  Expression* cond_;
  Statement* next_;
};


class ForInStatement: public IterationStatement {
 public:
  explicit ForInStatement(ZoneStringList* labels)
    : IterationStatement(labels), each_(NULL), enumerable_(NULL) { }

  void Initialize(Expression* each, Expression* enumerable, Statement* body) {
    IterationStatement::Initialize(body);
    each_ = each;
    enumerable_ = enumerable;
  }

  virtual void Accept(Visitor* v);

  Expression* each() const { return each_; }
  Expression* enumerable() const { return enumerable_; }

 private:
  Expression* each_;
  Expression* enumerable_;
};


class ExpressionStatement: public Statement {
 public:
  explicit ExpressionStatement(Expression* expression)
      : expression_(expression) { }

  virtual void Accept(Visitor* v);

  // Type testing & conversion.
  virtual ExpressionStatement* AsExpressionStatement() { return this; }

  void set_expression(Expression* e) { expression_ = e; }
  Expression* expression() { return expression_; }

 private:
  Expression* expression_;
};


class ContinueStatement: public Statement {
 public:
  explicit ContinueStatement(IterationStatement* target)
      : target_(target) { }

  virtual void Accept(Visitor* v);

  IterationStatement* target() const  { return target_; }

 private:
  IterationStatement* target_;
};


class BreakStatement: public Statement {
 public:
  explicit BreakStatement(BreakableStatement* target)
      : target_(target) { }

  virtual void Accept(Visitor* v);

  BreakableStatement* target() const  { return target_; }

 private:
  BreakableStatement* target_;
};


class ReturnStatement: public Statement {
 public:
  explicit ReturnStatement(Expression* expression)
      : expression_(expression) { }

  virtual void Accept(Visitor* v);

  // Type testing & conversion.
  virtual ReturnStatement* AsReturnStatement() { return this; }

  Expression* expression() { return expression_; }

 private:
  Expression* expression_;
};


class WithEnterStatement: public Statement {
 public:
  explicit WithEnterStatement(Expression* expression)
      : expression_(expression) { }

  virtual void Accept(Visitor* v);

  Expression* expression() const  { return expression_; }

 private: