parser.cc.svn-base

Google浏览器V8内核代码

  // empty statements, e.g. 'l1: l2: l3: break l2;'
  if (!label.is_null() && ContainsLabel(labels, label)) {
    return factory()->EmptyStatement();
  }
  BreakableStatement* target = NULL;
  if (!is_pre_parsing_) {
    target = LookupBreakTarget(label, CHECK_OK);
    if (target == NULL) {
      // Illegal break statement.  To be consistent with KJS we delay
      // reporting of the syntax error until runtime.
      Handle<String> error_type = Factory::illegal_break_symbol();
      if (!label.is_null()) error_type = Factory::unknown_label_symbol();
      Expression* throw_error = NewThrowSyntaxError(error_type, label);
      return NEW(ExpressionStatement(throw_error));
    }
  }
  ExpectSemicolon(CHECK_OK);
  return NEW(BreakStatement(target));
}


Statement* Parser::ParseReturnStatement(bool* ok) {
  // ReturnStatement ::
  //   'return' Expression? ';'

  // Consume the return token. It is necessary to do the before
  // reporting any errors on it, because of the way errors are
  // reported (underlining).
  Expect(Token::RETURN, CHECK_OK);

  // An ECMAScript program is considered syntactically incorrect if it
  // contains a return statement that is not within the body of a
  // function. See ECMA-262, section 12.9, page 67.
  //
  // To be consistent with KJS we report the syntax error at runtime.
  if (!is_pre_parsing_ && !top_scope_->is_function_scope()) {
    Handle<String> type = Factory::illegal_return_symbol();
    Expression* throw_error = NewThrowSyntaxError(type, Handle<Object>::null());
    return NEW(ExpressionStatement(throw_error));
  }

  Token::Value tok = peek();
  if (scanner_.has_line_terminator_before_next() ||
      tok == Token::SEMICOLON ||
      tok == Token::RBRACE ||
      tok == Token::EOS) {
    ExpectSemicolon(CHECK_OK);
    return NEW(ReturnStatement(GetLiteralUndefined()));
  }

  Expression* expr = ParseExpression(true, CHECK_OK);
  ExpectSemicolon(CHECK_OK);
  return NEW(ReturnStatement(expr));
}


Block* Parser::WithHelper(Expression* obj, ZoneStringList* labels, bool* ok) {
  // Parse the statement and collect escaping labels.
  ZoneList<Label*>* label_list = NEW(ZoneList<Label*>(0));
  LabelCollector collector(label_list);
  Statement* stat;
  { Target target(this, &collector);
    with_nesting_level_++;
    top_scope_->RecordWithStatement();
    stat = ParseStatement(labels, CHECK_OK);
    with_nesting_level_--;
  }
  // Create resulting block with two statements.
  // 1: Evaluate the with expression.
  // 2: The try-finally block evaluating the body.
  Block* result = NEW(Block(NULL, 2, false));

  if (result) {
    result->AddStatement(NEW(WithEnterStatement(obj)));

    // Create body block.
    Block* body = NEW(Block(NULL, 1, false));
    body->AddStatement(stat);

    // Create exit block.
    Block* exit = NEW(Block(NULL, 1, false));
    exit->AddStatement(NEW(WithExitStatement()));

    // Return a try-finally statement.
    TryFinally* wrapper = NEW(TryFinally(body, NULL, exit));
    wrapper->set_escaping_labels(collector.labels());
    result->AddStatement(wrapper);
    return result;
  } else {
    return NULL;
  }
}


Statement* Parser::ParseWithStatement(ZoneStringList* labels, bool* ok) {
  // WithStatement ::
  //   'with' '(' Expression ')' Statement

  // We do not allow the use of 'with' statements in the internal JS
  // code. If 'with' statements were allowed, the simplified setup of
  // the runtime context chain would allow access to properties in the
  // global object from within a 'with' statement.
  ASSERT(!Bootstrapper::IsActive());

  Expect(Token::WITH, CHECK_OK);
  Expect(Token::LPAREN, CHECK_OK);
  Expression* expr = ParseExpression(true, CHECK_OK);
  Expect(Token::RPAREN, CHECK_OK);

  return WithHelper(expr, labels, CHECK_OK);
}


CaseClause* Parser::ParseCaseClause(bool* default_seen_ptr, bool* ok) {
  // CaseClause ::
  //   'case' Expression ':' Statement*
  //   'default' ':' Statement*

  Expression* label = NULL;  // NULL expression indicates default case
  if (peek() == Token::CASE) {
    Expect(Token::CASE, CHECK_OK);
    label = ParseExpression(true, CHECK_OK);
  } else {
    Expect(Token::DEFAULT, CHECK_OK);
    if (*default_seen_ptr) {
      ReportMessage("multiple_defaults_in_switch",
                    Vector<const char*>::empty());
      *ok = false;
      return NULL;
    }
    *default_seen_ptr = true;
  }
  Expect(Token::COLON, CHECK_OK);

  ZoneListWrapper<Statement> statements = factory()->NewList<Statement>(5);
  while (peek() != Token::CASE &&
         peek() != Token::DEFAULT &&
         peek() != Token::RBRACE) {
    Statement* stat = ParseStatement(NULL, CHECK_OK);
    statements.Add(stat);
  }

  return NEW(CaseClause(label, statements.elements()));
}


SwitchStatement* Parser::ParseSwitchStatement(ZoneStringList* labels,
                                              bool* ok) {
  // SwitchStatement ::
  //   'switch' '(' Expression ')' '{' CaseClause* '}'

  SwitchStatement* statement = NEW(SwitchStatement(labels));
  Target target(this, statement);

  Expect(Token::SWITCH, CHECK_OK);
  Expect(Token::LPAREN, CHECK_OK);
  Expression* tag = ParseExpression(true, CHECK_OK);
  Expect(Token::RPAREN, CHECK_OK);

  bool default_seen = false;
  ZoneListWrapper<CaseClause> cases = factory()->NewList<CaseClause>(4);
  Expect(Token::LBRACE, CHECK_OK);
  while (peek() != Token::RBRACE) {
    CaseClause* clause = ParseCaseClause(&default_seen, CHECK_OK);
    cases.Add(clause);
  }
  Expect(Token::RBRACE, CHECK_OK);

  if (statement) statement->Initialize(tag, cases.elements());
  return statement;
}


Statement* Parser::ParseThrowStatement(bool* ok) {
  // ThrowStatement ::
  //   'throw' Expression ';'

  Expect(Token::THROW, CHECK_OK);
  int pos = scanner().location().beg_pos;
  if (scanner_.has_line_terminator_before_next()) {
    ReportMessage("newline_after_throw", Vector<const char*>::empty());
    *ok = false;
    return NULL;
  }
  Expression* exception = ParseExpression(true, CHECK_OK);
  ExpectSemicolon(CHECK_OK);

  return NEW(ExpressionStatement(new Throw(exception, pos)));
}


Expression* Parser::MakeCatchContext(Handle<String> id, VariableProxy* value) {
  ZoneListWrapper<ObjectLiteral::Property> properties =
      factory()->NewList<ObjectLiteral::Property>(1);
  Literal* key = NEW(Literal(id));
  ObjectLiteral::Property* property = NEW(ObjectLiteral::Property(key, value));
  properties.Add(property);

  // This must be called always, even during pre-parsing!
  // (Computation of literal index must happen before pre-parse bailout.)
  int literal_index = temp_scope_->NextMaterializedLiteralIndex();
  if (is_pre_parsing_) {
    return NULL;
  }

  // Construct the expression for calling Runtime::CreateObjectLiteral
  // with the literal array as argument.
  Handle<FixedArray> constant_properties = Factory::empty_fixed_array();
  ZoneList<Expression*>* arguments = new ZoneList<Expression*>(1);
  arguments->Add(new Literal(constant_properties));

  return new ObjectLiteral(constant_properties,
                           properties.elements(),
                           literal_index);
}


TryStatement* Parser::ParseTryStatement(bool* ok) {
  // TryStatement ::
  //   'try' Block Catch
  //   'try' Block Finally
  //   'try' Block Catch Finally
  //
  // Catch ::
  //   'catch' '(' Identifier ')' Block
  //
  // Finally ::
  //   'finally' Block

  Expect(Token::TRY, CHECK_OK);

  ZoneList<Label*>* label_list = NEW(ZoneList<Label*>(0));
  LabelCollector collector(label_list);
  Block* try_block;

  { Target target(this, &collector);
    try_block = ParseBlock(NULL, CHECK_OK);
  }

  Block* catch_block = NULL;
  VariableProxy* catch_var = NULL;
  Block* finally_block = NULL;

  Token::Value tok = peek();
  if (tok != Token::CATCH && tok != Token::FINALLY) {
    ReportMessage("no_catch_or_finally", Vector<const char*>::empty());
    *ok = false;
    return NULL;
  }

  // If we can break out from the catch block and there is a finally block,
  // then we will need to collect labels from the catch block. Since we don't
  // know yet if there will be a finally block, we always collect the labels.
  ZoneList<Label*>* catch_label_list = NEW(ZoneList<Label*>(0));
  LabelCollector catch_collector(catch_label_list);
  bool has_catch = false;
  if (tok == Token::CATCH) {
    has_catch = true;
    Consume(Token::CATCH);

    Expect(Token::LPAREN, CHECK_OK);
    Handle<String> name = ParseIdentifier(CHECK_OK);
    Expect(Token::RPAREN, CHECK_OK);

    if (peek() == Token::LBRACE) {
      // Allocate a temporary for holding the finally state while
      // executing the finally block.
      catch_var = top_scope_->NewTemporary(Factory::catch_var_symbol());
      Expression* obj = MakeCatchContext(name, catch_var);
      { Target target(this, &catch_collector);
        catch_block = WithHelper(obj, NULL, CHECK_OK);
      }
    } else {
      Expect(Token::LBRACE, CHECK_OK);
    }

    tok = peek();
  }

  VariableProxy* finally_var = NULL;
  if (tok == Token::FINALLY || !has_catch) {
    Consume(Token::FINALLY);
    // Declare a variable for holding the finally state while
    // executing the finally block.
    finally_var = top_scope_->NewTemporary(Factory::finally_state_symbol());
    finally_block = ParseBlock(NULL, CHECK_OK);
  }

  // Simplify the AST nodes by converting:
  //   'try { } catch { } finally { }'
  // to:
  //   'try { try { } catch { } } finally { }'

  if (!is_pre_parsing_ && catch_block != NULL && finally_block != NULL) {
    TryCatch* statement = NEW(TryCatch(try_block, catch_var, catch_block));
    statement->set_escaping_labels(collector.labels());
    try_block = NEW(Block(NULL, 1, false));
    try_block->AddStatement(statement);
    catch_block = NULL;
  }

  TryStatement* result = NULL;
  if (!is_pre_parsing_) {
    if (catch_block != NULL) {
      ASSERT(finally_block == NULL);
      result = NEW(TryCatch(try_block, catch_var, catch_block));
      result->set_escaping_labels(collector.labels());
    } else {
      ASSERT(finally_block != NULL);
      result = NEW(TryFinally(try_block, finally_var, finally_block));
      // Add the labels of the try block and the catch block.
      for (int i = 0; i < collector.labels()->length(); i++) {
        catch_collector.labels()->Add(collector.labels()->at(i));
      }
      result->set_escaping_labels(catch_collector.labels());
    }
  }

  return result;
}


LoopStatement* Parser::ParseDoStatement(ZoneStringList* labels, bool* ok) {
  // DoStatement ::
  //   'do' Statement 'while' '(' Expression ')' ';'

  LoopStatement* loop = NEW(LoopStatement(labels, LoopStatement::DO_LOOP));
  Target target(this, loop);

  Expect(Token::DO, CHECK_OK);
  Statement* body = ParseStatement(NULL, CHECK_OK);
  Expect(Token::WHILE, CHECK_OK);
  Expect(Token::LPAREN, CHECK_OK);
  Expression* cond = ParseExpression(true, CHECK_OK);
  Expect(Token::RPAREN, CHECK_OK);

  // Allow do-statements to be terminated with and without
  // semi-colons. This allows code such as 'do;while(0)return' to
  // parse, which would not be the case if we had used the
  // ExpectSemicolon() functionality here.
  if (peek() == Token::SEMICOLON) Consume(Token::SEMICOLON);

  if (loop) loop->Initialize(NULL, cond, NULL, body);
  return loop;
}


LoopStatement* Parser::ParseWhileStatement(ZoneStringList* labels, bool* ok) {
  // WhileStatement ::
  //   'while' '(' Expression ')' Statement

  LoopStatement* loop = NEW(LoopStatement(labels, LoopStatement::WHILE_LOOP));
  Target target(this, loop);

  Expect(Token::WHILE, CHECK_OK);
  Expect(Token::LPAREN, CHECK_OK);
  Expression* cond = ParseExpression(true, CHECK_OK);
  Expect(Token::RPAREN, CHECK_OK);
  Statement* body = ParseStatement(NULL, CHECK_OK);

  if (loop) loop->Initialize(NULL, cond, NULL, body);
  return loop;
}


Statement* Parser::ParseForStatement(ZoneStringList* labels, bool* ok) {
  // ForStatement ::
  //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement

  Statement* init = NULL;

  Expect(Token::FOR, CHECK_OK);
  Expect(Token::LPAREN, CHECK_OK);
  if (peek() != Token::SEMICOLON) {
    if (peek() == Token::VAR || peek() == Token::CONST) {