parser.cc.svn-base

Google浏览器V8内核代码

    LexicalScope lexical_scope(this, scope);
    TemporaryScope temp_scope(this);
    ZoneListWrapper<Statement> body(16);
    bool ok = true;
    ParseSourceElements(&body, Token::EOS, &ok);
    if (ok) {
      result = NEW(FunctionLiteral(no_name, top_scope_,
                                   body.elements(),
                                   temp_scope.materialized_literal_count(),
                                   temp_scope.contains_array_literal(),
                                   temp_scope.expected_property_count(),
                                   0, 0, source->length(), false));
    } else if (scanner().stack_overflow()) {
      Top::StackOverflow();
    }
  }

  // Make sure the target stack is empty.
  ASSERT(target_stack_ == NULL);

  // If there was a syntax error we have to get rid of the AST
  // and it is not safe to do so before the scope has been deleted.
  if (result == NULL) zone_scope.DeleteOnExit();
  return result;
}


FunctionLiteral* Parser::ParseLazy(Handle<String> source,
                                   Handle<String> name,
                                   int start_position,
                                   bool is_expression) {
  ZoneScope zone_scope(DONT_DELETE_ON_EXIT);
  StatsRateScope timer(&Counters::parse_lazy);
  Counters::total_parse_size.Increment(source->length());
  SafeStringInputBuffer buffer(source.location());

  // Initialize parser state.
  source->TryFlatten();
  scanner_.Init(source, &buffer, start_position);
  ASSERT(target_stack_ == NULL);
  mode_ = PARSE_EAGERLY;

  // Place holder for the result.
  FunctionLiteral* result = NULL;

  {
    // Parse the function literal.
    Handle<String> no_name = factory()->EmptySymbol();
    Scope* scope =
        factory()->NewScope(top_scope_, Scope::GLOBAL_SCOPE, inside_with());
    LexicalScope lexical_scope(this, scope);
    TemporaryScope temp_scope(this);

    FunctionLiteralType type = is_expression ? EXPRESSION : DECLARATION;
    bool ok = true;
    result = ParseFunctionLiteral(name, RelocInfo::kNoPosition, type, &ok);
    // Make sure the results agree.
    ASSERT(ok == (result != NULL));
    // The only errors should be stack overflows.
    ASSERT(ok || scanner_.stack_overflow());
  }

  // Make sure the target stack is empty.
  ASSERT(target_stack_ == NULL);

  // If there was a stack overflow we have to get rid of AST and it is
  // not safe to do before scope has been deleted.
  if (result == NULL) {
    Top::StackOverflow();
    zone_scope.DeleteOnExit();
  }
  return result;
}


void Parser::ReportMessage(const char* type, Vector<const char*> args) {
  Scanner::Location source_location = scanner_.location();
  ReportMessageAt(source_location, type, args);
}


void AstBuildingParser::ReportMessageAt(Scanner::Location source_location,
                                        const char* type,
                                        Vector<const char*> args) {
  MessageLocation location(script_,
                           source_location.beg_pos, source_location.end_pos);
  Handle<JSArray> array = Factory::NewJSArray(args.length());
  for (int i = 0; i < args.length(); i++) {
    SetElement(array, i, Factory::NewStringFromUtf8(CStrVector(args[i])));
  }
  Handle<Object> result = Factory::NewSyntaxError(type, array);
  Top::Throw(*result, &location);
}


void PreParser::ReportMessageAt(Scanner::Location source_location,
                                const char* type,
                                Vector<const char*> args) {
  recorder()->LogMessage(source_location, type, args);
}


void* Parser::ParseSourceElements(ZoneListWrapper<Statement>* processor,
                                  int end_token,
                                  bool* ok) {
  // SourceElements ::
  //   (Statement)* <end_token>

  // Allocate a target stack to use for this set of source
  // elements. This way, all scripts and functions get their own
  // target stack thus avoiding illegal breaks and continues across
  // functions.
  TargetScope scope(this);

  ASSERT(processor != NULL);
  while (peek() != end_token) {
    Statement* stat = ParseStatement(NULL, CHECK_OK);
    if (stat && !stat->IsEmpty()) processor->Add(stat);
  }
  return 0;
}


Statement* Parser::ParseStatement(ZoneStringList* labels, bool* ok) {
  // Statement ::
  //   Block
  //   VariableStatement
  //   EmptyStatement
  //   ExpressionStatement
  //   IfStatement
  //   IterationStatement
  //   ContinueStatement
  //   BreakStatement
  //   ReturnStatement
  //   WithStatement
  //   LabelledStatement
  //   SwitchStatement
  //   ThrowStatement
  //   TryStatement
  //   DebuggerStatement

  // Note: Since labels can only be used by 'break' and 'continue'
  // statements, which themselves are only valid within blocks,
  // iterations or 'switch' statements (i.e., BreakableStatements),
  // labels can be simply ignored in all other cases; except for
  // trivial labelled break statements 'label: break label' which is
  // parsed into an empty statement.

  // Keep the source position of the statement
  int statement_pos = scanner().peek_location().beg_pos;
  Statement* stmt = NULL;
  switch (peek()) {
    case Token::LBRACE:
      return ParseBlock(labels, ok);

    case Token::CONST:  // fall through
    case Token::VAR:
      stmt = ParseVariableStatement(ok);
      break;

    case Token::SEMICOLON:
      Next();
      return factory()->EmptyStatement();

    case Token::IF:
      stmt = ParseIfStatement(labels, ok);
      break;

    case Token::DO:
      stmt = ParseDoStatement(labels, ok);
      break;

    case Token::WHILE:
      stmt = ParseWhileStatement(labels, ok);
      break;

    case Token::FOR:
      stmt = ParseForStatement(labels, ok);
      break;

    case Token::CONTINUE:
      stmt = ParseContinueStatement(ok);
      break;

    case Token::BREAK:
      stmt = ParseBreakStatement(labels, ok);
      break;

    case Token::RETURN:
      stmt = ParseReturnStatement(ok);
      break;

    case Token::WITH:
      stmt = ParseWithStatement(labels, ok);
      break;

    case Token::SWITCH:
      stmt = ParseSwitchStatement(labels, ok);
      break;

    case Token::THROW:
      stmt = ParseThrowStatement(ok);
      break;

    case Token::TRY: {
      // NOTE: It is somewhat complicated to have labels on
      // try-statements. When breaking out of a try-finally statement,
      // one must take great care not to treat it as a
      // fall-through. It is much easier just to wrap the entire
      // try-statement in a statement block and put the labels there
      Block* result = NEW(Block(labels, 1, false));
      Target target(this, result);
      TryStatement* statement = ParseTryStatement(CHECK_OK);
      if (result) result->AddStatement(statement);
      return result;
    }

    case Token::FUNCTION:
      return ParseFunctionDeclaration(ok);

    case Token::NATIVE:
      return ParseNativeDeclaration(ok);

    case Token::DEBUGGER:
      stmt = ParseDebuggerStatement(ok);
      break;

    default:
      stmt = ParseExpressionOrLabelledStatement(labels, ok);
  }

  // Store the source position of the statement
  if (stmt != NULL) stmt->set_statement_pos(statement_pos);
  return stmt;
}


VariableProxy* AstBuildingParser::Declare(Handle<String> name,
                                          Variable::Mode mode,
                                          FunctionLiteral* fun,
                                          bool resolve,
                                          bool* ok) {
  Variable* var = NULL;
  // If we are inside a function, a declaration of a variable
  // is a truly local variable, and the scope of the variable
  // is always the function scope.

  // If a function scope exists, then we can statically declare this
  // variable and also set its mode. In any case, a Declaration node
  // will be added to the scope so that the declaration can be added
  // to the corresponding activation frame at runtime if necessary.
  // For instance declarations inside an eval scope need to be added
  // to the calling function context.
  if (top_scope_->is_function_scope()) {
    // Declare the variable in the function scope.
    var = top_scope_->Lookup(name);
    if (var == NULL) {
      // Declare the name.
      var = top_scope_->Declare(name, mode);
    } else {
      // The name was declared before; check for conflicting
      // re-declarations. If the previous declaration was a const or the
      // current declaration is a const then we have a conflict. There is
      // similar code in runtime.cc in the Declare functions.
      if ((mode == Variable::CONST) || (var->mode() == Variable::CONST)) {
        // We only have vars and consts in declarations.
        ASSERT(var->mode() == Variable::VAR ||
               var->mode() == Variable::CONST);
        const char* type = (var->mode() == Variable::VAR) ? "var" : "const";
        Handle<String> type_string =
            Factory::NewStringFromUtf8(CStrVector(type), TENURED);
        Expression* expression =
            NewThrowTypeError(Factory::redeclaration_symbol(),
                              type_string, name);
        top_scope_->SetIllegalRedeclaration(expression);
      }
    }
  }

  // We add a declaration node for every declaration. The compiler
  // will only generate code if necessary. In particular, declarations
  // for inner local variables that do not represent functions won't
  // result in any generated code.
  //
  // Note that we always add an unresolved proxy even if it's not
  // used, simply because we don't know in this method (w/o extra
  // parameters) if the proxy is needed or not. The proxy will be
  // bound during variable resolution time unless it was pre-bound
  // below.
  //
  // WARNING: This will lead to multiple declaration nodes for the
  // same variable if it is declared several times. This is not a
  // semantic issue as long as we keep the source order, but it may be
  // a performance issue since it may lead to repeated
  // Runtime::DeclareContextSlot() calls.
  VariableProxy* proxy = top_scope_->NewUnresolved(name, inside_with());
  top_scope_->AddDeclaration(NEW(Declaration(proxy, mode, fun)));

  // For global const variables we bind the proxy to a variable.
  if (mode == Variable::CONST && top_scope_->is_global_scope()) {
    ASSERT(resolve);  // should be set by all callers
    var = NEW(Variable(top_scope_, name, Variable::CONST, true, false));
  }

  // If requested and we have a local variable, bind the proxy to the variable
  // at parse-time. This is used for functions (and consts) declared inside
  // statements: the corresponding function (or const) variable must be in the
  // function scope and not a statement-local scope, e.g. as provided with a
  // 'with' statement:
  //
  //   with (obj) {
  //     function f() {}
  //   }
  //
  // which is translated into:
  //
  //   with (obj) {
  //     // in this case this is not: 'var f; f = function () {};'
  //     var f = function () {};
  //   }
  //
  // Note that if 'f' is accessed from inside the 'with' statement, it
  // will be allocated in the context (because we must be able to look
  // it up dynamically) but it will also be accessed statically, i.e.,
  // with a context slot index and a context chain length for this
  // initialization code. Thus, inside the 'with' statement, we need
  // both access to the static and the dynamic context chain; the
  // runtime needs to provide both.
  if (resolve && var != NULL) proxy->BindTo(var);

  return proxy;
}


// Language extension which is only enabled for source files loaded
// through the API's extension mechanism.  A native function
// declaration is resolved by looking up the function through a
// callback provided by the extension.
Statement* Parser::ParseNativeDeclaration(bool* ok) {
  if (extension_ == NULL) {
    ReportUnexpectedToken(Token::NATIVE);
    *ok = false;
    return NULL;
  }

  Expect(Token::NATIVE, CHECK_OK);
  Expect(Token::FUNCTION, CHECK_OK);
  Handle<String> name = ParseIdentifier(CHECK_OK);
  Expect(Token::LPAREN, CHECK_OK);
  bool done = (peek() == Token::RPAREN);
  while (!done) {
    ParseIdentifier(CHECK_OK);
    done = (peek() == Token::RPAREN);
    if (!done) Expect(Token::COMMA, CHECK_OK);
  }
  Expect(Token::RPAREN, CHECK_OK);
  Expect(Token::SEMICOLON, CHECK_OK);

  if (is_pre_parsing_) return NULL;

  // Make sure that the function containing the native declaration
  // isn't lazily compiled. The extension structures are only
  // accessible while parsing the first time not when reparsing
  // because of lazy compilation.
  top_scope_->ForceEagerCompilation();

  // Compute the function template for the native function.
  v8::Handle<v8::FunctionTemplate> fun_template =
      extension_->GetNativeFunction(v8::Utils::ToLocal(name));
  ASSERT(!fun_template.IsEmpty());

  // Instantiate the function and create a boilerplate function from it.
  Handle<JSFunction> fun = Utils::OpenHandle(*fun_template->GetFunction());
  const int literals = fun->NumberOfLiterals();
  Handle<Code> code = Handle<Code>(fun->shared()->code());
  Handle<JSFunction> boilerplate =
      Factory::NewFunctionBoilerplate(name, literals, false, code);

  // Copy the function data to the boilerplate. Used by