Stand-alone parser template.

src/preparser.h

+// Copyright 2010 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_PREPARSER_H
+#define V8_PREPARSER_H
+
+#include "unicode.h"
+
+namespace v8 {
+namespace internal {
+namespace preparser {
+
+// Preparsing checks a JavaScript program and emits preparse-data that helps
+// a later parsing to be faster.
+// See preparser-data.h for the data.
+
+// The PreParser checks that the syntax follows the grammar for JavaScript,
+// and collects some information about the program along the way.
+// The grammar check is only performed in order to understand the program
+// sufficiently to deduce some information about it, that can be used
+// to speed up later parsing. Finding errors is not the goal of pre-parsing,
+// rather it is to speed up properly written and correct programs.
+// That means that contextual checks (like a label being declared where
+// it is used) are generally omitted.
+
+enum StatementType {
+  kUnknownStatement
+};
+
+enum ExpressionType {
+  kUnknownExpression,
+  kIdentifierExpression,  // Used to detect labels.
+  kThisExpression,
+  kThisPropertyExpression
+};
+
+enum IdentifierType {
+  kUnknownIdentifier
+};
+
+enum SourceElementTypes {
+  kUnknownSourceElements
+};
+
+
+typedef int SourceElements;
+typedef int Expression;
+typedef int Statement;
+typedef int Identifier;
+typedef int Arguments;
+
+
+template <typename Scanner, typename PreParserLog>
+class PreParser {
+ public:
+  PreParser() : scope_(NULL), allow_lazy_(true) { }
+  ~PreParser() { }
+
+  // Pre-parse the program from the character stream; returns true on
+  // success (even if parsing failed, the pre-parse data successfully
+  // captured the syntax error), and false if a stack-overflow happened
+  // during parsing.
+  bool PreParseProgram(Scanner* scanner,
+                       PreParserLog* log,
+                       bool allow_lazy) {
+    allow_lazy_ = allow_lazy;
+    scanner_ = scanner;
+    log_ = log;
+    Scope top_scope(&scope_, kTopLevelScope);
+    bool ok = true;
+    ParseSourceElements(Token::EOS, &ok);
+    bool stack_overflow = scanner_->stack_overflow();
+    if (!ok && !stack_overflow) {
+      ReportUnexpectedToken(scanner_->current_token());
+    }
+    return !stack_overflow;
+  }
+
+ private:
+  enum ScopeType {
+    kTopLevelScope,
+    kFunctionScope
+  };
+
+  class Scope {
+   public:
+    Scope(Scope** variable, ScopeType type)
+        : variable_(variable),
+          prev_(*variable),
+          type_(type),
+          materialized_literal_count_(0),
+          expected_properties_(0),
+          with_nesting_count_(0) {
+      *variable = this;
+    }
+    ~Scope() { *variable_ = prev_; }
+    void NextMaterializedLiteralIndex() { materialized_literal_count_++; }
+    void AddProperty() { expected_properties_++; }
+    ScopeType type() { return type_; }
+    int expected_properties() { return expected_properties_; }
+    int materialized_literal_count() { return materialized_literal_count_; }
+    bool IsInsideWith() { return with_nesting_count_ != 0; }
+    void EnterWith() { with_nesting_count_++; }
+    void LeaveWith() { with_nesting_count_--; }
+
+   private:
+    Scope** const variable_;
+    Scope* const prev_;
+    const ScopeType type_;
+    int materialized_literal_count_;
+    int expected_properties_;
+    int with_nesting_count_;
+  };
+
+  // Types that allow us to recognize simple this-property assignments.
+  // A simple this-property assignment is a statement on the form
+  // "this.propertyName = {primitive constant or function parameter name);"
+  // where propertyName isn't "__proto__".
+  // The result is only relevant if the function body contains only
+  // simple this-property assignments.
+
+  // Report syntax error
+  void ReportUnexpectedToken(Token::Value token);
+  void ReportMessageAt(int start_pos,
+                       int end_pos,
+                       const char* type,
+                       const char* name_opt) {
+    log_->LogMessage(start_pos, end_pos, type, name_opt);
+  }
+
+  // All ParseXXX functions take as the last argument an *ok parameter
+  // which is set to false if parsing failed; it is unchanged otherwise.
+  // By making the 'exception handling' explicit, we are forced to check
+  // for failure at the call sites.
+  SourceElements ParseSourceElements(int end_token, bool* ok);
+  Statement ParseStatement(bool* ok);
+  Statement ParseFunctionDeclaration(bool* ok);
+  Statement ParseNativeDeclaration(bool* ok);
+  Statement ParseBlock(bool* ok);
+  Statement ParseVariableStatement(bool* ok);
+  Statement ParseVariableDeclarations(bool accept_IN, int* num_decl, bool* ok);
+  Statement ParseExpressionOrLabelledStatement(bool* ok);
+  Statement ParseIfStatement(bool* ok);
+  Statement ParseContinueStatement(bool* ok);
+  Statement ParseBreakStatement(bool* ok);
+  Statement ParseReturnStatement(bool* ok);
+  Statement ParseWithStatement(bool* ok);
+  Statement ParseSwitchStatement(bool* ok);
+  Statement ParseDoWhileStatement(bool* ok);
+  Statement ParseWhileStatement(bool* ok);
+  Statement ParseForStatement(bool* ok);
+  Statement ParseThrowStatement(bool* ok);
+  Statement ParseTryStatement(bool* ok);
+  Statement ParseDebuggerStatement(bool* ok);
+
+  Expression ParseExpression(bool accept_IN, bool* ok);
+  Expression ParseAssignmentExpression(bool accept_IN, bool* ok);
+  Expression ParseConditionalExpression(bool accept_IN, bool* ok);
+  Expression ParseBinaryExpression(int prec, bool accept_IN, bool* ok);
+  Expression ParseUnaryExpression(bool* ok);
+  Expression ParsePostfixExpression(bool* ok);
+  Expression ParseLeftHandSideExpression(bool* ok);
+  Expression ParseNewExpression(bool* ok);
+  Expression ParseMemberExpression(bool* ok);
+  Expression ParseNewPrefix(int* new_count, bool* ok);
+  Expression ParseMemberWithNewPrefixesExpression(int* new_count, bool* ok);
+  Expression ParsePrimaryExpression(bool* ok);
+  Expression ParseArrayLiteral(bool* ok);
+  Expression ParseObjectLiteral(bool* ok);
+  Expression ParseRegExpLiteral(bool seen_equal, bool* ok);
+  Expression ParseV8Intrinsic(bool* ok);
+
+  Arguments ParseArguments(bool* ok);
+  Expression ParseFunctionLiteral(bool* ok);
+
+  Identifier ParseIdentifier(bool* ok);
+  Identifier ParseIdentifierName(bool* ok);
+  Identifier ParseIdentifierOrGetOrSet(bool* is_get, bool* is_set, bool* ok);
+
+  Identifier GetIdentifierSymbol();
+  unsigned int HexDigitValue(char digit);
+  Expression GetStringSymbol();
+
+
+  Token::Value peek() { return scanner_->peek(); }
+  Token::Value Next() {
+    Token::Value next = scanner_->Next();
+    return next;
+  }
+
+  void Consume(Token::Value token) {
+    Next();
+  }
+
+  void Expect(Token::Value token, bool* ok) {
+    if (Next() != token) {
+      *ok = false;
+    }
+  }
+
+  bool Check(Token::Value token) {
+    Token::Value next = peek();
+    if (next == token) {
+      Consume(next);
+      return true;
+    }
+    return false;
+  }
+  void ExpectSemicolon(bool* ok);
+
+  static int Precedence(Token::Value tok, bool accept_IN);
+
+  Scanner* scanner_;
+  PreParserLog* log_;
+  Scope* scope_;
+  bool allow_lazy_;
+};
+
+
+#define CHECK_OK  ok);   \
+  if (!*ok) return -1; \

[Mads Ager (chromium), 2010/11/02 07:17:03]

Align the two '\'

+  ((void)0
+#define DUMMY )  // to make indentation work
+#undef DUMMY
+
+
+template <typename Scanner, typename Log>
+void PreParser<Scanner, Log>::ReportUnexpectedToken(Token::Value token) {
+  // We don't report stack overflows here, to avoid increasing the
+  // stack depth even further.  Instead we report it after parsing is
+  // over, in ParseProgram.
+  if (token == Token::ILLEGAL && scanner_->stack_overflow()) {
+    return;
+  }
+  typename Scanner::Location source_location = scanner_->location();
+
+  // Four of the tokens are treated specially
+  switch (token) {
+  case Token::EOS:
+    return ReportMessageAt(source_location.beg_pos, source_location.end_pos,
+                           "unexpected_eos", NULL);
+  case Token::NUMBER:
+    return ReportMessageAt(source_location.beg_pos, source_location.end_pos,
+                           "unexpected_token_number", NULL);
+  case Token::STRING:
+    return ReportMessageAt(source_location.beg_pos, source_location.end_pos,
+                           "unexpected_token_string", NULL);
+  case Token::IDENTIFIER:
+    return ReportMessageAt(source_location.beg_pos, source_location.end_pos,
+                           "unexpected_token_identifier", NULL);
+  default:
+    const char* name = Token::String(token);
+    ReportMessageAt(source_location.beg_pos, source_location.end_pos,
+                    "unexpected_token", name);
+  }
+}
+
+
+template <typename Scanner, typename Log>
+SourceElements PreParser<Scanner, Log>::ParseSourceElements(int end_token,
+                                                            bool* ok) {
+  // SourceElements ::
+  //   (Statement)* <end_token>
+
+  while (peek() != end_token) {
+    ParseStatement(CHECK_OK);
+  }
+  return kUnknownSourceElements;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseStatement(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 labeled break statements 'label: break label' which is
+  // parsed into an empty statement.
+
+  // Keep the source position of the statement
+  switch (peek()) {
+    case Token::LBRACE:
+      return ParseBlock(ok);
+
+    case Token::CONST:
+    case Token::VAR:
+      return ParseVariableStatement(ok);
+
+    case Token::SEMICOLON:
+      Next();
+      return kUnknownStatement;
+
+    case Token::IF:
+      return  ParseIfStatement(ok);
+
+    case Token::DO:
+      return ParseDoWhileStatement(ok);
+
+    case Token::WHILE:
+      return ParseWhileStatement(ok);
+
+    case Token::FOR:
+      return ParseForStatement(ok);
+
+    case Token::CONTINUE:
+      return ParseContinueStatement(ok);
+
+    case Token::BREAK:
+      return ParseBreakStatement(ok);
+
+    case Token::RETURN:
+      return ParseReturnStatement(ok);
+
+    case Token::WITH:
+      return ParseWithStatement(ok);
+
+    case Token::SWITCH:
+      return ParseSwitchStatement(ok);
+
+    case Token::THROW:
+      return ParseThrowStatement(ok);
+
+    case Token::TRY:
+      return ParseTryStatement(ok);
+
+    case Token::FUNCTION:
+      return ParseFunctionDeclaration(ok);
+
+    case Token::NATIVE:
+      return ParseNativeDeclaration(ok);
+
+    case Token::DEBUGGER:
+      return ParseDebuggerStatement(ok);
+
+    default:
+      return ParseExpressionOrLabelledStatement(ok);
+  }
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseFunctionDeclaration(bool* ok) {
+  // FunctionDeclaration ::
+  //   'function' Identifier '(' FormalParameterListopt ')' '{' FunctionBody '}'
+  Expect(Token::FUNCTION, CHECK_OK);
+  ParseIdentifier(CHECK_OK);
+  ParseFunctionLiteral(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+// 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.
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseNativeDeclaration(bool* ok) {
+  Expect(Token::NATIVE, CHECK_OK);
+  Expect(Token::FUNCTION, CHECK_OK);
+  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);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseBlock(bool* ok) {
+  // Block ::
+  //   '{' Statement* '}'
+
+  // Note that a Block does not introduce a new execution scope!
+  // (ECMA-262, 3rd, 12.2)
+  //
+  Expect(Token::LBRACE, CHECK_OK);
+  while (peek() != Token::RBRACE) {
+    ParseStatement(CHECK_OK);
+  }
+  Expect(Token::RBRACE, CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseVariableStatement(bool* ok) {
+  // VariableStatement ::
+  //   VariableDeclarations ';'
+
+  Statement result = ParseVariableDeclarations(true, NULL, CHECK_OK);
+  ExpectSemicolon(CHECK_OK);
+  return result;
+}
+
+
+// If the variable declaration declares exactly one non-const
+// variable, then *var is set to that variable. In all other cases,
+// *var is untouched; in particular, it is the caller's responsibility
+// to initialize it properly. This mechanism is also used for the parsing
+// of 'for-in' loops.
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseVariableDeclarations(bool accept_IN,
+                                                  int* num_decl,
+                                                  bool* ok) {
+  // VariableDeclarations ::
+  //   ('var' | 'const') (Identifier ('=' AssignmentExpression)?)+[',']
+
+  if (peek() == Token::VAR) {
+    Consume(Token::VAR);
+  } else if (peek() == Token::CONST) {
+    Consume(Token::CONST);
+  } else {
+    *ok = false;
+    return 0;
+  }
+
+  // The scope of a variable/const declared anywhere inside a function
+  // is the entire function (ECMA-262, 3rd, 10.1.3, and 12.2). .
+  int nvars = 0;  // the number of variables declared
+  do {
+    // Parse variable name.
+    if (nvars > 0) Consume(Token::COMMA);
+    ParseIdentifier(CHECK_OK);
+    nvars++;
+    if (peek() == Token::ASSIGN) {
+      Expect(Token::ASSIGN, CHECK_OK);
+      ParseAssignmentExpression(accept_IN, CHECK_OK);
+    }
+  } while (peek() == Token::COMMA);
+
+  if (num_decl != NULL) *num_decl = nvars;
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseExpressionOrLabelledStatement(
+    bool* ok) {
+  // ExpressionStatement | LabelledStatement ::
+  //   Expression ';'
+  //   Identifier ':' Statement
+
+  Expression expr = ParseExpression(true, CHECK_OK);
+  if (peek() == Token::COLON && expr == kIdentifierExpression) {
+    Consume(Token::COLON);
+    return ParseStatement(ok);
+  }
+  // Parsed expression statement.
+  ExpectSemicolon(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseIfStatement(bool* ok) {
+  // IfStatement ::
+  //   'if' '(' Expression ')' Statement ('else' Statement)?
+
+  Expect(Token::IF, CHECK_OK);
+  Expect(Token::LPAREN, CHECK_OK);
+  ParseExpression(true, CHECK_OK);
+  Expect(Token::RPAREN, CHECK_OK);
+  ParseStatement(CHECK_OK);
+  if (peek() == Token::ELSE) {
+    Next();
+    ParseStatement(CHECK_OK);
+  }
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseContinueStatement(bool* ok) {
+  // ContinueStatement ::
+  //   'continue' [no line terminator] Identifier? ';'
+
+  Expect(Token::CONTINUE, CHECK_OK);
+  Token::Value tok = peek();
+  if (!scanner_->has_line_terminator_before_next() &&
+      tok != Token::SEMICOLON &&
+      tok != Token::RBRACE &&
+      tok != Token::EOS) {
+    ParseIdentifier(CHECK_OK);
+  }
+  ExpectSemicolon(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseBreakStatement(bool* ok) {
+  // BreakStatement ::
+  //   'break' [no line terminator] Identifier? ';'
+
+  Expect(Token::BREAK, CHECK_OK);
+  Token::Value tok = peek();
+  if (!scanner_->has_line_terminator_before_next() &&
+      tok != Token::SEMICOLON &&
+      tok != Token::RBRACE &&
+      tok != Token::EOS) {
+    ParseIdentifier(CHECK_OK);
+  }
+  ExpectSemicolon(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseReturnStatement(bool* ok) {
+  // ReturnStatement ::
+  //   'return' [no line terminator] 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.
+  // This is not handled during preparsing.
+
+  Token::Value tok = peek();
+  if (!scanner_->has_line_terminator_before_next() &&
+      tok != Token::SEMICOLON &&
+      tok != Token::RBRACE &&
+      tok != Token::EOS) {
+    ParseExpression(true, CHECK_OK);
+  }
+  ExpectSemicolon(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseWithStatement(bool* ok) {
+  // WithStatement ::
+  //   'with' '(' Expression ')' Statement
+  Expect(Token::WITH, CHECK_OK);
+  Expect(Token::LPAREN, CHECK_OK);
+  ParseExpression(true, CHECK_OK);
+  Expect(Token::RPAREN, CHECK_OK);
+
+  scope_->EnterWith();
+  ParseStatement(CHECK_OK);
+  scope_->LeaveWith();
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseSwitchStatement(bool* ok) {
+  // SwitchStatement ::
+  //   'switch' '(' Expression ')' '{' CaseClause* '}'
+
+  Expect(Token::SWITCH, CHECK_OK);
+  Expect(Token::LPAREN, CHECK_OK);
+  ParseExpression(true, CHECK_OK);
+  Expect(Token::RPAREN, CHECK_OK);
+
+  Expect(Token::LBRACE, CHECK_OK);
+  Token::Value token = peek();
+  while (token != Token::RBRACE) {
+    if (token == Token::CASE) {
+      Expect(Token::CASE, CHECK_OK);
+      ParseExpression(true, CHECK_OK);
+      Expect(Token::COLON, CHECK_OK);
+    } else if (token == Token::DEFAULT) {
+      Expect(Token::DEFAULT, CHECK_OK);
+      Expect(Token::COLON, CHECK_OK);
+    } else {
+      ParseStatement(CHECK_OK);
+    }
+    token = peek();
+  }
+  Expect(Token::RBRACE, CHECK_OK);
+
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseDoWhileStatement(bool* ok) {
+  // DoStatement ::
+  //   'do' Statement 'while' '(' Expression ')' ';'
+
+  Expect(Token::DO, CHECK_OK);
+  ParseStatement(CHECK_OK);
+  Expect(Token::WHILE, CHECK_OK);
+  Expect(Token::LPAREN, CHECK_OK);
+  ParseExpression(true, CHECK_OK);
+  Expect(Token::RPAREN, CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseWhileStatement(bool* ok) {
+  // WhileStatement ::
+  //   'while' '(' Expression ')' Statement
+
+  Expect(Token::WHILE, CHECK_OK);
+  Expect(Token::LPAREN, CHECK_OK);
+  ParseExpression(true, CHECK_OK);
+  Expect(Token::RPAREN, CHECK_OK);
+  ParseStatement(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseForStatement(bool* ok) {
+  // ForStatement ::
+  //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
+
+  Expect(Token::FOR, CHECK_OK);
+  Expect(Token::LPAREN, CHECK_OK);
+  if (peek() != Token::SEMICOLON) {
+    if (peek() == Token::VAR || peek() == Token::CONST) {
+      int decl_count;
+      ParseVariableDeclarations(false, &decl_count, CHECK_OK);
+      if (peek() == Token::IN && decl_count == 1) {
+        Expect(Token::IN, CHECK_OK);
+        ParseExpression(true, CHECK_OK);
+        Expect(Token::RPAREN, CHECK_OK);
+
+        ParseStatement(CHECK_OK);
+        return kUnknownStatement;
+      }
+    } else {
+      ParseExpression(false, CHECK_OK);
+      if (peek() == Token::IN) {
+        Expect(Token::IN, CHECK_OK);
+        ParseExpression(true, CHECK_OK);
+        Expect(Token::RPAREN, CHECK_OK);
+
+        ParseStatement(CHECK_OK);
+        return kUnknownStatement;
+      }
+    }
+  }
+
+  // Parsed initializer at this point.
+  Expect(Token::SEMICOLON, CHECK_OK);
+
+  if (peek() != Token::SEMICOLON) {
+    ParseExpression(true, CHECK_OK);
+  }
+  Expect(Token::SEMICOLON, CHECK_OK);
+
+  if (peek() != Token::RPAREN) {
+    ParseExpression(true, CHECK_OK);
+  }
+  Expect(Token::RPAREN, CHECK_OK);
+
+  ParseStatement(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseThrowStatement(bool* ok) {
+  // ThrowStatement ::
+  //   'throw' [no line terminator] Expression ';'
+
+  Expect(Token::THROW, CHECK_OK);
+  if (scanner_->has_line_terminator_before_next()) {
+    typename Scanner::Location pos = scanner_->location();
+    ReportMessageAt(pos.beg_pos, pos.end_pos,
+                    "newline_after_throw", NULL);
+    *ok = false;
+    return NULL;
+  }
+  ParseExpression(true, CHECK_OK);
+  ExpectSemicolon(CHECK_OK);
+
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseTryStatement(bool* ok) {
+  // TryStatement ::
+  //   'try' Block Catch
+  //   'try' Block Finally
+  //   'try' Block Catch Finally
+  //
+  // Catch ::
+  //   'catch' '(' Identifier ')' Block
+  //
+  // Finally ::
+  //   'finally' Block
+
+  // In preparsing, allow any number of catch/finally blocks, including zero
+  // of both.
+
+  Expect(Token::TRY, CHECK_OK);
+
+  ParseBlock(CHECK_OK);
+
+  bool catch_or_finally_seen = false;
+  if (peek() == Token::CATCH) {
+    Expect(Token::CATCH, CHECK_OK);
+    Expect(Token::LPAREN, CHECK_OK);
+    ParseIdentifier(CHECK_OK);
+    Expect(Token::RPAREN, CHECK_OK);
+    ParseBlock(CHECK_OK);
+    catch_or_finally_seen = true;
+  }
+  if (peek() == Token::FINALLY) {
+    Expect(Token::FINALLY, CHECK_OK);
+    ParseBlock(CHECK_OK);
+    catch_or_finally_seen = true;
+  }
+  if (!catch_or_finally_seen) {
+    *ok = false;
+  }
+  return kUnknownStatement;
+}
+
+
+template <typename Scanner, typename Log>
+Statement PreParser<Scanner, Log>::ParseDebuggerStatement(bool* ok) {
+  // In ECMA-262 'debugger' is defined as a reserved keyword. In some browser
+  // contexts this is used as a statement which invokes the debugger as if a
+  // break point is present.
+  // DebuggerStatement ::
+  //   'debugger' ';'
+
+  Expect(Token::DEBUGGER, CHECK_OK);
+  ExpectSemicolon(CHECK_OK);
+  return kUnknownStatement;
+}
+
+
+// Precedence = 1
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseExpression(bool accept_IN, bool* ok) {
+  // Expression ::
+  //   AssignmentExpression
+  //   Expression ',' AssignmentExpression
+
+  Expression result = ParseAssignmentExpression(accept_IN, CHECK_OK);
+  while (peek() == Token::COMMA) {
+    Expect(Token::COMMA, CHECK_OK);
+    ParseAssignmentExpression(accept_IN, CHECK_OK);
+    result = kUnknownExpression;
+  }
+  return result;
+}
+
+
+// Precedence = 2
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseAssignmentExpression(bool accept_IN,
+                                                              bool* ok) {
+  // AssignmentExpression ::
+  //   ConditionalExpression
+  //   LeftHandSideExpression AssignmentOperator AssignmentExpression
+
+  Expression expression = ParseConditionalExpression(accept_IN, CHECK_OK);
+
+  if (!Token::IsAssignmentOp(peek())) {
+    // Parsed conditional expression only (no assignment).
+    return expression;
+  }
+
+  Token::Value op = Next();  // Get assignment operator.
+  ParseAssignmentExpression(accept_IN, CHECK_OK);
+
+  if ((op == Token::ASSIGN) && (expression == kThisPropertyExpression)) {
+    scope_->AddProperty();
+  }
+
+  return kUnknownExpression;
+}
+
+
+// Precedence = 3
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseConditionalExpression(bool accept_IN,
+                                                               bool* ok) {
+  // ConditionalExpression ::
+  //   LogicalOrExpression
+  //   LogicalOrExpression '?' AssignmentExpression ':' AssignmentExpression
+
+  // We start using the binary expression parser for prec >= 4 only!
+  Expression expression = ParseBinaryExpression(4, accept_IN, CHECK_OK);
+  if (peek() != Token::CONDITIONAL) return expression;
+  Consume(Token::CONDITIONAL);
+  // In parsing the first assignment expression in conditional
+  // expressions we always accept the 'in' keyword; see ECMA-262,
+  // section 11.12, page 58.
+  ParseAssignmentExpression(true, CHECK_OK);
+  Expect(Token::COLON, CHECK_OK);
+  ParseAssignmentExpression(accept_IN, CHECK_OK);
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+int PreParser<Scanner, Log>::Precedence(Token::Value tok, bool accept_IN) {
+  if (tok == Token::IN && !accept_IN)
+    return 0;  // 0 precedence will terminate binary expression parsing
+
+  return Token::Precedence(tok);
+}
+
+
+// Precedence >= 4
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseBinaryExpression(int prec,
+                                                          bool accept_IN,
+                                                          bool* ok) {
+  Expression result = ParseUnaryExpression(CHECK_OK);
+  for (int prec1 = Precedence(peek(), accept_IN); prec1 >= prec; prec1--) {
+    // prec1 >= 4
+    while (Precedence(peek(), accept_IN) == prec1) {
+      Next();
+      ParseBinaryExpression(prec1 + 1, accept_IN, CHECK_OK);
+      result = kUnknownExpression;
+    }
+  }
+  return result;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseUnaryExpression(bool* ok) {
+  // UnaryExpression ::
+  //   PostfixExpression
+  //   'delete' UnaryExpression
+  //   'void' UnaryExpression
+  //   'typeof' UnaryExpression
+  //   '++' UnaryExpression
+  //   '--' UnaryExpression
+  //   '+' UnaryExpression
+  //   '-' UnaryExpression
+  //   '~' UnaryExpression
+  //   '!' UnaryExpression
+
+  Token::Value op = peek();
+  if (Token::IsUnaryOp(op) || Token::IsCountOp(op)) {
+    op = Next();
+    ParseUnaryExpression(ok);
+    return kUnknownExpression;
+  } else {
+    return ParsePostfixExpression(ok);
+  }
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParsePostfixExpression(bool* ok) {
+  // PostfixExpression ::
+  //   LeftHandSideExpression ('++' | '--')?
+
+  Expression expression = ParseLeftHandSideExpression(CHECK_OK);
+  if (!scanner_->has_line_terminator_before_next() &&
+      Token::IsCountOp(peek())) {
+    Next();
+    return kUnknownExpression;
+  }
+  return expression;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseLeftHandSideExpression(bool* ok) {
+  // LeftHandSideExpression ::
+  //   (NewExpression | MemberExpression) ...
+
+  Expression result;
+  if (peek() == Token::NEW) {
+    result = ParseNewExpression(CHECK_OK);
+  } else {
+    result = ParseMemberExpression(CHECK_OK);
+  }
+
+  while (true) {
+    switch (peek()) {
+      case Token::LBRACK: {
+        Consume(Token::LBRACK);
+        ParseExpression(true, CHECK_OK);
+        Expect(Token::RBRACK, CHECK_OK);
+        if (result == kThisExpression) {
+          result = kThisPropertyExpression;
+        } else {
+          result = kUnknownExpression;
+        }
+        break;
+      }
+
+      case Token::LPAREN: {
+        ParseArguments(CHECK_OK);
+        result = kUnknownExpression;
+        break;
+      }
+
+      case Token::PERIOD: {
+        Consume(Token::PERIOD);
+        ParseIdentifierName(CHECK_OK);
+        if (result == kThisExpression) {
+          result = kThisPropertyExpression;
+        } else {
+          result = kUnknownExpression;
+        }
+        break;
+      }
+
+      default:
+        return result;
+    }
+  }
+}
+
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseNewPrefix(int* new_count, bool* ok) {
+  // NewExpression ::
+  //   ('new')+ MemberExpression
+
+  // The grammar for new expressions is pretty warped. The keyword
+  // 'new' can either be a part of the new expression (where it isn't
+  // followed by an argument list) or a part of the member expression,
+  // where it must be followed by an argument list. To accommodate
+  // this, we parse the 'new' keywords greedily and keep track of how
+  // many we have parsed. This information is then passed on to the
+  // member expression parser, which is only allowed to match argument
+  // lists as long as it has 'new' prefixes left
+  Expect(Token::NEW, CHECK_OK);
+  *new_count++;
+
+  if (peek() == Token::NEW) {
+    ParseNewPrefix(new_count, CHECK_OK);
+  } else {
+    ParseMemberWithNewPrefixesExpression(new_count, CHECK_OK);
+  }
+
+  if (*new_count > 0) {
+    *new_count--;
+  }
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseNewExpression(bool* ok) {
+  int new_count = 0;
+  return ParseNewPrefix(&new_count, ok);
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseMemberExpression(bool* ok) {
+  return ParseMemberWithNewPrefixesExpression(NULL, ok);
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseMemberWithNewPrefixesExpression(
+    int* new_count, bool* ok) {
+  // MemberExpression ::
+  //   (PrimaryExpression | FunctionLiteral)
+  //     ('[' Expression ']' | '.' Identifier | Arguments)*
+
+  // Parse the initial primary or function expression.
+  Expression result = NULL;
+  if (peek() == Token::FUNCTION) {
+    Consume(Token::FUNCTION);
+    if (peek() == Token::IDENTIFIER) {
+      ParseIdentifier(CHECK_OK);
+    }
+    result = ParseFunctionLiteral(CHECK_OK);
+  } else {
+    result = ParsePrimaryExpression(CHECK_OK);
+  }
+
+  while (true) {
+    switch (peek()) {
+      case Token::LBRACK: {
+        Consume(Token::LBRACK);
+        ParseExpression(true, CHECK_OK);
+        Expect(Token::RBRACK, CHECK_OK);
+        if (result == kThisExpression) {
+          result = kThisPropertyExpression;
+        } else {
+          result = kUnknownExpression;
+        }
+        break;
+      }
+      case Token::PERIOD: {
+        Consume(Token::PERIOD);
+        ParseIdentifierName(CHECK_OK);
+        if (result == kThisExpression) {
+          result = kThisPropertyExpression;
+        } else {
+          result = kUnknownExpression;
+        }
+        break;
+      }
+      case Token::LPAREN: {
+        if ((new_count == NULL) || *new_count == 0) return result;
+        // Consume one of the new prefixes (already parsed).
+        ParseArguments(CHECK_OK);
+        *new_count--;
+        result = kUnknownExpression;
+        break;
+      }
+      default:
+        return result;
+    }
+  }
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParsePrimaryExpression(bool* ok) {
+  // PrimaryExpression ::
+  //   'this'
+  //   'null'
+  //   'true'
+  //   'false'
+  //   Identifier
+  //   Number
+  //   String
+  //   ArrayLiteral
+  //   ObjectLiteral
+  //   RegExpLiteral
+  //   '(' Expression ')'
+
+  Expression result = kUnknownExpression;
+  switch (peek()) {
+    case Token::THIS: {
+      Next();
+      result = kThisExpression;
+      break;
+    }
+
+    case Token::IDENTIFIER: {
+      ParseIdentifier(CHECK_OK);
+      result = kIdentifierExpression;
+      break;
+    }
+
+    case Token::NULL_LITERAL:
+    case Token::TRUE_LITERAL:
+    case Token::FALSE_LITERAL:
+    case Token::NUMBER: {
+      Next();
+      break;
+    }
+    case Token::STRING: {
+      Next();
+      result = GetStringSymbol();
+      break;
+    }
+
+    case Token::ASSIGN_DIV:
+      result = ParseRegExpLiteral(true, CHECK_OK);
+      break;
+
+    case Token::DIV:
+      result = ParseRegExpLiteral(false, CHECK_OK);
+      break;
+
+    case Token::LBRACK:
+      result = ParseArrayLiteral(CHECK_OK);
+      break;
+
+    case Token::LBRACE:
+      result = ParseObjectLiteral(CHECK_OK);
+      break;
+
+    case Token::LPAREN:
+      Consume(Token::LPAREN);
+      result = ParseExpression(true, CHECK_OK);
+      Expect(Token::RPAREN, CHECK_OK);
+      if (result == kIdentifierExpression) result = kUnknownExpression;
+      break;
+
+    case Token::MOD:
+      result = ParseV8Intrinsic(CHECK_OK);
+      break;
+
+    default: {
+      Next();
+      *ok = false;
+      return kUnknownExpression;
+    }
+  }
+
+  return result;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseArrayLiteral(bool* ok) {
+  // ArrayLiteral ::
+  //   '[' Expression? (',' Expression?)* ']'
+  Expect(Token::LBRACK, CHECK_OK);
+  while (peek() != Token::RBRACK) {
+    if (peek() != Token::COMMA) {
+      ParseAssignmentExpression(true, CHECK_OK);
+    }
+    if (peek() != Token::RBRACK) {
+      Expect(Token::COMMA, CHECK_OK);
+    }
+  }
+  Expect(Token::RBRACK, CHECK_OK);
+
+  scope_->NextMaterializedLiteralIndex();
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseObjectLiteral(bool* ok) {
+  // ObjectLiteral ::
+  //   '{' (
+  //       ((IdentifierName | String | Number) ':' AssignmentExpression)
+  //     | (('get' | 'set') (IdentifierName | String | Number) FunctionLiteral)
+  //    )*[','] '}'
+
+  Expect(Token::LBRACE, CHECK_OK);
+  while (peek() != Token::RBRACE) {
+    Token::Value next = peek();
+    switch (next) {
+      case Token::IDENTIFIER: {
+        bool is_getter = false;
+        bool is_setter = false;
+        ParseIdentifierOrGetOrSet(&is_getter, &is_setter, CHECK_OK);
+        if ((is_getter || is_setter) && peek() != Token::COLON) {
+            Token::Value name = Next();
+            if (name != Token::IDENTIFIER &&
+                name != Token::NUMBER &&
+                name != Token::STRING &&
+                !Token::IsKeyword(name)) {
+              *ok = false;
+              return kUnknownExpression;
+            }
+            ParseFunctionLiteral(CHECK_OK);
+            if (peek() != Token::RBRACE) {
+              Expect(Token::COMMA, CHECK_OK);
+            }
+            continue;  // restart the while
+        }
+        break;
+      }
+      case Token::STRING:
+        Consume(next);
+        GetStringSymbol();
+        break;
+      case Token::NUMBER:
+        Consume(next);
+        break;
+      default:
+        if (Token::IsKeyword(next)) {
+          Consume(next);
+        } else {
+          // Unexpected token.
+          *ok = false;
+          return kUnknownExpression;
+        }
+    }
+
+    Expect(Token::COLON, CHECK_OK);
+    ParseAssignmentExpression(true, CHECK_OK);
+
+    // TODO(1240767): Consider allowing trailing comma.
+    if (peek() != Token::RBRACE) Expect(Token::COMMA, CHECK_OK);
+  }
+  Expect(Token::RBRACE, CHECK_OK);
+
+  scope_->NextMaterializedLiteralIndex();
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseRegExpLiteral(bool seen_equal,
+                                                       bool* ok) {
+  if (!scanner_->ScanRegExpPattern(seen_equal)) {
+    Next();
+    typename Scanner::Location location = scanner_->location();
+    ReportMessageAt(location.beg_pos, location.end_pos,
+                    "unterminated_regexp", NULL);
+    *ok = false;
+    return kUnknownExpression;
+  }
+
+  scope_->NextMaterializedLiteralIndex();
+
+  if (!scanner_->ScanRegExpFlags()) {
+    Next();
+    typename Scanner::Location location = scanner_->location();
+    ReportMessageAt(location.beg_pos, location.end_pos,
+                    "invalid_regexp_flags", NULL);
+    *ok = false;
+    return kUnknownExpression;
+  }
+  Next();
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Arguments PreParser<Scanner, Log>::ParseArguments(bool* ok) {
+  // Arguments ::
+  //   '(' (AssignmentExpression)*[','] ')'
+
+  Expect(Token::LPAREN, CHECK_OK);
+  bool done = (peek() == Token::RPAREN);
+  int argc = 0;
+  while (!done) {
+    ParseAssignmentExpression(true, CHECK_OK);
+    argc++;
+    done = (peek() == Token::RPAREN);
+    if (!done) Expect(Token::COMMA, CHECK_OK);
+  }
+  Expect(Token::RPAREN, CHECK_OK);
+  return argc;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseFunctionLiteral(bool* ok) {
+  // Function ::
+  //   '(' FormalParameterList? ')' '{' FunctionBody '}'
+
+  // Parse function body.
+  ScopeType outer_scope_type = scope_->type();
+  bool inside_with = scope_->IsInsideWith();
+  Scope function_scope(&scope_, kFunctionScope);
+
+  //  FormalParameterList ::
+  //    '(' (Identifier)*[','] ')'
+  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::LBRACE, CHECK_OK);
+  int function_block_pos = scanner_->location().beg_pos;
+
+  // Determine if the function will be lazily compiled.
+  // Currently only happens to top-level functions.
+  // Optimistically assume that all top-level functions are lazily compiled.
+  bool is_lazily_compiled =
+      (outer_scope_type == kTopLevelScope && !inside_with && allow_lazy_);
+
+  if (is_lazily_compiled) {
+    log_->PauseRecording();
+    ParseSourceElements(Token::RBRACE, ok);
+    log_->ResumeRecording();
+    if (!*ok) return kUnknownExpression;
+
+    Expect(Token::RBRACE, CHECK_OK);
+
+    int end_pos = scanner_->location().end_pos;
+    log_->LogFunction(function_block_pos, end_pos,
+                      function_scope.materialized_literal_count(),
+                      function_scope.expected_properties());
+  } else {
+    ParseSourceElements(Token::RBRACE, CHECK_OK);
+    Expect(Token::RBRACE, CHECK_OK);
+  }
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::ParseV8Intrinsic(bool* ok) {
+  // CallRuntime ::
+  //   '%' Identifier Arguments
+
+  Expect(Token::MOD, CHECK_OK);
+  ParseIdentifier(CHECK_OK);
+  ParseArguments(CHECK_OK);
+
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+void PreParser<Scanner, Log>::ExpectSemicolon(bool* ok) {
+  // Check for automatic semicolon insertion according to
+  // the rules given in ECMA-262, section 7.9, page 21.
+  Token::Value tok = peek();
+  if (tok == Token::SEMICOLON) {
+    Next();
+    return;
+  }
+  if (scanner_->has_line_terminator_before_next() ||
+      tok == Token::RBRACE ||
+      tok == Token::EOS) {
+    return;
+  }
+  Expect(Token::SEMICOLON, ok);
+}
+
+
+template <typename Scanner, typename Log>
+Identifier PreParser<Scanner, Log>::GetIdentifierSymbol() {
+  const char* literal_chars = scanner_->literal_string();
+  int literal_length = scanner_->literal_length();
+  int identifier_pos = scanner_->location().beg_pos;
+
+  log_->LogSymbol(identifier_pos, literal_chars, literal_length);
+
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Expression PreParser<Scanner, Log>::GetStringSymbol() {
+  const char* literal_chars = scanner_->literal_string();
+  int literal_length = scanner_->literal_length();
+
+  int literal_position = scanner_->location().beg_pos;
+  log_->LogSymbol(literal_position, literal_chars, literal_length);
+
+  return kUnknownExpression;
+}
+
+
+template <typename Scanner, typename Log>
+Identifier PreParser<Scanner, Log>::ParseIdentifier(bool* ok) {
+  Expect(Token::IDENTIFIER, ok);
+  return GetIdentifierSymbol();
+}
+
+
+template <typename Scanner, typename Log>
+Identifier PreParser<Scanner, Log>::ParseIdentifierName(bool* ok) {
+  Token::Value next = Next();
+  if (Token::IsKeyword(next)) {
+    int pos = scanner_->location().beg_pos;
+    const char* keyword = Token::String(next);
+    log_->LogSymbol(pos, keyword, strlen(keyword));
+    return kUnknownExpression;
+  }
+  if (next == Token::IDENTIFIER) {
+    return GetIdentifierSymbol();
+  }
+  *ok = false;
+  return kUnknownIdentifier;
+}
+
+
+// This function reads an identifier and determines whether or not it
+// is 'get' or 'set'.  The reason for not using ParseIdentifier and
+// checking on the output is that this involves heap allocation which
+// we can't do during preparsing.
+template <typename Scanner, typename Log>
+Identifier PreParser<Scanner, Log>::ParseIdentifierOrGetOrSet(bool* is_get,
+                                                   bool* is_set,
+                                                   bool* ok) {
+  Expect(Token::IDENTIFIER, CHECK_OK);
+  if (scanner_->literal_length() == 3) {
+    const char* token = scanner_->literal_string();
+    *is_get = strncmp(token, "get", 3) == 0;
+    *is_set = !*is_get && strncmp(token, "set", 3) == 0;
+  }
+  return GetIdentifierSymbol();
+}
+
+#undef CHECK_OK
+} } }  // v8::internal::preparser
+
+#endif  // V8_PREPARSER_H