src/preparser.h

// Copyright 2010 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
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//       with the distribution.
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#ifndef V8_PREPARSER_H
#define V8_PREPARSER_H

namespace v8 {
namespace preparser {

// Preparsing checks a JavaScript program and emits preparse-data that helps
// a later parsing to be faster.
// See preparse-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.

namespace i = v8::internal;

class PreParser {
 public:
  enum PreParseResult {
    kPreParseStackOverflow,
    kPreParseSuccess
  };

  ~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.
  static PreParseResult PreParseProgram(i::JavaScriptScanner* scanner,
                                        i::ParserRecorder* log,
                                        bool allow_lazy,
                                        uintptr_t stack_limit) {
    return PreParser(scanner, log, stack_limit, allow_lazy).PreParse();
  }

 private:
  enum ScopeType {
    kTopLevelScope,
    kFunctionScope
  };

  // 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.

  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;

  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_;
  };

  // Private constructor only used in PreParseProgram.
  PreParser(i::JavaScriptScanner* scanner,
            i::ParserRecorder* log,
            uintptr_t stack_limit,
            bool allow_lazy)
      : scanner_(scanner),
        log_(log),
        scope_(NULL),
        stack_limit_(stack_limit),
        stack_overflow_(false),
        allow_lazy_(true) { }

  // Preparse the program. Only called in PreParseProgram after creating
  // the instance.
  PreParseResult PreParse() {
    Scope top_scope(&scope_, kTopLevelScope);
    bool ok = true;
    ParseSourceElements(i::Token::EOS, &ok);
    if (stack_overflow_) return kPreParseStackOverflow;
    if (!ok) {
      ReportUnexpectedToken(scanner_->current_token());
    }
    return kPreParseSuccess;
  }

  // Report syntax error
  void ReportUnexpectedToken(i::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 ParseMemberWithNewPrefixesExpression(unsigned 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();

  i::Token::Value peek() {
    if (stack_overflow_) return i::Token::ILLEGAL;
    return scanner_->peek();
  }

  i::Token::Value Next() {
    if (stack_overflow_) return i::Token::ILLEGAL;
    {
      int marker;
      if (reinterpret_cast<uintptr_t>(&marker) < stack_limit_) {
        // Further calls to peek/Next will return illegal token.
        // The current one will still be returned. It might already
        // have been seen using peek.
        stack_overflow_ = true;
      }
    }
    return scanner_->Next();
  }

  void Consume(i::Token::Value token) { Next(); }

  void Expect(i::Token::Value token, bool* ok) {
    if (Next() != token) {
      *ok = false;
    }
  }

  bool Check(i::Token::Value token) {
    i::Token::Value next = peek();
    if (next == token) {
      Consume(next);
      return true;
    }
    return false;
  }
  void ExpectSemicolon(bool* ok);

  static int Precedence(i::Token::Value tok, bool accept_IN);

  i::JavaScriptScanner* scanner_;
  i::ParserRecorder* log_;
  Scope* scope_;
  uintptr_t stack_limit_;
  bool stack_overflow_;
  bool allow_lazy_;
};
} }  // v8::preparser

#endif  // V8_PREPARSER_H