src/parsing/expression-classifier.h - v8/v8.git - Git at Google

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #ifndef V8_PARSING_EXPRESSION_CLASSIFIER_H_
 #define V8_PARSING_EXPRESSION_CLASSIFIER_H_

 #include "src/messages.h"
 #include "src/parsing/scanner.h"

 namespace v8 {
 namespace internal {

 class DuplicateFinder;

 #define ERROR_CODES(T)                       \
   T(ExpressionProduction, 0)                 \
   T(FormalParameterInitializerProduction, 1) \
   T(BindingPatternProduction, 2)             \
   T(AssignmentPatternProduction, 3)          \
   T(DistinctFormalParametersProduction, 4)   \
   T(StrictModeFormalParametersProduction, 5) \
   T(ArrowFormalParametersProduction, 6)      \
   T(LetPatternProduction, 7)                 \
   T(AsyncArrowFormalParametersProduction, 8)

 // Expression classifiers serve two purposes:
 //
 // 1) They keep track of error messages that are pending (and other
 //    related information), waiting for the parser to decide whether
 //    the parsed expression is a pattern or not.
 // 2) They keep track of expressions that may need to be rewritten, if
 //    the parser decides that they are not patterns.  (A different
 //    mechanism implements the rewriting of patterns.)
 //
 // Expression classifiers are used by the parser in a stack fashion.
 // Each new classifier is pushed on top of the stack.  This happens
 // automatically by the class's constructor.  While on top of the
 // stack, the classifier records pending error messages and tracks the
 // pending non-patterns of the expression that is being parsed.
 //
 // At the end of its life, a classifier is either "accumulated" to the
 // one that is below it on the stack, or is "discarded".  The former
 // is achieved by calling the method Accumulate.  The latter is
 // achieved automatically by the destructor, but it can happen earlier
 // by calling the method Discard.  Both actions result in removing the
 // classifier from the parser's stack.

 template <typename Types>
 class ExpressionClassifier {
  public:
   enum ErrorKind : unsigned {
 #define DEFINE_ERROR_KIND(NAME, CODE) k##NAME = CODE,
     ERROR_CODES(DEFINE_ERROR_KIND)
 #undef DEFINE_ERROR_KIND
     kUnusedError = 15  // Larger than error codes; should fit in 4 bits
   };

   struct Error {
     V8_INLINE Error()
         : location(Scanner::Location::invalid()),
           message(MessageTemplate::kNone),
           kind(kUnusedError),
           type(kSyntaxError),
           arg(nullptr) {}
     V8_INLINE explicit Error(Scanner::Location loc,
                              MessageTemplate::Template msg, ErrorKind k,
                              const char* a = nullptr,
                              ParseErrorType t = kSyntaxError)
         : location(loc), message(msg), kind(k), type(t), arg(a) {}

     Scanner::Location location;
     MessageTemplate::Template message : 26;
     unsigned kind : 4;
     ParseErrorType type : 2;
     const char* arg;
   };

   // clang-format off
   enum TargetProduction : unsigned {
 #define DEFINE_PRODUCTION(NAME, CODE) NAME = 1 << CODE,
     ERROR_CODES(DEFINE_PRODUCTION)
 #undef DEFINE_PRODUCTION

 #define DEFINE_ALL_PRODUCTIONS(NAME, CODE) NAME |
     AllProductions = ERROR_CODES(DEFINE_ALL_PRODUCTIONS) /* | */ 0
 #undef DEFINE_ALL_PRODUCTIONS
   };
   // clang-format on

   enum FunctionProperties : unsigned {
     NonSimpleParameter = 1 << 0
   };

   explicit ExpressionClassifier(typename Types::Base* base,
                                 DuplicateFinder* duplicate_finder = nullptr)
       : base_(base),
         previous_(base->classifier_),
         zone_(base->impl()->zone()),
         reported_errors_(base->impl()->GetReportedErrorList()),
         duplicate_finder_(duplicate_finder),
         invalid_productions_(0),
         function_properties_(0) {
     base->classifier_ = this;
     reported_errors_begin_ = reported_errors_end_ = reported_errors_->length();
   }

   V8_INLINE ~ExpressionClassifier() {
     Discard();
     if (base_->classifier_ == this) base_->classifier_ = previous_;
   }

   V8_INLINE bool is_valid(unsigned productions) const {
     return (invalid_productions_ & productions) == 0;
   }

   V8_INLINE DuplicateFinder* duplicate_finder() const {
     return duplicate_finder_;
   }

   V8_INLINE bool is_valid_expression() const {
     return is_valid(ExpressionProduction);
   }

   V8_INLINE bool is_valid_formal_parameter_initializer() const {
     return is_valid(FormalParameterInitializerProduction);
   }

   V8_INLINE bool is_valid_binding_pattern() const {
     return is_valid(BindingPatternProduction);
   }

   V8_INLINE bool is_valid_assignment_pattern() const {
     return is_valid(AssignmentPatternProduction);
   }

   V8_INLINE bool is_valid_arrow_formal_parameters() const {
     return is_valid(ArrowFormalParametersProduction);
   }

   V8_INLINE bool is_valid_formal_parameter_list_without_duplicates() const {
     return is_valid(DistinctFormalParametersProduction);
   }

   // Note: callers should also check
   // is_valid_formal_parameter_list_without_duplicates().
   V8_INLINE bool is_valid_strict_mode_formal_parameters() const {
     return is_valid(StrictModeFormalParametersProduction);
   }

   V8_INLINE bool is_valid_let_pattern() const {
     return is_valid(LetPatternProduction);
   }

   bool is_valid_async_arrow_formal_parameters() const {
     return is_valid(AsyncArrowFormalParametersProduction);
   }

   V8_INLINE const Error& expression_error() const {
     return reported_error(kExpressionProduction);
   }

   V8_INLINE const Error& formal_parameter_initializer_error() const {
     return reported_error(kFormalParameterInitializerProduction);
   }

   V8_INLINE const Error& binding_pattern_error() const {
     return reported_error(kBindingPatternProduction);
   }

   V8_INLINE const Error& assignment_pattern_error() const {
     return reported_error(kAssignmentPatternProduction);
   }

   V8_INLINE const Error& arrow_formal_parameters_error() const {
     return reported_error(kArrowFormalParametersProduction);
   }

   V8_INLINE const Error& duplicate_formal_parameter_error() const {
     return reported_error(kDistinctFormalParametersProduction);
   }

   V8_INLINE const Error& strict_mode_formal_parameter_error() const {
     return reported_error(kStrictModeFormalParametersProduction);
   }

   V8_INLINE const Error& let_pattern_error() const {
     return reported_error(kLetPatternProduction);
   }

   V8_INLINE const Error& async_arrow_formal_parameters_error() const {
     return reported_error(kAsyncArrowFormalParametersProduction);
   }

   V8_INLINE bool is_simple_parameter_list() const {
     return !(function_properties_ & NonSimpleParameter);
   }

   V8_INLINE void RecordNonSimpleParameter() {
     function_properties_ |= NonSimpleParameter;
   }

   void RecordExpressionError(const Scanner::Location& loc,
                              MessageTemplate::Template message,
                              const char* arg = nullptr) {
     if (!is_valid_expression()) return;
     invalid_productions_ |= ExpressionProduction;
     Add(Error(loc, message, kExpressionProduction, arg));
   }

   void RecordExpressionError(const Scanner::Location& loc,
                              MessageTemplate::Template message,
                              ParseErrorType type, const char* arg = nullptr) {
     if (!is_valid_expression()) return;
     invalid_productions_ |= ExpressionProduction;
     Add(Error(loc, message, kExpressionProduction, arg, type));
   }

   void RecordFormalParameterInitializerError(const Scanner::Location& loc,
                                              MessageTemplate::Template message,
                                              const char* arg = nullptr) {
     if (!is_valid_formal_parameter_initializer()) return;
     invalid_productions_ |= FormalParameterInitializerProduction;
     Add(Error(loc, message, kFormalParameterInitializerProduction, arg));
   }

   void RecordBindingPatternError(const Scanner::Location& loc,
                                  MessageTemplate::Template message,
                                  const char* arg = nullptr) {
     if (!is_valid_binding_pattern()) return;
     invalid_productions_ |= BindingPatternProduction;
     Add(Error(loc, message, kBindingPatternProduction, arg));
   }

   void RecordAssignmentPatternError(const Scanner::Location& loc,
                                     MessageTemplate::Template message,
                                     const char* arg = nullptr) {
     if (!is_valid_assignment_pattern()) return;
     invalid_productions_ |= AssignmentPatternProduction;
     Add(Error(loc, message, kAssignmentPatternProduction, arg));
   }

   void RecordPatternError(const Scanner::Location& loc,
                           MessageTemplate::Template message,
                           const char* arg = nullptr) {
     RecordBindingPatternError(loc, message, arg);
     RecordAssignmentPatternError(loc, message, arg);
   }

   void RecordArrowFormalParametersError(const Scanner::Location& loc,
                                         MessageTemplate::Template message,
                                         const char* arg = nullptr) {
     if (!is_valid_arrow_formal_parameters()) return;
     invalid_productions_ |= ArrowFormalParametersProduction;
     Add(Error(loc, message, kArrowFormalParametersProduction, arg));
   }

   void RecordAsyncArrowFormalParametersError(const Scanner::Location& loc,
                                              MessageTemplate::Template message,
                                              const char* arg = nullptr) {
     if (!is_valid_async_arrow_formal_parameters()) return;
     invalid_productions_ |= AsyncArrowFormalParametersProduction;
     Add(Error(loc, message, kAsyncArrowFormalParametersProduction, arg));
   }

   void RecordDuplicateFormalParameterError(const Scanner::Location& loc) {
     if (!is_valid_formal_parameter_list_without_duplicates()) return;
     invalid_productions_ |= DistinctFormalParametersProduction;
     Add(Error(loc, MessageTemplate::kParamDupe,
               kDistinctFormalParametersProduction));
   }

   // Record a binding that would be invalid in strict mode.  Confusingly this
   // is not the same as StrictFormalParameterList, which simply forbids
   // duplicate bindings.
   void RecordStrictModeFormalParameterError(const Scanner::Location& loc,
                                             MessageTemplate::Template message,
                                             const char* arg = nullptr) {
     if (!is_valid_strict_mode_formal_parameters()) return;
     invalid_productions_ |= StrictModeFormalParametersProduction;
     Add(Error(loc, message, kStrictModeFormalParametersProduction, arg));
   }

   void RecordLetPatternError(const Scanner::Location& loc,
                              MessageTemplate::Template message,
                              const char* arg = nullptr) {
     if (!is_valid_let_pattern()) return;
     invalid_productions_ |= LetPatternProduction;
     Add(Error(loc, message, kLetPatternProduction, arg));
   }

   void Accumulate(ExpressionClassifier* inner, unsigned productions) {
     DCHECK_EQ(inner->reported_errors_, reported_errors_);
     DCHECK_EQ(inner->reported_errors_begin_, reported_errors_end_);
     DCHECK_EQ(inner->reported_errors_end_, reported_errors_->length());
     // Propagate errors from inner, but don't overwrite already recorded
     // errors.
     unsigned non_arrow_inner_invalid_productions =
         inner->invalid_productions_ & ~ArrowFormalParametersProduction;
     if (non_arrow_inner_invalid_productions) {
       unsigned errors = non_arrow_inner_invalid_productions & productions &
                         ~invalid_productions_;
       // The result will continue to be a valid arrow formal parameters if the
       // inner expression is a valid binding pattern.
       bool copy_BP_to_AFP = false;
       if (productions & ArrowFormalParametersProduction &&
           is_valid_arrow_formal_parameters()) {
         // Also copy function properties if expecting an arrow function
         // parameter.
         function_properties_ |= inner->function_properties_;
         if (!inner->is_valid_binding_pattern()) {
           copy_BP_to_AFP = true;
           invalid_productions_ |= ArrowFormalParametersProduction;
         }
       }
       // Traverse the list of errors reported by the inner classifier
       // to copy what's necessary.
       if (errors != 0 || copy_BP_to_AFP) {
         invalid_productions_ |= errors;
         int binding_pattern_index = inner->reported_errors_end_;
         for (int i = inner->reported_errors_begin_;
              i < inner->reported_errors_end_; i++) {
           int k = reported_errors_->at(i).kind;
           if (errors & (1 << k)) Copy(i);
           // Check if it's a BP error that has to be copied to an AFP error.
           if (k == kBindingPatternProduction && copy_BP_to_AFP) {
             if (reported_errors_end_ <= i) {
               // If the BP error itself has not already been copied,
               // copy it now and change it to an AFP error.
               Copy(i);
               reported_errors_->at(reported_errors_end_-1).kind =
                   kArrowFormalParametersProduction;
             } else {
               // Otherwise, if the BP error was already copied, keep its
               // position and wait until the end of the traversal.
               DCHECK_EQ(reported_errors_end_, i+1);
               binding_pattern_index = i;
             }
           }
         }
         // Do we still have to copy the BP error to an AFP error?
         if (binding_pattern_index < inner->reported_errors_end_) {
           // If there's still unused space in the list of the inner
           // classifier, copy it there, otherwise add it to the end
           // of the list.
           if (reported_errors_end_ < inner->reported_errors_end_)
             Copy(binding_pattern_index);
           else
             Add(reported_errors_->at(binding_pattern_index));
           reported_errors_->at(reported_errors_end_-1).kind =
               kArrowFormalParametersProduction;
         }
       }
     }
     reported_errors_->Rewind(reported_errors_end_);
     inner->reported_errors_begin_ = inner->reported_errors_end_ =
         reported_errors_end_;
   }

   V8_INLINE void Discard() {
     if (reported_errors_end_ == reported_errors_->length()) {
       reported_errors_->Rewind(reported_errors_begin_);
       reported_errors_end_ = reported_errors_begin_;
     }
     DCHECK_EQ(reported_errors_begin_, reported_errors_end_);
   }

   ExpressionClassifier* previous() const { return previous_; }

  private:
   V8_INLINE const Error& reported_error(ErrorKind kind) const {
     if (invalid_productions_ & (1 << kind)) {
       for (int i = reported_errors_begin_; i < reported_errors_end_; i++) {
         if (reported_errors_->at(i).kind == kind)
           return reported_errors_->at(i);
       }
       UNREACHABLE();
     }
     // We should only be looking for an error when we know that one has
     // been reported.  But we're not...  So this is to make sure we have
     // the same behaviour.
     UNREACHABLE();

     // Make MSVC happy by returning an error from this inaccessible path.
     static Error none;
     return none;
   }

   // Adds e to the end of the list of reported errors for this classifier.
   // It is expected that this classifier is the last one in the stack.
   V8_INLINE void Add(const Error& e) {
     DCHECK_EQ(reported_errors_end_, reported_errors_->length());
     reported_errors_->Add(e, zone_);
     reported_errors_end_++;
   }

   // Copies the error at position i of the list of reported errors, so that
   // it becomes the last error reported for this classifier.  Position i
   // could be either after the existing errors of this classifier (i.e.,
   // in an inner classifier) or it could be an existing error (in case a
   // copy is needed).
   V8_INLINE void Copy(int i) {
     DCHECK_LT(i, reported_errors_->length());
     if (reported_errors_end_ != i)
       reported_errors_->at(reported_errors_end_) = reported_errors_->at(i);
     reported_errors_end_++;
   }

   typename Types::Base* base_;
   ExpressionClassifier* previous_;
   Zone* zone_;
   ZoneList<Error>* reported_errors_;
   DuplicateFinder* duplicate_finder_;
   unsigned invalid_productions_ : 14;
   unsigned function_properties_ : 2;
   // The uint16_t for reported_errors_begin_ and reported_errors_end_ will
   // not be enough in the case of a long series of expressions using nested
   // classifiers, e.g., a long sequence of assignments, as in:
   // literals with spreads, as in:
   // var N=65536; eval("var x;" + "x=".repeat(N) + "42");
   // This should not be a problem, as such things currently fail with a
   // stack overflow while parsing.
   uint16_t reported_errors_begin_;
   uint16_t reported_errors_end_;

   DISALLOW_COPY_AND_ASSIGN(ExpressionClassifier);
 };


 #undef ERROR_CODES


 }  // namespace internal
 }  // namespace v8

 #endif  // V8_PARSING_EXPRESSION_CLASSIFIER_H_
	// Copyright 2015 the V8 project authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#ifndef V8_PARSING_EXPRESSION_CLASSIFIER_H_
	#define V8_PARSING_EXPRESSION_CLASSIFIER_H_

	#include "src/messages.h"
	#include "src/parsing/scanner.h"

	namespace v8 {
	namespace internal {

	class DuplicateFinder;

	#define ERROR_CODES(T) \
	T(ExpressionProduction, 0) \
	T(FormalParameterInitializerProduction, 1) \
	T(BindingPatternProduction, 2) \
	T(AssignmentPatternProduction, 3) \
	T(DistinctFormalParametersProduction, 4) \
	T(StrictModeFormalParametersProduction, 5) \
	T(ArrowFormalParametersProduction, 6) \
	T(LetPatternProduction, 7) \
	T(AsyncArrowFormalParametersProduction, 8)

	// Expression classifiers serve two purposes:
	//
	// 1) They keep track of error messages that are pending (and other
	// related information), waiting for the parser to decide whether
	// the parsed expression is a pattern or not.
	// 2) They keep track of expressions that may need to be rewritten, if
	// the parser decides that they are not patterns. (A different
	// mechanism implements the rewriting of patterns.)
	//
	// Expression classifiers are used by the parser in a stack fashion.
	// Each new classifier is pushed on top of the stack. This happens
	// automatically by the class's constructor. While on top of the
	// stack, the classifier records pending error messages and tracks the
	// pending non-patterns of the expression that is being parsed.
	//
	// At the end of its life, a classifier is either "accumulated" to the
	// one that is below it on the stack, or is "discarded". The former
	// is achieved by calling the method Accumulate. The latter is
	// achieved automatically by the destructor, but it can happen earlier
	// by calling the method Discard. Both actions result in removing the
	// classifier from the parser's stack.

	template <typename Types>
	class ExpressionClassifier {
	public:
	enum ErrorKind : unsigned {
	#define DEFINE_ERROR_KIND(NAME, CODE) k##NAME = CODE,
	ERROR_CODES(DEFINE_ERROR_KIND)
	#undef DEFINE_ERROR_KIND
	kUnusedError = 15 // Larger than error codes; should fit in 4 bits
	};

	struct Error {
	V8_INLINE Error()
	: location(Scanner::Location::invalid()),
	message(MessageTemplate::kNone),
	kind(kUnusedError),
	type(kSyntaxError),
	arg(nullptr) {}
	V8_INLINE explicit Error(Scanner::Location loc,
	MessageTemplate::Template msg, ErrorKind k,
	const char* a = nullptr,
	ParseErrorType t = kSyntaxError)
	: location(loc), message(msg), kind(k), type(t), arg(a) {}

	Scanner::Location location;
	MessageTemplate::Template message : 26;
	unsigned kind : 4;
	ParseErrorType type : 2;
	const char* arg;
	};

	// clang-format off
	enum TargetProduction : unsigned {
	#define DEFINE_PRODUCTION(NAME, CODE) NAME = 1 << CODE,
	ERROR_CODES(DEFINE_PRODUCTION)
	#undef DEFINE_PRODUCTION

	#define DEFINE_ALL_PRODUCTIONS(NAME, CODE) NAME \|
	AllProductions = ERROR_CODES(DEFINE_ALL_PRODUCTIONS) /* \| */ 0
	#undef DEFINE_ALL_PRODUCTIONS
	};
	// clang-format on

	enum FunctionProperties : unsigned {
	NonSimpleParameter = 1 << 0
	};

	explicit ExpressionClassifier(typename Types::Base* base,
	DuplicateFinder* duplicate_finder = nullptr)
	: base_(base),
	previous_(base->classifier_),
	zone_(base->impl()->zone()),
	reported_errors_(base->impl()->GetReportedErrorList()),
	duplicate_finder_(duplicate_finder),
	invalid_productions_(0),
	function_properties_(0) {
	base->classifier_ = this;
	reported_errors_begin_ = reported_errors_end_ = reported_errors_->length();
	}

	V8_INLINE ~ExpressionClassifier() {
	Discard();
	if (base_->classifier_ == this) base_->classifier_ = previous_;
	}

	V8_INLINE bool is_valid(unsigned productions) const {
	return (invalid_productions_ & productions) == 0;
	}

	V8_INLINE DuplicateFinder* duplicate_finder() const {
	return duplicate_finder_;
	}

	V8_INLINE bool is_valid_expression() const {
	return is_valid(ExpressionProduction);
	}

	V8_INLINE bool is_valid_formal_parameter_initializer() const {
	return is_valid(FormalParameterInitializerProduction);
	}

	V8_INLINE bool is_valid_binding_pattern() const {
	return is_valid(BindingPatternProduction);
	}

	V8_INLINE bool is_valid_assignment_pattern() const {
	return is_valid(AssignmentPatternProduction);
	}

	V8_INLINE bool is_valid_arrow_formal_parameters() const {
	return is_valid(ArrowFormalParametersProduction);
	}

	V8_INLINE bool is_valid_formal_parameter_list_without_duplicates() const {
	return is_valid(DistinctFormalParametersProduction);
	}

	// Note: callers should also check
	// is_valid_formal_parameter_list_without_duplicates().
	V8_INLINE bool is_valid_strict_mode_formal_parameters() const {
	return is_valid(StrictModeFormalParametersProduction);
	}

	V8_INLINE bool is_valid_let_pattern() const {
	return is_valid(LetPatternProduction);
	}

	bool is_valid_async_arrow_formal_parameters() const {
	return is_valid(AsyncArrowFormalParametersProduction);
	}

	V8_INLINE const Error& expression_error() const {
	return reported_error(kExpressionProduction);
	}

	V8_INLINE const Error& formal_parameter_initializer_error() const {
	return reported_error(kFormalParameterInitializerProduction);
	}

	V8_INLINE const Error& binding_pattern_error() const {
	return reported_error(kBindingPatternProduction);
	}

	V8_INLINE const Error& assignment_pattern_error() const {
	return reported_error(kAssignmentPatternProduction);
	}

	V8_INLINE const Error& arrow_formal_parameters_error() const {
	return reported_error(kArrowFormalParametersProduction);
	}

	V8_INLINE const Error& duplicate_formal_parameter_error() const {
	return reported_error(kDistinctFormalParametersProduction);
	}

	V8_INLINE const Error& strict_mode_formal_parameter_error() const {
	return reported_error(kStrictModeFormalParametersProduction);
	}

	V8_INLINE const Error& let_pattern_error() const {
	return reported_error(kLetPatternProduction);
	}

	V8_INLINE const Error& async_arrow_formal_parameters_error() const {
	return reported_error(kAsyncArrowFormalParametersProduction);
	}

	V8_INLINE bool is_simple_parameter_list() const {
	return !(function_properties_ & NonSimpleParameter);
	}

	V8_INLINE void RecordNonSimpleParameter() {
	function_properties_ \|= NonSimpleParameter;
	}

	void RecordExpressionError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_expression()) return;
	invalid_productions_ \|= ExpressionProduction;
	Add(Error(loc, message, kExpressionProduction, arg));
	}

	void RecordExpressionError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	ParseErrorType type, const char* arg = nullptr) {
	if (!is_valid_expression()) return;
	invalid_productions_ \|= ExpressionProduction;
	Add(Error(loc, message, kExpressionProduction, arg, type));
	}

	void RecordFormalParameterInitializerError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_formal_parameter_initializer()) return;
	invalid_productions_ \|= FormalParameterInitializerProduction;
	Add(Error(loc, message, kFormalParameterInitializerProduction, arg));
	}

	void RecordBindingPatternError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_binding_pattern()) return;
	invalid_productions_ \|= BindingPatternProduction;
	Add(Error(loc, message, kBindingPatternProduction, arg));
	}

	void RecordAssignmentPatternError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_assignment_pattern()) return;
	invalid_productions_ \|= AssignmentPatternProduction;
	Add(Error(loc, message, kAssignmentPatternProduction, arg));
	}

	void RecordPatternError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	RecordBindingPatternError(loc, message, arg);
	RecordAssignmentPatternError(loc, message, arg);
	}

	void RecordArrowFormalParametersError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_arrow_formal_parameters()) return;
	invalid_productions_ \|= ArrowFormalParametersProduction;
	Add(Error(loc, message, kArrowFormalParametersProduction, arg));
	}

	void RecordAsyncArrowFormalParametersError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_async_arrow_formal_parameters()) return;
	invalid_productions_ \|= AsyncArrowFormalParametersProduction;
	Add(Error(loc, message, kAsyncArrowFormalParametersProduction, arg));
	}

	void RecordDuplicateFormalParameterError(const Scanner::Location& loc) {
	if (!is_valid_formal_parameter_list_without_duplicates()) return;
	invalid_productions_ \|= DistinctFormalParametersProduction;
	Add(Error(loc, MessageTemplate::kParamDupe,
	kDistinctFormalParametersProduction));
	}

	// Record a binding that would be invalid in strict mode. Confusingly this
	// is not the same as StrictFormalParameterList, which simply forbids
	// duplicate bindings.
	void RecordStrictModeFormalParameterError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_strict_mode_formal_parameters()) return;
	invalid_productions_ \|= StrictModeFormalParametersProduction;
	Add(Error(loc, message, kStrictModeFormalParametersProduction, arg));
	}

	void RecordLetPatternError(const Scanner::Location& loc,
	MessageTemplate::Template message,
	const char* arg = nullptr) {
	if (!is_valid_let_pattern()) return;
	invalid_productions_ \|= LetPatternProduction;
	Add(Error(loc, message, kLetPatternProduction, arg));
	}

	void Accumulate(ExpressionClassifier* inner, unsigned productions) {
	DCHECK_EQ(inner->reported_errors_, reported_errors_);
	DCHECK_EQ(inner->reported_errors_begin_, reported_errors_end_);
	DCHECK_EQ(inner->reported_errors_end_, reported_errors_->length());
	// Propagate errors from inner, but don't overwrite already recorded
	// errors.
	unsigned non_arrow_inner_invalid_productions =
	inner->invalid_productions_ & ~ArrowFormalParametersProduction;
	if (non_arrow_inner_invalid_productions) {
	unsigned errors = non_arrow_inner_invalid_productions & productions &
	~invalid_productions_;
	// The result will continue to be a valid arrow formal parameters if the
	// inner expression is a valid binding pattern.
	bool copy_BP_to_AFP = false;
	if (productions & ArrowFormalParametersProduction &&
	is_valid_arrow_formal_parameters()) {
	// Also copy function properties if expecting an arrow function
	// parameter.
	function_properties_ \|= inner->function_properties_;
	if (!inner->is_valid_binding_pattern()) {
	copy_BP_to_AFP = true;
	invalid_productions_ \|= ArrowFormalParametersProduction;
	}
	}
	// Traverse the list of errors reported by the inner classifier
	// to copy what's necessary.
	if (errors != 0 \|\| copy_BP_to_AFP) {
	invalid_productions_ \|= errors;
	int binding_pattern_index = inner->reported_errors_end_;
	for (int i = inner->reported_errors_begin_;
	i < inner->reported_errors_end_; i++) {
	int k = reported_errors_->at(i).kind;
	if (errors & (1 << k)) Copy(i);
	// Check if it's a BP error that has to be copied to an AFP error.
	if (k == kBindingPatternProduction && copy_BP_to_AFP) {
	if (reported_errors_end_ <= i) {
	// If the BP error itself has not already been copied,
	// copy it now and change it to an AFP error.
	Copy(i);
	reported_errors_->at(reported_errors_end_-1).kind =
	kArrowFormalParametersProduction;
	} else {
	// Otherwise, if the BP error was already copied, keep its
	// position and wait until the end of the traversal.
	DCHECK_EQ(reported_errors_end_, i+1);
	binding_pattern_index = i;
	}
	}
	}
	// Do we still have to copy the BP error to an AFP error?
	if (binding_pattern_index < inner->reported_errors_end_) {
	// If there's still unused space in the list of the inner
	// classifier, copy it there, otherwise add it to the end
	// of the list.
	if (reported_errors_end_ < inner->reported_errors_end_)
	Copy(binding_pattern_index);
	else
	Add(reported_errors_->at(binding_pattern_index));
	reported_errors_->at(reported_errors_end_-1).kind =
	kArrowFormalParametersProduction;
	}
	}
	}
	reported_errors_->Rewind(reported_errors_end_);
	inner->reported_errors_begin_ = inner->reported_errors_end_ =
	reported_errors_end_;
	}

	V8_INLINE void Discard() {
	if (reported_errors_end_ == reported_errors_->length()) {
	reported_errors_->Rewind(reported_errors_begin_);
	reported_errors_end_ = reported_errors_begin_;
	}
	DCHECK_EQ(reported_errors_begin_, reported_errors_end_);
	}

	ExpressionClassifier* previous() const { return previous_; }

	private:
	V8_INLINE const Error& reported_error(ErrorKind kind) const {
	if (invalid_productions_ & (1 << kind)) {
	for (int i = reported_errors_begin_; i < reported_errors_end_; i++) {
	if (reported_errors_->at(i).kind == kind)
	return reported_errors_->at(i);
	}
	UNREACHABLE();
	}
	// We should only be looking for an error when we know that one has
	// been reported. But we're not... So this is to make sure we have
	// the same behaviour.
	UNREACHABLE();

	// Make MSVC happy by returning an error from this inaccessible path.
	static Error none;
	return none;
	}

	// Adds e to the end of the list of reported errors for this classifier.
	// It is expected that this classifier is the last one in the stack.
	V8_INLINE void Add(const Error& e) {
	DCHECK_EQ(reported_errors_end_, reported_errors_->length());
	reported_errors_->Add(e, zone_);
	reported_errors_end_++;
	}

	// Copies the error at position i of the list of reported errors, so that
	// it becomes the last error reported for this classifier. Position i
	// could be either after the existing errors of this classifier (i.e.,
	// in an inner classifier) or it could be an existing error (in case a
	// copy is needed).
	V8_INLINE void Copy(int i) {
	DCHECK_LT(i, reported_errors_->length());
	if (reported_errors_end_ != i)
	reported_errors_->at(reported_errors_end_) = reported_errors_->at(i);
	reported_errors_end_++;
	}

	typename Types::Base* base_;
	ExpressionClassifier* previous_;
	Zone* zone_;
	ZoneList<Error>* reported_errors_;
	DuplicateFinder* duplicate_finder_;
	unsigned invalid_productions_ : 14;
	unsigned function_properties_ : 2;
	// The uint16_t for reported_errors_begin_ and reported_errors_end_ will
	// not be enough in the case of a long series of expressions using nested
	// classifiers, e.g., a long sequence of assignments, as in:
	// literals with spreads, as in:
	// var N=65536; eval("var x;" + "x=".repeat(N) + "42");
	// This should not be a problem, as such things currently fail with a
	// stack overflow while parsing.
	uint16_t reported_errors_begin_;
	uint16_t reported_errors_end_;

	DISALLOW_COPY_AND_ASSIGN(ExpressionClassifier);
	};


	#undef ERROR_CODES


	} // namespace internal
	} // namespace v8

	#endif // V8_PARSING_EXPRESSION_CLASSIFIER_H_