[es8] More spec compliant syntactic tail calls implementation.

src/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"
 #include "src/parsing/token.h"
@@ skipping 21 matching lines @@
   enum TargetProduction {
     ExpressionProduction = 1 << 0,
     FormalParameterInitializerProduction = 1 << 1,
     BindingPatternProduction = 1 << 2,
     AssignmentPatternProduction = 1 << 3,
     DistinctFormalParametersProduction = 1 << 4,
     StrictModeFormalParametersProduction = 1 << 5,
     ArrowFormalParametersProduction = 1 << 6,
     LetPatternProduction = 1 << 7,
     CoverInitializedNameProduction = 1 << 8,
+    TailCallExpressionProduction = 1 << 9,
 
     ExpressionProductions =
-        (ExpressionProduction | FormalParameterInitializerProduction),
+        (ExpressionProduction | FormalParameterInitializerProduction |
+         TailCallExpressionProduction),
     PatternProductions = (BindingPatternProduction |
                           AssignmentPatternProduction | LetPatternProduction),
     FormalParametersProductions = (DistinctFormalParametersProduction |
                                    StrictModeFormalParametersProduction),
     StandardProductions = ExpressionProductions | PatternProductions,
     AllProductions =
         (StandardProductions | FormalParametersProductions |
          ArrowFormalParametersProduction | CoverInitializedNameProduction)
   };
 
@@ skipping 81 matching lines @@
 
   const Error& let_pattern_error() const { return let_pattern_error_; }
 
   bool has_cover_initialized_name() const {
     return !is_valid(CoverInitializedNameProduction);
   }
   const Error& cover_initialized_name_error() const {
     return cover_initialized_name_error_;
   }
 
+  bool has_tail_call_expression() const {
+    return !is_valid(TailCallExpressionProduction);
+  }
+  const Error& tail_call_expression_error() const {
+    return tail_call_expression_error_;
+  }
+
   bool is_simple_parameter_list() const {
     return !(function_properties_ & NonSimpleParameter);
   }
 
   void RecordNonSimpleParameter() {
     function_properties_ |= NonSimpleParameter;
   }
 
   void RecordExpressionError(const Scanner::Location& loc,
                              MessageTemplate::Template message,
@@ skipping 97 matching lines @@
   void RecordCoverInitializedNameError(const Scanner::Location& loc,
                                        MessageTemplate::Template message,
                                        const char* arg = nullptr) {
     if (has_cover_initialized_name()) return;
     invalid_productions_ |= CoverInitializedNameProduction;
     cover_initialized_name_error_.location = loc;
     cover_initialized_name_error_.message = message;
     cover_initialized_name_error_.arg = arg;
   }
 
+  void RecordTailCallExpressionError(const Scanner::Location& loc,
+                                     MessageTemplate::Template message,
+                                     const char* arg = nullptr) {
+    if (has_tail_call_expression()) return;
+    invalid_productions_ |= TailCallExpressionProduction;
+    tail_call_expression_error_.location = loc;
+    tail_call_expression_error_.message = message;
+    tail_call_expression_error_.arg = arg;
+  }
+
   void ForgiveCoverInitializedNameError() {
     invalid_productions_ &= ~CoverInitializedNameProduction;
     cover_initialized_name_error_ = Error();
   }
 
   void ForgiveAssignmentPatternError() {
     invalid_productions_ &= ~AssignmentPatternProduction;
     assignment_pattern_error_ = Error();
   }
 
@@ skipping 25 matching lines @@
       if (errors & DistinctFormalParametersProduction)
         duplicate_formal_parameter_error_ =
             inner->duplicate_formal_parameter_error_;
       if (errors & StrictModeFormalParametersProduction)
         strict_mode_formal_parameter_error_ =
             inner->strict_mode_formal_parameter_error_;
       if (errors & LetPatternProduction)
         let_pattern_error_ = inner->let_pattern_error_;
       if (errors & CoverInitializedNameProduction)
         cover_initialized_name_error_ = inner->cover_initialized_name_error_;
+      if (errors & TailCallExpressionProduction)
+        tail_call_expression_error_ = inner->tail_call_expression_error_;
     }
 
     // As an exception to the above, the result continues to be a valid arrow
     // formal parameters if the inner expression is a valid binding pattern.
     if (productions & ArrowFormalParametersProduction &&
         is_valid_arrow_formal_parameters()) {
       // Also copy function properties if expecting an arrow function
       // parameter.
       function_properties_ |= inner->function_properties_;
 
@@ skipping 15 matching lines @@
     DCHECK_LE(non_pattern_begin_, inner->non_pattern_begin_);
     inner->non_pattern_begin_ = inner->non_patterns_to_rewrite_->length();
   }
 
  private:
   Zone* zone_;
   ZoneList<typename Traits::Type::Expression>* non_patterns_to_rewrite_;
   int non_pattern_begin_;
   unsigned invalid_productions_;
   unsigned function_properties_;
+  // TODO(ishell): consider using Zone[Hash]Map<TargetProduction, Error>
+  // here to consume less stack space during parsing.
   Error expression_error_;
   Error formal_parameter_initializer_error_;
   Error binding_pattern_error_;
   Error assignment_pattern_error_;
   Error arrow_formal_parameters_error_;
   Error duplicate_formal_parameter_error_;
   Error strict_mode_formal_parameter_error_;
   Error let_pattern_error_;
   Error cover_initialized_name_error_;
+  Error tail_call_expression_error_;
   DuplicateFinder* duplicate_finder_;
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_EXPRESSION_CLASSIFIER_H