[destructuring] Implement parameter pattern matching.

src/preparser.cc

 // Copyright 2011 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.
 
 #include <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 1020 matching lines @@
 
   // Parse function body.
   bool outer_is_script_scope = scope_->is_script_scope();
   Scope* function_scope = NewScope(scope_, FUNCTION_SCOPE, kind);
   PreParserFactory factory(NULL);
   FunctionState function_state(&function_state_, &scope_, function_scope, kind,
                                &factory);
   DuplicateFinder duplicate_finder(scanner()->unicode_cache());
   ExpressionClassifier formals_classifier(&duplicate_finder);
 
-  bool has_rest = false;
   Expect(Token::LPAREN, CHECK_OK);
   int start_position = scanner()->location().beg_pos;
   function_scope->set_start_position(start_position);
-  int num_parameters = ParseFormalParameterList(nullptr, &has_rest,
-                                                &formals_classifier, CHECK_OK);
+  PreParserFormalParameterParsingState parsing_state(nullptr);
+  int num_parameters =
+      ParseFormalParameterList(&parsing_state, &formals_classifier, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
   int formals_end_position = scanner()->location().end_pos;
 
-  CheckArityRestrictions(num_parameters, arity_restriction, has_rest,
-                         start_position, formals_end_position, CHECK_OK);
+  CheckArityRestrictions(num_parameters, arity_restriction,
+                         parsing_state.has_rest, start_position,
+                         formals_end_position, CHECK_OK);
 
   // See Parser::ParseFunctionLiteral for more information about lazy parsing
   // and lazy compilation.
   bool is_lazily_parsed =
       (outer_is_script_scope && allow_lazy() && !parenthesized_function_);
   parenthesized_function_ = false;
 
   Expect(Token::LBRACE, CHECK_OK);
   if (is_lazily_parsed) {
     ParseLazyFunctionLiteralBody(CHECK_OK);
   } else {
     ParseStatementList(Token::RBRACE, CHECK_OK);
   }
   Expect(Token::RBRACE, CHECK_OK);
 
   // Validate name and parameter names. We can do this only after parsing the
   // function, since the function can declare itself strict.
   CheckFunctionName(language_mode(), kind, function_name,
                     name_is_strict_reserved, function_name_location, CHECK_OK);
-  const bool strict_formal_parameters = has_rest || IsConciseMethod(kind);
+  const bool strict_formal_parameters =
+      !parsing_state.is_simple_parameter_list || IsConciseMethod(kind);
   const bool allow_duplicate_parameters =
       is_sloppy(language_mode()) && !strict_formal_parameters;
   ValidateFormalParameters(&formals_classifier, language_mode(),
                            allow_duplicate_parameters, CHECK_OK);
 
   if (is_strict(language_mode())) {
     int end_position = scanner()->location().end_pos;
     CheckStrictOctalLiteral(start_position, end_position, CHECK_OK);
   }
 
@@ skipping 104 matching lines @@
 
   DCHECK(!spread_pos.IsValid());
 
   return Expression::Default();
 }
 
 #undef CHECK_OK
 
 
 } }  // v8::internal