[destructuring] Implement parameter pattern matching.

src/parser.h

 // Copyright 2012 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_PARSER_H_
 #define V8_PARSER_H_
 
 #include "src/allocation.h"
 #include "src/ast.h"
 #include "src/compiler.h"  // TODO(titzer): remove this include dependency
@@ skipping 733 matching lines @@
   Expression* GetIterator(Expression* iterable, AstNodeFactory* factory);
   ZoneList<v8::internal::Expression*>* NewExpressionList(int size, Zone* zone) {
     return new(zone) ZoneList<v8::internal::Expression*>(size, zone);
   }
   ZoneList<ObjectLiteral::Property*>* NewPropertyList(int size, Zone* zone) {
     return new(zone) ZoneList<ObjectLiteral::Property*>(size, zone);
   }
   ZoneList<v8::internal::Statement*>* NewStatementList(int size, Zone* zone) {
     return new(zone) ZoneList<v8::internal::Statement*>(size, zone);
   }
+
+  V8_INLINE void AddParameterInitializationBlock(
+      ZoneList<v8::internal::Statement*>* body, bool* ok);
+
   V8_INLINE Scope* NewScope(Scope* parent_scope, ScopeType scope_type,
                             FunctionKind kind = kNormalFunction);
 
   V8_INLINE void DeclareFormalParameter(Scope* scope, Expression* name,
                                         ExpressionClassifier* classifier,
                                         bool is_rest);
   void ParseArrowFunctionFormalParameters(Scope* scope, Expression* params,
                                           const Scanner::Location& params_loc,
                                           bool* has_rest,
                                           Scanner::Location* duplicate_loc,
@@ skipping 350 matching lines @@
   // If bookmark is set, the (pre-)parser may decide to abort skipping
   // in order to force the function to be eagerly parsed, after all.
   // In this case, it'll reset the scanner using the bookmark.
   void SkipLazyFunctionBody(int* materialized_literal_count,
                             int* expected_property_count, bool* ok,
                             Scanner::BookmarkScope* bookmark = nullptr);
 
   PreParser::PreParseResult ParseLazyFunctionBodyWithPreParser(
       SingletonLogger* logger, Scanner::BookmarkScope* bookmark = nullptr);
 
+  Block* BuildParameterInitializationBlock(bool* ok);
+
   // Consumes the ending }.
   ZoneList<Statement*>* ParseEagerFunctionBody(
       const AstRawString* function_name, int pos, Variable* fvar,
       Token::Value fvar_init_op, FunctionKind kind, bool* ok);
 
   void ThrowPendingError(Isolate* isolate, Handle<Script> script);
 
   TemplateLiteralState OpenTemplateLiteral(int pos);
   void AddTemplateSpan(TemplateLiteralState* state, bool tail);
   void AddTemplateExpression(TemplateLiteralState* state,
@@ skipping 133 matching lines @@
 Expression* ParserTraits::SpreadCallNew(
     Expression* function, ZoneList<v8::internal::Expression*>* args, int pos) {
   return parser_->SpreadCallNew(function, args, pos);
 }
 
 
 void ParserTraits::DeclareFormalParameter(Scope* scope, Expression* pattern,
                                           ExpressionClassifier* classifier,
                                           bool is_rest) {
   bool is_duplicate = false;
-  if (!pattern->IsVariableProxy()) {
-    // TODO(dslomov): implement.
-    DCHECK(parser_->allow_harmony_destructuring());
-    return;
-  }
-  auto name = pattern->AsVariableProxy()->raw_name();
-  Variable* var = scope->DeclareParameter(name, VAR, is_rest, &is_duplicate);
+  bool is_simple_name = pattern->IsVariableProxy();
+  DCHECK(parser_->allow_harmony_destructuring() || is_simple_name);
+
+  const AstRawString* name = is_simple_name
+                                 ? pattern->AsVariableProxy()->raw_name()
+                                 : parser_->ast_value_factory()->empty_string();
+  Variable* var = scope->DeclareParameter(
+      name, is_simple_name ? nullptr : pattern, VAR, is_rest, &is_duplicate);
   if (is_sloppy(scope->language_mode())) {
     // TODO(sigurds) Mark every parameter as maybe assigned. This is a
     // conservative approximation necessary to account for parameters
     // that are assigned via the arguments array.
     var->set_maybe_assigned();
   }
   if (is_duplicate) {
     classifier->RecordDuplicateFormalParameterError(
         parser_->scanner()->location());
   }
 }
+
+
+void ParserTraits::AddParameterInitializationBlock(
+    ZoneList<v8::internal::Statement*>* body, bool* ok) {
+  auto* init_block = parser_->BuildParameterInitializationBlock(ok);
+  if (!*ok) return;
+  if (init_block != nullptr) {
+    body->Add(init_block, parser_->zone());
+  }
+}
 } }  // namespace v8::internal
 
 #endif  // V8_PARSER_H_