[es6] Implement destructuring for `catch`

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 478 matching lines @@
 // *var is untouched; in particular, it is the caller's responsibility
 // to initialize it properly. This mechanism is also used for the parsing
 // of 'for-in' loops.
 PreParser::Statement PreParser::ParseVariableDeclarations(
     VariableDeclarationContext var_context, int* num_decl,
     Scanner::Location* first_initializer_loc, Scanner::Location* bindings_loc,
     bool* ok) {
   // VariableDeclarations ::
   //   ('var' | 'const') (Identifier ('=' AssignmentExpression)?)+[',']
   //
-  // The ES6 Draft Rev3 specifies the following grammar for const declarations
-  //
   // ConstDeclaration ::
   //   const ConstBinding (',' ConstBinding)* ';'
+  //
   // ConstBinding ::
   //   Identifier '=' AssignmentExpression
-  //
-  // TODO(ES6):
-  // ConstBinding ::
   //   BindingPattern '=' AssignmentExpression
   bool require_initializer = false;
   bool is_strict_const = false;
   if (peek() == Token::VAR) {
     if (is_strong(language_mode())) {
       Scanner::Location location = scanner()->peek_location();
       ReportMessageAt(location, MessageTemplate::kStrongVar);
       *ok = false;
       return Statement::Default();
     }
@@ skipping 455 matching lines @@
 
 
 PreParser::Statement PreParser::ParseTryStatement(bool* ok) {
   // TryStatement ::
   //   'try' Block Catch
   //   'try' Block Finally
   //   'try' Block Catch Finally
   //
   // Catch ::
   //   'catch' '(' Identifier ')' Block
+  //   'catch' '(' BindingPattern ')' Block
   //
   // Finally ::
   //   'finally' Block
 
   Expect(Token::TRY, CHECK_OK);
 
   ParseBlock(CHECK_OK);
 
   Token::Value tok = peek();
   if (tok != Token::CATCH && tok != Token::FINALLY) {
     ReportMessageAt(scanner()->location(), MessageTemplate::kNoCatchOrFinally);
     *ok = false;
     return Statement::Default();
   }
   if (tok == Token::CATCH) {
     Consume(Token::CATCH);
     Expect(Token::LPAREN, CHECK_OK);
-    ParseIdentifier(kDontAllowRestrictedIdentifiers, CHECK_OK);
+
+    ExpressionClassifier pattern_classifier;
+    Token::Value next = peek();
+    PreParserExpression pattern =
+        ParsePrimaryExpression(&pattern_classifier, CHECK_OK);
+    ValidateBindingPattern(&pattern_classifier, CHECK_OK);
+
+    if (!allow_harmony_destructuring() && !pattern.IsIdentifier()) {
+      ReportUnexpectedToken(next);
+      *ok = false;
+      return Statement::Default();
+    }
+
     Expect(Token::RPAREN, CHECK_OK);
-    {
-      Scope* with_scope = NewScope(scope_, WITH_SCOPE);
-      BlockState block_state(&scope_, with_scope);
+
+    if (pattern.IsIdentifier()) {
+      Scope* catch_scope = NewScope(scope_, CATCH_SCOPE);
+      BlockState block_state(&scope_, catch_scope);
+      ParseBlock(CHECK_OK);
+    } else {
+      Scope* catch_scope = NewScope(scope_, CATCH_SCOPE);
+      Scope* destruct_scope = NewScope(catch_scope, BLOCK_SCOPE);
+      BlockState block_state(&scope_, destruct_scope);
       ParseBlock(CHECK_OK);
     }
     tok = peek();
   }
   if (tok == Token::FINALLY) {
     Consume(Token::FINALLY);
     ParseBlock(CHECK_OK);
   }
   return Statement::Default();
 }
@@ skipping 189 matching lines @@
 
   DCHECK(!spread_pos.IsValid());
 
   return Expression::Default();
 }
 
 #undef CHECK_OK
 
 
 } }  // v8::internal