[ESnext] Parse dynamic import expression

src/parsing/parser-base.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_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
@@ skipping 206 matching lines @@
         stack_overflow_(false),
         default_eager_compile_hint_(FunctionLiteral::kShouldLazyCompile),
         function_literal_id_(0),
         allow_natives_(false),
         allow_tailcalls_(false),
         allow_harmony_do_expressions_(false),
         allow_harmony_function_sent_(false),
         allow_harmony_restrictive_generators_(false),
         allow_harmony_trailing_commas_(false),
         allow_harmony_class_fields_(false),
-        allow_harmony_object_rest_spread_(false) {}
+        allow_harmony_object_rest_spread_(false),
+        allow_harmony_dynamic_import_(false) {}
 
 #define ALLOW_ACCESSORS(name)                           \
   bool allow_##name() const { return allow_##name##_; } \
   void set_allow_##name(bool allow) { allow_##name##_ = allow; }
 
   ALLOW_ACCESSORS(natives);
   ALLOW_ACCESSORS(tailcalls);
   ALLOW_ACCESSORS(harmony_do_expressions);
   ALLOW_ACCESSORS(harmony_function_sent);
   ALLOW_ACCESSORS(harmony_restrictive_generators);
   ALLOW_ACCESSORS(harmony_trailing_commas);
   ALLOW_ACCESSORS(harmony_class_fields);
   ALLOW_ACCESSORS(harmony_object_rest_spread);
+  ALLOW_ACCESSORS(harmony_dynamic_import);
 
 #undef ALLOW_ACCESSORS
 
   uintptr_t stack_limit() const { return stack_limit_; }
 
   void set_stack_limit(uintptr_t stack_limit) { stack_limit_ = stack_limit; }
 
   void set_default_eager_compile_hint(
       FunctionLiteral::EagerCompileHint eager_compile_hint) {
     default_eager_compile_hint_ = eager_compile_hint;
@@ skipping 948 matching lines @@
   void ParseAsyncFunctionBody(Scope* scope, StatementListT body,
                               FunctionKind kind, FunctionBodyType type,
                               bool accept_IN, int pos, bool* ok);
   ExpressionT ParseAsyncFunctionLiteral(bool* ok);
   ExpressionT ParseClassLiteral(IdentifierT name,
                                 Scanner::Location class_name_location,
                                 bool name_is_strict_reserved,
                                 int class_token_pos, bool* ok);
   ExpressionT ParseTemplateLiteral(ExpressionT tag, int start, bool* ok);
   ExpressionT ParseSuperExpression(bool is_new, bool* ok);
+  ExpressionT ParseDynamicImportExpression(bool* ok);
   ExpressionT ParseNewTargetExpression(bool* ok);
 
   void ParseFormalParameter(FormalParametersT* parameters, bool* ok);
   void ParseFormalParameterList(FormalParametersT* parameters, bool* ok);
   void CheckArityRestrictions(int param_count, FunctionKind function_type,
                               bool has_rest, int formals_start_pos,
                               int formals_end_pos, bool* ok);
 
   BlockT ParseVariableDeclarations(VariableDeclarationContext var_context,
                                    DeclarationParsingResult* parsing_result,
@@ skipping 258 matching lines @@
   int function_literal_id_;
 
   bool allow_natives_;
   bool allow_tailcalls_;
   bool allow_harmony_do_expressions_;
   bool allow_harmony_function_sent_;
   bool allow_harmony_restrictive_generators_;
   bool allow_harmony_trailing_commas_;
   bool allow_harmony_class_fields_;
   bool allow_harmony_object_rest_spread_;
+  bool allow_harmony_dynamic_import_;
 
   friend class DiscardableZoneScope;
 };
 
 template <typename Impl>
 ParserBase<Impl>::FunctionState::FunctionState(
     FunctionState** function_state_stack, ScopeState** scope_stack,
     DeclarationScope* scope)
     : ScopeState(scope_stack, scope),
       next_materialized_literal_index_(0),
@@ skipping 1846 matching lines @@
   // No 'new' or 'super' keyword.
   return ParseMemberExpression(is_async, ok);
 }
 
 template <typename Impl>
 typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParseMemberExpression(
     bool* is_async, bool* ok) {
   // MemberExpression ::
   //   (PrimaryExpression | FunctionLiteral | ClassLiteral)
   //     ('[' Expression ']' | '.' Identifier | Arguments | TemplateLiteral)*
 

[neis, 2017/01/31 11:20:09]

Please update the comment.

I'm a bit confused, though, this doesn't seem to match the spec anymore.

[gsathya, 2017/01/31 18:26:07]

This hasn't matched the spec in a while. Fixed

   // The '[' Expression ']' and '.' Identifier parts are parsed by
   // ParseMemberExpressionContinuation, and the Arguments part is parsed by the
   // caller.
 
   // Parse the initial primary or function expression.
   ExpressionT result;
   if (peek() == Token::FUNCTION) {
     BindingPatternUnexpectedToken();
     ArrowFormalParametersUnexpectedToken();
 
@@ skipping 32 matching lines @@
     }
     result = impl()->ParseFunctionLiteral(
         name, function_name_location,
         is_strict_reserved_name ? kFunctionNameIsStrictReserved
                                 : kFunctionNameValidityUnknown,
         function_kind, function_token_position, function_type, language_mode(),
         CHECK_OK);
   } else if (peek() == Token::SUPER) {
     const bool is_new = false;
     result = ParseSuperExpression(is_new, CHECK_OK);
+  } else if (allow_harmony_dynamic_import() && peek() == Token::IMPORT) {
+    result = ParseDynamicImportExpression(CHECK_OK);
   } else {
     result = ParsePrimaryExpression(is_async, CHECK_OK);
   }
 
   result = ParseMemberExpressionContinuation(result, is_async, CHECK_OK);
   return result;
 }
 
 template <typename Impl>
+typename ParserBase<Impl>::ExpressionT
+ParserBase<Impl>::ParseDynamicImportExpression(bool* ok) {
+  DCHECK(allow_harmony_dynamic_import());
+  Consume(Token::IMPORT);
+  int pos = position();
+  Expect(Token::LPAREN, CHECK_OK);
+  ExpressionT arg = ParseAssignmentExpression(true, CHECK_OK);
+  Expect(Token::RPAREN, CHECK_OK);
+  ZoneList<ExpressionT>* args = new (zone()) ZoneList<ExpressionT>(1, zone());
+  args->Add(arg, zone());
+  return factory()->NewCallRuntime(Runtime::kDynamicImportCall, args, pos);
+}
+
+template <typename Impl>
 typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParseSuperExpression(
     bool is_new, bool* ok) {
   Expect(Token::SUPER, CHECK_OK);
   int pos = position();
 
   DeclarationScope* scope = GetReceiverScope();
   FunctionKind kind = scope->function_kind();
   if (IsConciseMethod(kind) || IsAccessorFunction(kind) ||
       IsClassConstructor(kind)) {
     if (peek() == Token::PERIOD || peek() == Token::LBRACK) {
@@ skipping 2298 matching lines @@
     return;
   }
 }
 
 #undef CHECK_OK_VOID
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H