[ESnext] Parse dynamic import expression

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 36268493e971ae185e2f88b5254cc5a88a7dde70..07a2479bf12fb57cdef972d79bb62adc9d066c13 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -553,6 +553,7 @@ Parser::Parser(ParseInfo* info)
   set_allow_harmony_trailing_commas(FLAG_harmony_trailing_commas);
   set_allow_harmony_class_fields(FLAG_harmony_class_fields);
   set_allow_harmony_object_rest_spread(FLAG_harmony_object_rest_spread);
+  set_allow_harmony_dynamic_import(FLAG_harmony_dynamic_import);
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     use_counts_[feature] = 0;
@@ -962,15 +963,24 @@ Statement* Parser::ParseModuleItem(bool* ok) {
   //    ExportDeclaration
   //    StatementListItem
 
-  switch (peek()) {
-    case Token::IMPORT:
-      ParseImportDeclaration(CHECK_OK);
-      return factory()->NewEmptyStatement(kNoSourcePosition);
-    case Token::EXPORT:
-      return ParseExportDeclaration(ok);
-    default:
+  Token::Value next = peek();
+
+  if (next == Token::IMPORT) {
+    // This makes sure we don't parse a dynamic import expression as
+    // an import declaration.
+    if (allow_harmony_dynamic_import() && PeekAhead() == Token::LPAREN) {
       return ParseStatementListItem(ok);
+    }
+
+    ParseImportDeclaration(CHECK_OK);
+    return factory()->NewEmptyStatement(kNoSourcePosition);
+  }
+
+  if (next == Token::EXPORT) {
+    return ParseExportDeclaration(ok);
   }
+
+  return ParseStatementListItem(ok);
 }

[neis, 2017/01/31 10:47:57]

Nit: I find this version a little nicer as it doesn't duplicate the default
case:

if (next == Token::EXPORT) {
  return ParseExportDeclaration(ok);
}

// We must be careful not to parse a dynamic import expression as an import
declaration.
if (next == Token::IMPORT &&
    (!allow_harmony_dynamic_import() || PeekAhead() != Token::LPAREN) {
  ParseImportDeclaration(CHECK_OK);
  return factory()->NewEmptyStatement(kNoSourcePosition);
}

return ParseStatementListItem(ok);

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

I did this initially and found the if conditional less readable. Changed anyway

 
 
@@ -2792,6 +2802,7 @@ Parser::LazyParsingResult Parser::SkipFunction(
     SET_ALLOW(harmony_trailing_commas);
     SET_ALLOW(harmony_class_fields);
     SET_ALLOW(harmony_object_rest_spread);
+    SET_ALLOW(harmony_dynamic_import);
 #undef SET_ALLOW
   }
   // Aborting inner function preparsing would leave scopes in an inconsistent