Implement a character stream for external one byte streams

src/parsing/parser.cc

 // 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.
 
 #include "src/parsing/parser.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/ast/ast.h"
@@ skipping 870 matching lines @@
 
   if (produce_cached_parse_data()) {
     log_ = &recorder;
   } else if (consume_cached_parse_data()) {
     cached_parse_data_->Initialize();
   }
 
   source = String::Flatten(source);
   FunctionLiteral* result;
 
-  if (source->IsExternalTwoByteString()) {
-    // Notice that the stream is destroyed at the end of the branch block.
-    // The last line of the blocks can't be moved outside, even though they're
-    // identical calls.
-    ExternalTwoByteStringUtf16CharacterStream stream(
-        Handle<ExternalTwoByteString>::cast(source), 0, source->length());
-    scanner_.Initialize(&stream);
-    result = DoParseProgram(info);
-  } else {
-    GenericStringUtf16CharacterStream stream(source, 0, source->length());
-    scanner_.Initialize(&stream);
+  {
+    std::unique_ptr<Utf16CharacterStream> stream;
+    if (source->IsExternalTwoByteString()) {
+      stream.reset(new ExternalTwoByteStringUtf16CharacterStream(
+          Handle<ExternalTwoByteString>::cast(source), 0, source->length()));
+    } else if (source->IsExternalOneByteString()) {
+      stream.reset(new ExternalOneByteStringUtf16CharacterStream(
+          Handle<ExternalOneByteString>::cast(source), 0, source->length()));
+    } else {
+      stream.reset(
+          new GenericStringUtf16CharacterStream(source, 0, source->length()));
+    }
+    scanner_.Initialize(stream.get());
     result = DoParseProgram(info);
   }
   if (result != NULL) {
     DCHECK_EQ(scanner_.peek_location().beg_pos, source->length());
   }
   HandleSourceURLComments(isolate, info->script());
 
   if (FLAG_trace_parse && result != NULL) {
     double ms = timer.Elapsed().InMillisecondsF();
     if (info->is_eval()) {
@@ skipping 6182 matching lines @@
   node->Print(Isolate::Current());
 }
 #endif  // DEBUG
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8