Create frequently used symbols in the vm isolate

vm/symbols.h

Index: vm/symbols.h
===================================================================
--- vm/symbols.h	(revision 0)
+++ vm/symbols.h	(revision 0)
@@ -0,0 +1,48 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef VM_SYMBOLS_H_
+#define VM_SYMBOLS_H_
+
+#include "vm/object.h"
+
+namespace dart {
+
+// Forward declarations.
+class Isolate;
+class ObjectPointerVisitor;
+
+// Contains a list of frequently used strings in a canonicalized form. This
+// list is kept in the vm_isolate in order to share the copy across isolates
+// without having to maintain copies in each isolate.
+class Symbols {
+ public:
+  ~Symbols();
+
+  void VisitObjectPointers(ObjectPointerVisitor* visitor);
+
+  // Access methods for symbols stored in the vm isolate.
+  static RawString* Dot() { return Dart::vm_isolate()->symbols()->dot_; }

[Ivan Posva, 2012/07/18 04:09:22]

static RawString dot() { return dot_; }

See below.

[siva, 2012/07/19 01:12:34]

Done.

+
+  // Initialize frequently used symbols in the vm isolate.
+  static void Init(Isolate* isolate);
+
+ private:
+  Symbols();
+
+  RawObject** from() { return reinterpret_cast<RawObject**>(&dot_); }

[Ivan Posva, 2012/07/18 04:09:22]

from() and to() should not be needed, neither is VisitObjectPointers.

[siva, 2012/07/19 01:12:34]

Done.

+
+  // List of symbols that are stored in the vm isolate for easy access.
+  RawString* dot_;  // "." string.

[Ivan Posva, 2012/07/18 04:09:22]

Why is this not a static? That would avoid having to go through
Dart::vm_isolate->...

Similar to the way we handle other VM isolate allocated objects in object.cc
such as class_class_ or null_.

[siva, 2012/07/19 01:12:34]

Made a static entry.

On 2012/07/18 04:09:22, Ivan Posva wrote:

+
+  RawObject** to() { return reinterpret_cast<RawObject**>(&dot_); }
+
+  friend class SnapshotReader;
+
+  DISALLOW_COPY_AND_ASSIGN(Symbols);
+};
+
+}  // namespace dart
+
+#endif  // VM_SYMBOLS_H_