dom/bindings/PinnedStringId.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef DOM_BINDINGS_PINNEDSTRINGID_H_
   8 #define DOM_BINDINGS_PINNEDSTRINGID_H_
   9
  10 #include "js/GCAnnotations.h"
  11 #include "js/Id.h"
  12 #include "js/RootingAPI.h"
  13 #include "js/String.h"
  14 #include "jsapi.h"
  15
  16 class JSString;
  17 struct JSContext;
  18
  19 namespace mozilla::dom {
  20 /*
  21  * Holds a jsid that is initialized to a pinned string, with automatic
  22  * conversion to Handle<jsid>, as it is held live forever by pinning.
  23  */
  24 class PinnedStringId {
  25   jsid id;
  26
  27  public:
  28   constexpr PinnedStringId() : id(JS::PropertyKey::Void()) {}
  29
  30   bool init(JSContext* cx, const char* string) {
  31     JSString* str = JS_AtomizeAndPinString(cx, string);
  32     if (!str) {
  33       return false;
  34     }
  35     id = JS::PropertyKey::fromPinnedString(str);
  36     return true;
  37   }
  38
  39   operator const jsid&() const { return id; }
  40
  41   operator JS::Handle<jsid>() const {
  42     /* This is safe because we have pinned the string. */
  43     return JS::Handle<jsid>::fromMarkedLocation(&id);
  44   }
  45 } JS_HAZ_ROOTED;
  46 }  // namespace mozilla::dom
  47
  48 #endif