xpcom/ds/nsStaticAtomUtils.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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsStaticAtomUtils_h
   8 #define nsStaticAtomUtils_h
   9
  10 #include <stdint.h>
  11 #include "nsAtom.h"
  12 #include "mozilla/ArrayUtils.h"
  13 #include "mozilla/Maybe.h"
  14
  15 // This class holds basic operations on arrays of static atoms.
  16 class nsStaticAtomUtils {
  17  public:
  18   static mozilla::Maybe<uint32_t> Lookup(nsAtom* aAtom,
  19                                          const nsStaticAtom* aAtoms,
  20                                          uint32_t aCount) {
  21     if (aAtom->IsStatic()) {
  22       ptrdiff_t index = aAtom->AsStatic() - aAtoms;
  23       if (index >= 0 && index < static_cast<ptrdiff_t>(aCount)) {
  24         return mozilla::Some(static_cast<uint32_t>(index));
  25       }
  26     }
  27     return mozilla::Nothing();
  28   }
  29
  30   static bool IsMember(nsAtom* aAtom, const nsStaticAtom* aAtoms,
  31                        uint32_t aCount) {
  32     return Lookup(aAtom, aAtoms, aCount).isSome();
  33   }
  34 };
  35
  36 #endif  // nsStaticAtomUtils_h