xpcom/ds/Dafsa.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 mozilla_Dafsa_h
   8 #define mozilla_Dafsa_h
   9
  10 #include "stdint.h"
  11
  12 #include "mozilla/Span.h"
  13 #include "nsStringFwd.h"
  14
  15 namespace mozilla {
  16
  17 /**
  18  * A deterministic acyclic finite state automaton suitable for storing static
  19  * dictionaries of tagged ascii strings. Consider using this if you have a very
  20  * large set of strings that need an associated enum value.
  21  *
  22  * Currently the string tag is limited by `make_dafsa.py` to a value of [0-4].
  23  * In theory [0-15] can easily be supported.
  24  *
  25  * See `make_dafsa.py` for more details.
  26  */
  27 class Dafsa {
  28  public:
  29   using Graph = Span<const uint8_t>;
  30
  31   /**
  32    * Initializes the DAFSA with a binary encoding generated by `make_dafsa.py`.
  33    */
  34   explicit Dafsa(const Graph& aData) : mData(aData) {}
  35
  36   ~Dafsa() = default;
  37
  38   /**
  39    * Searches for the given string in the DAFSA.
  40    *
  41    * @param aKey The string to search for.
  42    * @returns kKeyNotFound if not found, otherwise the associated tag.
  43    */
  44   int Lookup(const nsACString& aKey) const;
  45
  46   static const int kKeyNotFound;
  47
  48  private:
  49   const Graph mData;
  50 };
  51
  52 }  // namespace mozilla
  53
  54 #endif  // mozilla_Dafsa_h