layout/generic/nsIntervalSet.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 // vim:cindent:ts=8:et:sw=4:
   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 /* a set of ranges on a number-line */
   8
   9 #ifndef nsIntervalSet_h___
  10 #define nsIntervalSet_h___
  11
  12 #include "nsCoord.h"
  13
  14 namespace mozilla {
  15 class PresShell;
  16 }  // namespace mozilla
  17
  18 /*
  19  * A list-based class (hopefully tree-based when I get around to it)
  20  * for representing a set of ranges on a number-line.
  21  */
  22 class nsIntervalSet {
  23  public:
  24   typedef nscoord coord_type;
  25
  26   explicit nsIntervalSet(mozilla::PresShell* aPresShell);
  27   ~nsIntervalSet();
  28
  29   /*
  30    * Include the interval [aBegin, aEnd] in the set.
  31    *
  32    * Removal of intervals added is not supported because that would
  33    * require keeping track of the individual intervals that were
  34    * added (nsIntervalMap should do that).  It would be simple to
  35    * implement ExcludeInterval if anyone wants it, though.
  36    */
  37   void IncludeInterval(coord_type aBegin, coord_type aEnd);
  38
  39   /*
  40    * Are _some_ points in [aBegin, aEnd] contained within the set
  41    * of intervals?
  42    */
  43   bool Intersects(coord_type aBegin, coord_type aEnd) const;
  44
  45   /*
  46    * Are _all_ points in [aBegin, aEnd] contained within the set
  47    * of intervals?
  48    */
  49   bool Contains(coord_type aBegin, coord_type aEnd) const;
  50
  51   bool IsEmpty() const { return !mList; }
  52
  53  private:
  54   class Interval {
  55    public:
  56     Interval(coord_type aBegin, coord_type aEnd)
  57         : mBegin(aBegin), mEnd(aEnd), mPrev(nullptr), mNext(nullptr) {}
  58
  59     coord_type mBegin;
  60     coord_type mEnd;
  61     Interval* mPrev;
  62     Interval* mNext;
  63   };
  64
  65   void* AllocateInterval();
  66   void FreeInterval(Interval* aInterval);
  67
  68   Interval* mList;
  69   mozilla::PresShell* mPresShell;
  70 };
  71
  72 #endif  // !defined(nsIntervalSet_h___)