layout/generic/nsIntervalSet.cpp

   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 #include "nsIntervalSet.h"
  10 #include <new>
  11 #include <algorithm>
  12 #include "mozilla/PresShell.h"  // for allocation
  13
  14 using namespace mozilla;
  15
  16 nsIntervalSet::nsIntervalSet(PresShell* aPresShell)
  17     : mList(nullptr), mPresShell(aPresShell) {}
  18
  19 nsIntervalSet::~nsIntervalSet() {
  20   Interval* current = mList;
  21   while (current) {
  22     Interval* trash = current;
  23     current = current->mNext;
  24     FreeInterval(trash);
  25   }
  26 }
  27
  28 void* nsIntervalSet::AllocateInterval() {
  29   return mPresShell->AllocateByObjectID(eArenaObjectID_nsIntervalSet_Interval,
  30                                         sizeof(Interval));
  31 }
  32
  33 void nsIntervalSet::FreeInterval(nsIntervalSet::Interval* aInterval) {
  34   NS_ASSERTION(aInterval, "null interval");
  35
  36   aInterval->Interval::~Interval();
  37   mPresShell->FreeByObjectID(eArenaObjectID_nsIntervalSet_Interval, aInterval);
  38 }
  39
  40 void nsIntervalSet::IncludeInterval(coord_type aBegin, coord_type aEnd) {
  41   auto newInterval = static_cast<Interval*>(AllocateInterval());
  42   new (newInterval) Interval(aBegin, aEnd);
  43
  44   Interval** current = &mList;
  45   while (*current && (*current)->mEnd < aBegin) current = &(*current)->mNext;
  46
  47   newInterval->mNext = *current;
  48   *current = newInterval;
  49
  50   Interval* subsumed = newInterval->mNext;
  51   while (subsumed && subsumed->mBegin <= aEnd) {
  52     newInterval->mBegin = std::min(newInterval->mBegin, subsumed->mBegin);
  53     newInterval->mEnd = std::max(newInterval->mEnd, subsumed->mEnd);
  54     newInterval->mNext = subsumed->mNext;
  55     FreeInterval(subsumed);
  56     subsumed = newInterval->mNext;
  57   }
  58 }
  59
  60 bool nsIntervalSet::Intersects(coord_type aBegin, coord_type aEnd) const {
  61   Interval* current = mList;
  62   while (current && current->mBegin <= aEnd) {
  63     if (current->mEnd >= aBegin) return true;
  64     current = current->mNext;
  65   }
  66   return false;
  67 }
  68
  69 bool nsIntervalSet::Contains(coord_type aBegin, coord_type aEnd) const {
  70   Interval* current = mList;
  71   while (current && current->mBegin <= aBegin) {
  72     if (current->mEnd >= aEnd) return true;
  73     current = current->mNext;
  74   }
  75   return false;
  76 }