gecko-dev/layout/generic/nsIntervalSet.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
// vim:cindent:ts=8:et:sw=4:
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* a set of ranges on a number-line */

#include "nsIntervalSet.h"
#include <new>
#include <algorithm>
#include "nsIPresShell.h" // for allocation

using namespace mozilla;

nsIntervalSet::nsIntervalSet(nsIPresShell* aPresShell)
    : mList(nullptr),
      mPresShell(aPresShell)
{
}

nsIntervalSet::~nsIntervalSet()
{
    Interval *current = mList;
    while (current) {
        Interval *trash = current;
        current = current->mNext;
        FreeInterval(trash);
    }
}

void*
nsIntervalSet::AllocateInterval()
{
    return mPresShell->AllocateByObjectID(
        eArenaObjectID_nsIntervalSet_Interval, sizeof(Interval));
}

void nsIntervalSet::FreeInterval(nsIntervalSet::Interval *aInterval)
{
    NS_ASSERTION(aInterval, "null interval");

    aInterval->Interval::~Interval();
    mPresShell->FreeByObjectID(eArenaObjectID_nsIntervalSet_Interval, aInterval);
}

void nsIntervalSet::IncludeInterval(coord_type aBegin, coord_type aEnd)
{
    auto newInterval = static_cast<Interval*>(AllocateInterval());
    new(newInterval) Interval(aBegin, aEnd);

    Interval **current = &mList;
    while (*current && (*current)->mEnd < aBegin)
        current = &(*current)->mNext;

    newInterval->mNext = *current;
    *current = newInterval;

    Interval *subsumed = newInterval->mNext;
    while (subsumed && subsumed->mBegin <= aEnd) {
        newInterval->mBegin = std::min(newInterval->mBegin, subsumed->mBegin);
        newInterval->mEnd = std::max(newInterval->mEnd, subsumed->mEnd);
        newInterval->mNext = subsumed->mNext;
        FreeInterval(subsumed);
        subsumed = newInterval->mNext;
    }
}

bool nsIntervalSet::Intersects(coord_type aBegin, coord_type aEnd) const
{
    Interval *current = mList;
    while (current && current->mBegin <= aEnd) {
        if (current->mEnd >= aBegin)
            return true;
        current = current->mNext;
    }
    return false;
}

bool nsIntervalSet::Contains(coord_type aBegin, coord_type aEnd) const
{
    Interval *current = mList;
    while (current && current->mBegin <= aBegin) {
        if (current->mEnd >= aEnd)
            return true;
        current = current->mNext;
    }
    return false;
}