gecko-dev/layout/generic/nsIntervalSet.h

/* -*- 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 */

#ifndef nsIntervalSet_h___
#define nsIntervalSet_h___

#include "nsCoord.h"

typedef void *
(* IntervalSetAlloc)(size_t aBytes, void *aClosure);

typedef void
(* IntervalSetFree) (size_t aBytes, void *aPtr, void *aClosure);

/*
 * A list-based class (hopefully tree-based when I get around to it)
 * for representing a set of ranges on a number-line.
 */
class nsIntervalSet {

public:

    typedef nscoord coord_type;

    nsIntervalSet(IntervalSetAlloc aAlloc, IntervalSetFree aFree,
                  void* aAllocatorClosure);
    ~nsIntervalSet();

    /*
     * Include the interval [aBegin, aEnd] in the set.
     *
     * Removal of intervals added is not supported because that would
     * require keeping track of the individual intervals that were
     * added (nsIntervalMap should do that).  It would be simple to
     * implement ExcludeInterval if anyone wants it, though.
     */
    void IncludeInterval(coord_type aBegin, coord_type aEnd);

    /*
     * Are _some_ points in [aBegin, aEnd] contained within the set
     * of intervals?
     */
    bool Intersects(coord_type aBegin, coord_type aEnd) const;

    /*
     * Are _all_ points in [aBegin, aEnd] contained within the set
     * of intervals?
     */
    bool Contains(coord_type aBegin, coord_type aEnd) const;

    bool IsEmpty() const
    {
        return !mList;
    }

private:

    class Interval {

    public:
        Interval(coord_type aBegin, coord_type aEnd)
            : mBegin(aBegin),
              mEnd(aEnd),
              mPrev(nullptr),
              mNext(nullptr)
        {
        }

        coord_type mBegin;
        coord_type mEnd;
        Interval *mPrev;
        Interval *mNext;
    };

    void FreeInterval(Interval *aInterval);

    Interval           *mList;
    IntervalSetAlloc    mAlloc;
    IntervalSetFree     mFree;
    void               *mAllocatorClosure;
        
};

#endif // !defined(nsIntervalSet_h___)