gecko-dev/dom/media/Intervals.h
2015-11-30 11:29:36 +11:00

747 lines
17 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
#ifndef INTERVALS_H
#define INTERVALS_H
#include <algorithm>
#include "mozilla/TypeTraits.h"
#include "nsTArray.h"
// Specialization for nsTArray CopyChooser.
namespace mozilla {
namespace media {
template<class T>
class IntervalSet;
} // namespace media
} // namespace mozilla
template<class E>
struct nsTArray_CopyChooser<mozilla::media::IntervalSet<E>>
{
typedef nsTArray_CopyWithConstructors<mozilla::media::IntervalSet<E>> Type;
};
namespace mozilla {
namespace media {
/* Interval defines an interval between two points. Unlike a traditional
interval [A,B] where A <= x <= B, the upper boundary B is exclusive: A <= x < B
(e.g [A,B[ or [A,B) depending on where you're living)
It provides basic interval arithmetic and fuzzy edges.
The type T must provides a default constructor and +, -, <, <= and ==
operators.
*/
template<typename T>
class Interval
{
public:
typedef Interval<T> SelfType;
Interval()
: mStart(T())
, mEnd(T())
, mFuzz(T())
{}
template<typename StartArg, typename EndArg>
Interval(StartArg&& aStart, EndArg&& aEnd)
: mStart(Forward<StartArg>(aStart))
, mEnd(Forward<EndArg>(aEnd))
, mFuzz()
{
MOZ_ASSERT(aStart <= aEnd);
}
template<typename StartArg, typename EndArg, typename FuzzArg>
Interval(StartArg&& aStart, EndArg&& aEnd, FuzzArg&& aFuzz)
: mStart(Forward<StartArg>(aStart))
, mEnd(Forward<EndArg>(aEnd))
, mFuzz(Forward<FuzzArg>(aFuzz))
{
MOZ_ASSERT(aStart <= aEnd);
}
Interval(const SelfType& aOther)
: mStart(aOther.mStart)
, mEnd(aOther.mEnd)
, mFuzz(aOther.mFuzz)
{}
Interval(SelfType&& aOther)
: mStart(Move(aOther.mStart))
, mEnd(Move(aOther.mEnd))
, mFuzz(Move(aOther.mFuzz))
{ }
SelfType& operator= (const SelfType& aOther)
{
mStart = aOther.mStart;
mEnd = aOther.mEnd;
mFuzz = aOther.mFuzz;
return *this;
}
SelfType& operator= (SelfType&& aOther)
{
MOZ_ASSERT(&aOther != this, "self-moves are prohibited");
this->~Interval();
new(this) Interval(Move(aOther));
return *this;
}
// Basic interval arithmetic operator definition.
SelfType operator+ (const SelfType& aOther) const
{
return SelfType(mStart + aOther.mStart,
mEnd + aOther.mEnd,
mFuzz + aOther.mFuzz);
}
// Basic interval arithmetic operator definition.
SelfType operator- (const SelfType& aOther) const
{
return SelfType(mStart - aOther.mEnd,
mEnd - aOther.mStart,
mFuzz + aOther.mFuzz);
}
bool operator== (const SelfType& aOther) const
{
return mStart == aOther.mStart && mEnd == aOther.mEnd;
}
bool operator!= (const SelfType& aOther) const
{
return !(*this == aOther);
}
bool Contains(const T& aX) const
{
return mStart - mFuzz <= aX && aX < mEnd + mFuzz;
}
bool ContainsStrict(const T& aX) const
{
return mStart <= aX && aX < mEnd;
}
bool ContainsWithStrictEnd(const T& aX) const
{
return mStart - mFuzz <= aX && aX < mEnd;
}
bool Contains(const SelfType& aOther) const
{
return (mStart - mFuzz <= aOther.mStart + aOther.mFuzz) &&
(aOther.mEnd - aOther.mFuzz <= mEnd + mFuzz);
}
bool ContainsStrict(const SelfType& aOther) const
{
return mStart <= aOther.mStart && aOther.mEnd <= mEnd;
}
bool ContainsWithStrictEnd(const SelfType& aOther) const
{
return (mStart - mFuzz <= aOther.mStart + aOther.mFuzz) &&
aOther.mEnd <= mEnd;
}
bool Intersects(const SelfType& aOther) const
{
return (mStart - mFuzz < aOther.mEnd + aOther.mFuzz) &&
(aOther.mStart - aOther.mFuzz < mEnd + mFuzz);
}
bool IntersectsStrict(const SelfType& aOther) const
{
return mStart < aOther.mEnd && aOther.mStart < mEnd;
}
// Same as Intersects, but including the boundaries.
bool Touches(const SelfType& aOther) const
{
return (mStart - mFuzz <= aOther.mEnd + aOther.mFuzz) &&
(aOther.mStart - aOther.mFuzz <= mEnd + mFuzz);
}
// Returns true if aOther is strictly to the right of this and contiguous.
// This operation isn't commutative.
bool Contiguous(const SelfType& aOther) const
{
return mEnd <= aOther.mStart && aOther.mStart - mEnd <= mFuzz + aOther.mFuzz;
}
bool RightOf(const SelfType& aOther) const
{
return aOther.mEnd - aOther.mFuzz <= mStart + mFuzz;
}
bool LeftOf(const SelfType& aOther) const
{
return mEnd - mFuzz <= aOther.mStart + aOther.mFuzz;
}
SelfType Span(const SelfType& aOther) const
{
if (IsEmpty()) {
return aOther;
}
SelfType result(*this);
if (aOther.mStart < mStart) {
result.mStart = aOther.mStart;
}
if (mEnd < aOther.mEnd) {
result.mEnd = aOther.mEnd;
}
if (mFuzz < aOther.mFuzz) {
result.mFuzz = aOther.mFuzz;
}
return result;
}
SelfType Intersection(const SelfType& aOther) const
{
const T& s = std::max(mStart, aOther.mStart);
const T& e = std::min(mEnd, aOther.mEnd);
const T& f = std::max(mFuzz, aOther.mFuzz);
if (s < e) {
return SelfType(s, e, f);
}
// Return an empty interval.
return SelfType();
}
T Length() const
{
return mEnd - mStart;
}
bool IsEmpty() const
{
return mStart == mEnd;
}
void SetFuzz(const T& aFuzz)
{
mFuzz = aFuzz;
}
// Returns true if the two intervals intersect with this being on the right
// of aOther
bool TouchesOnRight(const SelfType& aOther) const
{
return aOther.mStart <= mStart &&
(mStart - mFuzz <= aOther.mEnd + aOther.mFuzz) &&
(aOther.mStart - aOther.mFuzz <= mEnd + mFuzz);
}
T mStart;
T mEnd;
T mFuzz;
private:
};
// An IntervalSet in a collection of Intervals. The IntervalSet is always
// normalized.
template<typename T>
class IntervalSet
{
public:
typedef IntervalSet<T> SelfType;
typedef Interval<T> ElemType;
typedef nsAutoTArray<ElemType,4> ContainerType;
typedef typename ContainerType::index_type IndexType;
IntervalSet()
{
}
virtual ~IntervalSet()
{
}
IntervalSet(const SelfType& aOther)
: mIntervals(aOther.mIntervals)
{
}
IntervalSet(SelfType&& aOther)
{
mIntervals.AppendElements(Move(aOther.mIntervals));
}
explicit IntervalSet(const ElemType& aOther)
{
if (!aOther.IsEmpty()) {
mIntervals.AppendElement(aOther);
}
}
explicit IntervalSet(ElemType&& aOther)
{
if (!aOther.IsEmpty()) {
mIntervals.AppendElement(Move(aOther));
}
}
bool operator== (const SelfType& aOther) const
{
return mIntervals == aOther.mIntervals;
}
bool operator!= (const SelfType& aOther) const
{
return mIntervals != aOther.mIntervals;
}
SelfType& operator= (const SelfType& aOther)
{
mIntervals = aOther.mIntervals;
return *this;
}
SelfType& operator= (SelfType&& aOther)
{
MOZ_ASSERT(&aOther != this, "self-moves are prohibited");
this->~IntervalSet();
new(this) IntervalSet(Move(aOther));
return *this;
}
SelfType& operator= (const ElemType& aInterval)
{
mIntervals.Clear();
if (!aInterval.IsEmpty()) {
mIntervals.AppendElement(aInterval);
}
return *this;
}
SelfType& operator= (ElemType&& aInterval)
{
mIntervals.Clear();
if (!aInterval.IsEmpty()) {
mIntervals.AppendElement(Move(aInterval));
}
return *this;
}
SelfType& Add(const SelfType& aIntervals)
{
mIntervals.AppendElements(aIntervals.mIntervals);
Normalize();
return *this;
}
SelfType& Add(const ElemType& aInterval)
{
if (aInterval.IsEmpty()) {
return *this;
}
if (mIntervals.IsEmpty()) {
mIntervals.AppendElement(aInterval);
return *this;
}
ElemType& last = mIntervals.LastElement();
if (aInterval.TouchesOnRight(last)) {
last = last.Span(aInterval);
return *this;
}
// Most of our actual usage is adding an interval that will be outside the
// range. We can speed up normalization here.
if (aInterval.RightOf(last)) {
mIntervals.AppendElement(aInterval);
return *this;
}
ContainerType normalized;
ElemType current(aInterval);
IndexType i = 0;
for (; i < mIntervals.Length(); i++) {
ElemType& interval = mIntervals[i];
if (current.Touches(interval)) {
current = current.Span(interval);
} else if (current.LeftOf(interval)) {
break;
} else {
normalized.AppendElement(Move(interval));
}
}
normalized.AppendElement(Move(current));
for (; i < mIntervals.Length(); i++) {
normalized.AppendElement(Move(mIntervals[i]));
}
mIntervals.Clear();
mIntervals.AppendElements(Move(normalized));
return *this;
}
SelfType& operator+= (const SelfType& aIntervals)
{
Add(aIntervals);
return *this;
}
SelfType& operator+= (const ElemType& aInterval)
{
Add(aInterval);
return *this;
}
SelfType operator+ (const SelfType& aIntervals) const
{
SelfType intervals(*this);
intervals.Add(aIntervals);
return intervals;
}
SelfType operator+ (const ElemType& aInterval) const
{
SelfType intervals(*this);
intervals.Add(aInterval);
return intervals;
}
friend SelfType operator+ (const ElemType& aInterval,
const SelfType& aIntervals)
{
SelfType intervals;
intervals.Add(aInterval);
intervals.Add(aIntervals);
return intervals;
}
// Excludes an interval from an IntervalSet.
// This is done by inverting aInterval within the bounds of mIntervals
// and then doing the intersection.
SelfType& operator-= (const ElemType& aInterval)
{
if (aInterval.IsEmpty() || mIntervals.IsEmpty()) {
return *this;
}
T firstEnd = std::max(mIntervals[0].mStart, aInterval.mStart);
T secondStart = std::min(mIntervals.LastElement().mEnd, aInterval.mEnd);
ElemType startInterval(mIntervals[0].mStart, firstEnd);
ElemType endInterval(secondStart, mIntervals.LastElement().mEnd);
SelfType intervals(Move(startInterval));
intervals += Move(endInterval);
return Intersection(intervals);
}
SelfType& operator-= (const SelfType& aIntervals)
{
for (const auto& interval : aIntervals.mIntervals) {
*this -= interval;
}
return *this;
}
SelfType operator- (const SelfType& aInterval) const
{
SelfType intervals(*this);
intervals -= aInterval;
return intervals;
}
SelfType operator- (const ElemType& aInterval) const
{
SelfType intervals(*this);
intervals -= aInterval;
return intervals;
}
// Mutate this IntervalSet to be the union of this and aOther.
SelfType& Union(const SelfType& aOther)
{
Add(aOther);
return *this;
}
SelfType& Union(const ElemType& aInterval)
{
Add(aInterval);
return *this;
}
// Mutate this TimeRange to be the intersection of this and aOther.
SelfType& Intersection(const SelfType& aOther)
{
ContainerType intersection;
const ContainerType& other = aOther.mIntervals;
IndexType i = 0, j = 0;
for (; i < mIntervals.Length() && j < other.Length();) {
if (mIntervals[i].IntersectsStrict(other[j])) {
intersection.AppendElement(mIntervals[i].Intersection(other[j]));
}
if (mIntervals[i].mEnd < other[j].mEnd) {
i++;
} else {
j++;
}
}
mIntervals.Clear();
mIntervals.AppendElements(Move(intersection));
return *this;
}
SelfType& Intersection(const ElemType& aInterval)
{
SelfType intervals(aInterval);
return Intersection(intervals);
}
const ElemType& operator[] (IndexType aIndex) const
{
return mIntervals[aIndex];
}
// Returns the start boundary of the first interval. Or a default constructed
// T if IntervalSet is empty (and aExists if provided will be set to false).
T GetStart(bool* aExists = nullptr) const
{
bool exists = !mIntervals.IsEmpty();
if (aExists) {
*aExists = exists;
}
if (exists) {
return mIntervals[0].mStart;
} else {
return T();
}
}
// Returns the end boundary of the last interval. Or a default constructed T
// if IntervalSet is empty (and aExists if provided will be set to false).
T GetEnd(bool* aExists = nullptr) const
{
bool exists = !mIntervals.IsEmpty();
if (aExists) {
*aExists = exists;
}
if (exists) {
return mIntervals.LastElement().mEnd;
} else {
return T();
}
}
IndexType Length() const
{
return mIntervals.Length();
}
T Start(IndexType aIndex) const
{
return mIntervals[aIndex].mStart;
}
T Start(IndexType aIndex, bool& aExists) const
{
aExists = aIndex < mIntervals.Length();
if (aExists) {
return mIntervals[aIndex].mStart;
} else {
return T();
}
}
T End(IndexType aIndex) const
{
return mIntervals[aIndex].mEnd;
}
T End(IndexType aIndex, bool& aExists) const
{
aExists = aIndex < mIntervals.Length();
if (aExists) {
return mIntervals[aIndex].mEnd;
} else {
return T();
}
}
bool Contains(const ElemType& aInterval) const {
for (const auto& interval : mIntervals) {
if (aInterval.LeftOf(interval)) {
// Will never succeed.
return false;
}
if (interval.Contains(aInterval)) {
return true;
}
}
return false;
}
bool Contains(const T& aX) const {
for (const auto& interval : mIntervals) {
if (interval.Contains(aX)) {
return true;
}
}
return false;
}
bool ContainsStrict(const T& aX) const {
for (const auto& interval : mIntervals) {
if (interval.ContainsStrict(aX)) {
return true;
}
}
return false;
}
bool ContainsWithStrictEnd(const T& aX) const {
for (const auto& interval : mIntervals) {
if (interval.ContainsWithStrictEnd(aX)) {
return true;
}
}
return false;
}
// Shift all values by aOffset.
SelfType& Shift(const T& aOffset)
{
for (auto& interval : mIntervals) {
interval.mStart = interval.mStart + aOffset;
interval.mEnd = interval.mEnd + aOffset;
}
return *this;
}
void SetFuzz(const T& aFuzz) {
for (auto& interval : mIntervals) {
interval.SetFuzz(aFuzz);
}
Normalize();
}
static const IndexType NoIndex = IndexType(-1);
IndexType Find(const T& aValue) const
{
for (IndexType i = 0; i < mIntervals.Length(); i++) {
if (mIntervals[i].Contains(aValue)) {
return i;
}
}
return NoIndex;
}
// Methods for range-based for loops.
typename ContainerType::iterator begin()
{
return mIntervals.begin();
}
typename ContainerType::const_iterator begin() const
{
return mIntervals.begin();
}
typename ContainerType::iterator end()
{
return mIntervals.end();
}
typename ContainerType::const_iterator end() const
{
return mIntervals.end();
}
ElemType& LastInterval()
{
MOZ_ASSERT(!mIntervals.IsEmpty());
return mIntervals.LastElement();
}
const ElemType& LastInterval() const
{
MOZ_ASSERT(!mIntervals.IsEmpty());
return mIntervals.LastElement();
}
void Clear()
{
mIntervals.Clear();
}
protected:
ContainerType mIntervals;
private:
void Normalize()
{
if (mIntervals.Length() >= 2) {
ContainerType normalized;
mIntervals.Sort(CompareIntervals());
// This merges the intervals.
ElemType current(mIntervals[0]);
for (IndexType i = 1; i < mIntervals.Length(); i++) {
ElemType& interval = mIntervals[i];
if (current.Touches(interval)) {
current = current.Span(interval);
} else {
normalized.AppendElement(Move(current));
current = Move(interval);
}
}
normalized.AppendElement(Move(current));
mIntervals.Clear();
mIntervals.AppendElements(Move(normalized));
}
}
struct CompareIntervals
{
bool Equals(const ElemType& aT1, const ElemType& aT2) const
{
return aT1.mStart == aT2.mStart && aT1.mEnd == aT2.mEnd;
}
bool LessThan(const ElemType& aT1, const ElemType& aT2) const {
return aT1.mStart - aT1.mFuzz < aT2.mStart + aT2.mFuzz;
}
};
};
// clang doesn't allow for this to be defined inline of IntervalSet.
template<typename T>
IntervalSet<T> Union(const IntervalSet<T>& aIntervals1,
const IntervalSet<T>& aIntervals2)
{
IntervalSet<T> intervals(aIntervals1);
intervals.Union(aIntervals2);
return intervals;
}
template<typename T>
IntervalSet<T> Intersection(const IntervalSet<T>& aIntervals1,
const IntervalSet<T>& aIntervals2)
{
IntervalSet<T> intersection(aIntervals1);
intersection.Intersection(aIntervals2);
return intersection;
}
} // namespace media
} // namespace mozilla
#endif // INTERVALS_H