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++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
++ // Qt-Security score:significant
++
++ #include "qqmlchangeset_p.h"
++
++ QT_BEGIN_NAMESPACE
++
++
++ /*!
++ \class QQmlChangeSet
++ \brief The QQmlChangeSet class stores an ordered list of notifications about
++ changes to a linear data set.
++ \internal
++
++ QQmlChangeSet can be used to record a series of notifications about items in an indexed list
++ being inserted, removed, moved, and changed. Notifications in the set are re-ordered so that
++ all notifications of a single type are grouped together and sorted in order of ascending index,
++ with remove notifications preceding all others, followed by insert notification, and then
++ change notifications.
++
++ Moves in a change set are represented by a remove notification paired with an insert
++ notification by way of a shared unique moveId. Re-ordering may result in one or both of the
++ paired notifications being divided, when this happens the offset member of the notification
++ will indicate the relative offset of the divided notification from the beginning of the
++ original.
++ */
++
++ /*!
++ Constructs an empty change set.
++ */
++
++ QQmlChangeSet::QQmlChangeSet()
++ : m_difference(0)
++ {
++ }
++
++ /*!
++ Constructs a copy of a \a changeSet.
++ */
++
++ QQmlChangeSet::QQmlChangeSet(const QQmlChangeSet &changeSet)
++ : m_removes(changeSet.m_removes)
++ , m_inserts(changeSet.m_inserts)
++ , m_changes(changeSet.m_changes)
++ , m_difference(changeSet.m_difference)
++ {
++ }
++
++ /*!
++ Destroys a change set.
++ */
++
++ QQmlChangeSet::~QQmlChangeSet()
++ {
++ }
++
++ /*!
++ Assigns the value of a \a changeSet to another.
++ */
++
++ QQmlChangeSet &QQmlChangeSet::operator =(const QQmlChangeSet &changeSet)
++ {
++ m_removes = changeSet.m_removes;
++ m_inserts = changeSet.m_inserts;
++ m_changes = changeSet.m_changes;
++ m_difference = changeSet.m_difference;
++ return *this;
++ }
++
++ /*!
++ Appends a notification that \a count items were inserted at \a index.
++ */
++
++ void QQmlChangeSet::insert(int index, int count)
++ {
++ insert(QList<Change>() << Change(index, count));
++ }
++
++ /*!
++ Appends a notification that \a count items were removed at \a index.
++ */
++
++ void QQmlChangeSet::remove(int index, int count)
++ {
++ QList<Change> removes;
++ removes.append(Change(index, count));
++ remove(&removes, nullptr);
++ }
++
++ /*!
++ Appends a notification that \a count items were moved \a from one index \a to another.
++
++ The \a moveId must be unique across the lifetime of the change set and any related
++ change sets.
++ */
++
++ void QQmlChangeSet::move(int from, int to, int count, int moveId)
++ {
++ QList<Change> removes;
++ removes.append(Change(from, count, moveId));
++ QList<Change> inserts;
++ inserts.append(Change(to, count, moveId));
++ remove(&removes, &inserts);
++ insert(inserts);
++ }
++
++ /*!
++ Appends a notification that \a count items were changed at \a index.
++ */
++
++ void QQmlChangeSet::change(int index, int count)
++ {
++ QList<Change> changes;
++ changes.append(Change(index, count));
++ change(changes);
++ }
++
++ /*!
++ Applies the changes in a \a changeSet to another.
++ */
++
++ void QQmlChangeSet::apply(const QQmlChangeSet &changeSet)
++ {
++ QList<Change> r = changeSet.m_removes;
++ QList<Change> i = changeSet.m_inserts;
++ QList<Change> c = changeSet.m_changes;
++ remove(&r, &i);
++ insert(i);
++ change(c);
++ }
++
++ /*!
++ Applies a list of \a removes to a change set.
++
++ If a remove contains a moveId then any intersecting insert in the set will replace the
++ corresponding intersection in the optional \a inserts list.
++ */
++
++ void QQmlChangeSet::remove(const QList<Change> &removes, QList<Change> *inserts)
++ {
++ QList<Change> r = removes;
++ remove(&r, inserts);
++ }
++
++ void QQmlChangeSet::remove(QList<Change> *removes, QList<Change> *inserts)
++ {
++ int removeCount = 0;
++ int insertCount = 0;
++ QList<Change>::iterator insert = m_inserts.begin();
++ QList<Change>::iterator change = m_changes.begin();
++ QList<Change>::iterator rit = removes->begin();
++ for (; rit != removes->end(); ++rit) {
++ int index = rit->index + removeCount;
++ int count = rit->count;
++
++ // Decrement the accumulated remove count from the indexes of any changes prior to the
++ // current remove.
++ for (; change != m_changes.end() && change->end() < rit->index; ++change)
++ change->index -= removeCount;
++ // Remove any portion of a change notification that intersects the current remove.
++ for (; change != m_changes.end() && change->index > rit->end(); ++change) {
++ change->count -= qMin(change->end(), rit->end()) - qMax(change->index, rit->index);
++ if (change->count == 0) {
++ change = m_changes.erase(change);
++ } else if (rit->index < change->index) {
++ change->index = rit->index;
++ }
++ }
++
++ // Decrement the accumulated remove count from the indexes of any inserts prior to the
++ // current remove.
++ for (; insert != m_inserts.end() && insert->end() <= index; ++insert) {
++ insertCount += insert->count;
++ insert->index -= removeCount;
++ }
++
++ rit->index -= insertCount;
++
++ // Remove any portion of a insert notification that intersects the current remove.
++ while (insert != m_inserts.end() && insert->index < index + count) {
++ int offset = index - insert->index;
++ const int difference = qMin(insert->end(), index + count) - qMax(insert->index, index);
++
++ // If part of the remove or insert that precedes the intersection has a moveId create
++ // a new delta for that portion and subtract the size of that delta from the current
++ // one.
++ if (offset < 0 && rit->moveId != -1) {
++ rit = removes->insert(rit, Change(
++ rit->index, -offset, rit->moveId, rit->offset));
++ ++rit;
++ rit->count -= -offset;
++ rit->offset += -offset;
++ index += -offset;
++ count -= -offset;
++ removeCount += -offset;
++ offset = 0;
++ } else if (offset > 0 && insert->moveId != -1) {
++ insert = m_inserts.insert(insert, Change(
++ insert->index - removeCount, offset, insert->moveId, insert->offset));
++ ++insert;
++ insert->index += offset;
++ insert->count -= offset;
++ insert->offset += offset;
++ rit->index -= offset;
++ insertCount += offset;
++ }
++
++ // If the current remove has a move id, find any inserts with the same move id and
++ // replace the corresponding sections with the insert removed from the change set.
++ if (rit->moveId != -1 && difference > 0 && inserts) {
++ for (QList<Change>::iterator iit = inserts->begin(); iit != inserts->end(); ++iit) {
++ if (iit->moveId != rit->moveId
++ || rit->offset > iit->offset + iit->count
++ || iit->offset > rit->offset + difference) {
++ continue;
++ }
++ // If the intersecting insert starts before the replacement one create
++ // a new insert for the portion prior to the replacement insert.
++ const int overlapOffset = rit->offset - iit->offset;
++ if (overlapOffset > 0) {
++ iit = inserts->insert(iit, Change(
++ iit->index, overlapOffset, iit->moveId, iit->offset));
++ ++iit;
++ iit->index += overlapOffset;
++ iit->count -= overlapOffset;
++ iit->offset += overlapOffset;
++ }
++ if (iit->offset >= rit->offset
++ && iit->offset + iit->count <= rit->offset + difference) {
++ // If the replacement insert completely encapsulates the existing
++ // one just change the moveId.
++ iit->moveId = insert->moveId;
++ iit->offset = insert->offset + qMax(0, -overlapOffset);
++ } else {
++ // Create a new insertion before the intersecting one with the number of intersecting
++ // items and remove that number from that insert.
++ const int count
++ = qMin(iit->offset + iit->count, rit->offset + difference)
++ - qMax(iit->offset, rit->offset);
++ iit = inserts->insert(iit, Change(
++ iit->index,
++ count,
++ insert->moveId,
++ insert->offset + qMax(0, -overlapOffset)));
++ ++iit;
++ iit->index += count;
++ iit->count -= count;
++ iit->offset += count;
++ }
++ }
++ }
++
++ // Subtract the number of intersecting items from the current remove and insert.
++ insert->count -= difference;
++ insert->offset += difference;
++ rit->count -= difference;
++ rit->offset += difference;
++
++ index += difference;
++ count -= difference;
++ removeCount += difference;
++
++ if (insert->count == 0) {
++ insert = m_inserts.erase(insert);
++ } else if (rit->count == -offset || rit->count == 0) {
++ insert->index += difference;
++ break;
++ } else {
++ insert->index -= removeCount - difference;
++ rit->index -= insert->count;
++ insertCount += insert->count;
++ ++insert;
++ }
++ }
++ removeCount += rit->count;
++ }
++ for (; insert != m_inserts.end(); ++insert)
++ insert->index -= removeCount;
++
++ removeCount = 0;
++ QList<Change>::iterator remove = m_removes.begin();
++ for (rit = removes->begin(); rit != removes->end(); ++rit) {
++ if (rit->count == 0)
++ continue;
++ // Accumulate consecutive removes into a single delta before attempting to apply.
++ for (QList<Change>::iterator next = rit + 1; next != removes->end()
++ && next->index == rit->index
++ && next->moveId == -1
++ && rit->moveId == -1; ++next) {
++ next->count += rit->count;
++ rit = next;
++ }
++ int index = rit->index + removeCount;
++ // Decrement the accumulated remove count from the indexes of any inserts prior to the
++ // current remove.
++ for (; remove != m_removes.end() && index > remove->index; ++remove)
++ remove->index -= removeCount;
++ while (remove != m_removes.end() && index + rit->count >= remove->index) {
++ int count = 0;
++ const int offset = remove->index - index;
++ QList<Change>::iterator rend = remove;
++ for (; rend != m_removes.end()
++ && rit->moveId == -1
++ && rend->moveId == -1
++ && index + rit->count >= rend->index; ++rend) {
++ count += rend->count;
++ }
++ if (remove != rend) {
++ // Accumulate all existing non-move removes that are encapsulated by or immediately
++ // follow the current remove into it.
++ int difference = 0;
++ if (rend == m_removes.end()) {
++ difference = rit->count;
++ } else if (rit->index + rit->count < rend->index - removeCount) {
++ difference = rit->count;
++ } else if (rend->moveId != -1) {
++ difference = rend->index - removeCount - rit->index;
++ index += difference;
++ }
++ count += difference;
++
++ rit->count -= difference;
++ removeCount += difference;
++ remove->index = rit->index;
++ remove->count = count;
++ remove = m_removes.erase(++remove, rend);
++ } else {
++ // Insert a remove for the portion of the unmergable current remove prior to the
++ // point of intersection.
++ if (offset > 0) {
++ remove = m_removes.insert(remove, Change(
++ rit->index, offset, rit->moveId, rit->offset));
++ ++remove;
++ rit->count -= offset;
++ rit->offset += offset;
++ removeCount += offset;
++ index += offset;
++ }
++ remove->index = rit->index;
++
++ ++remove;
++ }
++ }
++
++ if (rit->count > 0) {
++ remove = m_removes.insert(remove, *rit);
++ ++remove;
++ }
++ removeCount += rit->count;
++ }
++ for (; remove != m_removes.end(); ++remove)
++ remove->index -= removeCount;
++ m_difference -= removeCount;
++ }
++
++ /*!
++ Applies a list of \a inserts to a change set.
++ */
++
++ void QQmlChangeSet::insert(const QList<Change> &inserts)
++ {
++ int insertCount = 0;
++ QList<Change>::iterator insert = m_inserts.begin();
++ QList<Change>::iterator change = m_changes.begin();
++ for (QList<Change>::const_iterator iit = inserts.begin(); iit != inserts.end(); ++iit) {
++ if (iit->count == 0)
++ continue;
++ int index = iit->index - insertCount;
++
++ Change current = *iit;
++ // Accumulate consecutive inserts into a single delta before attempting to insert.
++ for (QList<Change>::const_iterator next = iit + 1; next != inserts.end()
++ && next->index == iit->index + iit->count
++ && next->moveId == -1
++ && iit->moveId == -1; ++next) {
++ current.count += next->count;
++ iit = next;
++ }
++
++ // Increment the index of any changes before the current insert by the accumlated insert
++ // count.
++ for (; change != m_changes.end() && change->index >= index; ++change)
++ change->index += insertCount;
++ // If the current insert index is in the middle of a change split it in two at that
++ // point and increment the index of the latter half.
++ if (change != m_changes.end() && change->index < index + iit->count) {
++ int offset = index - change->index;
++ change = m_changes.insert(change, Change(change->index + insertCount, offset));
++ ++change;
++ change->index += iit->count + offset;
++ change->count -= offset;
++ }
++
++ // Increment the index of any inserts before the current insert by the accumlated insert
++ // count.
++ for (; insert != m_inserts.end() && index > insert->index + insert->count; ++insert)
++ insert->index += insertCount;
++ if (insert == m_inserts.end()) {
++ insert = m_inserts.insert(insert, current);
++ ++insert;
++ } else {
++ const int offset = index - insert->index;
++
++ if (offset < 0) {
++ // If the current insert is before an existing insert and not adjacent just insert
++ // it into the list.
++ insert = m_inserts.insert(insert, current);
++ ++insert;
++ } else if (iit->moveId == -1 && insert->moveId == -1) {
++ // If neither the current nor existing insert has a moveId add the current insert
++ // to the existing one.
++ if (offset < insert->count) {
++ insert->index -= current.count;
++ insert->count += current.count;
++ } else {
++ insert->index += insertCount;
++ insert->count += current.count;
++ ++insert;
++ }
++ } else if (offset < insert->count) {
++ // If either insert has a moveId then split the existing insert and insert the
++ // current one in the middle.
++ if (offset > 0) {
++ insert = m_inserts.insert(insert, Change(
++ insert->index + insertCount, offset, insert->moveId, insert->offset));
++ ++insert;
++ insert->index += offset;
++ insert->count -= offset;
++ insert->offset += offset;
++ }
++ insert = m_inserts.insert(insert, current);
++ ++insert;
++ } else {
++ insert->index += insertCount;
++ ++insert;
++ insert = m_inserts.insert(insert, current);
++ ++insert;
++ }
++ }
++ insertCount += current.count;
++ }
++ for (; insert != m_inserts.end(); ++insert)
++ insert->index += insertCount;
++ m_difference += insertCount;
++ }
++
++ /*!
++ Applies a combined list of \a removes and \a inserts to a change set. This is equivalent
++ calling \l remove() followed by \l insert() with the same lists.
++ */
++
++ void QQmlChangeSet::move(const QList<Change> &removes, const QList<Change> &inserts)
++ {
++ QList<Change> r = removes;
++ QList<Change> i = inserts;
++ remove(&r, &i);
++ insert(i);
++ }
++
++ /*!
++ Applies a list of \a changes to a change set.
++ */
++
++ void QQmlChangeSet::change(const QList<Change> &changes)
++ {
++ QList<Change> c = changes;
++ change(&c);
++ }
++
++ void QQmlChangeSet::change(QList<Change> *changes)
++ {
++ QList<Change>::iterator insert = m_inserts.begin();
++ QList<Change>::iterator change = m_changes.begin();
++ for (QList<Change>::iterator cit = changes->begin(); cit != changes->end(); ++cit) {
++ for (; insert != m_inserts.end() && insert->end() < cit->index; ++insert) {}
++ for (; insert != m_inserts.end() && insert->index < cit->end(); ++insert) {
++ const int offset = insert->index - cit->index;
++ const int count = cit->count + cit->index - insert->index - insert->count;
++ if (offset == 0) {
++ cit->index = insert->index + insert->count;
++ cit->count = count;
++ } else {
++ cit = changes->insert(++cit, Change(insert->index + insert->count, count));
++ --cit;
++ cit->count = offset;
++ }
++ }
++
++ for (; change != m_changes.end() && change->index + change->count < cit->index; ++change) {}
++ if (change == m_changes.end() || change->index > cit->index + cit->count) {
++ if (cit->count > 0) {
++ change = m_changes.insert(change, *cit);
++ ++change;
++ }
++ } else {
++ if (cit->index < change->index) {
++ change->count += change->index - cit->index;
++ change->index = cit->index;
++ }
++
++ if (cit->index + cit->count > change->index + change->count) {
++ change->count = cit->index + cit->count - change->index;
++ QList<Change>::iterator cbegin = change;
++ QList<Change>::iterator cend = ++cbegin;
++ for (; cend != m_changes.end() && cend->index <= change->index + change->count; ++cend) {
++ if (cend->index + cend->count > change->index + change->count)
++ change->count = cend->index + cend->count - change->index;
++ }
++ if (cbegin != cend) {
++ change = m_changes.erase(cbegin, cend);
++ --change;
++ }
++ }
++ }
++ }
++ }
++
++ /*!
++ \internal
++ \relates QQmlChangeSet
++ Prints the contents of a change \a set to the \a debug stream.
++ */
++
++ QDebug operator <<(QDebug debug, const QQmlChangeSet &set)
++ {
++ QDebugStateSaver stateSaver(debug);
++ debug.nospace() << "QQmlChangeSet(";
++ const QList<QQmlChangeSet::Change> &removes = set.removes();
++ for (const QQmlChangeSet::Change &remove : removes)
++ debug << remove << ' ';
++ const QList<QQmlChangeSet::Change> &inserts = set.inserts();
++ for (const QQmlChangeSet::Change &insert : inserts)
++ debug << insert << ' ';
++ const QList<QQmlChangeSet::Change> &changes = set.changes();
++ for (const QQmlChangeSet::Change &change : changes)
++ debug << change << ' ';
++ return debug.nospace() << ')';
++ }
++
++ /*!
++ \internal
++ \relates QQmlChangeSet
++ Prints a \a change to the \a debug stream.
++ */
++
++ QDebug operator <<(QDebug debug, const QQmlChangeSet::Change &change)
++ {
++ QDebugStateSaver stateSaver(debug);
++ return debug.nospace() << "Change(" << change.index << ',' << change.count << ')';
++ }
++
++ QT_END_NAMESPACE
++