PDF4QT/Pdf4QtLibCore/sources/pdfalgorithmlcs.cpp

// MIT License
//
// Copyright (c) 2018-2025 Jakub Melka and Contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "pdfalgorithmlcs.h"
#include "pdfdbgheap.h"

namespace pdf
{

void PDFAlgorithmLongestCommonSubsequenceBase::markSequence(Sequence& sequence,
                                                            const std::vector<size_t>& movedItemsLeft,
                                                            const std::vector<size_t>& movedItemsRight)
{
    Sequence updatedSequence;

    Q_ASSERT(std::is_sorted(movedItemsLeft.cbegin(), movedItemsLeft.cend()));
    Q_ASSERT(std::is_sorted(movedItemsRight.cbegin(), movedItemsRight.cend()));

    for (auto it = sequence.cbegin(); it != sequence.cend();)
    {
        if (it->isMatch())
        {
            updatedSequence.push_back(*it);
            ++it;
            continue;
        }

        Sequence leftItems;
        Sequence rightItems;

        for (; it != sequence.cend() && !it->isMatch(); ++it)
        {
            const SequenceItem& currentItem = *it;
            Q_ASSERT(currentItem.isLeft() || currentItem.isRight());

            if (currentItem.isLeft())
            {
                if (std::binary_search(movedItemsLeft.cbegin(), movedItemsLeft.cend(), currentItem.index1))
                {
                    SequenceItem item = *it;
                    item.markMovedLeft();
                    updatedSequence.push_back(item);
                }
                else
                {
                    leftItems.push_back(currentItem);
                }
            }

            if (currentItem.isRight())
            {
                if (std::binary_search(movedItemsRight.cbegin(), movedItemsRight.cend(), currentItem.index2))
                {
                    SequenceItem item = *it;
                    item.markMovedRight();
                    updatedSequence.push_back(item);
                }
                else
                {
                    rightItems.push_back(currentItem);
                }
            }
        }

        std::reverse(leftItems.begin(), leftItems.end());
        std::reverse(rightItems.begin(), rightItems.end());

        bool isReplaced = !leftItems.empty() && !rightItems.empty();

        while (!leftItems.empty() && !rightItems.empty())
        {
            SequenceItem item;
            item.index1 = leftItems.back().index1;
            item.index2 = rightItems.back().index2;
            item.markReplaced();
            updatedSequence.push_back(item);

            leftItems.pop_back();
            rightItems.pop_back();
        }

        while (!leftItems.empty())
        {
            SequenceItem item = leftItems.back();
            item.markRemoved();

            if (isReplaced)
            {
                item.markReplaced();
            }

            updatedSequence.push_back(item);
            leftItems.pop_back();
        }

        while (!rightItems.empty())
        {
            SequenceItem item = rightItems.back();
            item.markAdded();

            if (isReplaced)
            {
                item.markReplaced();
            }

            updatedSequence.push_back(item);
            rightItems.pop_back();
        }
    }

    for (SequenceItem& item : updatedSequence)
    {
        if (item.isMatch() && !item.isRemoved() && !item.isReplaced() && !item.isAdded() && item.index1 != item.index2)
        {
            item.markMoved();
        }
    }

    sequence = qMove(updatedSequence);
}

PDFAlgorithmLongestCommonSubsequenceBase::SequenceItemRanges PDFAlgorithmLongestCommonSubsequenceBase::getModifiedRanges(Sequence& sequence)
{
    SequenceItemRanges result;

    for (auto it = sequence.begin(); it != sequence.end();)
    {
        const SequenceItem& item = *it;
        if (!item.isModified())
        {
            ++it;
            continue;
        }

        // Jakub Melka: now, we have iterator pointing on item,
        // which has been modified. We will search for modification
        // range.

        auto itEnd = it;
        while (itEnd != sequence.end() && itEnd->isModified())
        {
            ++itEnd;
        }

        result.emplace_back(it, itEnd);
        it = itEnd;
    }

    return result;
}

PDFAlgorithmLongestCommonSubsequenceBase::SequenceItemFlags PDFAlgorithmLongestCommonSubsequenceBase::collectFlags(const SequenceItemRange& range)
{
    SequenceItemFlags flags = SequenceItemFlags();

    for (auto it = range.first; it != range.second; ++it)
    {
        flags |= it->flags;
    }

    return flags;
}

}   // namespace pdf