Function updateSnapshot

programs/git-import/git-import.cpp:677–745

Enrich the line changes data with the history info from the snapshot * - the author, time and commit of the previous change to every found line (blame). * And update the snapshot. */

  * And update the snapshot.
  */
void updateSnapshot(Snapshot & snapshot, const Commit & commit, CommitDiff & file_changes)
{
    /// Renames and copies.
    for (auto & elem : file_changes)
    {
        auto & file = elem.second.file_change;
        if (!file.old_path.empty() && file.path != file.old_path)
            snapshot[file.path] = snapshot[file.old_path];
    }

    for (auto & elem : file_changes)
    {
//        std::cerr << elem.first << "\n";

        FileBlame & file_snapshot = snapshot[elem.first];
        std::unordered_map<uint32_t, Commit> deleted_lines;

        /// Obtain blame info from previous state of the snapshot

        for (auto & line_change : elem.second.line_changes)
        {
            if (line_change.sign == -1)
            {
                if (const Commit * prev_commit = file_snapshot.find(line_change.line_number_old);
                    prev_commit && prev_commit->time <= commit.time)
                {
                    line_change.prev_commit_hash = prev_commit->hash;
                    line_change.prev_author = prev_commit->author;
                    line_change.prev_time = prev_commit->time;
                    deleted_lines[line_change.line_number_old] = *prev_commit;
                }
                else
                {
                    // std::cerr << "Did not find line " << line_change.line_number_old << " from file " << elem.first << ": " << line_change.line << "\n";
                }
            }
            else if (line_change.sign == 1)
            {
                uint32_t this_line_in_prev_commit = line_change.hunk_start_line_number_old
                    + (line_change.line_number_new - line_change.hunk_start_line_number_new);

                if (deleted_lines.count(this_line_in_prev_commit))
                {
                    const auto & prev_commit = deleted_lines[this_line_in_prev_commit];
                    if (prev_commit.time <= commit.time)
                    {
                        line_change.prev_commit_hash = prev_commit.hash;
                        line_change.prev_author = prev_commit.author;
                        line_change.prev_time = prev_commit.time;
                    }
                }
            }
        }

        /// Update the snapshot

        for (const auto & line_change : elem.second.line_changes)
        {