com.almworks.jira.structure.api.row.RowMapper Maven / Gradle / Ivy

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package com.almworks.jira.structure.api.row;

import com.almworks.integers.LongList;
import com.almworks.integers.wrappers.LongLongHppcOpenHashMap;
import com.almworks.jira.structure.api.attribute.ValueColumn;
import com.atlassian.annotations.Internal;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * {@code RowMapper} helps track the original row IDs for copied row. It is a temporary instance, received
 * from {@code RowManager#createMapper(Forest)}.
 *
 * Mapping is done by traversing {@code originalId} links backwards, until {@code originalId} is zero and
 * while the row ID stay in the forest.
 */
@Internal
public interface RowMapper {
  long mapRow(long requestedRow);

  Mapping map(LongList rows);


  class Mapping {
    private final LongList myRequestedRows;
    private final LongList myMappedRows;
    private final LongLongHppcOpenHashMap myMap;

    private Mapping(LongList requestedRows, LongList mappedRows, LongLongHppcOpenHashMap map) {
      myRequestedRows = requestedRows;
      myMappedRows = mappedRows;
      myMap = map;
    }

    public static Mapping identical(LongList rows) {
      return new Mapping(rows, rows, null);
    }


    public static Mapping mapped(LongList rows, LongList mappedRows, LongLongHppcOpenHashMap map) {
      return new Mapping(rows, mappedRows, map);
    }

    public LongList getRequestedRows() {
      return myRequestedRows;
    }

    /**
     * @return a mapped list of requested row. If a row was mapped, the mapped row ID is present instead of the requested ID.
     * IF row mapped to nothing, nothing is present. Otherwise, if row was not mapped (present in the forest), the requested
     * row ID is present.
     */
    public LongList getMappedRows() {
      return myMappedRows;
    }

    /**
     * @return a map with entries for the rows that are mapped to other rows -- rows that mapped to nothing (0) are
     * not present, as well as rows that were mapped to themselves
     *
     * Returns null when no mapping was made
     */
    @Nullable
    public LongLongHppcOpenHashMap getMap() {
      return myMap;
    }

    public boolean isMapped() {
      return myMap != null;
    }

    @NotNull
    public  ValueColumn createMappedResultColumn(@Nullable ValueColumn actualColumn) {
      if (actualColumn == null) {
        // weird
        return ValueColumn.empty();
      }
      if (myMap == null) {
        return actualColumn;
      }
      return row -> {
        if (row == null) row = 0L;
        long mapped = myMap.containsKey(row) ? myMap.lget() : row;
        return actualColumn.getValue(mapped);
      };
    }
  }
}