Package uk.ac.starlink.table

Class MappingRowSplittable

java.lang.Object
uk.ac.starlink.table.WrapperRowSequence
uk.ac.starlink.table.MappingRowSplittable
All Implemented Interfaces:
Closeable, AutoCloseable, RowData, RowSequence, RowSplittable, uk.ac.starlink.util.Sequence, uk.ac.starlink.util.Splittable<RowSplittable>
public class MappingRowSplittable extends WrapperRowSequence implements RowSplittable
RowSplittable which wraps another RowSplittable but presents different column contents as controlled by a supplied column data mapping function. The methods other than the data access are delegated to a supplied base RowSplittable, so that the row structure must be the same as for the base.

Note: this cannot in general be extended by an anonymous class to change aspects of the behaviour other than the column mapping, since the split() method has to return an instance of the same class rather than of its superclass.

Since:
12 Oct 2020
Author:
Mark Taylor

  • Constructor Details

    • MappingRowSplittable

      public MappingRowSplittable(RowSplittable baseSplit, Function<RowSplittable,RowData> dataMapper)
      Constructor.
      Parameters:
      baseSplit - base splittable
      dataMapper - used to acquire data access behaviour from newly split base instances

  • Method Details

    • getCell

      public Object getCell(int icol) throws IOException
      Description copied from interface: RowSequence
      Returns the contents of a cell in the current row. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass(). An unchecked exception will be thrown if there is no current row (next has not yet been called).
      Specified by:
      getCell in interface RowData
      Specified by:
      getCell in interface RowSequence
      Overrides:
      getCell in class WrapperRowSequence
      Parameters:
      icol - column index
      Returns:
      the contents of cell icol in the current row
      Throws:
      IOException - if there is an error reading the data

    • getRow

      public Object[] getRow() throws IOException
      Description copied from interface: RowSequence
      Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table. An unchecked exception will be thrown if there is no current row (next has not yet been called).
      Specified by:
      getRow in interface RowData
      Specified by:
      getRow in interface RowSequence
      Overrides:
      getRow in class WrapperRowSequence
      Returns:
      an array of the objects in each cell in row irow
      Throws:
      IOException - if there is an error reading the data

    • splittableSize

      public long splittableSize()
      Specified by:
      splittableSize in interface uk.ac.starlink.util.Splittable<RowSplittable>

    • rowIndex

      public LongSupplier rowIndex()
      Description copied from interface: RowSplittable
      Returns a supplier for the index of the row currently being processed, if possible. The row index is a global value; when accessing the first row of a top-level RowSplittable, the value returned by this supplier should be the first index in the table. But for objects resulting from splitting a top-level instance into sub-instances, the return value should reflect the index in the original sequence of rows; each index should be returned from only one of the splittables resulting from splitting a top-level instance.

      Typically, the row index will start at 0 and increment for each row, but the numbering may be different depending on the requirements of the implementation or usage.

      Before the RowSequence.next() method has been called, the return value will be one less than the first row index. After RowSequence.next has returned false, the value is undefined.

      Depending on the implementation, it may not be possible to determine the row index (for instance if the sequence is split into sub-splittables of unknown size). In such cases, this method returns null. The null-ness of the return value must be the same for all instances of the splittable hierarchy for a given sequence, so don't return a non-null value for the first splittable and then null values for some or all of its children.

      Specified by:
      rowIndex in interface RowSplittable
      Returns:
      supplier for the globally-referenced row index value of the current row of this sequence, or null

    • split

      public RowSplittable split()
      Specified by:
      split in interface uk.ac.starlink.util.Splittable<RowSplittable>