Class ViewHandler

core/src/main/java/io/ddf/content/ViewHandler.java:22–525

 *
 */
public class ViewHandler extends ADDFFunctionalGroupHandler implements IHandleViews {

  public ViewHandler(DDF theDDF) {
    super(theDDF);
  }

  // @SuppressWarnings("unchecked")
  // @Override
  // public <T> Iterator<T> getRowIterator(Class<T> dataType) {
  // if (dataType == null) dataType = (Class<T>) this.getDDF().getRepresentationHandler().getDefaultDataType();
  //
  // Object repr = this.getDDF().getRepresentationHandler().get(dataType);
  // return (repr instanceof Iterable<?>) ? ((Iterable<T>) repr).iterator() : null;
  // }

  @Override
  public List<Object[]> getRandomSample(int numSamples, boolean withReplacement, int seed) {
    return null;
  }

  @Override
  public DDF getRandomSampleByNum(long numSamples, boolean withReplacement,
                                  int seed) {
    return null;
  }

  @Override
  public DDF getRandomSample(double percent, boolean withReplacement, int seed) {
    return null;
  }

  @Override
  public DDF getRandomSampleApprox(double percent, boolean withReplacement, int seed) {
    return null;
  }


  @Override
  public List<String> head(int numRows) throws DDFException {
    return this.getDDF().sql(String.format("SELECT * FROM @this LIMIT %d", numRows),
        String.format("Unable to fetch %d row(s) from table %%s", numRows)).getRows();
  }

  public List<String> top(int numRows, String orderColumns, String mode) throws DDFException {

    DDF temp = sql2ddf(String.format("SELECT * FROM %%s order by %s %s", orderColumns, mode),
        String.format("Unable to fetch %d row(s) from table %%s", numRows));

    return (temp.VIEWS.head(numRows));
  }

  @Override
  public DDF project(String... columnNames) throws DDFException {
    if (columnNames == null || columnNames.length == 0) throw new DDFException("columnNames must be specified");
    List<String> colNames = new ArrayList<String>(columnNames.length);
    for(String col: columnNames) {colNames.add(col);}
    return project(colNames);
  }