content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  /*
   * GRAL: GRAphing Library for Java(R)
   *
   * (C) Copyright 2009-2013 Erich Seifert <dev[at]erichseifert.de>,
   * Michael Seifert <mseifert[at]error-reports.org>
   *
   * This file is part of GRAL.
   *
   * GRAL is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * GRAL is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with GRAL.  If not, see <http://www.gnu.org/licenses/>.
   */
  package de.erichseifert.gral.data;
  
  import de.erichseifert.gral.data.statistics.Statistics;
  
  /**
   * Interface for an immutable access to tabular data.
   *
   * @see MutableDataSource
   */
  public interface DataSource extends Iterable<Comparable<?>> {
  	/**
  	 * Returns the column with the specified index.
  	 * @param col index of the column to return
  	 * @return the specified column of the data source
  	 */
  	Column getColumn(int col);
  
  	/**
  	 * Returns the data types of all columns.
  	 * @return The data types of all column in the data source
  	 */
  	Class<? extends Comparable<?>>[] getColumnTypes();
  
  	/**
  	 * Returns the row with the specified index.
  	 * @param row index of the row to return
  	 * @return the specified row of the data source
  	 */
  	Row getRow(int row);
  
  	/**
  	 * Returns the value with the specified row and column index.
  	 * @param col index of the column to return
  	 * @param row index of the row to return
  	 * @return the specified value of the data cell
  	 */
  	Comparable<?> get(int col, int row);
  
  	/**
  	 * Retrieves a object instance that contains various statistical
  	 * information on the current data source.
  	 * @return statistical information
  	 */
  	Statistics getStatistics();
  
  	/**
  	 * Returns the number of rows of the data source.
  	 * @return number of rows in the data source.
  	 */
  	int getRowCount();
  
  	/**
  	 * Returns the number of columns of the data source.
  	 * @return number of columns in the data source.
  	 */
  	int getColumnCount();
  
  	/**
  	 * Returns whether the column at the specified index contains numbers.
  	 * @param columnIndex Index of the column to test.
  	 * @return {@code true} if the column is numeric, otherwise {@code false}.
  	 */
  	boolean isColumnNumeric(int columnIndex);
  
  	/**
  	 * Adds the specified {@code DataListener} to this data source.
  	 * @param dataListener listener to be added.
  	 */
  	void addDataListener(DataListener dataListener);
  
  	/**
  	 * Removes the specified {@code DataListener} from this data source.
  	 * @param dataListener listener to be removed.
  	 */
  	void removeDataListener(DataListener dataListener);
  }
  