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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.rapiddweller.common.iterator;

import com.rapiddweller.common.ConfigurationError;
import com.rapiddweller.common.StringUtil;

/**
 * Iterates through another {@link TabularIterator},
 * picking and possibly reordering a sub set of its columns.
 * Created: 26.01.2012 18:33:10
 *
 * @author Volker Bergmann
 * @since 0.5.14
 */
public class SelectiveTabularIterator extends IteratorProxy implements TabularIterator {

  private final String[] columnNames;
  private final int[] sourceIndexes;

  /**
   * Instantiates a new Selective tabular iterator.
   *
   * @param source      the source
   * @param columnNames the column names
   */
  public SelectiveTabularIterator(TabularIterator source, String[] columnNames) {
    super(source);
    String[] sourceColumnNames = source.getColumnNames();
    if (columnNames != null) {
      this.columnNames = columnNames;
      this.sourceIndexes = new int[columnNames.length];
      for (int i = 0; i < columnNames.length; i++) {
        String columnName = columnNames[i];
        int sourceIndex = StringUtil.indexOfIgnoreCase(columnName, sourceColumnNames);
        if (sourceIndex < 0) {
          throw new ConfigurationError("Column '" + columnName + "' not defined in source: " + source);
        }
        this.sourceIndexes[i] = sourceIndex;
      }
    } else {
      this.columnNames = sourceColumnNames;
      this.sourceIndexes = null;
    }
  }

  @Override
  public String[] getColumnNames() {
    return columnNames;
  }

  @Override
  public Object[] next() {
    Object[] sourceArray = super.next();
    if (sourceIndexes == null) {
      return sourceArray;
    }
    Object[] result = new Object[sourceIndexes.length];
    for (int i = 0; i < sourceIndexes.length; i++) {
      result[i] = (i < sourceArray.length ? sourceArray[sourceIndexes[i]] : null);
    }
    return result;
  }

}