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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.converter;

import com.rapiddweller.common.ConversionException;

/**
 * Extracts a sub string from a string.
 * Created: 26.02.2010 10:55:11
 *
 * @author Volker Bergmann
 * @since 0.5.0
 */
public class SubstringExtractor extends ThreadSafeConverter {

  private int from;
  private Integer to;

  /**
   * Instantiates a new Substring extractor.
   */
  public SubstringExtractor() {
    this(0);
  }

  /**
   * Instantiates a new Substring extractor.
   *
   * @param from the from
   */
  public SubstringExtractor(int from) {
    this(from, null);
  }

  /**
   * Instantiates a new Substring extractor.
   *
   * @param from the from
   * @param to   the to
   */
  public SubstringExtractor(int from, Integer to) {
    super(String.class, String.class);
    this.from = from;
    this.to = to;
  }

  /**
   * Sets from.
   *
   * @param from the from
   */
  public void setFrom(int from) {
    this.from = from;
  }

  /**
   * Sets to.
   *
   * @param to the to
   */
  public void setTo(Integer to) {
    this.to = to;
  }

  @Override
  public String convert(String sourceValue) throws ConversionException {
    if (sourceValue == null) {
      return null;
    }
    int startIndex = relativeIndex(from, sourceValue);
    if (startIndex >= sourceValue.length()) {
      return "";
    }
    if (to == null) {
      return sourceValue.substring(startIndex);
    } else {
      int endIndex = relativeIndex(to, sourceValue);
      if (endIndex < startIndex) {
        return "";
      }
      if (endIndex > sourceValue.length()) {
        endIndex = sourceValue.length();
      }
      return sourceValue.substring(startIndex, endIndex);
    }
  }

  private static int relativeIndex(int index, String sourceValue) {
    return (index >= 0 ? index : sourceValue.length() + index);
  }

}