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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;

import java.util.HashSet;
import java.util.Set;

/**
 * Assures uniqueness for all processed Strings by appending unique numbers to recurring instances.
 * Created: 24.06.2008 19:41:08
 *
 * @author Volker Bergmann
 * @since 0.4.4
 */
public class UniqueStringConverter extends AbstractConverter {

  private static final int MAX_TRIES = 10000;
  private final Set usedStrings;

  /**
   * Instantiates a new Unique string converter.
   */
  public UniqueStringConverter() {
    super(String.class, String.class);
    usedStrings = new HashSet<>();
  }

  @Override
  public synchronized String convert(String sourceValue) throws ConversionException {
    String resultValue = sourceValue;
    if (usedStrings.contains(sourceValue)) {
      boolean ok = false;
      for (int i = 0; !ok && i < MAX_TRIES; i++) {
        resultValue = sourceValue + i;
        if (!usedStrings.contains(resultValue)) {
          ok = true;
        }
      }
      if (!ok) {
        throw new UnsupportedOperationException("not more than " + MAX_TRIES + " identical Strings can be made unique");
      }
    }
    usedStrings.add(resultValue);
    return resultValue;
  }

  @Override
  public boolean isParallelizable() {
    return false;
  }

  @Override
  public boolean isThreadSafe() {
    return true;
  }

}