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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.version;

import com.rapiddweller.common.Parser;
import com.rapiddweller.common.StringUtil;

import java.text.ParseException;
import java.text.ParsePosition;
import java.util.ArrayList;
import java.util.List;

/**
 * Parses a {@link VersionNumber}.
 * Created: 10.03.2011 16:28:06
 *
 * @author Volker Bergmann
 * @since 0.5.8
 */
public class VersionNumberParser extends Parser {

  @Override
  public VersionNumber parseObject(String text, ParsePosition pos) {
    List components = new ArrayList<>();
    List delimiters = new ArrayList<>();
    if (StringUtil.isEmpty(text)) {
      components.add(new NumberVersionNumberComponent(1));
    } else {
      String delimiter;
      do {
        components.add(parseComponent(text, pos));
        delimiter = parseDelimiter(text, pos);
        if (delimiter != null) {
          delimiters.add(delimiter);
        }
      } while (delimiter != null);
    }
    return new VersionNumber(components, delimiters);
  }

  private static String parseDelimiter(String number, ParsePosition pos) {
    int index = pos.getIndex();
    if (index >= number.length()) {
      return null;
    }
    char c = number.charAt(index);
    if (c == '.' || c == '-' || c == '_') {
      pos.setIndex(pos.getIndex() + 1);
      return String.valueOf(c);
    } else {
      return (Character.isLetterOrDigit(c) ? "" : null);
    }
  }

  private static VersionNumberComponent parseComponent(String number, ParsePosition pos) {
    char c = number.charAt(pos.getIndex());
    if (Character.isDigit(c)) {
      return parseNumberOrDateComponent(number, pos);
    } else {
      return new StringVersionNumberComponent(parseLetters(number, pos));
    }
  }

  private static VersionNumberComponent parseNumberOrDateComponent(String text, ParsePosition pos) {
    String number = parseNonNegativeInteger(text, pos);
    if (number.length() == 8) {
      try {
        return new DateVersionNumberComponent(number);
      } catch (ParseException e) {
        // oops - no date. Fall back to NumberVersionNumberComponent in the following code
      }
    }
    return new NumberVersionNumberComponent(number);
  }

  private static String parseNonNegativeInteger(String number, ParsePosition pos) {
    int index = pos.getIndex();
    StringBuilder result = new StringBuilder(2);
    char c;
    while (index < number.length() && Character.isDigit(c = number.charAt(index))) {
      result.append(c);
      index++;
    }
    pos.setIndex(index);
    return result.toString();
  }

  private static String parseLetters(String number, ParsePosition pos) {
    int index = pos.getIndex();
    StringBuilder result = new StringBuilder(10);
    char c;
    while (index < number.length() && Character.isLetter(c = number.charAt(index))) {
      result.append(c);
      index++;
    }
    pos.setIndex(index);
    return result.toString();
  }

}