DateFormatParser.java

/*
** Module   : DateFormatParser.java
** Abstract : Base class for Progress date format parsers/formatters.
**
** Copyright (c) 2021, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description---------------------------------
** 001 VVT 20210413 Created initial version.
**     VVT 20210417 Moved here from the test/ directory.
**     VVT 20210426 The visitYear/Month/Day callbacks eliminated in favor of
**                  visitDateComponent.
**     VVT 20210624 Javadoc fixed
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program 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 Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
**   Under Section 7 of the GNU Affero GPL version 3, the following additional
**   terms apply to the works covered under the License.  These additional terms
**   are non-permissive additional terms allowed under Section 7 of the GNU
**   Affero GPL version 3 and may not be removed by you.
**
**   0. Attribution Requirement.
**
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**     work or Appropriate Legal Notices displayed by works containing the covered
**     work.  You may not remove from the covered work any author or developer
**     credit already included within the covered work.
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*/
package com.goldencode.p2j.util;

/**
 * Base class for Progress date format parsers/formatters.
 * 
 * The {@link #parse(String)} method is responsible for checking the
 * Progress date format validity.
 * 
 * Also this class provides a set of callback methods,
 * each callback is called when the corresponding format component is parsed.
 * 
 * By default, all callbacks do nothing, they are expected to be re-defined in subclasses.
 */
public class DateFormatParser
{
   /**
    * The first date component separator was parsed: one of '.', '-' or '/'.
    * <p>
    * Subclasses are expected to overload this method,
    * default implementation does nothing.
    * <p>
    * Note: if date format has no separators, this callback is never called.
    * 
    * @param sep
    *        the first separator character
    */
   protected void visitSep1(final char sep)
   {
      // no-op
   }

   /**
    * The second date component separator was parsed: one of '.', '-' or '/'.
    * <p>
    * Subclasses are expected to overload this method,
    * default implementation does nothing.
    * <p>
    * Note: if date format has no separators, this callback is never called.
    * 
    * @param sep
    *        the second separator character
    */
   protected void visitSep2(final char sep)
   {
      // no-op
   }

   /**
    * Dispatch the date component to a matching callback.
    * 
    * @param componentIndex
    *        the number of the component in the format spec
    * @param startIdx
    *        the component start index, zero based
    * @param endIdx
    *        the component end index, zero based, exclusive
    */
   protected void visitDateComponent(final int componentIndex, final int startIdx, final int endIdx)
   {
      // no-op
   }

   /**
    * Parse date format, call callbacks while parsing.
    * 
    * @param format
    *        the format to parse
    * 
    * @throws ErrorConditionException
    *         in case the date format is invalid
    */
   public void parse(final String format)
   throws ErrorConditionException
   {
      final int len = format.length();

      // handle special cases first
      switch (format)
      {
         case "999999":
         case "99999999":
            visitDateComponent(0, 0, 2);
            visitDateComponent(1, 2, 4);
            visitDateComponent(2, 4, len);
            return;

         default:
      }

      int idx = 0;

      for (; idx < len && format.charAt(idx) == '9'; idx++)
         ;

      if (idx == len)
      {
         genDateFormatIncomleteError(format);
         return;
      }

      // Start if component 2 if exist
      final int comp2idx;
      char c = format.charAt(idx);
      switch (c)
      {
         case '.':
         case '-':
         case '/':
            visitDateComponent(0, 0, idx);
            visitSep1(c);
            idx++;
            comp2idx = idx;
            break;
         default:
            ErrorManager.genInvalidCharError(idx, format);
            return;
      }

      if (idx == len)
      {
         genDateFormatIncomleteError(format);
         return;
      }

      int sectionStart = idx;
      for (; idx < len && format.charAt(idx) == '9'; idx++)
         ;
      if (idx == len)
      {
         genDateFormatIncomleteError(format);
         return;
      }

      if (idx == sectionStart)
      {
         ErrorManager.genInvalidCharError(idx, format);
         return;
      }

      final int comp3idx;
      c = format.charAt(idx);
      switch (c)
      {
         case '.':
         case '-':
         case '/':
            visitDateComponent(1, comp2idx, idx);
            visitSep2(c);
            idx++;
            comp3idx = idx;
            break;
         default:
            ErrorManager.genInvalidCharError(idx, format);
            return;
      }

      sectionStart = idx;
      for (; idx < len && format.charAt(idx) == '9'; idx++)
         ;

      // We must check these two error conditions in this very order to match the OE error handling.
      if (idx < len)
      {
         ErrorManager.genInvalidCharError(idx, format);
         return;
      }

      if (idx == sectionStart)
      {
         genDateFormatIncomleteError(format);
         return;
      }

      visitDateComponent(2, comp3idx, len);
   }

   /**
    * Record or throw the error number 154.
    * 
    * @param fmt
    *        the problematic format string
    */
   private static final void genDateFormatIncomleteError(final String fmt)
   {
      ErrorManager.recordOrThrowError(154, "Date format " + fmt + " is incomplete");
   }
}