# NullField.java

    /*
    ** Module   : NullField.java
    ** Abstract : outputs null characters to a stream
    **
    ** Copyright (c) 2006-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ---------------------------Description------------------------------
    ** 001 GES 20060925   @29904 Created initial version which outputs null
    **                           characters to a stream.
    ** 002 SIY 20071001   @35317 Made class suitable for network transfers and
    **                           for code reuse. Ref: #35314
    ** 003 SIY 20071003   @35349 Header cleanup. Added implementation of
    **                           resolveData() method.
    **                           Ref: #35347.
    ** 004 CA  20130308          Added protected setters for the explicit and num fields.
    ** 005 OM  20130527          Added int64 support. Added 16 bit restriction observed in Progress.
    */
    /*
    ** 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.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     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.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.util;

    import java.io.*;

    /**
     * Outputs null characters to a stream.
     */
    public class NullField
    extends FieldEntry
    {
       /** Contains an explicit column position. */
       private boolean explicit = false;

       /**
        * An explicit column position.
        * From experimental tests one can observe that Progress handles the number of Fields
        * (CONTROL NULL, SPACE and SKIP) on a signed 16 bit memory space. Although Progress will
        * accept any 64-bit value it will be automatically truncate it to short.
        */
       private short num = 0;

       /**
        * Default constructor (outputs a single space).
        */
       public NullField()
       {
       }

       /**
        * Constructor for an explicit number of null characters.
        *
        * @param    num
        *           The number of null characters to output.
        */
       public NullField(long num)
       {
          this.explicit = true;
          this.num      = (short) num;
       }

       /**
        * Renders the contained field definition to the given stream.
        *
        * @param    out
        *           The stream to which the field should be rendered.
        * @throws ErrorConditionException
        */
       public void output(Stream out)
       throws ErrorConditionException
       {
          if (explicit)
          {
             out.putNull(num);
          }
          else
          {
             out.putNull();
          }
       }

       /**
        * Notify instance that it is about to be transferred so all resolvable
        * data should be resolved and prepared for sending via network.
        */
       public void resolveData()
       {
          // do nothing
       }

       /**
        * Replacement for the default object reading method. The latest
        * state is read from the input source.
        *
        * @param    in
        *           The input source from which fields will be restored.
        *
        * @throws   IOException
        *           In case of I/O errors.
        * @throws   ClassNotFoundException
        *           If payload can't be instantiated.
        */
       public void readExternal(ObjectInput in)
       throws IOException,
              ClassNotFoundException
       {
          explicit = in.readBoolean();
          num      = in.readShort();
       }

       /**
        * Replacement for the default object writing method. The latest
        * state is written to the output destination.
        *
        * @param    out
        *           The output destination to which fields will be saved.
        *
        * @throws   IOException
        *           In case of I/O errors.
        */
       public void writeExternal(ObjectOutput out)
       throws IOException
       {
          out.writeBoolean(explicit);
          out.writeShort(num);
       }

       /**
        * Get current value of explicit flag.
        *
        * @return   The current value of flag.
        */
       boolean isExplicit()
       {
          return explicit;
       }

       /**
        * Get explicit count.
        *
        * @return   The explicit count.
        */
       int getNum()
       {
          return num;
       }

       /**
        * Set explicit count. The value is automatically truncated to 16-bit value.
        *
        * @param    num
        *           The explicit count.
        */
       protected void setNum(long num)
       {
          this.num = (short) num;
       }

       /**
        * Set value of explicit flag.
        *
        * @param    explicit
        *           The value of flag.
        */
       protected void setExplicit(boolean explicit)
       {
          this.explicit = explicit;
       }
    }