# HandleFieldRef.java

    /*
    ** Module   : HandleFieldRef.java
    ** Abstract : Data wrapper which associates with a DMO property and provides direct access to
    **            this property.
    **
    ** Copyright (c) 2014-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description----------------------------------
    ** 001 CA  20140103 Created initial version.
    ** 002 CA  20180515 Added extent c'tors.
    ** 003 OM  20200325 Moved to com.goldencode.p2j.util package.
    ** 004 AIL 20210615 Indicate that this type of handle should be set after run ... persistent set.
    ** 005 CA  20240215 Fixed issues using CALL property/field references as arguments, associated with a
    **                  DATASET/TABLE-HANDLE parameter.
    */

    /*
    ** 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.
    **
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    **
    **     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 com.goldencode.p2j.persist.*;

    /**
     * Data wrapper which associates with a DMO property and provides direct access to this property.
     * <p>
     * All writing is done to both the DMO and the local {@link handle}'s private {@code value}.
     * On instantiation, the current field value is saved in the {@link handle}'s private
     * {@code value}, and this instance will be used for reading until {@link #set} or
     * {@link #setUnknown} is called again.
     * <p>
     * This usage is OK
     */
    public class HandleFieldRef
    extends handle
    {
       /** The field referenced by this instance. */
       private final FieldReference fieldRef;

       /**
        * Initialize using the given field.
        *
        * @param    fieldRef
        *           The field reference.
        */
       public HandleFieldRef(FieldReference fieldRef)
       {
          this.fieldRef = fieldRef;

          init((DataModelObject) fieldRef.getDMO());
       }

       /**
        * Constructor.
        *
        * @param   dmo
        *          Proxy for record whose field is being accessed.
        * @param   property
        *          Name of dmo field.
        */
       public HandleFieldRef(DataModelObject dmo, String property)
       {
          this.fieldRef = new FieldReference(dmo, property);

          init(dmo);
       }

       /**
        * Constructor.
        *
        * @param   dmo
        *          Proxy for record whose field is being accessed.
        * @param   property
        *          Name of dmo field.
        * @param   index
        *          Index to pass to property's getter method at resolve time.
        */
       public HandleFieldRef(DataModelObject dmo, String property, int64 index)
       {
          this.fieldRef = new FieldReference(dmo, property, index);

          init(dmo);
       }

       /**
        * Constructor.
        *
        * @param   dmo
        *          Proxy for record whose field is being accessed.
        * @param   property
        *          Name of dmo field.
        * @param   index
        *          Index to pass to property's getter method at resolve time.
        */
       public HandleFieldRef(DataModelObject dmo, String property, int index)
       {
          this.fieldRef = new FieldReference(dmo, property, index);

          init(dmo);
       }

       /**
        * Set the value of this instance as a {@link WrappedResource}.
        * <p>
        * Also updates the {@link #fieldRef} with the new state of this handle instance.
        *
        * @param    value
        *           The value to be represented in this instance.
        */
       @Override
       public void set(WrappedResource value)
       {
          super.set(value);

          fieldRef.set(this);
       }

       /**
        * Sets the state of this instance's {@code unknown value} flag or state to {@code true}.
        * <p>
        * <b>Warning: the data stored in this instance may be invalid after calling this method.</b>
        * <p>
        * Also updates the {@link #fieldRef} with the new state of this handle instance.
        */
       public void setUnknown()
       {
          super.setUnknown();

          fieldRef.set(this);
       }

       /**
        * Indicate if in a {@code RUN ... PERSISTENT SET} statement, this handle should receive
        * the resource before the called procedure is executed (this returns {@code false}) or
        * after the called procedure is executed (this returns {@code true}).
        * In the particular case of a {@link HandleFieldRef}, the handle should be set after
        * the called procedure is executed.
        *
        * @return   {@code true} if the handle should be set after the called procedure is executed.
        */
       @Override
       public boolean delayPersistentSet()
       {
          return true;
       }

       /**
        * Initialize this instance.
        *
        * @param   dmo
        *          Proxy for record whose field is being accessed.
        */
       private void init(DataModelObject dmo)
       {
          RecordBuffer rb = ((BufferReference) dmo).buffer();
          // initialize this instance based on the current buffer state; if no record is loaded in the
          // buffer, then set it to unknown. there will be a 142 - Unable to update field error raised
          // when we try to assign a new value to this instance.
          if (rb.getCurrentRecord() != null)
          {
             super.set(((handle) fieldRef.get()).getResource());
          }
          else
          {
             super.setUnknown();
          }
       }
    }