DatetimeExpression.java

/*
** Module   : DatetimeExpression.java
** Abstract : Resolvable interface adapter for a date runtime expression
**
** Copyright (c) 2013-2017, Golden Code Development Corporation.
**
** -#- -I- --Date-- -----------------------Description------------------------
** 001 GES 20130123 Created initial version.
*/
/*
** 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
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**   Affero GPL version 3 and may not be removed by you.
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package com.goldencode.p2j.util;

/**
 * A convenience adapter class for a {@link Resolvable} runtime expression
 * which must return a {@link datetime} result.  Subclasses need implement
 * only the {@link #execute} method.
 */
public class DatetimeExpression
implements Resolvable
{
   /** Any fixed value for the expression or <code>null</code>. */
   private Accessor value = null;
   
   /**
    * Default constructor.
    */
   public DatetimeExpression()
   {
   }
   
   /**
    * Create an instance that has a fixed (non-varying) value.
    *
    * @param    value
    *           The fixed value for this instance.
    */
   public DatetimeExpression(Accessor value)
   {
      this.value = value;
   }
   
   /**
    * Create an instance that has a fixed (non-varying) value.
    *
    * @param    value
    *           The fixed value for this instance.
    */
   public DatetimeExpression(datetime value)
   {
      this(new AccessorWrapper(value));
   }
   
   /**
    * Execute the underlying expression and get its result.
    *
    * @return  Result of expression execution.
    */
   public final BaseDataType resolve()
   {
      return execute();
   }
   
   /**
    * Report the return type expected from executing the expression.
    *
    * @return  Class indicating the type which will be returned by the
    *          expression.  Must be a variant of {@link BaseDataType}.
    */
   public final Class getType()
   {
      return datetime.class;
   }
   
   /**
    * Execute the underlying expression and get its result.
    *
    * @return  Result of expression execution as an <code>date</code>.
    */
   public datetime execute()
   {
      return (datetime) value.get();
   }
}