AbstractExtentParameter.java

/*
** Module   : AbstractExtentParameter.java
** Abstract : Base class for special wrapper classes used for variables passed as extent
**            parameters to functions or procedures.
**
** Copyright (c) 2014-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
** 001 HC  20140613 Created initial version.
** 002 OM  20150701 Extracted AbstractParameter super class. Added implicit conversion support.
** 003 EVL 20160224 Javadoc fixes to make compatible with Oracle Java 8 for Solaris 10.
** 004 GES 20171207 Removed explicit bypass on pending error to match new silent error mode.
** 005 CA  20190508 Added support for CASE-SENSITIVE extent var option.
** 006 CA  20210223 If the original array is dynamic extent, register the new array reference as dynamic 
**                  extent, too.
**     CA  20210609 Reworked INPUT/INPUT-OUTPUT parameters to a new approach, where they are explicitly 
**                  initialized at the method's execution, and not at the caller's arguments.
**     TJD 20220504 Java 11 compatibility related minor changes
**     CA  20220428 Avoid a NPE when precision is not known.
**     CA  20220609 Release all the callee's resources for this parameter, after assignment has taken place.
**     CA  20220613 Do not release memptr variables, as these are passed 'by pointer'.
** 007 CA  20230711 Extent arguments must be explicitly copied to the field parameter at the caller.
*/

/*
** 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.lang.reflect.*;

/**
 * Abstract class for special wrappers used for variables passed as extent parameters
 * to functions or procedures. The class introduces common logic for all extent parameter cases.
 */
public abstract class AbstractExtentParameter<T extends BaseDataType>
extends AbstractParameter
{
   /** The original variable set to the parameter. */
   private T[] variable = null;
   
   /** The latest parameter reference. */
   private T[] parameter = null;
   
   /** 
    * The class of the elements of the extent argument that was passed to procedure. When it is
    * finished we need to implicitly converted to back this type. 
    */
   protected Class<? extends BaseDataType> argType = null;
   
   /**
    * The class of the elements of the extent parameter that procedure expects. When procedure is
    * about to start, the elements of the extent argument are implicitly converted to this type.
    */
   protected Class<? extends BaseDataType> paramType = null;
   
   /**
    * The optional conversion constructor that will convert the local parameter values back to
    * argument item when the calling routine ends.
    */
   protected Constructor<?> retConvCtor = null;
   
   /**
    * The optional conversion constructor that will convert the argument item to local parameter
    * values back when the calling routine is about to start.
    */
   protected Constructor<?> convCtor = null;
   
   /**
    * The constructor responsible for instance initialization.
    * <p>
    * The c'tor caches the variable reference in this instance. If {@code null} is 
    * passed to {@code variable}, the value reference is retrieved by calling 
    * {@link #getVariable()}, otherwise the passed-in value is used.
    * 
    * @param   variable
    *          The value reference passed to the function/procedure's parameter or {@code null}.
    */
   protected AbstractExtentParameter(T[] variable)
   {
      // save the original array, in case it gets changed (at this time, the only way to change
      // references is by a resize).
      this.variable = (variable != null) ? variable : getVariableSafe();
   }
   
   /**
    * Get the variable reference, passed to the function/procedure's parameter. Emitted and to be
    * used only in cases of OUTPUT and INPUT-OUTPUT extent parameters.
    * 
    * @return   See above.
    */
   public abstract T[] getVariable();
   
   /**
    * Change the caller's reference to the new reference.  Emitted and to be used only in cases of
    * OUTPUT and INPUT-OUTPUT extent parameters.
    * 
    * @param    reference
    *           The new reference.
    */
   public abstract void setVariable(T[] reference);
   
   /**
    * Initializes the parameter value reference which is used in the function/procedure
    * scope. The method is responsible for its proper initialization and registering
    * the reference in this instance.
    * <p>
    * Use this method to initialize parameter values representing unfixed indeterminate 
    * extents.
    * 
    * @return  A valid and initialized parameter value reference.
    */
   public abstract T[] initParameter();
   
   /**
    * Initializes the parameter value reference which is used in the function/procedure
    * scope. The method is responsible for its proper initialization and registering
    * the reference in this instance.
    * <p>
    * Use this method to initialize parameter values representing determinate extents.
    * 
    * @param   extent
    *          The extent size declared by the function/procedure parameter.
    * 
    * @return  A valid and initialized parameter value reference.
    */
   public abstract T[] initParameter(int extent);
   
   /**
    * Resolve the variable reference, making sure the {@link OutputParameterAssigner} is not compromised if 
    * the reference is for a legacy OO property, for which its getter method is called.
    * 
    * @return   See above.
    */
   public T[] getVariableSafe()
   {
      OutputParameterAssigner opa = TransactionManager.deregisterOutputParameterAssigner();
      try
      {
         return getVariable();
      }
      finally
      {
         TransactionManager.registerOutputParameterAssigner(opa);
      }
   }
   
   /**
    * Returns the current reference for the parameter.
    *
    * @return  Current parameter reference.
    */
   public T[] getParameter()
   {
      return parameter;
   }
   
   /**
    * Set the current reference for the parameter. As this is mutable, we need to save it each
    * time the parameter's reference gets changed.
    */
   public void setParameter(T[] parameter)
   {
      this.parameter = parameter;
   }
   
   /**
    * Prepare the input and (backward) output (implicit) conversion constructors for the base type
    * of this extent argument.
    * <br>
    * In the case of OUTPUT parameters, only the {@code retConvCtor} will be used to convert the
    * resulted values to caller datatype.
    * <br>
    * In case of INPUT-OUTPUT parameters, both constructors are used to convert the
    * compatible datatypes forth and back.
    * 
    * @param   argType
    *          The element argument type that was used in procedure call.
    * @param   paramType
    *          The element type of expected parameter.
    * @param   convCtor
    *          The conversion constructor. Only for INPUT-OUTPUT parameters. In the case of
    *          OUTPUT parameters, this is ignored and should be {@code null}.
    * @param   retConvCtor
    *          The return conversion constructor.
    */
   public void setReturnConversion(Class<? extends BaseDataType> argType,
                                   Class<? extends BaseDataType> paramType,
                                   Constructor<?> convCtor,
                                   Constructor<?> retConvCtor)
   {
      this.argType = argType;
      this.paramType = paramType;
      this.convCtor = convCtor;
      this.retConvCtor = retConvCtor;
   }

   /**
    * Get the {@link #variable} direct reference.
    * 
    * @return   See above.
    */
   protected T[] getVariableRef()
   {
      return variable;
   }
   
   /**
    * Assign the current value of the parameter variable back to the caller's variable 
    * reference. This is expected to occur upon exit from the function or procedure 
    * with which this object is associated to.
    *
    * @param   endingRoutine
    *          The legacy name of the routine that is ending when these back assignments are
    *          performed.
    * @param   function
    *          {@code true} if the called routine is a function.
    */
   protected void assign(String endingRoutine, boolean function)
   {
      if (parameter == null)
      {
         throw new IllegalStateException(
            "The extent parameter reference was not set, before the function/procedure end !");
      }
      
      if (parameter != variable)
      {
         // validate the assignment
         boolean valid = validateAssignment(endingRoutine, function);
         if (valid)
         {
            // if the reference has changed and validated ok, perform the assignment
            performAssignment();
         }
      }
   }
   
   /**
    * Release all the callee's resources for this parameter, after assignment has taken place.
    */
   @Override
   protected void release()
   {
      if (parameter == null)
      {
         return;
      }
      
      for (int i = 0; i < parameter.length; i++)
      {
         BaseDataType bdt = parameter[i];
         if (canRelease(bdt))
         {
            bdt.setUnknown();
         }
      }
   }
   
   /**
    * An extension point to allow the descendants to provide validation logic
    * for parameter reference to variable assignment on exit from the function 
    * or procedure with which this object is associated to.
    * <p>
    * To indicate a failed validation, indicate an error with help of {@link ErrorManager}.
    *
    * @param   endingRoutine
    *          The legacy name of the routine that is ending when these back assignments are
    *          performed. 
    * @param   function
    *          {@code true} is the called routine is a function.
    *
    * @return  This method always returns {@code true} which means that the parameters are safe
    *          to be assigned back to original data holders. Subclasses may return false (and
    *          use {@link ErrorManager} to indicate an error) if the held vaues are invalid.
    */
   protected boolean validateAssignment(String endingRoutine, boolean function)
   {
      // no special validation at this level
      return true;
   }
   
   /**
    * An extension point to allow the descendants to provide custom logic for parameter reference
    * to variable assignment on exit from the function or procedure with which this object is
    * associated to.
    * <p>
    * The default implementation creates an array copy of the current parameter reference,
    * implements decimal precision management and stores the copy to the target variable by
    * calling {@link #setVariable(BaseDataType[])}.
    * <p>
    * The method is called only when there is no pending error being indicated by
    * {@link ErrorManager}.
    */
   @SuppressWarnings("unchecked")
   protected void performAssignment()
   {
      // TODO: this need to use ObjectVar?
      T[] retValues;
      if (argType == null)
      {
         // get copy of the latest data
         retValues = ArrayAssigner.copyOf(parameter, false);
      }
      else
      {
         retValues = (T[]) Array.newInstance(argType, parameter.length);
         
         // copy the parameter array through retConvCtor morphism
         for (int k = 0; k < parameter.length; k++)
         {
            try
            {
               retValues[k] = (T) retConvCtor.newInstance(parameter[k]);
            }
            catch (ReflectiveOperationException e)
            {
               // constructor-related exception should not happen, the constructor have been
               // detected based on actual data types
               throw new RuntimeException("Bad implicit conversion constructor");
            }
         }
      }

      if (ArrayAssigner.isDynamicArray(variable))
      {
         ArrayAssigner.registerDynamicArray(retValues, false);
      }
      
      if (decimal.class.equals(retValues.getClass().getComponentType()))
      {
         T[] variable = getVariableSafe();
         Integer precision = ArrayAssigner.getDecimalPrecision((decimal[]) variable);
         if (precision != null)
         {
            // precision can be null for dynamic arrays received from a remote side, outside of FWD server
            for (T param : retValues)
            {
               // keep the decimal precision of the target variable value.
               // note that the precision on the target variable will become effective
               // only after the next value assignment, which is the expected behavior.
               ((decimal) param).setPrecision(precision);
            }
         }
      }
      
      if (Text.class.isAssignableFrom(retValues.getClass().getComponentType()))
      {
         T[] variable = getVariableSafe();
         Boolean caseSens = ArrayAssigner.getCaseSensitive((Text[]) variable);
         if (caseSens != null)
         {
            for (T param : retValues)
            {
               // keep the case-sensitive of the target variable value.
               ((Text) param).setCaseSensitive(caseSens);
            }
         }
      }
      
      if (variable.length == 0)
      {
         // update the reference, but via a resize
         T[] newVar = ArrayAssigner.resize(variable, 
                                           retValues.length == 0 ? new int64() : new int64(retValues.length), 
                                           false, 
                                           false);
         ArrayAssigner.assignMulti(newVar, retValues);
         setVariable(newVar);
      }
      else
      {
         ArrayAssigner.assignMulti(variable, retValues);
      }
   }
   
   /**
    * Register this extent parameter in the current scope.
    */
   void registerParameter()
   {
      getCurrentScope().addExtentParameter(this);
   }
}