# NativeTypeArray.java

    /*
    ** Module   : NativeTypeArray.java
    ** Abstract : an array of descriptors passed as a single argument to a native function
    **
    ** Copyright (c) 2013-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description---------------------------------
    ** 001 GES 20131211 First version.
    ** 002 GES 20140130 Even arrays need to be passed as a pointer to a pointer (one more level of
    **                  indirection than we were providing).
    */
    /*
    ** 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.
    **
    **   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
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    **
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    **     attribution required in this license.
    */

    package com.goldencode.p2j.library;

    import java.io.*;
    import com.goldencode.p2j.util.*;

    /**
     * An array of descriptors passed as a single argument to a native function.  4GL RETURN
     * parameters cannot have an extent, so this can only be used for INPUT, INPUT-OUTPUT and
     * OUTPUT parameters.  This class hides the complexity of rendering/restoring arrays to
     * native memory.
     */
    public class NativeTypeArray
    extends BaseNativeType
    {
       /** Stores the contained elements for the array. */
       private BaseNativeType[] elements = new BaseNativeType[0];

       /**
        * Default constructor.
        */
       public NativeTypeArray()
       {
          super();
          setPassByPointer(true);
          type = LibraryManager.TYPE_POINTER;
       }

       /**
        * Constructor that takes a list of elements.
        *
        * @param    elements
        *           The elements for this array.
        */
       public NativeTypeArray(BaseNativeType[] elements)
       {
          this();
          this.elements = elements;
       }

       /**
        * Access the array of data elements.
        *
        * @return   The array of elements.
        */
       public BaseNativeType[] getElements()
       {
          return elements;
       }

       /**
        * Assign the array of data elements.
        *
        * @param    elements
        *           The array of elements.
        */
       public void setElements(BaseNativeType[] elements)
       {
          this.elements = elements;
       }

       /**
        * Report the size (in bytes) of the native memory needed to store this instance.
        * <p>
        * This should never be called on the server, only on the client side.
        *
        * @return   The number of bytes needed.
        */
       public int size()
       {
          return (elements.length > 0) ? elements.length * elements[0].size() : 0;
       }

       /**
        * Render the data into native memory, which will be allocated if the address is not
        * given.
        * <p>
        * This should never be called on the server, only on the client side.
        * <p>
        * Arrays are rendered as a pointer to a block of memory in which each element is
        * written contiguously from lowest address to highest address and the size of the
        * block is the number of elements multiplied by the size of each element (which
        * must be the same for all elements). This is consistent with how native code ('C'
        * language) handles arrays.
        *
        * @param    addr
        *           The memory address to which the data should be rendered, if the caller
        *           is supplying a buffer or 0 if the buffer should be allocated.
        *
        * @return   The memory address of the rendered data or 0 if there is no data to
        *           output.
        */
       public long render(long addr)
       {
          if (elements.length > 0)
          {
             // all elements of the array must have the same size
             int sz = elements[0].size();

             memptr local = new memptr();

             if (addr == 0)
             {
                // save off for restore use later
                ref = local;

                // allocate the block which must be big enough to store the array
                local.setLength(elements.length * sz);

                addr = local.getPointerValue().longValue();
             }
             else
             {
                local.setPointerValue(addr);
             }

             if (copyIn || elements[0].isPassByPointer())
             {
                for (int i = 0; i < elements.length; i++)
                {
                   // calculate the address at which to write our next element
                   long idx = addr + (i * sz);

                   // give each element a chance to render itself
                   elements[i].render(idx);
                }
             }
          }
          else
          {
             addr = 0;
          }

          return addr;
       }

       /**
        * Copy back (if necessary) data from the native memory and deallocate the memory
        * if this instance allocated it in the first place.
        * <p>
        * This should never be called on the server, only on the client side.
        *
        * @param    addr
        *           The memory address from which the data should be restored, if the caller
        *           is supplying a buffer or 0 if the buffer should already exist.
        */
       public void restore(long addr)
       {
          memptr local = ref;

          if (local == null && addr != 0)
          {
             local = new memptr();
             local.setPointerValue(addr);
          }

          if (copyOut && local != null && elements.length > 0)
          {
             addr = local.getPointerValue().longValue();

             // all elements of the array must have the same size
             int sz = elements[0].size();

             // each element must have a chance to restore and deallocate the native resources
             for (int i = 0; i < elements.length; i++)
             {
                // calculate the address at which to read our next element
                long idx = addr + (i * sz);

                elements[i].restore(idx);
             }
          }

          // deallocate memory if we allocated it
          if (ref != null)
             ref.setLength(0);
       }

       /**
        * Replacement for the default object reading method. The latest
        * state is read from the input source.  The parent's state is
        * read first.
        *
        * @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
       {
          super.readExternal(in);

          int len = in.readInt();

          elements = new BaseNativeType[len];

          for (int i = 0; i < len; i++)
          {
             elements[i] = (BaseNativeType) in.readObject();
          }
       }

       /**
        * Replacement for the default object writing method. The latest
        * state is written to the output destination.  The parent's state is
        * written first.
        *
        * @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
       {
          super.writeExternal(out);

          out.writeInt(elements.length);

          for (int i = 0; i < elements.length; i++)
          {
             out.writeObject(elements[i]);
          }
       }
    }