ArraySerializer.java

/*
** Module   : ArraySerializer.java
** Abstract : A serializer and parser for Java arrays.
**
** Copyright (c) 2022, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
** 001 CA  20220323 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
**   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.
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**   1. No License To Use Trademarks.
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**     This license does not grant any license or rights to use the trademarks
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*/

package com.goldencode.p2j.rest.serializers;

import java.lang.reflect.*;
import java.util.*;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.node.*;
import com.goldencode.p2j.rest.*;

/**
 * A parser and serializer for Java arrays.
 */
class ArraySerializer
extends JavaTypeSerializer<Object>
{
   /** The array's component serializer. */
   private final JavaTypeSerializer component;
   
   /** The array's length. */
   private final int extent;

   /**
    * Create a new serializer and parser for the given type.
    * 
    * @param    type
    *           The component type.
    * @param    ctype
    *           The component serializer.
    */
   public ArraySerializer(Class<Object> type, JavaTypeSerializer ctype)
   {
      super(type);
      
      this.component = ctype;
      this.extent = -1;
   }

   /**
    * Create a copy of the given array serializer, and set its length.
    * 
    * @param    serializer
    *           The initial instance.
    * @param    extent
    *           The array's length.
    */
   public ArraySerializer(ArraySerializer serializer, int extent)
   {
      super(serializer.getType());
      
      this.component = serializer.component;
      this.extent = extent;
   }

   /**
    * Create an initial (default) instance for this serializer.
    * <p>
    * The array's length will be either zero or the {@link #extent}, if non-negative.
    * 
    * @param    definitionType
    *           The type as it appears at the parameter's definition.
    *           
    * @return   A new array of the given type.
    */
   @Override
   public Object initialize(Class<?> definitionType)
   {
      return Array.newInstance(definitionType.getComponentType(), Math.max(extent, 0));
   }

   /**
    * Parse the string JSON representation and assign it to the given argument.  If null or not mutable, a 
    * new instance will be created.
    *  
    * @param    arg
    *           The argument (obtained via {@link #initialize}.
    * @param    sval
    *           The string JSON representation of this argument.
    *           
    * @return   The argument instance.
    * 
    * @throws   RequestArgumentError
    *           If the argument can't be parsed.
    */
   @Override
   public Object fromJson(Object arg, String sval) 
   throws RequestArgumentError
   {
      if (sval == null)
      {
         return arg;
      }
      
      Class<?> ctype = arg.getClass().getComponentType();
      List<Object> elements = readArray(component, ctype, sval);
      
      Object res = Array.newInstance(ctype, elements.size());
      for (int i = 0; i < elements.size(); i++)
      {
         Object val = elements.get(i);
         Array.set(res, i, val);
      }

      if (extent > 0 && Array.getLength(arg) >= elements.size())
      {
         System.arraycopy(res, 0, arg, 0, elements.size());
      }
      else
      {
         arg = res;
      }
      
      return arg;
   }

   /**
    * Serialize the given instance to JSON.
    * 
    * @param    val
    *           The instance to serialize.
    *           
    * @return   The JSON representation of this instance.
    */
   @Override
   public JsonNode toJson(Object val)
   {
      if (val == null)
      {
         return JsonNodeFactory.instance.nullNode();
      }
      
      int size = Array.getLength(val);
      
      ArrayNode arr = JsonNodeFactory.instance.arrayNode(size);
      for (int i = 0; i < size; i++)
      {
         Object v = Array.get(val, i);
         JsonNode el = component.toJson(v);
         arr.add(el);
      }
      
      return arr;
   }
}