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  1. #region License
  2. // Copyright (c) 2007 James Newton-King
  3. //
  4. // Permission is hereby granted, free of charge, to any person
  5. // obtaining a copy of this software and associated documentation
  6. // files (the "Software"), to deal in the Software without
  7. // restriction, including without limitation the rights to use,
  8. // copy, modify, merge, publish, distribute, sublicense, and/or sell
  9. // copies of the Software, and to permit persons to whom the
  10. // Software is furnished to do so, subject to the following
  11. // conditions:
  12. //
  13. // The above copyright notice and this permission notice shall be
  14. // included in all copies or substantial portions of the Software.
  15. //
  16. // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  17. // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  18. // OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  19. // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  20. // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  21. // WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  22. // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23. // OTHER DEALINGS IN THE SOFTWARE.
  24. #endregion
  25. using System;
  26. using System.Reflection;
  27. using Newtonsoft.Json.Utilities;
  28. namespace Newtonsoft.Json.Converters
  29. {
  30. /// <summary>
  31. /// Creates a custom object.
  32. /// </summary>
  33. /// <typeparam name="T">The object type to convert.</typeparam>
  34. internal abstract class CustomCreationConverter<T> : JsonConverter
  35. {
  36. /// <summary>
  37. /// Writes the JSON representation of the object.
  38. /// </summary>
  39. /// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
  40. /// <param name="value">The value.</param>
  41. /// <param name="serializer">The calling serializer.</param>
  42. public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
  43. {
  44. throw new NotSupportedException("CustomCreationConverter should only be used while deserializing.");
  45. }
  46. /// <summary>
  47. /// Reads the JSON representation of the object.
  48. /// </summary>
  49. /// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
  50. /// <param name="objectType">Type of the object.</param>
  51. /// <param name="existingValue">The existing value of object being read.</param>
  52. /// <param name="serializer">The calling serializer.</param>
  53. /// <returns>The object value.</returns>
  54. public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
  55. {
  56. if (reader.TokenType == JsonToken.Null)
  57. {
  58. return null;
  59. }
  60. T value = Create(objectType);
  61. if (value == null)
  62. {
  63. throw new JsonSerializationException("No object created.");
  64. }
  65. serializer.Populate(reader, value);
  66. return value;
  67. }
  68. /// <summary>
  69. /// Creates an object which will then be populated by the serializer.
  70. /// </summary>
  71. /// <param name="objectType">Type of the object.</param>
  72. /// <returns>The created object.</returns>
  73. public abstract T Create(Type objectType);
  74. /// <summary>
  75. /// Determines whether this instance can convert the specified object type.
  76. /// </summary>
  77. /// <param name="objectType">Type of the object.</param>
  78. /// <returns>
  79. /// <c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.
  80. /// </returns>
  81. public override bool CanConvert(Type objectType)
  82. {
  83. return typeof(T).IsAssignableFrom(objectType);
  84. }
  85. /// <summary>
  86. /// Gets a value indicating whether this <see cref="JsonConverter"/> can write JSON.
  87. /// </summary>
  88. /// <value>
  89. /// <c>true</c> if this <see cref="JsonConverter"/> can write JSON; otherwise, <c>false</c>.
  90. /// </value>
  91. public override bool CanWrite => false;
  92. }
  93. }