/interpreter/tags/at_build150307/src/edu/vub/at/objects/mirrors/NativeField.java

http://ambienttalk.googlecode.com/ · Java · 133 lines · 61 code · 17 blank · 55 comment · 6 complexity · c5828682a065dd2b6953199eb241677d MD5 · raw file

  1. /**
  2. * AmbientTalk/2 Project
  3. * NATPrimitiveField.java created on Aug 2, 2006 at 12:47:02 AM
  4. * (c) Programming Technology Lab, 2006 - 2007
  5. * Authors: Tom Van Cutsem & Stijn Mostinckx
  6. *
  7. * Permission is hereby granted, free of charge, to any person
  8. * obtaining a copy of this software and associated documentation
  9. * files (the "Software"), to deal in the Software without
  10. * restriction, including without limitation the rights to use,
  11. * copy, modify, merge, publish, distribute, sublicense, and/or
  12. * sell copies of the Software, and to permit persons to whom the
  13. * Software is furnished to do so, subject to the following
  14. * conditions:
  15. *
  16. * The above copyright notice and this permission notice shall be
  17. * included in all copies or substantial portions of the Software.
  18. *
  19. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  20. * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  21. * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  22. * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  23. * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  24. * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  25. * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  26. * OTHER DEALINGS IN THE SOFTWARE.
  27. */
  28. package edu.vub.at.objects.mirrors;
  29. import edu.vub.at.exceptions.InterpreterException;
  30. import edu.vub.at.exceptions.XIllegalOperation;
  31. import edu.vub.at.objects.ATField;
  32. import edu.vub.at.objects.ATNil;
  33. import edu.vub.at.objects.ATObject;
  34. import edu.vub.at.objects.ATTable;
  35. import edu.vub.at.objects.coercion.NativeStripes;
  36. import edu.vub.at.objects.grammar.ATSymbol;
  37. import edu.vub.at.objects.natives.NATByRef;
  38. import edu.vub.at.objects.natives.NATNil;
  39. import edu.vub.at.objects.natives.NATNumber;
  40. import edu.vub.at.objects.natives.NATTable;
  41. import edu.vub.at.objects.natives.NATText;
  42. import java.lang.reflect.Method;
  43. /**
  44. * Native Fields are represented in our reflective implementation as a pair
  45. * of accessor and mutator methods in the class of the native AmbientTalk object.
  46. * For instance, a native AmbientTalk object of class C has a field 'f' if the
  47. * class C implements a method 'getF()'. If the class also implements 'setF(v)'
  48. * the field is assignable.
  49. *
  50. * @author tvcutsem
  51. * @author smostinc
  52. */
  53. public class NativeField extends NATByRef implements ATField {
  54. /**
  55. * The AmbientTalk name of the field
  56. */
  57. private final ATSymbol name_;
  58. /**
  59. * The AmbientTalk native object to which this field belongs
  60. */
  61. private ATObject host_;
  62. /**
  63. * The native Java accessor method to be called when accessing the field
  64. */
  65. private final Method accessor_;
  66. /**
  67. * The native Java mutator method to be called when assigning to the field.
  68. * This field may be null which indicates a read-only field
  69. */
  70. private final Method mutator_;
  71. public NativeField(ATObject host, ATSymbol name, Method accessor, Method mutator) {
  72. host_ = host;
  73. name_ = name;
  74. accessor_ = accessor;
  75. mutator_ = mutator;
  76. }
  77. public ATSymbol base_getName() {
  78. return name_;
  79. }
  80. public ATObject base_readField() throws InterpreterException {
  81. return JavaInterfaceAdaptor.invokeNativeATMethod(accessor_, host_, NATTable.EMPTY.elements_);
  82. }
  83. public ATNil base_writeField(ATObject newValue) throws InterpreterException {
  84. // certain fields may not have setters
  85. if (mutator_ != null) {
  86. JavaInterfaceAdaptor.invokeNativeATMethod(accessor_, host_, new ATObject[] { newValue });
  87. return NATNil._INSTANCE_;
  88. } else {
  89. throw new XIllegalOperation("Field " + name_ + " cannot be set.");
  90. }
  91. }
  92. /**
  93. * Fields can be re-initialized when installed in an object that is being cloned.
  94. * They expect the new owner of the field as the sole instance to their 'new' method
  95. */
  96. public ATObject meta_newInstance(ATTable initargs) throws InterpreterException {
  97. if (initargs.base_getLength() != NATNumber.ONE) {
  98. return super.meta_newInstance(initargs);
  99. } else {
  100. ATObject newhost = initargs.base_at(NATNumber.ONE);
  101. return new NativeField(newhost, name_, accessor_, mutator_);
  102. }
  103. }
  104. public NATText meta_print() throws InterpreterException {
  105. return NATText.atValue("<native field:"+name_+" of "+ host_.meta_print().javaValue +">");
  106. }
  107. public ATTable meta_getStripes() throws InterpreterException {
  108. return NATTable.of(NativeStripes._FIELD_);
  109. }
  110. public boolean isNativeField() {
  111. return true;
  112. }
  113. public ATField asField() {
  114. return this;
  115. }
  116. }