/interpreter/tags/at2dist090708/src/edu/vub/at/objects/natives/grammar/AGSelf.java

http://ambienttalk.googlecode.com/ · Java · 70 lines · 18 code · 9 blank · 43 comment · 0 complexity · 41b13658229c40bc0ff40d4393a84f86 MD5 · raw file

  1. /**
  2. * AmbientTalk/2 Project
  3. * AGSelf.java created on 27-jul-2006 at 12:57:41
  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.natives.grammar;
  29. import edu.vub.at.exceptions.InterpreterException;
  30. import edu.vub.at.objects.ATContext;
  31. import edu.vub.at.objects.ATObject;
  32. /**
  33. * @author tvc
  34. *
  35. * The abstract grammar element denoting the symbol 'self'
  36. */
  37. public final class AGSelf extends AGSymbol {
  38. private static final String SELF_NAM = "self";
  39. public static final AGSelf _INSTANCE_ = new AGSelf();
  40. private AGSelf() { super(SELF_NAM); }
  41. /**
  42. * To evaluate a self reference, simply select the current self from the current evaluation context.
  43. *
  44. * AGSelf().eval(ctx) = ctx.self
  45. */
  46. public ATObject meta_eval(ATContext ctx) throws InterpreterException {
  47. return ctx.base_receiver();
  48. }
  49. /**
  50. * Quoting a self reference results in the same self reference.
  51. */
  52. public ATObject meta_quote(ATContext ctx) {
  53. return this;
  54. }
  55. /**
  56. * After deserialization, ensure that the self pseudovariable remains unique.
  57. */
  58. public ATObject meta_resolve() throws InterpreterException {
  59. return _INSTANCE_;
  60. }
  61. }