src/code/destructuring-bind.lisp

   1 ;;;; This software is part of the SBCL system. See the README file for
   2 ;;;; more information.
   3 ;;;;
   4 ;;;; This software is derived from the CMU CL system, which was
   5 ;;;; written at Carnegie Mellon University and released into the
   6 ;;;; public domain. The software is in the public domain and is
   7 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
   8 ;;;; files for more information.
   9
  10 (in-package "SB!IMPL")
  11
  12 (defmacro-mundanely destructuring-bind (lambda-list expression &body body)
  13   #!+sb-doc
  14   "Bind the variables in LAMBDA-LIST to the corresponding values in the
  15 tree structure resulting from the evaluation of EXPRESSION."
  16   (let ((whole-name (gensym "WHOLE")))
  17     (multiple-value-bind (body local-decls)
  18         (parse-defmacro lambda-list whole-name body nil 'destructuring-bind
  19                         :anonymousp t
  20                         :doc-string-allowed nil
  21                         :wrap-block nil)
  22       `(let ((,whole-name ,expression))
  23          ;; This declaration-as-assertion should protect us from
  24          ;; (DESTRUCTURING-BIND (X . Y) 'NOT-A-LIST ...).
  25          (declare (type list ,whole-name))
  26          ,@local-decls
  27          ,body))))