src/code/defmacro.lisp

   1 ;;;; DEFMACRO machinery
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!IMPL")
  13
  14 ;;; the guts of the DEFMACRO macro, pulled out into a separate
  15 ;;; function in order to make it easier to express the common
  16 ;;; bootstrap idiom
  17 ;;;   CL:DEFMACRO SB!XC:DEFMACRO
  18 ;;;   SB!XC:DEFMACRO CL:DEFMACRO
  19 (eval-when (#-sb-xc :compile-toplevel :load-toplevel :execute)
  20   (defun %expander-for-defmacro (name lambda-list body)
  21     (unless (symbolp name)
  22       (error "The macro name ~S is not a symbol." name))
  23     ;; When we are building the cross-compiler, we could be in a host
  24     ;; lisp which implements CL macros (e.g. CL:AND) as special
  25     ;; operators (while still providing a macroexpansion for
  26     ;; compliance): therefore can't use the host's SPECIAL-OPERATOR-P
  27     ;; as a discriminator, but that's OK because the set of forms the
  28     ;; cross-compiler compiles is tightly controlled.  -- CSR,
  29     ;; 2003-04-20
  30     #-sb-xc-host
  31     (when (special-operator-p name)
  32       (error "The special operator ~S can't be redefined as a macro."
  33              name))
  34     (with-unique-names (whole environment)
  35       (multiple-value-bind (new-body local-decs doc)
  36           (parse-defmacro lambda-list whole body name 'defmacro
  37                           :environment environment)
  38         (let ((def `(#+sb-xc-host lambda
  39                      ;; Use a named-lambda rather than a lambda so that
  40                      ;; proper xref information can be stored. Use a
  41                      ;; list-based name, since otherwise the compiler
  42                      ;; will momentarily assume that it names a normal
  43                      ;; function, and report spurious warnings about
  44                      ;; redefinition a macro as a function, and then
  45                      ;; vice versa.
  46                      #-sb-xc-host named-lambda #-sb-xc-host (defmacro ,name)
  47                      (,whole ,environment)
  48                       ,@local-decs
  49                       ,new-body))
  50               (debug-name (sb!c::debug-name 'macro-function name)))
  51           `(eval-when (:compile-toplevel :load-toplevel :execute)
  52              (sb!c::%defmacro ',name #',def ',lambda-list
  53                               ,doc ',debug-name)))))))
  54
  55 (macrolet
  56     ((def (times set-p)
  57        `(eval-when (,@times)
  58           (defun sb!c::%defmacro (name definition lambda-list doc debug-name)
  59             ;; old note (ca. 1985, maybe:-): "Eventually %%DEFMACRO
  60             ;; should deal with clearing old compiler information for
  61             ;; the functional value."
  62             ,@(unless set-p
  63                 '((declare (ignore lambda-list debug-name))))
  64             (ecase (info :function :kind name)
  65               ((nil))
  66               (:function
  67                ;; (remhash name *free-funs*)
  68                (undefine-fun-name name)
  69                (style-warn
  70                 "~S is being redefined as a macro when it was ~
  71                  previously ~(~A~) to be a function."
  72                 name
  73                 (info :function :where-from name)))
  74               (:macro)
  75               (:special-form
  76                (error "The special form ~S can't be redefined as a macro."
  77                       name)))
  78             (clear-info :function :where-from name)
  79             ;; FIXME: It would be nice to warn about DEFMACRO of an
  80             ;; already-defined macro, but that's slightly hard to do
  81             ;; because in common usage DEFMACRO is defined at compile
  82             ;; time and then redefined at load time. We'd need to make a
  83             ;; distinction between the defined-at-compile-time state and
  84             ;; the defined-at-load-time state to make this work. (Trying
  85             ;; to warn about duplicate DEFTYPEs runs into the same
  86             ;; problem.)
  87             #+nil (when (sb!xc:macro-function name)
  88                     ;; Someday we could check for macro arguments
  89                     ;; being incompatibly redefined. Doing this right
  90                     ;; will involve finding the old macro lambda-list
  91                     ;; and comparing it with the new one.
  92                     (style-warn "redefining ~S in DEFMACRO" name))
  93             (setf (sb!xc:macro-function name) definition
  94                   (fdocumentation name 'function) doc)
  95             ,(when set-p
  96                    `(case (widetag-of definition)
  97                       (#.sb!vm:closure-header-widetag
  98                        (setf (%simple-fun-arglist (%closure-fun definition))
  99                              lambda-list
 100                              (%simple-fun-name (%closure-fun definition))
 101                              debug-name))
 102                       (#.sb!vm:simple-fun-header-widetag
 103                        (setf (%simple-fun-arglist definition) lambda-list
 104                              (%simple-fun-name definition) debug-name))))
 105             name))))
 106   (progn
 107     (def (:load-toplevel :execute) #-sb-xc-host t #+sb-xc-host nil)
 108     (def (#-sb-xc :compile-toplevel) nil)))
 109
 110 ;;; Parse the definition and make an expander function. The actual
 111 ;;; definition is done by %DEFMACRO which we expand into. After the
 112 ;;; compiler has gotten the information it wants out of macro
 113 ;;; definition, it compiles a call to %DEFMACRO which happens at load
 114 ;;; time.
 115 (defmacro sb!xc:defmacro (name lambda-list &rest body)
 116   (%expander-for-defmacro name lambda-list body))
 117
 118 ;;; In the cross-compiler, we not only need to support the definition
 119 ;;; of target macros at cross-compiler-build-time (with SB!XC:DEFMACRO
 120 ;;; running in the cross-compilation host), we also need to support
 121 ;;; the definition of target macros at target compilation time (with
 122 ;;; CL:DEFMACRO processed by the cross-compiler)..
 123 #+sb-xc-host
 124 (sb!xc:defmacro defmacro (name lambda-list &rest body)
 125   (%expander-for-defmacro name lambda-list body))
 126
 127 ;;; DEFMACRO-MUNDANELY is like SB!XC:DEFMACRO, except that it doesn't
 128 ;;; have any EVAL-WHEN or IR1 magic associated with it, so it only
 129 ;;; takes effect in :LOAD-TOPLEVEL or :EXECUTE situations.
 130 (def!macro defmacro-mundanely (name lambda-list &body body)
 131
 132   ;; old way:
 133   ;;(let ((whole (gensym "WHOLE-"))
 134   ;;      (environment (gensym "ENVIRONMENT-")))
 135   ;;  (multiple-value-bind (new-body local-decs doc)
 136   ;;      (parse-defmacro lambda-list whole body name 'defmacro
 137   ;;                      :environment environment)
 138   ;;    `(progn
 139   ;;       (setf (sb!xc:macro-function ',name)
 140   ;;             (lambda (,whole ,environment)
 141   ;;                 ,@local-decs
 142   ;;                 (block ,name
 143   ;;                 ,new-body)))
 144   ;;       (setf (fdocumentation ',name 'macro)
 145   ;;             ,doc)
 146   ;;       ',name)))
 147
 148   `(let ()
 149      (sb!xc:defmacro ,name ,lambda-list ,@body)))