;;; ([a] means that a should be converted according to the previous table)
;;;
;;; \ car || otherwise | QUOTE or | |`,@| | |`,.|
-;;;cdr \ || | T or NIL | |
+;;;cdr \ || | T or NIL | |
;;;================================================================================
;;; |`,| || LIST* ([a] [d]) | LIST* ([a] [d]) | APPEND (a [d]) | NCONC (a [d])
;;; NIL || LIST ([a]) | QUOTE (a) | <hair> a | <hair> a
(let ((*backquote-count* (1+ *backquote-count*)))
(multiple-value-bind (flag thing)
(backquotify stream (read stream t nil t))
- (if (eq flag *bq-at-flag*)
- (%reader-error stream ",@ after backquote in ~S" thing))
- (if (eq flag *bq-dot-flag*)
- (%reader-error stream ",. after backquote in ~S" thing))
- (values (backquotify-1 flag thing) 'list))))
+ (when (eq flag *bq-at-flag*)
+ (%reader-error stream ",@ after backquote in ~S" thing))
+ (when (eq flag *bq-dot-flag*)
+ (%reader-error stream ",. after backquote in ~S" thing))
+ (backquotify-1 flag thing))))
(/show0 "backq.lisp 64")
(%reader-error stream "comma not inside a backquote"))
(let ((c (read-char stream))
(*backquote-count* (1- *backquote-count*)))
- (values
- (cond ((char= c #\@)
- (cons *bq-at-flag* (read stream t nil t)))
- ((char= c #\.)
- (cons *bq-dot-flag* (read stream t nil t)))
- (t (unread-char c stream)
- (cons *bq-comma-flag* (read stream t nil t))))
- 'list)))
+ (cond ((char= c #\@)
+ (cons *bq-at-flag* (read stream t nil t)))
+ ((char= c #\.)
+ (cons *bq-dot-flag* (read stream t nil t)))
+ (t (unread-char c stream)
+ (cons *bq-comma-flag* (read stream t nil t))))))
(/show0 "backq.lisp 83")
+;;;
+(defun expandable-backq-expression-p (object)
+ (and (consp object)
+ (let ((flag (car object)))
+ (or (eq flag *bq-at-flag*)
+ (eq flag *bq-dot-flag*)))))
+
;;; This does the expansion from table 2.
(defun backquotify (stream code)
(cond ((atom code)
(cond ((null code) (values nil nil))
- ((or (numberp code)
- (eq code t))
+ ((or (consp code)
+ (symbolp code))
;; Keywords are self-evaluating. Install after packages.
- (values t code))
- (t (values 'quote code))))
+ (values 'quote code))
+ (t (values t code))))
((or (eq (car code) *bq-at-flag*)
(eq (car code) *bq-dot-flag*))
(values (car code) (cdr code)))
(values 'vector (backquotify-1 dflag d))))
(t (multiple-value-bind (aflag a) (backquotify stream (car code))
(multiple-value-bind (dflag d) (backquotify stream (cdr code))
- (if (eq dflag *bq-at-flag*)
- ;; Get the errors later.
- (%reader-error stream ",@ after dot in ~S" code))
- (if (eq dflag *bq-dot-flag*)
- (%reader-error stream ",. after dot in ~S" code))
+ (when (eq dflag *bq-at-flag*)
+ ;; Get the errors later.
+ (%reader-error stream ",@ after dot in ~S" code))
+ (when (eq dflag *bq-dot-flag*)
+ (%reader-error stream ",. after dot in ~S" code))
(cond
((eq aflag *bq-at-flag*)
(if (null dflag)
- (comma a)
+ (if (expandable-backq-expression-p a)
+ (values 'append (list a))
+ (comma a))
(values 'append
(cond ((eq dflag 'append)
(cons a d ))
(t (list a (backquotify-1 dflag d)))))))
((eq aflag *bq-dot-flag*)
(if (null dflag)
- (comma a)
+ (if (expandable-backq-expression-p a)
+ (values 'nconc (list a))
+ (comma a))
(values 'nconc
(cond ((eq dflag 'nconc)
(cons a d))
((or (numberp code) (eq code t))
(values t code))
(t (values *bq-comma-flag* code))))
- ((eq (car code) 'quote)
- (values (car code) (cadr code)))
+ ((and (eq (car code) 'quote)
+ (not (expandable-backq-expression-p (cadr code))))
+ (values (car code) (cadr code)))
((member (car code) '(append list list* nconc))
(values (car code) (cdr code)))
((eq (car code) 'cons)
((eq flag 'quote)
(list 'quote thing))
((eq flag 'list*)
- (cond ((null (cddr thing))
+ (cond ((and (null (cddr thing))
+ (not (expandable-backq-expression-p (cadr thing))))
(cons 'backq-cons thing))
- (t
+ ((expandable-backq-expression-p (car (last thing)))
+ (list 'backq-append
+ (cons 'backq-list (butlast thing))
+ ;; Can it be optimized further? -- APD, 2001-12-21
+ (car (last thing))))
+ (t
(cons 'backq-list* thing))))
((eq flag 'vector)
(list 'backq-vector thing))
- (t (cons (cdr
- (assoc flag
- '((cons . backq-cons)
- (list . backq-list)
- (append . backq-append)
- (nconc . backq-nconc))
- :test #'equal))
+ (t (cons (ecase flag
+ ((list) 'backq-list)
+ ((append) 'backq-append)
+ ((nconc) 'backq-nconc))
thing))))
\f
;;;; magic BACKQ- versions of builtin functions
;;; Define synonyms for the lisp functions we use, so that by using
;;; them, the backquoted material will be recognizable to the
;;; pretty-printer.
-(macrolet ((def-frob (b-name name)
+(macrolet ((def (b-name name)
(let ((args (gensym "ARGS")))
;; FIXME: This function should be INLINE so that the lists
;; aren't consed twice, but I ran into an optimizer bug the
;; whether there's still an optimizer bug, and fix it if so, and
;; then make these INLINE.
`(defun ,b-name (&rest ,args)
+ (declare (dynamic-extent ,args))
(apply #',name ,args)))))
- (def-frob backq-list list)
- (def-frob backq-list* list*)
- (def-frob backq-append append)
- (def-frob backq-nconc nconc)
- (def-frob backq-cons cons))
+ (def backq-list list)
+ (def backq-list* list*)
+ (def backq-append append)
+ (def backq-nconc nconc)
+ (def backq-cons cons))
(/show0 "backq.lisp 204")
(set-macro-character #\, #'comma-macro))
#+sb-xc-host (!backq-cold-init)
+;;; The pretty-printer needs to know about our special tokens
+(defvar *backq-tokens*
+ '(backq-comma backq-comma-at backq-comma-dot backq-list
+ backq-list* backq-append backq-nconc backq-cons backq-vector))
+
+;;; Since our backquote is installed on the host lisp, and since
+;;; developers make mistakes with backquotes and commas too, let's
+;;; ensure that we can report errors rather than get an undefined
+;;; function condition on %READER-ERROR.
+#+sb-xc-host ; proper definition happens for the target
+(defun %reader-error (stream format-string &rest format-args)
+ (bug "READER-ERROR on stream ~S: ~?" stream format-string format-args))
+
(/show0 "done with backq.lisp")