X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Flate-extensions.lisp;h=f6c5f25aed6233787d28f4714510ee50e7cbf27b;hb=102b7c83b326855e16c3bc3ce4fa60c6d7aaba85;hp=4f1ffd0b52aea1e865e2dd2ab9b46022a6e1796d;hpb=959057baab99d4328fc386aee3fcc812f5fcb3ed;p=sbcl.git diff --git a/src/code/late-extensions.lisp b/src/code/late-extensions.lisp index 4f1ffd0..f6c5f25 100644 --- a/src/code/late-extensions.lisp +++ b/src/code/late-extensions.lisp @@ -19,3 +19,124 @@ ;;; not improper and which is not circular? (defun list-with-length-p (x) (values (ignore-errors (list-length x)))) + +;;; not used in 0.7.8, but possibly useful for defensive programming +;;; in e.g. (COERCE ... 'VECTOR) +;;;(defun list-length-or-die (x) +;;; (or (list-length x) +;;; ;; not clear how to do this best: +;;; ;; * Should this be a TYPE-ERROR? Colloquially that'd make +;;; ;; lots of sense, but since I'm not sure how to express +;;; ;; "noncircular list" as a Lisp type expression, coding +;;; ;; it seems awkward. +;;; ;; * Should the ERROR object include the offending value? +;;; ;; Ordinarily that's helpful, but if the user doesn't have +;;; ;; his printer set up to deal with cyclicity, we might not +;;; ;; be doing him a favor by printing the object here. +;;; ;; -- WHN 2002-10-19 +;;; (error "can't calculate length of cyclic list"))) + +;;; This is used in constructing arg lists for debugger printing, +;;; and when needing to print unbound slots in PCL. +(defstruct (unprintable-object + (:constructor make-unprintable-object (string)) + (:print-object (lambda (x s) + (print-unreadable-object (x s) + (write-string (unprintable-object-string x) s)))) + (:copier nil)) + string) + +;;; Used internally, but it would be nice to provide something +;;; like this for users as well. + +#!+sb-thread +(defmacro define-structure-slot-addressor (name &key structure slot) + (let* ((dd (find-defstruct-description structure t)) + (slotd (when dd (find slot (dd-slots dd) :key #'dsd-name))) + (index (when slotd (dsd-index slotd)))) + (unless index + (error "Slot ~S not found in ~S." slot structure)) + `(progn + (declaim (inline ,name)) + (defun ,name (instance) + (declare (type ,structure instance) (optimize speed)) + (sb!ext:truly-the + sb!vm:word + (+ (sb!kernel:get-lisp-obj-address instance) + (- (* ,(+ sb!vm:instance-slots-offset index) sb!vm:n-word-bytes) + sb!vm:instance-pointer-lowtag))))))) + +(defmacro compare-and-swap (place old new) + "Atomically stores NEW in PLACE if OLD matches the current value of PLACE. +Two values are considered to match if they are EQ. Returns the previous value +of PLACE: if the returned value if EQ to OLD, the swap was carried out. + +PLACE must be an accessor form whose CAR is one of the following: + + CAR, CDR, FIRST, REST, SYMBOL-PLIST, SYMBOL-VALUE, SVREF + +or the name of a DEFSTRUCT created accessor for a slot whose declared type is +either FIXNUM or T. Results are unspecified if the slot has a declared type +other then FIXNUM or T. + +EXPERIMENTAL: Interface subject to change." + (flet ((invalid-place () + (error "Invalid first argument to COMPARE-AND-SWAP: ~S" place))) + (unless (consp place) + (invalid-place)) + ;; FIXME: Not the nicest way to do this... + (destructuring-bind (op &rest args) place + (case op + ((car first) + `(%compare-and-swap-car (the cons ,@args) ,old ,new)) + ((cdr rest) + `(%compare-and-swap-cdr (the cons ,@args) ,old ,new)) + (symbol-plist + `(%compare-and-swap-symbol-plist (the symbol ,@args) ,old ,new)) + (symbol-value + `(%compare-and-swap-symbol-value (the symbol ,@args) ,old ,new)) + (svref + (let ((vector (car args)) + (index (cadr args))) + (unless (and vector index (not (cddr args))) + (invalid-place)) + (with-unique-names (v) + `(let ((,v ,vector)) + (declare (simple-vector ,v)) + (%compare-and-swap-svref ,v (%check-bound ,v (length ,v) ,index) ,old ,new))))) + (t + (let ((dd (info :function :structure-accessor op))) + (if dd + (let* ((structure (dd-name dd)) + (slotd (find op (dd-slots dd) :key #'dsd-accessor-name)) + (index (dsd-index slotd)) + (type (dsd-type slotd))) + (unless (eq t (dsd-raw-type slotd)) + (error "Cannot use COMPARE-AND-SWAP with structure accessor for a typed slot: ~S" + place)) + (when (dsd-read-only slotd) + (error "Cannot use COMPARE-AND-SWAP with structure accessor for a read-only slot: ~S" + place)) + `(truly-the (values ,type &optional) + (%compare-and-swap-instance-ref (the ,structure ,@args) + ,index + (the ,type ,old) (the ,type ,new)))) + (error "Invalid first argument to COMPARE-AND-SWAP: ~S" place)))))))) + +(macrolet ((def (name lambda-list ref &optional set) + `(defun ,name (,@lambda-list old new) + #!+compare-and-swap-vops + (,name ,@lambda-list old new) + #!-compare-and-swap-vops + (let ((current (,ref ,@lambda-list))) + (when (eq current old) + ,(if set + `(,set ,@lambda-list new) + `(setf (,ref ,@lambda-list) new))) + current)))) + (def %compare-and-swap-car (cons) car) + (def %compare-and-swap-cdr (cons) cdr) + (def %compare-and-swap-instance-ref (instance index) %instance-ref %instance-set) + (def %compare-and-swap-symbol-plist (symbol) symbol-plist) + (def %compare-and-swap-symbol-value (symbol) symbol-value) + (def %compare-and-swap-svref (vector index) svref))