;;;----- Licensing notice ---------------------------------------------------
;;;
-;;; This file is part of the Sensble Object Design, an object system for C.
+;;; This file is part of the Sensible Object Design, an object system for C.
;;;
;;; SOD is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; along with SOD; if not, write to the Free Software Foundation,
;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
-(cl:defpackage #:sod-utilities
- (:use #:common-lisp
+(eval-when (:compile-toplevel :load-toplevel :execute)
+ (handler-bind ((warning #'muffle-warning))
+ (cl:defpackage #:sod-utilities
+ (:use #:common-lisp
- ;; MOP from somewhere.
- #+sbcl #:sb-mop
- #+(or cmu clisp) #:mop
- #+ecl #:clos))
+ ;; MOP from somewhere.
+ #+sbcl #:sb-mop
+ #+(or cmu clisp) #:mop
+ #+ecl #:clos))))
(cl:in-package #:sod-utilities)
;;;--------------------------------------------------------------------------
+;;; Common symbols.
+;;;
+;;; Sometimes, logically independent packages will want to use the same
+;;; symbol, and these uses (by careful design) don't conflict with each
+;;; other. If we export the symbols here, then the necessary sharing will
+;;; happen automatically.
+
+(export 'int) ; used by c-types and optparse
+
+;;;--------------------------------------------------------------------------
;;; Macro hacks.
(export 'with-gensyms)
form))))
(export 'once-only)
-(defmacro once-only (binds &body body)
+(defmacro once-only ((&rest binds) &body body)
"Macro helper for preventing repeated evaluation.
The syntax is actually hairier than shown:
(,bodyfunc))))))))
(export 'parse-body)
-(defun parse-body (body)
+(defun parse-body (body &key (docp t) (declp t))
"Parse the BODY into a docstring, declarations and the body forms.
These are returned as three lists, so that they can be spliced into a
macro expansion easily. The declarations are consolidated into a single
- `declare' form."
+ `declare' form. If DOCP is nil then a docstring is not permitted; if
+ DECLP is nil, then declarations are not permitted."
(let ((decls nil)
(doc nil))
(loop
(cond ((null body) (return))
- ((and (consp (car body)) (eq (caar body) 'declare))
+ ((and declp (consp (car body)) (eq (caar body) 'declare))
(setf decls (append decls (cdr (pop body)))))
- ((and (stringp (car body)) (not doc) (cdr body))
+ ((and docp (stringp (car body)) (not doc) (cdr body))
(setf doc (pop body)))
(t (return))))
(values (and doc (list doc))
body)))
;;;--------------------------------------------------------------------------
+;;; Locatives.
+
+(export '(loc locp))
+(defstruct (loc (:predicate locp) (:constructor make-loc (reader writer)))
+ "Locative data type. See `locf' and `ref'."
+ (reader nil :type function)
+ (writer nil :type function))
+
+(export 'locf)
+(defmacro locf (place &environment env)
+ "Slightly cheesy locatives.
+
+ (locf PLACE) returns an object which, using the `ref' function, can be
+ used to read or set the value of PLACE. It's cheesy because it uses
+ closures rather than actually taking the address of something. Also,
+ unlike Zetalisp, we don't overload `car' to do our dirty work."
+ (multiple-value-bind
+ (valtmps valforms newtmps setform getform)
+ (get-setf-expansion place env)
+ `(let* (,@(mapcar #'list valtmps valforms))
+ (make-loc (lambda () ,getform)
+ (lambda (,@newtmps) ,setform)))))
+
+(export 'ref)
+(declaim (inline ref (setf ref)))
+(defun ref (loc)
+ "Fetch the value referred to by a locative."
+ (funcall (loc-reader loc)))
+(defun (setf ref) (new loc)
+ "Store a new value in the place referred to by a locative."
+ (funcall (loc-writer loc) new))
+
+(export 'with-locatives)
+(defmacro with-locatives (locs &body body)
+ "Evaluate BODY with implicit locatives.
+
+ LOCS is a list of items of the form (SYM [LOC-EXPR]), where SYM is a
+ symbol and LOC-EXPR evaluates to a locative. If LOC-EXPR is omitted, it
+ defaults to SYM. As an abbreviation for a common case, LOCS may be a
+ symbol instead of a list.
+
+ The BODY is evaluated in an environment where each SYM is a symbol macro
+ which expands to (ref LOC-EXPR) -- or, in fact, something similar which
+ doesn't break if LOC-EXPR has side-effects. Thus, references, including
+ `setf' forms, fetch or modify the thing referred to by the LOC-EXPR.
+ Useful for covering over where something uses a locative."
+ (setf locs (mapcar (lambda (item)
+ (cond ((atom item) (list item item))
+ ((null (cdr item)) (list (car item) (car item)))
+ (t item)))
+ (if (listp locs) locs (list locs))))
+ (let ((tt (mapcar (lambda (l) (declare (ignore l)) (gensym)) locs))
+ (ll (mapcar #'cadr locs))
+ (ss (mapcar #'car locs)))
+ `(let (,@(mapcar (lambda (tmp loc) `(,tmp ,loc)) tt ll))
+ (symbol-macrolet (,@(mapcar (lambda (sym tmp)
+ `(,sym (ref ,tmp))) ss tt))
+ ,@body))))
+
+;;;--------------------------------------------------------------------------
;;; Anaphorics.
(export 'it)
"If COND, evaluate BODY as a progn with `it' bound to the value of COND."
`(let ((it ,cond)) (when it ,@body)))
+(export 'aand)
+(defmacro aand (&rest forms)
+ "Like `and', but anaphoric.
+
+ Each FORM except the first is evaluated with `it' bound to the value of
+ the previous one. If there are no forms, then the result it `t'; if there
+ is exactly one, then wrapping it in `aand' is pointless."
+ (labels ((doit (first rest)
+ (if (null rest)
+ first
+ `(let ((it ,first))
+ (if it ,(doit (car rest) (cdr rest)) nil)))))
+ (if (null forms)
+ 't
+ (doit (car forms) (cdr forms)))))
+
(export 'acond)
(defmacro acond (&body clauses &environment env)
"Like COND, but with `it' bound to the value of the condition.
(export 'mappend)
(defun mappend (function list &rest more-lists)
- "Like a nondestructive MAPCAN.
+ "Like a nondestructive `mapcan'.
Map FUNCTION over the the corresponding elements of LIST and MORE-LISTS,
and return the result of appending all of the resulting lists."
(reduce #'append (apply #'mapcar function list more-lists) :from-end t))
-(export '(inconsistent-merge-error merge-error-candidates))
+(export 'distinguished-point-shortest-paths)
+(defun distinguished-point-shortest-paths (root neighbours-func)
+ "Moderately efficient shortest-paths-from-root computation.
+
+ The ROOT is a distinguished vertex in a graph. The NEIGHBOURS-FUNC
+ accepts a VERTEX as its only argument, and returns a list of conses (V .
+ C) for each of the VERTEX's neighbours, indicating that there is an edge
+ from VERTEX to V, with cost C.
+
+ The return value is a list of entries (COST . REV-PATH) for each vertex
+ reachable from the ROOT; the COST is the total cost of the shortest path,
+ and REV-PATH is the path from the ROOT, in reverse order -- so the first
+ element is the vertex itself and the last element is the ROOT.
+
+ The NEIGHBOURS-FUNC is called at most N times, and may take O(N) time to
+ produce its output list. The computation as a whole takes O(N^2) time,
+ where N is the number of vertices in the graph, assuming there is at most
+ one edge between any pair of vertices."
+
+ ;; This is a listish version of Dijkstra's shortest-path algorithm. It
+ ;; could be made more efficient by using a fancy priority queue rather than
+ ;; a linear search for finding the nearest live element (see below), but it
+ ;; still runs pretty well.
+
+ (let ((map (make-hash-table))
+ (dead nil)
+ (live (list (list 0 root))))
+ (setf (gethash root map) (cons :live (car live)))
+ (loop
+ ;; The dead list contains a record, in output format (COST . PATH), for
+ ;; each vertex whose shortest path has been finally decided. The live
+ ;; list contains a record for the vertices of current interest, also in
+ ;; output format; the COST for a live record shows the best cost for a
+ ;; path using only dead vertices.
+ ;;
+ ;; Each time through here, we pull an item off the live list and
+ ;; push it onto the dead list, so we do at most N iterations total.
+
+ ;; If there are no more live items, then we're done; the remaining
+ ;; vertices, if any, are unreachable from the ROOT.
+ (when (null live) (return))
+
+ ;; Find the closest live vertex to the root. The linear scan through
+ ;; the live list costs at most N time.
+ (let* ((best (reduce (lambda (x y) (if (< (car x) (car y)) x y)) live))
+ (best-cost (car best))
+ (best-path (cdr best))
+ (best-vertex (car best-path)))
+
+ ;; Remove the chosen vertex from the LIVE list, and add the
+ ;; appropriate record to the dead list. We must have the shortest
+ ;; path to this vertex now: we have the shortest path using currently
+ ;; dead vertices; any other path must use at least one live vertex,
+ ;; and, by construction, the path through any such vertex must be
+ ;; further than the path we already have.
+ ;;
+ ;; Removal from the live list uses a linear scan which costs N time.
+ (setf live (delete best live))
+ (push best dead)
+ (setf (car (gethash best-vertex map)) :dead)
+
+ ;; Work through the chosen vertex's neighbours, adding each of them
+ ;; to the live list if they're not already there. If a neighbour is
+ ;; already live, and we find a shorter path to it through our chosen
+ ;; vertex, then update the neighbour's record.
+ ;;
+ ;; The chosen vertex obviously has at most N neighbours. There's no
+ ;; more looping in here, so performance is as claimed.
+ (dolist (neigh (funcall neighbours-func best-vertex))
+ (let* ((neigh-vertex (car neigh))
+ (neigh-cost (+ best-cost (cdr neigh)))
+ (neigh-record (gethash neigh-vertex map)))
+ (cond ((null neigh-record)
+ ;; If the neighbour isn't known, then now's the time to
+ ;; make a fresh live record for it.
+ (let ((new-record (list* :live neigh-cost
+ neigh-vertex best-path)))
+ (push (cdr new-record) live)
+ (setf (gethash neigh-vertex map) new-record)))
+ ((and (eq (car neigh-record) :live)
+ (< neigh-cost (cadr neigh-record)))
+ ;; If the neighbour is live, and we've found a better path
+ ;; to it, then update its record.
+ (setf (cadr neigh-record) neigh-cost
+ (cdddr neigh-record) best-path)))))))
+ dead))
+
+(export '(inconsistent-merge-error
+ merge-error-candidates merge-error-present-function))
(define-condition inconsistent-merge-error (error)
((candidates :initarg :candidates
- :reader merge-error-candidates))
+ :reader merge-error-candidates)
+ (present :initarg :present :initform #'identity
+ :reader merge-error-present-function))
(:documentation
- "Reports an inconsistency in the arguments passed to MERGE-LISTS.")
+ "Reports an inconsistency in the arguments passed to `merge-lists'.")
(:report (lambda (condition stream)
- (format stream "Merge inconsistency: failed to decide among ~A."
- (merge-error-candidates condition)))))
+ (format stream "Merge inconsistency: failed to decide between ~
+ ~{~#[~;~A~;~A and ~A~:;~
+ ~@{~A, ~#[~;and ~A~]~}~]~}"
+ (mapcar (merge-error-present-function condition)
+ (merge-error-candidates condition))))))
(export 'merge-lists)
-(defun merge-lists (lists &key pick (test #'eql))
+(defun merge-lists (lists &key pick (test #'eql) (present #'identity))
"Return a merge of the given LISTS.
- The resulting LIST contains the items of the given lists, with duplicates
+ The resulting list contains the items of the given LISTS, with duplicates
removed. The order of the resulting list is consistent with the orders of
the input LISTS in the sense that if A precedes B in some input list then
A will also precede B in the output list. If the lists aren't consistent
(e.g., some list contains A followed by B, and another contains B followed
- by A) then an error of type `inconsistent-merge-error' is signalled.
+ by A) then an error of type `inconsistent-merge-error' is signalled. The
+ offending items are filtered for presentation through the PRESENT function
+ before being attached to the condition, so as to produce a more useful
+ diagnostic message.
Item equality is determined by TEST.
If there is an ambiguity at any point -- i.e., a choice between two or
more possible next items to emit -- then PICK is called to arbitrate.
PICK is called with two arguments: the list of candidate next items, and
- the current output list. It should return one of the candidate items. If
- PICK is omitted then an arbitrary choice is made.
+ the current output list. It should return one of the candidate items.
+ The order of the candidates in the list given to the PICK function
+ reflects their order in the input LISTS: item A will precede item B in the
+ candidates list if and only if an occurrence of A appears in an earlier
+ input list than any occurrence of item B. (This completely determines the
+ order of the candidates: it is not possible that two candidates appear in
+ the same input list, since that would resolve the ambiguity between them.)
+ If PICK is omitted then the item chosen is the one appearing in the
+ earliest of the input lists: i.e., effectively, the default PICK function
+ is
+
+ (lambda (candidates output-so-far)
+ (declare (ignore output-so-far))
+ (car candidates))
The primary use of this function is in computing class precedence lists.
By building the input lists and selecting the PICK function appropriately,
a variety of different CPL algorithms can be implemented."
- (do* ((lb (make-list-builder)))
- ((null lists) (lbuild-list lb))
+ (do ((lb (make-list-builder)))
+ ((null lists) (lbuild-list lb))
;; The candidate items are the ones at the front of the input lists.
;; Gather them up, removing duplicates. If a candidate is somewhere in
;; one of the other lists other than at the front then we reject it. If
;; we've just rejected everything, then we can make no more progress and
;; the input lists were inconsistent.
- (let* ((candidates (delete-duplicates (mapcar #'car lists) :test test))
+ (let* ((candidates (delete-duplicates (mapcar #'car lists)
+ :test test :from-end t))
(leasts (remove-if (lambda (item)
(some (lambda (list)
(member item (cdr list) :test test))
candidates))
(winner (cond ((null leasts)
(error 'inconsistent-merge-error
- :candidates candidates))
+ :candidates candidates
+ :present present))
((null (cdr leasts))
(car leasts))
(pick
(symbol-name name) "-")))
cat-names))
(items-var (gensym "ITEMS-")))
- `(let ((,items-var ,items)
- ,@(mapcar (lambda (cat-var) (list cat-var nil)) cat-vars))
- (dolist (,itemvar ,items-var)
- (let* ,bind
- (cond ,@(mapcar (lambda (cat-match-form cat-var)
- `(,cat-match-form
- (push ,itemvar ,cat-var)))
- cat-match-forms cat-vars)
- ,@(and (not (member t cat-match-forms))
- `((t (error "Failed to categorize ~A" ,itemvar)))))))
+ `(let (,@(mapcar (lambda (cat-var) (list cat-var nil)) cat-vars))
+ (let ((,items-var ,items))
+ (dolist (,itemvar ,items-var)
+ (let* ,bind
+ (cond ,@(mapcar (lambda (cat-match-form cat-var)
+ `(,cat-match-form
+ (push ,itemvar ,cat-var)))
+ cat-match-forms cat-vars)
+ ,@(and (not (member t cat-match-forms))
+ `((t (error "Failed to categorize ~A"
+ ,itemvar))))))))
(let ,(mapcar (lambda (name var)
`(,name (nreverse ,var)))
cat-names cat-vars)
,@body))))
+(export 'partial-order-minima)
+(defun partial-order-minima (items order)
+ "Return a list of minimal items according to the non-strict partial ORDER.
+
+ The ORDER function describes the partial order: (funcall ORDER X Y) should
+ return true if X precedes or is equal to Y in the order."
+ (reduce (lambda (tops this)
+ (let ((new nil) (keep t))
+ (dolist (top tops)
+ (cond ((funcall order top this)
+ (setf keep nil)
+ (push top new))
+ ((not (funcall order this top))
+ (push top new))))
+ (nreverse (if keep (cons this new) new))))
+ items
+ :initial-value nil))
+
+(export 'find-duplicates)
+(defun find-duplicates (report sequence &key (key #'identity) (test #'eql))
+ "Call REPORT on each pair of duplicate items in SEQUENCE.
+
+ Duplicates are determined according to the KEY and TEST funcitons."
+ (when (symbolp test) (setf test (symbol-function test)))
+ (cond ((zerop (length sequence)) nil)
+ ((or (eq test #'eq)
+ (eq test #'eql)
+ (eq test #'equal)
+ (eq test #'equalp))
+ (let ((seen (make-hash-table :test test)))
+ (map nil (lambda (item)
+ (let ((k (funcall key item)))
+ (multiple-value-bind (previous matchp)
+ (gethash k seen)
+ (if matchp (funcall report item previous)
+ (setf (gethash k seen) item)))))
+ sequence)))
+ ((listp sequence)
+ (do ((tail sequence (cdr tail))
+ (i 0 (1+ i)))
+ ((endp tail))
+ (let* ((item (car tail))
+ (match (find (funcall key item) sequence
+ :test test :key key :end i)))
+ (when match (funcall report item match)))))
+ ((vectorp sequence)
+ (dotimes (i (length sequence))
+ (let* ((item (aref sequence i))
+ (pos (position (funcall key item) sequence
+ :key key :test test :end i)))
+ (when pos (funcall report item (aref sequence pos))))))
+ (t
+ (error 'type-error :datum sequence :expected-type 'sequence))))
+
;;;--------------------------------------------------------------------------
;;; Strings and characters.
;;; Functions.
(export 'compose)
-(defun compose (function &rest more-functions)
+(defun compose (&rest functions)
"Composition of functions. Functions are applied left-to-right.
This is the reverse order of the usual mathematical notation, but I find
(labels ((compose1 (func-a func-b)
(lambda (&rest args)
(multiple-value-call func-b (apply func-a args)))))
- (reduce #'compose1 more-functions :initial-value function)))
+ (if (null functions) #'values
+ (reduce #'compose1 (cdr functions)
+ :initial-value (car functions)))))
+
+;;;--------------------------------------------------------------------------
+;;; Variables.
+
+(export 'defvar-unbound)
+(defmacro defvar-unbound (var doc)
+ "Make VAR a special variable with documentation DOC, but leave it unbound."
+ `(eval-when (:compile-toplevel :load-toplevel :execute)
+ (defvar ,var)
+ (setf (documentation ',var 'variable) ',doc)
+ ',var))
;;;--------------------------------------------------------------------------
;;; Symbols.
(,print))
(,print)))))
+(export 'print-ugly-stuff)
+(defun print-ugly-stuff (stream func)
+ "Print not-pretty things to the stream underlying STREAM.
+
+ The Lisp pretty-printing machinery, notably `pprint-logical-block', may
+ interpose additional streams between its body and the original target
+ stream. This makes it difficult to make use of the underlying stream's
+ special features, whatever they might be."
+
+ ;; This is unpleasant. Hacky hacky.
+ #.(or #+sbcl '(if (typep stream 'sb-pretty:pretty-stream)
+ (let ((target (sb-pretty::pretty-stream-target stream)))
+ (pprint-newline :mandatory stream)
+ (funcall func target))
+ (funcall func stream))
+ #+cmu '(if (typep stream 'pp:pretty-stream)
+ (let ((target (pp::pretty-stream-target stream)))
+ (pprint-newline :mandatory stream)
+ (funcall func target))
+ (funcall func stream))
+ '(funcall func stream)))
+
;;;--------------------------------------------------------------------------
;;; Iteration macros.
The loop is surrounded by an anonymous BLOCK and the loop body forms an
implicit TAGBODY, as is usual. There is no result-form, however."
- (once-only (:environment env seq start end)
- (with-gensyms ((ivar "INDEX-") (endvar "END-") (bodyfunc "BODY-"))
-
- (flet ((loopguts (indexp listp endvar)
- ;; Build a DO-loop to do what we want.
- (let* ((do-vars nil)
- (end-condition (if endvar
- `(>= ,ivar ,endvar)
- `(endp ,seq)))
- (item (if listp
- `(car ,seq)
- `(aref ,seq ,ivar)))
- (body-call `(,bodyfunc ,item)))
- (when listp
- (push `(,seq (nthcdr ,start ,seq) (cdr ,seq))
- do-vars))
- (when indexp
- (push `(,ivar ,start (1+ ,ivar)) do-vars))
- (when indexvar
- (setf body-call (append body-call (list ivar))))
- `(do ,do-vars (,end-condition) ,body-call))))
-
- `(block nil
- (flet ((,bodyfunc (,var ,@(and indexvar `(,indexvar)))
- (tagbody ,@body)))
- (etypecase ,seq
- (vector
- (let ((,endvar (or ,end (length ,seq))))
- ,(loopguts t nil endvar)))
- (list
- (if ,end
- ,(loopguts t t end)
- ,(loopguts indexvar t nil))))))))))
+ (once-only (:environment env start end)
+ (with-gensyms ((seqvar "SEQ-") (ivar "INDEX-")
+ (endvar "END-") (bodyfunc "BODY-"))
+ (multiple-value-bind (docs decls body) (parse-body body :docp nil)
+ (declare (ignore docs))
+
+ (flet ((loopguts (indexp listp endvar)
+ ;; Build a DO-loop to do what we want.
+ (let* ((do-vars nil)
+ (end-condition (if endvar
+ `(>= ,ivar ,endvar)
+ `(endp ,seqvar)))
+ (item (if listp
+ `(car ,seqvar)
+ `(aref ,seqvar ,ivar)))
+ (body-call `(,bodyfunc ,item)))
+ (when listp
+ (push `(,seqvar (nthcdr ,start ,seqvar) (cdr ,seqvar))
+ do-vars))
+ (when indexp
+ (push `(,ivar ,start (1+ ,ivar)) do-vars))
+ (when indexvar
+ (setf body-call (append body-call (list ivar))))
+ `(do ,do-vars (,end-condition) ,body-call))))
+
+ `(block nil
+ (let ((,seqvar ,seq))
+ (flet ((,bodyfunc (,var ,@(and indexvar `(,indexvar)))
+ ,@decls
+ (tagbody ,@body)))
+ (etypecase ,seqvar
+ (vector
+ (let ((,endvar (or ,end (length ,seqvar))))
+ ,(loopguts t nil endvar)))
+ (list
+ (if ,end
+ ,(loopguts t t end)
+ ,(loopguts indexvar t nil))))))))))))
;;;--------------------------------------------------------------------------
;;; Structure accessor hacks.
`((defun (setf ,from) (value object)
(setf (,to object) value))))))
-(export 'define-on-demand-slot)
-(defmacro define-on-demand-slot (class slot (instance) &body body)
- "Defines a slot which computes its initial value on demand.
+;;;--------------------------------------------------------------------------
+;;; Condition and error utilities.
+
+(export 'designated-condition)
+(defun designated-condition (default-type datum arguments
+ &key allow-pointless-arguments)
+ "Return the condition designated by DATUM and ARGUMENTS.
+
+ DATUM and ARGUMENTS together are a `condition designator' of (some
+ supertype of) DEFAULT-TYPE; return the condition so designated."
+ (typecase datum
+ (condition
+ (unless (or allow-pointless-arguments (null arguments))
+ (error "Argument list provided with specific condition"))
+ datum)
+ (symbol
+ (apply #'make-condition datum arguments))
+ ((or string function)
+ (make-condition default-type
+ :format-control datum
+ :format-arguments arguments))
+ (t
+ (error "Unexpected condition designator datum ~S" datum))))
+
+(export 'simple-control-error)
+(define-condition simple-control-error (control-error simple-error)
+ ())
+
+(export 'invoke-associated-restart)
+(defun invoke-associated-restart (restart condition &rest arguments)
+ "Invoke the active RESTART associated with CONDITION, with the ARGUMENTS.
+
+ Find an active restart designated by RESTART; if CONDITION is not nil,
+ then restrict the search to restarts associated with CONDITION, and
+ restarts not associated with any condition. If no such restart is found
+ then signal an error of type `control-error'; otherwise invoke the restart
+ with the given ARGUMENTS."
+ (apply #'invoke-restart
+ (or (find-restart restart condition)
+ (error 'simple-control-error
+ :format-control "~:[Restart ~S is not active~;~
+ No active `~(~A~)' restart~]~
+ ~@[ for condition ~S~]"
+ :format-arguments (list (symbolp restart)
+ restart
+ condition)))
+ arguments))
+
+(export '(enclosing-condition enclosed-condition))
+(define-condition enclosing-condition (condition)
+ ((%enclosed-condition :initarg :condition :type condition
+ :reader enclosed-condition))
+ (:documentation
+ "A condition which encloses another condition
- Sets up the named SLOT of CLASS to establish its value as the implicit
- progn BODY, by defining an appropriate method on `slot-unbound'."
- (with-gensyms (classvar slotvar)
- `(defmethod slot-unbound
- (,classvar (,instance ,class) (,slotvar (eql ',slot)))
- (declare (ignore ,classvar))
- (setf (slot-value ,instance ',slot) (progn ,@body)))))
+ This is useful if one wants to attach additional information to an
+ existing condition. The enclosed condition can be obtained using the
+ `enclosed-condition' function.")
+ (:report (lambda (condition stream)
+ (princ (enclosed-condition condition) stream))))
+
+(export 'information)
+(define-condition information (condition)
+ ())
+
+(export 'simple-information)
+(define-condition simple-information (simple-condition information)
+ ())
+
+(export 'info)
+(defun info (datum &rest arguments)
+ "Report some useful diagnostic information.
+
+ Establish a simple restart named `noted', and signal the condition of type
+ `information' designated by DATUM and ARGUMENTS. Return non-nil if the
+ restart was invoked, otherwise nil."
+ (restart-case
+ (signal (designated-condition 'simple-information datum arguments))
+ (noted () :report "Noted." t)))
+
+(export 'noted)
+(defun noted (&optional condition)
+ "Invoke the `noted' restart, possibly associated with the given CONDITION."
+ (invoke-associated-restart 'noted condition))
+
+(export 'promiscuous-cerror)
+(defun promiscuous-cerror (continue-string datum &rest arguments)
+ "Like standard `cerror', but robust against sneaky changes of conditions.
+
+ It seems that `cerror' (well, at least the version in SBCL) is careful
+ to limit its restart to the specific condition it signalled. But that's
+ annoying, because `sod-parser:with-default-error-location' substitutes
+ different conditions carrying the error-location information."
+ (restart-case (apply #'error datum arguments)
+ (continue ()
+ :report (lambda (stream)
+ (apply #'format stream continue-string datum arguments))
+ nil)))
+
+(export 'cerror*)
+(defun cerror* (datum &rest arguments)
+ (apply #'promiscuous-cerror "Continue" datum arguments))
;;;--------------------------------------------------------------------------
;;; CLOS hacking.
(setf (slot-value ,instance ,slot)
(progn ,@value)))))
+(export 'define-on-demand-slot)
+(defmacro define-on-demand-slot (class slot (instance) &body body)
+ "Defines a slot which computes its initial value on demand.
+
+ Sets up the named SLOT of CLASS to establish its value as the implicit
+ progn BODY, by defining an appropriate method on `slot-unbound'."
+ (multiple-value-bind (docs decls body) (parse-body body)
+ (with-gensyms (classvar slotvar)
+ `(defmethod slot-unbound
+ (,classvar (,instance ,class) (,slotvar (eql ',slot)))
+ ,@docs ,@decls
+ (declare (ignore ,classvar))
+ (setf (slot-value ,instance ',slot) (block ,slot ,@body))))))
+
;;;----- That's all, folks --------------------------------------------------
~mdw / sod / blobdiff