3 ;;; Various handy utilities
5 ;;; (c) 2009 Straylight/Edgeware
8 ;;;----- Licensing notice ---------------------------------------------------
10 ;;; This file is part of the Sensible Object Design, an object system for C.
12 ;;; SOD is free software; you can redistribute it and/or modify
13 ;;; it under the terms of the GNU General Public License as published by
14 ;;; the Free Software Foundation; either version 2 of the License, or
15 ;;; (at your option) any later version.
17 ;;; SOD is distributed in the hope that it will be useful,
18 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;;; GNU General Public License for more details.
22 ;;; You should have received a copy of the GNU General Public License
23 ;;; along with SOD; if not, write to the Free Software Foundation,
24 ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
26 (cl:defpackage #:sod-utilities
29 ;; MOP from somewhere.
31 #+(or cmu clisp) #:mop
34 (cl:in-package #:sod-utilities)
36 ;;;--------------------------------------------------------------------------
39 ;;; Sometimes, logically independent packages will want to use the same
40 ;;; symbol, and these uses (by careful design) don't conflict with each
41 ;;; other. If we export the symbols here, then the necessary sharing will
42 ;;; happen automatically.
44 (export 'int) ; used by c-types and optparse
46 ;;;--------------------------------------------------------------------------
49 (export 'with-gensyms)
50 (defmacro with-gensyms ((&rest binds) &body body)
51 "Evaluate BODY with variables bound to fresh symbols.
53 The BINDS are a list of entries (VAR [NAME]), and a singleton list can be
54 replaced by just a symbol; each VAR is bound to a fresh symbol generated
55 by (gensym NAME), where NAME defaults to the symbol-name of VAR."
56 `(let (,@(mapcar (lambda (bind)
57 (multiple-value-bind (var name)
59 (values bind (concatenate 'string
60 (symbol-name bind) "-"))
63 (name (concatenate 'string
64 (symbol-name var) "-")))
67 `(,var (gensym ,name))))
71 (eval-when (:compile-toplevel :load-toplevel :execute)
72 (defun strip-quote (form)
73 "If FORM looks like (quote FOO) for self-evaluating FOO, return FOO.
75 If FORM is a symbol whose constant value is `nil' then return `nil'.
76 Otherwise return FORM unchanged. This makes it easier to inspect constant
77 things. This is a utility for `once-only'."
79 (cond ((and (consp form)
80 (eq (car form) 'quote)
83 (let ((body (cadr form)))
84 (if (or (not (or (consp body) (symbolp body)))
85 (member body '(t nil))
89 ((and (symbolp form) (boundp form) (null (symbol-value form)))
95 (defmacro once-only ((&rest binds) &body body)
96 "Macro helper for preventing repeated evaluation.
98 The syntax is actually hairier than shown:
100 once-only ( [[ :environment ENV ]] { VAR | (VAR [VALUE-FORM]) }* )
103 So, the BINDS are a list of entries (VAR [VALUE-FORM]); a singleton list
104 can be replaced by just a symbol VAR, and the VALUE-FORM defaults to VAR.
105 But before them you can have keyword arguments. Only one is defined so
106 far. See below for the crazy things that does.
108 The result of evaluating a ONCE-ONLY form is a form with the structure
110 (let ((#:GS1 VALUE-FORM1)
115 where STUFF is the value of the BODY forms, as an implicit progn, in an
116 environment with the VARs bound to the corresponding gensyms.
118 As additional magic, if any of the VALUE-FORMs is actually constant (as
119 determined by inspection, and aided by `constantp' if an :environment is
120 supplied, then no gensym is constructed for it, and the VAR is bound
121 directly to the constant form. Moreover, if the constant form looks like
122 (quote FOO) for a self-evaluating FOO then the outer layer of quoting is
125 ;; We need an extra layer of gensyms in our expansion: we'll want the
126 ;; expansion to examine the various VALUE-FORMs to find out whether they're
127 ;; constant without evaluating them repeatedly. This also helps with
128 ;; another problem: we explicitly encourage the rebinding of a VAR
129 ;; (probably a macro argument) to a gensym which will be bound to the value
130 ;; of the form previously held in VAR itself -- so the gensym and value
131 ;; form must exist at the same time and we need two distinct variables.
133 (with-gensyms ((envvar "ENV-") lets sym (bodyfunc "BODY-"))
136 ;; First things first: let's pick up the keywords.
138 (unless (and binds (keywordp (car binds)))
141 (:environment (setf env (pop binds)))))
143 ;; Now we'll investigate the bindings. Turn each one into a list (VAR
144 ;; VALUE-FORM TEMP) where TEMP is an appropriate gensym -- see the note
146 (let ((canon (mapcar (lambda (bind)
147 (multiple-value-bind (var form)
151 (var &optional (form var)) bind
154 (gensym (format nil "T-~A-"
155 (symbol-name var))))))
158 `(let* (,@(and env `((,envvar ,env)))
160 ,@(mapcar (lambda (bind)
161 (destructuring-bind (var form temp) bind
162 (declare (ignore var))
165 ,@(mapcar (lambda (bind)
166 (destructuring-bind (var form temp) bind
167 (declare (ignore form))
169 (cond ((constantp ,temp
170 ,@(and env `(,envvar)))
176 ,(concatenate 'string
179 (push (list ,sym ,temp) ,lets)
182 (flet ((,bodyfunc () ,@body))
184 `(let (,@(nreverse ,lets)) ,(,bodyfunc))
188 (defun parse-body (body &key (docp t) (declp t))
189 "Parse the BODY into a docstring, declarations and the body forms.
191 These are returned as three lists, so that they can be spliced into a
192 macro expansion easily. The declarations are consolidated into a single
193 `declare' form. If DOCP is nil then a docstring is not permitted; if
194 DECLP is nil, then declarations are not permitted."
198 (cond ((null body) (return))
199 ((and declp (consp (car body)) (eq (caar body) 'declare))
200 (setf decls (append decls (cdr (pop body)))))
201 ((and docp (stringp (car body)) (not doc) (cdr body))
202 (setf doc (pop body)))
204 (values (and doc (list doc))
205 (and decls (list (cons 'declare decls)))
208 ;;;--------------------------------------------------------------------------
212 (defstruct (loc (:predicate locp) (:constructor make-loc (reader writer)))
213 "Locative data type. See `locf' and `ref'."
214 (reader nil :type function)
215 (writer nil :type function))
218 (defmacro locf (place &environment env)
219 "Slightly cheesy locatives.
221 (locf PLACE) returns an object which, using the `ref' function, can be
222 used to read or set the value of PLACE. It's cheesy because it uses
223 closures rather than actually taking the address of something. Also,
224 unlike Zetalisp, we don't overload `car' to do our dirty work."
226 (valtmps valforms newtmps setform getform)
227 (get-setf-expansion place env)
228 `(let* (,@(mapcar #'list valtmps valforms))
229 (make-loc (lambda () ,getform)
230 (lambda (,@newtmps) ,setform)))))
233 (declaim (inline ref (setf ref)))
235 "Fetch the value referred to by a locative."
236 (funcall (loc-reader loc)))
237 (defun (setf ref) (new loc)
238 "Store a new value in the place referred to by a locative."
239 (funcall (loc-writer loc) new))
241 (export 'with-locatives)
242 (defmacro with-locatives (locs &body body)
243 "Evaluate BODY with implicit locatives.
245 LOCS is a list of items of the form (SYM [LOC-EXPR]), where SYM is a
246 symbol and LOC-EXPR evaluates to a locative. If LOC-EXPR is omitted, it
247 defaults to SYM. As an abbreviation for a common case, LOCS may be a
248 symbol instead of a list.
250 The BODY is evaluated in an environment where each SYM is a symbol macro
251 which expands to (ref LOC-EXPR) -- or, in fact, something similar which
252 doesn't break if LOC-EXPR has side-effects. Thus, references, including
253 `setf' forms, fetch or modify the thing referred to by the LOC-EXPR.
254 Useful for covering over where something uses a locative."
255 (setf locs (mapcar (lambda (item)
256 (cond ((atom item) (list item item))
257 ((null (cdr item)) (list (car item) (car item)))
259 (if (listp locs) locs (list locs))))
260 (let ((tt (mapcar (lambda (l) (declare (ignore l)) (gensym)) locs))
261 (ll (mapcar #'cadr locs))
262 (ss (mapcar #'car locs)))
263 `(let (,@(mapcar (lambda (tmp loc) `(,tmp ,loc)) tt ll))
264 (symbol-macrolet (,@(mapcar (lambda (sym tmp)
265 `(,sym (ref ,tmp))) ss tt))
268 ;;;--------------------------------------------------------------------------
274 (defmacro aif (cond cons &optional (alt nil altp))
275 "If COND is not nil, evaluate CONS with `it' bound to the value of COND.
277 Otherwise, if given, evaluate ALT; `it' isn't bound in ALT."
279 `(if ,cond (let ((it ,cond)) ,cons) ,@(and altp `(,alt)))))
282 (defmacro awhen (cond &body body)
283 "If COND, evaluate BODY as a progn with `it' bound to the value of COND."
284 `(let ((it ,cond)) (when it ,@body)))
287 (defmacro aand (&rest forms)
288 "Like `and', but anaphoric.
290 Each FORM except the first is evaluated with `it' bound to the value of
291 the previous one. If there are no forms, then the result it `t'; if there
292 is exactly one, then wrapping it in `aand' is pointless."
293 (labels ((doit (first rest)
297 (if it ,(doit (car rest) (cdr rest)) nil)))))
300 (doit (car forms) (cdr forms)))))
303 (defmacro acond (&body clauses &environment env)
304 "Like COND, but with `it' bound to the value of the condition.
306 Each of the CLAUSES has the form (CONDITION FORM*); if a CONDITION is
307 non-nil then evaluate the FORMs with `it' bound to the non-nil value, and
308 return the value of the last FORM; if there are no FORMs, then return `it'
309 itself. If the CONDITION is nil then continue with the next clause; if
310 all clauses evaluate to nil then the result is nil."
311 (labels ((walk (clauses)
314 (once-only (:environment env (cond (caar clauses)))
315 (if (and (constantp cond)
316 (if (and (consp cond) (eq (car cond) 'quote))
320 (declare (ignorable it))
326 (declare (ignorable it))
329 ,(walk (cdr clauses))))))))
332 (export '(acase aecase atypecase aetypecase))
333 (defmacro acase (value &body clauses)
334 `(let ((it ,value)) (case it ,@clauses)))
335 (defmacro aecase (value &body clauses)
336 `(let ((it ,value)) (ecase it ,@clauses)))
337 (defmacro atypecase (value &body clauses)
338 `(let ((it ,value)) (typecase it ,@clauses)))
339 (defmacro aetypecase (value &body clauses)
340 `(let ((it ,value)) (etypecase it ,@clauses)))
343 (defmacro asetf (&rest places-and-values &environment env)
344 "Anaphoric update of places.
346 The PLACES-AND-VALUES are alternating PLACEs and VALUEs. Each VALUE is
347 evaluated with IT bound to the current value stored in the corresponding
349 `(progn ,@(loop for (place value) on places-and-values by #'cddr
350 collect (multiple-value-bind
351 (temps inits newtemps setform getform)
352 (get-setf-expansion place env)
353 `(let* (,@(mapcar #'list temps inits)
355 (multiple-value-bind ,newtemps ,value
358 ;;;--------------------------------------------------------------------------
359 ;;; MOP hacks (not terribly demanding).
361 (export 'instance-initargs)
362 (defgeneric instance-initargs (instance)
364 "Return a plausble list of initargs for INSTANCE.
366 The idea is that you can make a copy of INSTANCE by invoking
368 (apply #'make-instance (class-of INSTANCE)
369 (instance-initargs INSTANCE))
371 The default implementation works by inspecting the slot definitions and
372 extracting suitable initargs, so this will only succeed if enough slots
373 actually have initargs specified that `initialize-instance' can fill in
376 The list returned is freshly consed, and you can destroy it if you like.")
377 (:method ((instance standard-object))
378 (mapcan (lambda (slot)
379 (aif (slot-definition-initargs slot)
381 (slot-value instance (slot-definition-name slot)))
383 (class-slots (class-of instance)))))
385 (export '(copy-instance copy-instance-using-class))
386 (defgeneric copy-instance-using-class (class instance &rest initargs)
388 "Metaobject protocol hook for `copy-instance'.")
389 (:method ((class standard-class) instance &rest initargs)
390 (let ((copy (allocate-instance class)))
391 (dolist (slot (class-slots class))
392 (let ((name (slot-definition-name slot)))
393 (when (slot-boundp instance name)
394 (setf (slot-value copy name) (slot-value instance name)))))
395 (apply #'shared-initialize copy nil initargs))))
396 (defun copy-instance (object &rest initargs)
397 "Construct and return a copy of OBJECT.
399 The new object has the same class as OBJECT, and the same slot values
400 except where overridden by INITARGS."
401 (apply #'copy-instance-using-class (class-of object) object initargs))
403 (export '(generic-function-methods method-specializers
404 eql-specializer eql-specializer-object))
406 ;;;--------------------------------------------------------------------------
409 (export 'make-list-builder)
410 (defun make-list-builder (&optional initial)
411 "Return a simple list builder."
413 ;; The `builder' is just a cons cell whose cdr will be the list that's
414 ;; wanted. Effectively, then, we have a list that's one item longer than
415 ;; we actually want. The car of this extra initial cons cell is always the
416 ;; last cons in the list -- which is now well defined because there's
417 ;; always at least one.
419 (let ((builder (cons nil initial)))
420 (setf (car builder) (last builder))
424 (defun lbuild-add (builder item)
425 "Add an ITEM to the end of a list BUILDER."
426 (let ((new (cons item nil)))
427 (setf (cdar builder) new
431 (export 'lbuild-add-list)
432 (defun lbuild-add-list (builder list)
433 "Add a LIST to the end of a list BUILDER. The LIST will be clobbered."
435 (setf (cdar builder) list
436 (car builder) (last list)))
439 (export 'lbuild-list)
440 (defun lbuild-list (builder)
441 "Return the constructed list."
445 (defun mappend (function list &rest more-lists)
446 "Like a nondestructive `mapcan'.
448 Map FUNCTION over the the corresponding elements of LIST and MORE-LISTS,
449 and return the result of appending all of the resulting lists."
450 (reduce #'append (apply #'mapcar function list more-lists) :from-end t))
452 (export 'distinguished-point-shortest-paths)
453 (defun distinguished-point-shortest-paths (root neighbours-func)
454 "Moderately efficient shortest-paths-from-root computation.
456 The ROOT is a distinguished vertex in a graph. The NEIGHBOURS-FUNC
457 accepts a VERTEX as its only argument, and returns a list of conses (V .
458 C) for each of the VERTEX's neighbours, indicating that there is an edge
459 from VERTEX to V, with cost C.
461 The return value is a list of entries (COST . REV-PATH) for each vertex
462 reachable from the ROOT; the COST is the total cost of the shortest path,
463 and REV-PATH is the path from the ROOT, in reverse order -- so the first
464 element is the vertex itself and the last element is the ROOT.
466 The NEIGHBOURS-FUNC is called at most N times, and may take O(N) time to
467 produce its output list. The computation as a whole takes O(N^2) time,
468 where N is the number of vertices in the graph, assuming there is at most
469 one edge between any pair of vertices."
471 ;; This is a listish version of Dijkstra's shortest-path algorithm. It
472 ;; could be made more efficient by using a fancy priority queue rather than
473 ;; a linear search for finding the nearest live element (see below), but it
474 ;; still runs pretty well.
476 (let ((map (make-hash-table))
478 (live (list (list 0 root))))
479 (setf (gethash root map) (cons :live (car live)))
481 ;; The dead list contains a record, in output format (COST . PATH), for
482 ;; each vertex whose shortest path has been finally decided. The live
483 ;; list contains a record for the vertices of current interest, also in
484 ;; output format; the COST for a live record shows the best cost for a
485 ;; path using only dead vertices.
487 ;; Each time through here, we pull an item off the live list and
488 ;; push it onto the dead list, so we do at most N iterations total.
490 ;; If there are no more live items, then we're done; the remaining
491 ;; vertices, if any, are unreachable from the ROOT.
492 (when (null live) (return))
494 ;; Find the closest live vertex to the root. The linear scan through
495 ;; the live list costs at most N time.
496 (let* ((best (reduce (lambda (x y) (if (< (car x) (car y)) x y)) live))
497 (best-cost (car best))
498 (best-path (cdr best))
499 (best-vertex (car best-path)))
501 ;; Remove the chosen vertex from the LIVE list, and add the
502 ;; appropriate record to the dead list. We must have the shortest
503 ;; path to this vertex now: we have the shortest path using currently
504 ;; dead vertices; any other path must use at least one live vertex,
505 ;; and, by construction, the path through any such vertex must be
506 ;; further than the path we already have.
508 ;; Removal from the live list uses a linear scan which costs N time.
509 (setf live (delete best live))
511 (setf (car (gethash best-vertex map)) :dead)
513 ;; Work through the chosen vertex's neighbours, adding each of them
514 ;; to the live list if they're not already there. If a neighbour is
515 ;; already live, and we find a shorter path to it through our chosen
516 ;; vertex, then update the neighbour's record.
518 ;; The chosen vertex obviously has at most N neighbours. There's no
519 ;; more looping in here, so performance is as claimed.
520 (dolist (neigh (funcall neighbours-func best-vertex))
521 (let* ((neigh-vertex (car neigh))
522 (neigh-cost (+ best-cost (cdr neigh)))
523 (neigh-record (gethash neigh-vertex map)))
524 (cond ((null neigh-record)
525 ;; If the neighbour isn't known, then now's the time to
526 ;; make a fresh live record for it.
527 (let ((new-record (list* :live neigh-cost
528 neigh-vertex best-path)))
529 (push (cdr new-record) live)
530 (setf (gethash neigh-vertex map) new-record)))
531 ((and (eq (car neigh-record) :live)
532 (< neigh-cost (cadr neigh-record)))
533 ;; If the neighbour is live, and we've found a better path
534 ;; to it, then update its record.
535 (setf (cadr neigh-record) neigh-cost
536 (cdddr neigh-record) best-path)))))))
539 (export '(inconsistent-merge-error
540 merge-error-candidates merge-error-present-function))
541 (define-condition inconsistent-merge-error (error)
542 ((candidates :initarg :candidates
543 :reader merge-error-candidates)
544 (present :initarg :present :initform #'identity
545 :reader merge-error-present-function))
547 "Reports an inconsistency in the arguments passed to `merge-lists'.")
548 (:report (lambda (condition stream)
549 (format stream "Merge inconsistency: failed to decide between ~
550 ~{~#[~;~A~;~A and ~A~:;~
551 ~@{~A, ~#[~;and ~A~]~}~]~}"
552 (mapcar (merge-error-present-function condition)
553 (merge-error-candidates condition))))))
555 (export 'merge-lists)
556 (defun merge-lists (lists &key pick (test #'eql) (present #'identity))
557 "Return a merge of the given LISTS.
559 The resulting list contains the items of the given LISTS, with duplicates
560 removed. The order of the resulting list is consistent with the orders of
561 the input LISTS in the sense that if A precedes B in some input list then
562 A will also precede B in the output list. If the lists aren't consistent
563 (e.g., some list contains A followed by B, and another contains B followed
564 by A) then an error of type `inconsistent-merge-error' is signalled. The
565 offending items are filtered for presentation through the PRESENT function
566 before being attached to the condition, so as to produce a more useful
569 Item equality is determined by TEST.
571 If there is an ambiguity at any point -- i.e., a choice between two or
572 more possible next items to emit -- then PICK is called to arbitrate.
573 PICK is called with two arguments: the list of candidate next items, and
574 the current output list. It should return one of the candidate items.
575 The order of the candidates in the list given to the PICK function
576 reflects their order in the input LISTS: item A will precede item B in the
577 candidates list if and only if an occurrence of A appears in an earlier
578 input list than any occurrence of item B. (This completely determines the
579 order of the candidates: it is not possible that two candidates appear in
580 the same input list, since that would resolve the ambiguity between them.)
581 If PICK is omitted then the item chosen is the one appearing in the
582 earliest of the input lists: i.e., effectively, the default PICK function
585 (lambda (candidates output-so-far)
586 (declare (ignore output-so-far))
589 The primary use of this function is in computing class precedence lists.
590 By building the input lists and selecting the PICK function appropriately,
591 a variety of different CPL algorithms can be implemented."
593 (do ((lb (make-list-builder)))
594 ((null lists) (lbuild-list lb))
596 ;; The candidate items are the ones at the front of the input lists.
597 ;; Gather them up, removing duplicates. If a candidate is somewhere in
598 ;; one of the other lists other than at the front then we reject it. If
599 ;; we've just rejected everything, then we can make no more progress and
600 ;; the input lists were inconsistent.
601 (let* ((candidates (delete-duplicates (mapcar #'car lists)
602 :test test :from-end t))
603 (leasts (remove-if (lambda (item)
605 (member item (cdr list) :test test))
608 (winner (cond ((null leasts)
609 (error 'inconsistent-merge-error
610 :candidates candidates
615 (funcall pick leasts (lbuild-list lb)))
618 ;; Check that the PICK function isn't conning us.
619 (assert (member winner leasts :test test))
621 ;; Update the output list and remove the winning item from the input
622 ;; lists. We know that it must be at the front of each input list
623 ;; containing it. At this point, we discard input lists entirely when
624 ;; they run out of entries. The loop ends when there are no more input
625 ;; lists left, i.e., when we've munched all of the input items.
626 (lbuild-add lb winner)
627 (setf lists (delete nil (mapcar (lambda (list)
628 (if (funcall test winner (car list))
634 (defmacro categorize ((itemvar items &key bind) categories &body body)
635 "Categorize ITEMS into lists and invoke BODY.
637 The ITEMVAR is a symbol; as the macro iterates over the ITEMS, ITEMVAR
638 will contain the current item. The BIND argument is a list of LET*-like
639 clauses. The CATEGORIES are a list of clauses of the form (SYMBOL
642 The behaviour of the macro is as follows. ITEMVAR is assigned (not
643 bound), in turn, each item in the list ITEMS. The PREDICATEs in the
644 CATEGORIES list are evaluated in turn, in an environment containing
645 ITEMVAR and the BINDings, until one of them evaluates to a non-nil value.
646 At this point, the item is assigned to the category named by the
647 corresponding SYMBOL. If none of the PREDICATEs returns non-nil then an
648 error is signalled; a PREDICATE consisting only of T will (of course)
649 match anything; it is detected specially so as to avoid compiler warnings.
651 Once all of the ITEMS have been categorized in this fashion, the BODY is
652 evaluated as an implicit PROGN. For each SYMBOL naming a category, a
653 variable named after that symbol will be bound in the BODY's environment
654 to a list of the items in that category, in the same order in which they
655 were found in the list ITEMS. The final values of the macro are the final
658 (let* ((cat-names (mapcar #'car categories))
659 (cat-match-forms (mapcar #'cadr categories))
660 (cat-vars (mapcar (lambda (name) (gensym (concatenate 'string
661 (symbol-name name) "-")))
663 (items-var (gensym "ITEMS-")))
664 `(let (,@(mapcar (lambda (cat-var) (list cat-var nil)) cat-vars))
665 (let ((,items-var ,items))
666 (dolist (,itemvar ,items-var)
668 (cond ,@(mapcar (lambda (cat-match-form cat-var)
670 (push ,itemvar ,cat-var)))
671 cat-match-forms cat-vars)
672 ,@(and (not (member t cat-match-forms))
673 `((t (error "Failed to categorize ~A"
675 (let ,(mapcar (lambda (name var)
676 `(,name (nreverse ,var)))
680 (export 'partial-order-minima)
681 (defun partial-order-minima (items order)
682 "Return a list of minimal items according to the non-strict partial ORDER.
684 The ORDER function describes the partial order: (funcall ORDER X Y) should
685 return true if X precedes or is equal to Y in the order."
686 (reduce (lambda (tops this)
687 (let ((new nil) (keep t))
689 (cond ((funcall order top this)
692 ((not (funcall order this top))
694 (nreverse (if keep (cons this new) new))))
698 (export 'find-duplicates)
699 (defun find-duplicates (report sequence &key (key #'identity) (test #'eql))
700 "Call REPORT on each pair of duplicate items in SEQUENCE.
702 Duplicates are determined according to the KEY and TEST funcitons."
703 (when (symbolp test) (setf test (symbol-function test)))
704 (cond ((zerop (length sequence)) nil)
709 (let ((seen (make-hash-table :test test)))
710 (map nil (lambda (item)
711 (let ((k (funcall key item)))
712 (multiple-value-bind (previous matchp)
714 (if matchp (funcall report item previous)
715 (setf (gethash k seen) item)))))
719 (let* ((item (car tail))
721 (match (member (funcall key item) rest
722 :test test :key key)))
723 (when match (funcall report item (car match)))))
726 (dotimes (i (length sequence))
727 (let* ((item (aref sequence i))
728 (pos (position (funcall key item) sequence
729 :key key :test test :start (1+ i))))
730 (when pos (funcall report item (aref sequence pos))))))
732 (error 'type-error :datum sequence :expected-type 'sequence))))
734 ;;;--------------------------------------------------------------------------
735 ;;; Strings and characters.
737 (export 'frob-identifier)
738 (defun frob-identifier (string &key (swap-case t) (swap-hyphen t))
739 "Twiddles the case of STRING.
741 If all the letters in STRING are uppercase, and SWAP-CASE is true, then
742 switch them to lowercase; if they're all lowercase then switch them to
743 uppercase. If there's a mix then leave them all alone. At the same time,
744 if there are underscores but no hyphens, and SWAP-HYPHEN is true, then
745 switch them to hyphens, if there are hyphens and no underscores, switch
746 them underscores, and if there are both then leave them alone.
748 This is an invertible transformation, which turns vaguely plausible Lisp
749 names into vaguely plausible C names and vice versa. Lisp names with
750 `funny characters' like stars and percent signs won't be any use, of
753 ;; Work out what kind of a job we've got to do. Gather flags: bit 0 means
754 ;; there are upper-case letters; bit 1 means there are lower-case letters;
755 ;; bit 2 means there are hyphens; bit 3 means there are underscores.
757 ;; Consequently, (logxor flags (ash flags 1)) is interesting: bit 1 is set
758 ;; if we have to frob case; bit 3 is set if we have to swap hyphens and
759 ;; underscores. So use this to select functions which do bits of the
760 ;; mapping, and then compose them together.
761 (let* ((flags (reduce (lambda (state ch)
763 (cond ((upper-case-p ch) 1)
764 ((lower-case-p ch) 2)
770 (mask (logxor flags (ash flags 1)))
771 (letter (cond ((or (not swap-case) (not (logbitp 1 mask)))
775 (and (alpha-char-p ch) (char-downcase ch))))
778 (and (alpha-char-p ch) (char-upcase ch))))))
779 (uscore-hyphen (cond ((or (not (logbitp 3 mask)) (not swap-hyphen))
782 (lambda (ch) (and (char= ch #\-) #\_)))
784 (lambda (ch) (and (char= ch #\_) #\-))))))
786 (if (logbitp 3 (logior mask (ash mask 2)))
787 (map 'string (lambda (ch)
788 (or (funcall letter ch)
789 (funcall uscore-hyphen ch)
794 (export 'whitespace-char-p)
795 (declaim (inline whitespace-char-p))
796 (defun whitespace-char-p (char)
797 "Returns whether CHAR is a whitespace character.
799 Whitespaceness is determined relative to the compile-time readtable, which
800 is probably good enough for most purposes."
802 (#.(loop for i below char-code-limit
803 for ch = (code-char i)
804 unless (with-input-from-string (in (string ch))
805 (peek-char t in nil))
809 (export 'update-position)
810 (declaim (inline update-position))
811 (defun update-position (char line column)
812 "Updates LINE and COLUMN appropriately for having read the character CHAR.
814 Returns the new LINE and COLUMN numbers."
816 ((#\newline #\vt #\page)
817 (values (1+ line) 0))
819 (values line (logandc2 (+ column 8) 7)))
821 (values line (1+ column)))))
823 (export 'backtrack-position)
824 (declaim (inline backtrack-position))
825 (defun backtrack-position (char line column)
826 "Updates LINE and COLUMN appropriately for having unread CHAR.
828 Well, actually an approximation for it; it will likely be wrong if the
829 last character was a tab. But when the character is read again, it will
832 ;; This isn't perfect: if the character doesn't actually match what was
833 ;; really read then it might not actually be possible: for example, if we
834 ;; push back a newline while in the middle of a line, or a tab while not at
835 ;; a tab stop. In that case, we'll just lose, but hopefully not too badly.
838 ;; In the absence of better ideas, I'll set the column number to zero.
839 ;; This is almost certainly wrong, but with a little luck nobody will ask
840 ;; and it'll be all right soon.
841 ((#\newline #\vt #\page) (values (1- line) 0))
843 ;; Winding back a single space is sufficient. If the position is
844 ;; currently on a tab stop then it'll advance back here next time. If
845 ;; not, we're going to lose anyway because the previous character
846 ;; certainly couldn't have been a tab.
847 (#\tab (values line (1- column)))
849 ;; Anything else: just decrement the column and cross fingers.
850 (t (values line (1- column)))))
852 ;;;--------------------------------------------------------------------------
856 (defun compose (&rest functions)
857 "Composition of functions. Functions are applied left-to-right.
859 This is the reverse order of the usual mathematical notation, but I find
860 it easier to read. It's also slightly easier to work with in programs.
861 That is, (compose F1 F2 ... Fn) is what a category theorist might write as
862 F1 ; F2 ; ... ; Fn, rather than F1 o F2 o ... o Fn."
864 (labels ((compose1 (func-a func-b)
866 (multiple-value-call func-b (apply func-a args)))))
867 (if (null functions) #'values
868 (reduce #'compose1 (cdr functions)
869 :initial-value (car functions)))))
871 ;;;--------------------------------------------------------------------------
874 (export 'defvar-unbound)
875 (defmacro defvar-unbound (var doc)
876 "Make VAR a special variable with documentation DOC, but leave it unbound."
877 `(eval-when (:compile-toplevel :load-toplevel :execute)
879 (setf (documentation ',var 'variable) ',doc)
882 ;;;--------------------------------------------------------------------------
885 (export 'symbolicate)
886 (defun symbolicate (&rest symbols)
887 "Return a symbol named after the concatenation of the names of the SYMBOLS.
889 The symbol is interned in the current `*package*'. Trad."
890 (intern (apply #'concatenate 'string (mapcar #'symbol-name symbols))))
892 ;;;--------------------------------------------------------------------------
895 (export 'maybe-print-unreadable-object)
896 (defmacro maybe-print-unreadable-object
897 ((object stream &rest args) &body body)
898 "Print helper for usually-unreadable objects.
900 If `*print-escape*' is set then print OBJECT unreadably using BODY.
901 Otherwise just print using BODY."
902 (with-gensyms (print)
903 `(flet ((,print () ,@body))
905 (print-unreadable-object (,object ,stream ,@args)
909 (export 'print-ugly-stuff)
910 (defun print-ugly-stuff (stream func)
911 "Print not-pretty things to the stream underlying STREAM.
913 The Lisp pretty-printing machinery, notably `pprint-logical-block', may
914 interpose additional streams between its body and the original target
915 stream. This makes it difficult to make use of the underlying stream's
916 special features, whatever they might be."
918 ;; This is unpleasant. Hacky hacky.
919 #.(or #+sbcl '(if (typep stream 'sb-pretty:pretty-stream)
920 (let ((target (sb-pretty::pretty-stream-target stream)))
921 (pprint-newline :mandatory stream)
922 (funcall func target))
923 (funcall func stream))
924 #+cmu '(if (typep stream 'pp:pretty-stream)
925 (let ((target (pp::pretty-stream-target stream)))
926 (pprint-newline :mandatory stream)
927 (funcall func target))
928 (funcall func stream))
929 '(funcall func stream)))
931 ;;;--------------------------------------------------------------------------
932 ;;; Iteration macros.
935 (defmacro dosequence ((var seq &key (start 0) (end nil) indexvar)
938 "Macro for iterating over general sequences.
940 Iterates over a (sub)sequence SEQ, delimited by START and END (which are
941 evaluated). For each item of SEQ, BODY is invoked with VAR bound to the
942 item, and INDEXVAR (if requested) bound to the item's index. (Note that
943 this is different from most iteration constructs in Common Lisp, which
944 work by mutating the variable.)
946 The loop is surrounded by an anonymous BLOCK and the loop body forms an
947 implicit TAGBODY, as is usual. There is no result-form, however."
949 (once-only (:environment env start end)
950 (with-gensyms ((seqvar "SEQ-") (ivar "INDEX-")
951 (endvar "END-") (bodyfunc "BODY-"))
952 (multiple-value-bind (docs decls body) (parse-body body :docp nil)
953 (declare (ignore docs))
955 (flet ((loopguts (indexp listp endvar)
956 ;; Build a DO-loop to do what we want.
958 (end-condition (if endvar
963 `(aref ,seqvar ,ivar)))
964 (body-call `(,bodyfunc ,item)))
966 (push `(,seqvar (nthcdr ,start ,seqvar) (cdr ,seqvar))
969 (push `(,ivar ,start (1+ ,ivar)) do-vars))
971 (setf body-call (append body-call (list ivar))))
972 `(do ,do-vars (,end-condition) ,body-call))))
975 (let ((,seqvar ,seq))
976 (flet ((,bodyfunc (,var ,@(and indexvar `(,indexvar)))
981 (let ((,endvar (or ,end (length ,seqvar))))
982 ,(loopguts t nil endvar)))
986 ,(loopguts indexvar t nil))))))))))))
988 ;;;--------------------------------------------------------------------------
989 ;;; Structure accessor hacks.
991 (export 'define-access-wrapper)
992 (defmacro define-access-wrapper (from to &key read-only)
993 "Make (FROM THING) work like (TO THING).
995 If not READ-ONLY, then also make (setf (FROM THING) VALUE) work like
996 (setf (TO THING) VALUE).
998 This is mostly useful for structure slot accessors where the slot has to
999 be given an unpleasant name to avoid it being an external symbol."
1001 (declaim (inline ,from ,@(and (not read-only) `((setf ,from)))))
1002 (defun ,from (object)
1004 ,@(and (not read-only)
1005 `((defun (setf ,from) (value object)
1006 (setf (,to object) value))))))
1008 ;;;--------------------------------------------------------------------------
1009 ;;; Condition and error utilities.
1011 (export 'designated-condition)
1012 (defun designated-condition (default-type datum arguments
1013 &key allow-pointless-arguments)
1014 "Return the condition designated by DATUM and ARGUMENTS.
1016 DATUM and ARGUMENTS together are a `condition designator' of (some
1017 supertype of) DEFAULT-TYPE; return the condition so designated."
1020 (unless (or allow-pointless-arguments (null arguments))
1021 (error "Argument list provided with specific condition"))
1024 (apply #'make-condition datum arguments))
1025 ((or string function)
1026 (make-condition default-type
1027 :format-control datum
1028 :format-arguments arguments))
1030 (error "Unexpected condition designator datum ~S" datum))))
1032 (export 'simple-control-error)
1033 (define-condition simple-control-error (control-error simple-error)
1036 (export 'invoke-associated-restart)
1037 (defun invoke-associated-restart (restart condition &rest arguments)
1038 "Invoke the active RESTART associated with CONDITION, with the ARGUMENTS.
1040 Find an active restart designated by RESTART; if CONDITION is not nil,
1041 then restrict the search to restarts associated with CONDITION, and
1042 restarts not associated with any condition. If no such restart is found
1043 then signal an error of type `control-error'; otherwise invoke the restart
1044 with the given ARGUMENTS."
1045 (apply #'invoke-restart
1046 (or (find-restart restart condition)
1047 (error 'simple-control-error
1048 :format-control "~:[Restart ~S is not active~;~
1049 No active `~(~A~)' restart~]~
1050 ~@[ for condition ~S~]"
1051 :format-arguments (list (symbolp restart)
1056 (export '(enclosing-condition enclosed-condition))
1057 (define-condition enclosing-condition (condition)
1058 ((%enclosed-condition :initarg :condition :type condition
1059 :reader enclosed-condition))
1061 "A condition which encloses another condition
1063 This is useful if one wants to attach additional information to an
1064 existing condition. The enclosed condition can be obtained using the
1065 `enclosed-condition' function.")
1066 (:report (lambda (condition stream)
1067 (princ (enclosed-condition condition) stream))))
1069 (export 'information)
1070 (define-condition information (condition)
1073 (export 'simple-information)
1074 (define-condition simple-information (simple-condition information)
1078 (defun info (datum &rest arguments)
1079 "Report some useful diagnostic information.
1081 Establish a simple restart named `noted', and signal the condition of type
1082 `information' designated by DATUM and ARGUMENTS. Return non-nil if the
1083 restart was invoked, otherwise nil."
1085 (signal (designated-condition 'simple-information datum arguments))
1086 (noted () :report "Noted." t)))
1089 (defun noted (&optional condition)
1090 "Invoke the `noted' restart, possibly associated with the given CONDITION."
1091 (invoke-associated-restart 'noted condition))
1093 (export 'promiscuous-cerror)
1094 (defun promiscuous-cerror (continue-string datum &rest arguments)
1095 "Like standard `cerror', but robust against sneaky changes of conditions.
1097 It seems that `cerror' (well, at least the version in SBCL) is careful
1098 to limit its restart to the specific condition it signalled. But that's
1099 annoying, because `sod-parser:with-default-error-location' substitutes
1100 different conditions carrying the error-location information."
1101 (restart-case (apply #'error datum arguments)
1103 :report (lambda (stream)
1104 (apply #'format stream continue-string datum arguments))
1108 (defun cerror* (datum &rest arguments)
1109 (apply #'promiscuous-cerror "Continue" datum arguments))
1111 ;;;--------------------------------------------------------------------------
1114 (export 'default-slot)
1115 (defmacro default-slot ((instance slot &optional (slot-names t))
1118 "If INSTANCE's slot named SLOT is unbound, set it to VALUE.
1120 Only set SLOT if it's listed in SLOT-NAMES, or SLOT-NAMES is `t' (i.e., we
1121 obey the `shared-initialize' protocol). SLOT-NAMES defaults to `t', so
1122 you can use it in `initialize-instance' or similar without ill effects.
1123 Both INSTANCE and SLOT are evaluated; VALUE is an implicit progn and only
1124 evaluated if it's needed."
1126 (once-only (:environment env instance slot slot-names)
1127 `(when ,(if (eq slot-names t)
1128 `(not (slot-boundp ,instance ,slot))
1129 `(and (not (slot-boundp ,instance ,slot))
1130 (or (eq ,slot-names t)
1131 (member ,slot ,slot-names))))
1132 (setf (slot-value ,instance ,slot)
1135 (export 'define-on-demand-slot)
1136 (defmacro define-on-demand-slot (class slot (instance) &body body)
1137 "Defines a slot which computes its initial value on demand.
1139 Sets up the named SLOT of CLASS to establish its value as the implicit
1140 progn BODY, by defining an appropriate method on `slot-unbound'."
1141 (multiple-value-bind (docs decls body) (parse-body body)
1142 (with-gensyms (classvar slotvar)
1143 `(defmethod slot-unbound
1144 (,classvar (,instance ,class) (,slotvar (eql ',slot)))
1146 (declare (ignore ,classvar))
1147 (setf (slot-value ,instance ',slot) (block ,slot ,@body))))))
1149 ;;;----- That's all, folks --------------------------------------------------