+ "Keyword values can't be changed.")
+ (t
+ nil)))
+
+;;; This function is to be called just before a change which would
+;;; affect the symbol value. (We don't absolutely have to call this
+;;; function before such changes, since such changes are given as
+;;; undefined behavior. In particular, we don't if the runtime cost
+;;; would be annoying. But otherwise it's nice to do so.)
+(defun about-to-modify-symbol-value (symbol)
+ (declare (type symbol symbol))
+ (let ((reason (symbol-self-evaluating-p symbol)))
+ (when reason
+ (error reason)))
+ ;; (Note: Just because a value is CONSTANTP is not a good enough
+ ;; reason to complain here, because we want DEFCONSTANT to be able
+ ;; to use this function, and it's legal to DEFCONSTANT a constant as
+ ;; long as the new value is EQL to the old value.)
+ (values))
+
+
+;;; If COLD-FSET occurs not at top level, just treat it as an ordinary
+;;; assignment instead of doing cold static linking. That way things like
+;;; (FLET ((FROB (X) ..))
+;;; (DEFUN FOO (X Y) (FROB X) ..)
+;;; (DEFUN BAR (Z) (AND (FROB X) ..)))
+;;; can still "work" for cold init: they don't do magical static
+;;; linking the way that true toplevel DEFUNs do, but at least they do
+;;; the linking eventually, so as long as #'FOO and #'BAR aren't
+;;; needed until "cold toplevel forms" have executed, it's OK.
+(defmacro cold-fset (name lambda)
+ (style-warn
+ "~@<COLD-FSET ~S not cross-compiled at top level: demoting to ~
+(SETF FDEFINITION)~:@>"
+ name)
+ ;; We convert the LAMBDA expression to the corresponding NAMED-LAMBDA
+ ;; expression so that the compiler can use NAME in debug names etc.
+ (destructuring-bind (lambda-symbol &rest lambda-rest) lambda
+ (assert (eql lambda-symbol 'lambda)) ; else dunno how to do conversion
+ `(setf (fdefinition ',name)
+ (named-lambda ,name ,@lambda-rest))))
+\f
+;;;; ONCE-ONLY
+;;;;
+;;;; "The macro ONCE-ONLY has been around for a long time on various
+;;;; systems [..] if you can understand how to write and when to use
+;;;; ONCE-ONLY, then you truly understand macro." -- Peter Norvig,
+;;;; _Paradigms of Artificial Intelligence Programming: Case Studies
+;;;; in Common Lisp_, p. 853
+
+;;; ONCE-ONLY is a utility useful in writing source transforms and
+;;; macros. It provides a concise way to wrap a LET around some code
+;;; to ensure that some forms are only evaluated once.
+;;;
+;;; Create a LET* which evaluates each value expression, binding a
+;;; temporary variable to the result, and wrapping the LET* around the
+;;; result of the evaluation of BODY. Within the body, each VAR is
+;;; bound to the corresponding temporary variable.
+(defmacro once-only (specs &body body)
+ (named-let frob ((specs specs)
+ (body body))
+ (if (null specs)
+ `(progn ,@body)
+ (let ((spec (first specs)))
+ ;; FIXME: should just be DESTRUCTURING-BIND of SPEC
+ (unless (proper-list-of-length-p spec 2)
+ (error "malformed ONCE-ONLY binding spec: ~S" spec))
+ (let* ((name (first spec))
+ (exp-temp (gensym (symbol-name name))))
+ `(let ((,exp-temp ,(second spec))
+ (,name (gensym "ONCE-ONLY-")))
+ `(let ((,,name ,,exp-temp))
+ ,,(frob (rest specs) body))))))))
+\f
+;;;; various error-checking utilities
+
+;;; This function can be used as the default value for keyword
+;;; arguments that must be always be supplied. Since it is known by
+;;; the compiler to never return, it will avoid any compile-time type
+;;; warnings that would result from a default value inconsistent with
+;;; the declared type. When this function is called, it signals an
+;;; error indicating that a required &KEY argument was not supplied.
+;;; This function is also useful for DEFSTRUCT slot defaults
+;;; corresponding to required arguments.
+(declaim (ftype (function () nil) missing-arg))
+(defun missing-arg ()
+ #!+sb-doc
+ (/show0 "entering MISSING-ARG")
+ (error "A required &KEY or &OPTIONAL argument was not supplied."))
+
+;;; like CL:ASSERT and CL:CHECK-TYPE, but lighter-weight
+;;;
+;;; (As of sbcl-0.6.11.20, we were using some 400 calls to CL:ASSERT.
+;;; The CL:ASSERT restarts and whatnot expand into a significant
+;;; amount of code when you multiply them by 400, so replacing them
+;;; with this should reduce the size of the system by enough to be
+;;; worthwhile. ENFORCE-TYPE is much less common, but might still be
+;;; worthwhile, and since I don't really like CERROR stuff deep in the
+;;; guts of complex systems anyway, I replaced it too.)
+(defmacro aver (expr)
+ `(unless ,expr
+ (%failed-aver ,(format nil "~A" expr))))
+
+(defun %failed-aver (expr-as-string)
+ (bug "~@<failed AVER: ~2I~_~S~:>" expr-as-string))
+
+(defun bug (format-control &rest format-arguments)
+ (error 'bug
+ :format-control format-control
+ :format-arguments format-arguments))
+
+(defmacro enforce-type (value type)
+ (once-only ((value value))
+ `(unless (typep ,value ',type)
+ (%failed-enforce-type ,value ',type))))
+
+(defun %failed-enforce-type (value type)
+ (error 'simple-type-error ; maybe should be TYPE-BUG, subclass of BUG?
+ :value value
+ :expected-type type
+ :format-control "~@<~S ~_is not a ~_~S~:>"
+ :format-arguments (list value type)))
+\f
+;;; Return a function like FUN, but expecting its (two) arguments in
+;;; the opposite order that FUN does.
+(declaim (inline swapped-args-fun))
+(defun swapped-args-fun (fun)
+ (declare (type function fun))
+ (lambda (x y)
+ (funcall fun y x)))
+
+;;; Return the numeric value of a type bound, i.e. an interval bound
+;;; more or less in the format of bounds in ANSI's type specifiers,
+;;; where a bare numeric value is a closed bound and a list of a
+;;; single numeric value is an open bound.
+;;;
+;;; The "more or less" bit is that the no-bound-at-all case is
+;;; represented by NIL (not by * as in ANSI type specifiers); and in
+;;; this case we return NIL.
+(defun type-bound-number (x)
+ (if (consp x)
+ (destructuring-bind (result) x result)
+ x))
+
+;;; some commonly-occuring CONSTANTLY forms
+(macrolet ((def-constantly-fun (name constant-expr)
+ `(setf (symbol-function ',name)
+ (constantly ,constant-expr))))
+ (def-constantly-fun constantly-t t)
+ (def-constantly-fun constantly-nil nil)
+ (def-constantly-fun constantly-0 0))
+
+;;; If X is an atom, see whether it is present in *FEATURES*. Also
+;;; handle arbitrary combinations of atoms using NOT, AND, OR.
+(defun featurep (x)
+ (if (consp x)
+ (case (car x)
+ ((:not not)
+ (if (cddr x)
+ (error "too many subexpressions in feature expression: ~S" x)
+ (not (featurep (cadr x)))))
+ ((:and and) (every #'featurep (cdr x)))
+ ((:or or) (some #'featurep (cdr x)))
+ (t
+ (error "unknown operator in feature expression: ~S." x)))
+ (not (null (memq x *features*)))))
+
+;;; Given a list of keyword substitutions `(,OLD ,NEW), and a
+;;; &KEY-argument-list-style list of alternating keywords and
+;;; arbitrary values, return a new &KEY-argument-list-style list with
+;;; all substitutions applied to it.
+;;;
+;;; Note: If efficiency mattered, we could do less consing. (But if
+;;; efficiency mattered, why would we be using &KEY arguments at
+;;; all, much less renaming &KEY arguments?)
+;;;
+;;; KLUDGE: It would probably be good to get rid of this. -- WHN 19991201
+(defun rename-key-args (rename-list key-args)
+ (declare (type list rename-list key-args))
+ ;; Walk through RENAME-LIST modifying RESULT as per each element in
+ ;; RENAME-LIST.
+ (do ((result (copy-list key-args))) ; may be modified below
+ ((null rename-list) result)
+ (destructuring-bind (old new) (pop rename-list)
+ ;; ANSI says &KEY arg names aren't necessarily KEYWORDs.
+ (declare (type symbol old new))
+ ;; Walk through RESULT renaming any OLD key argument to NEW.
+ (do ((in-result result (cddr in-result)))
+ ((null in-result))
+ (declare (type list in-result))
+ (when (eq (car in-result) old)
+ (setf (car in-result) new))))))
+
+;;; ANSI Common Lisp's READ-SEQUENCE function, unlike most of the
+;;; other ANSI input functions, is defined to communicate end of file
+;;; status with its return value, not by signalling. That is not the
+;;; behavior that we usually want. This function is a wrapper which
+;;; restores the behavior that we usually want, causing READ-SEQUENCE
+;;; to communicate end-of-file status by signalling.
+(defun read-sequence-or-die (sequence stream &key start end)
+ ;; implementation using READ-SEQUENCE
+ #-no-ansi-read-sequence
+ (let ((read-end (read-sequence sequence
+ stream
+ :start start
+ :end end)))
+ (unless (= read-end end)
+ (error 'end-of-file :stream stream))
+ (values))
+ ;; workaround for broken READ-SEQUENCE
+ #+no-ansi-read-sequence
+ (progn
+ (aver (<= start end))
+ (let ((etype (stream-element-type stream)))
+ (cond ((equal etype '(unsigned-byte 8))
+ (do ((i start (1+ i)))
+ ((>= i end)
+ (values))
+ (setf (aref sequence i)
+ (read-byte stream))))
+ (t (error "unsupported element type ~S" etype))))))
+\f
+;;;; utilities for two-VALUES predicates
+
+(defmacro not/type (x)
+ (let ((val (gensym "VAL"))
+ (win (gensym "WIN")))
+ `(multiple-value-bind (,val ,win)
+ ,x
+ (if ,win
+ (values (not ,val) t)
+ (values nil nil)))))
+
+(defmacro and/type (x y)
+ `(multiple-value-bind (val1 win1) ,x
+ (if (and (not val1) win1)
+ (values nil t)
+ (multiple-value-bind (val2 win2) ,y
+ (if (and val1 val2)
+ (values t t)
+ (values nil (and win2 (not val2))))))))
+
+;;; sort of like ANY and EVERY, except:
+;;; * We handle two-VALUES predicate functions, as SUBTYPEP does.
+;;; (And if the result is uncertain, then we return (VALUES NIL NIL),
+;;; as SUBTYPEP does.)
+;;; * THING is just an atom, and we apply OP (an arity-2 function)
+;;; successively to THING and each element of LIST.
+(defun any/type (op thing list)
+ (declare (type function op))
+ (let ((certain? t))
+ (dolist (i list (values nil certain?))
+ (multiple-value-bind (sub-value sub-certain?) (funcall op thing i)
+ (if sub-certain?
+ (when sub-value (return (values t t)))
+ (setf certain? nil))))))
+(defun every/type (op thing list)
+ (declare (type function op))
+ (let ((certain? t))
+ (dolist (i list (if certain? (values t t) (values nil nil)))
+ (multiple-value-bind (sub-value sub-certain?) (funcall op thing i)
+ (if sub-certain?
+ (unless sub-value (return (values nil t)))
+ (setf certain? nil))))))
+\f
+;;;; DEFPRINTER
+
+;;; These functions are called by the expansion of the DEFPRINTER
+;;; macro to do the actual printing.
+(declaim (ftype (function (symbol t stream) (values))
+ defprinter-prin1 defprinter-princ))
+(defun defprinter-prin1 (name value stream)
+ (defprinter-prinx #'prin1 name value stream))
+(defun defprinter-princ (name value stream)
+ (defprinter-prinx #'princ name value stream))
+(defun defprinter-prinx (prinx name value stream)
+ (declare (type function prinx))
+ (when *print-pretty*
+ (pprint-newline :linear stream))
+ (format stream ":~A " name)
+ (funcall prinx value stream)
+ (values))
+(defun defprinter-print-space (stream)
+ (write-char #\space stream))
+
+;;; Define some kind of reasonable PRINT-OBJECT method for a
+;;; STRUCTURE-OBJECT class.
+;;;
+;;; NAME is the name of the structure class, and CONC-NAME is the same
+;;; as in DEFSTRUCT.
+;;;
+;;; The SLOT-DESCS describe how each slot should be printed. Each
+;;; SLOT-DESC can be a slot name, indicating that the slot should
+;;; simply be printed. A SLOT-DESC may also be a list of a slot name
+;;; and other stuff. The other stuff is composed of keywords followed
+;;; by expressions. The expressions are evaluated with the variable
+;;; which is the slot name bound to the value of the slot. These
+;;; keywords are defined:
+;;;
+;;; :PRIN1 Print the value of the expression instead of the slot value.
+;;; :PRINC Like :PRIN1, only PRINC the value
+;;; :TEST Only print something if the test is true.
+;;;
+;;; If no printing thing is specified then the slot value is printed
+;;; as if by PRIN1.
+;;;
+;;; The structure being printed is bound to STRUCTURE and the stream
+;;; is bound to STREAM.
+(defmacro defprinter ((name
+ &key
+ (conc-name (concatenate 'simple-string
+ (symbol-name name)
+ "-"))
+ identity)
+ &rest slot-descs)
+ (let ((first? t)
+ maybe-print-space
+ (reversed-prints nil)
+ (stream (gensym "STREAM")))
+ (flet ((sref (slot-name)
+ `(,(symbolicate conc-name slot-name) structure)))
+ (dolist (slot-desc slot-descs)
+ (if first?
+ (setf maybe-print-space nil
+ first? nil)
+ (setf maybe-print-space `(defprinter-print-space ,stream)))
+ (cond ((atom slot-desc)
+ (push maybe-print-space reversed-prints)
+ (push `(defprinter-prin1 ',slot-desc ,(sref slot-desc) ,stream)
+ reversed-prints))
+ (t
+ (let ((sname (first slot-desc))
+ (test t))
+ (collect ((stuff))
+ (do ((option (rest slot-desc) (cddr option)))
+ ((null option)
+ (push `(let ((,sname ,(sref sname)))
+ (when ,test
+ ,maybe-print-space
+ ,@(or (stuff)
+ `((defprinter-prin1
+ ',sname ,sname ,stream)))))
+ reversed-prints))
+ (case (first option)
+ (:prin1
+ (stuff `(defprinter-prin1
+ ',sname ,(second option) ,stream)))
+ (:princ
+ (stuff `(defprinter-princ
+ ',sname ,(second option) ,stream)))
+ (:test (setq test (second option)))
+ (t
+ (error "bad option: ~S" (first option)))))))))))
+ `(def!method print-object ((structure ,name) ,stream)
+ (pprint-logical-block (,stream nil)
+ (print-unreadable-object (structure
+ ,stream
+ :type t
+ :identity ,identity)
+ ,@(nreverse reversed-prints))))))
+\f
+;;;; etc.
+
+;;; Given a pathname, return a corresponding physical pathname.
+(defun physicalize-pathname (possibly-logical-pathname)
+ (if (typep possibly-logical-pathname 'logical-pathname)
+ (translate-logical-pathname possibly-logical-pathname)
+ possibly-logical-pathname))
+
+(defun deprecation-warning (bad-name &optional good-name)
+ (warn "using deprecated ~S~@[, should use ~S instead~]"
+ bad-name
+ good-name))
+
+;;; Anaphoric macros
+(defmacro awhen (test &body body)
+ `(let ((it ,test))
+ (when it ,@body)))
+
+(defmacro acond (&rest clauses)
+ (if (null clauses)
+ `()
+ (destructuring-bind ((test &body body) &rest rest) clauses
+ (once-only ((test test))
+ `(if ,test
+ (let ((it ,test)) (declare (ignorable it)),@body)
+ (acond ,@rest))))))
+
+;;; (binding* ({(names initial-value [flag])}*) body)
+;;; FLAG may be NIL or :EXIT-IF-NULL
+;;;
+;;; This form unites LET*, MULTIPLE-VALUE-BIND and AWHEN.
+(defmacro binding* ((&rest bindings) &body body)
+ (let ((bindings (reverse bindings)))
+ (loop with form = `(progn ,@body)
+ for binding in bindings
+ do (destructuring-bind (names initial-value &optional flag)
+ binding
+ (multiple-value-bind (names declarations)
+ (etypecase names
+ (null
+ (let ((name (gensym)))
+ (values (list name) `((declare (ignorable ,name))))))
+ (symbol
+ (values (list names) nil))
+ (list
+ (collect ((new-names) (ignorable))
+ (dolist (name names)
+ (when (eq name nil)
+ (setq name (gensym))
+ (ignorable name))
+ (new-names name))
+ (values (new-names)
+ (when (ignorable)
+ `((declare (ignorable ,@(ignorable)))))))))
+ (setq form `(multiple-value-bind ,names
+ ,initial-value
+ ,@declarations
+ ,(ecase flag
+ ((nil) form)
+ ((:exit-if-null)
+ `(when ,(first names) ,form)))))))
+ finally (return form))))
+\f
+;;; Delayed evaluation
+(defmacro delay (form)
+ `(cons nil (lambda () ,form)))
+
+(defun force (promise)
+ (cond ((not (consp promise)) promise)
+ ((car promise) (cdr promise))
+ (t (setf (car promise) t
+ (cdr promise) (funcall (cdr promise))))))
+
+(defun promise-ready-p (promise)
+ (or (not (consp promise))
+ (car promise)))