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;;;; "format.scm" Common LISP text output formatter for SLIB
;;; Copyright (C) 2010-2013,2019 Free Software Foundation, Inc.
;;;
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;
;;; This code was orignally in the public domain.
;;;
;;; Written 1992-1994 by Dirk Lutzebaeck (lutzeb@cs.tu-berlin.de).
;;;
;;; Authors of the version from SLIB (< 1.4) were Ken Dickey and Aubrey
;;; Jaffer.
;;;
;;; Assimilated into Guile May 1999.
;;;
;;; Please don't bother the original authors with bug reports, though;
;;; send them to bug-guile@gnu.org.
;;;
(define-module (ice-9 format)
#:autoload (ice-9 pretty-print) (pretty-print truncated-print)
#:autoload (ice-9 i18n) (%global-locale number->locale-string)
#:replace (format))
(define format:version "3.0")
(define (format destination format-string . format-args)
(define port
(begin
(unless (string? format-string)
(error "format: expected a string for format string" format-string))
(cond
((not destination) (open-output-string))
((boolean? destination) (current-output-port)) ; boolean but not false
((output-port? destination) destination)
(else
(error "format: bad destination `~a'" destination)))))
(define %output-col (or (port-column port) 0))
(define %flush-output? #f)
(define %case-conversion #f)
(define %pos 0) ; curr. format string parsing position
(define %arg-pos 0) ; curr. format argument position
;; format string and char output routines on port
(define (put-string str)
(if %case-conversion
(display (%case-conversion str) port)
(display str port))
(set! %output-col
(+ %output-col (string-length str))))
(define (put-char ch)
(if %case-conversion
(display (%case-conversion (string ch))
port)
(write-char ch port))
(set! %output-col
(if (char=? ch #\newline)
0
(+ %output-col 1))))
(define (put-substring str i n)
(put-string (substring str i n)))
(define (put-fill-chars n ch)
(put-string (make-string n ch)))
;; format's user error handler
(define (format-error . args) ; never returns!
(with-throw-handler #t
(lambda ()
(let ((port (current-error-port)))
(unless (zero? %arg-pos)
(set! %arg-pos (- %arg-pos 1)))
(format port
"~%FORMAT: error with call: (format ~a \"~a<===~a\" ~
~{~a ~}===>~{~a ~})~% "
destination
(substring format-string 0 %pos)
(substring format-string %pos
(string-length format-string))
(list-head format-args %arg-pos)
(list-tail format-args %arg-pos))
(apply format port args)
(newline port)
(error "error in format")))
(lambda (key . args)
(display "FORMAT: INTERNAL ERROR IN FORMAT-ERROR!") (newline)
(display " destination: ") (write destination) (newline)
(display " format string: ") (write format-string) (newline)
(display " format args: ") (write format-args) (newline)
(display " error args: ") (write args) (newline))))
(define format:parameter-characters
'(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9 #\- #\+ #\v #\# #\'))
(define (format:format-work format-string arglist) ; does the formatting work
(define format-string-len (string-length format-string))
(define arg-pos 0) ; argument position in arglist
(define arg-len (length arglist)) ; number of arguments
(define modifier #f) ; 'colon | 'at | 'colon-at | #f
(define params '()) ; directive parameter list
(define param-value-found #f) ; a directive parameter value found
(define conditional-nest 0) ; conditional nesting level
(define clause-pos 0) ; last cond. clause beginning char pos
(define clause-default #f) ; conditional default clause string
(define clauses '()) ; conditional clause string list
(define conditional-type #f) ; reflects the conditional modifiers
(define conditional-arg #f) ; argument to apply the conditional
(define iteration-nest 0) ; iteration nesting level
(define iteration-pos 0) ; iteration string beginning char pos
(define iteration-type #f) ; reflects the iteration modifiers
(define max-iterations #f) ; maximum number of iterations
(define recursive-pos-save %pos)
(define (next-char) ; gets the next char from format-string
(let ((ch (peek-next-char)))
(set! %pos (+ 1 %pos))
ch))
(define (peek-next-char)
(when (>= %pos format-string-len)
(format-error "illegal format string"))
(string-ref format-string %pos))
(define (one-positive-integer? params )
(cond
((null? params) #f)
((and (integer? (car params))
(>= (car params) 0)
(= (length params) 1)) #t)
(else
(format-error
"one positive integer parameter expected"))))
(define (next-arg)
(when (>= arg-pos arg-len)
(set! %arg-pos (+ arg-len 1))
(format-error "missing argument(s)"))
(add-arg-pos 1)
(list-ref arglist (- arg-pos 1)))
(define (prev-arg)
(add-arg-pos -1)
(when (negative? arg-pos)
(format-error "missing backward argument(s)"))
(list-ref arglist arg-pos))
(define (rest-args)
(let loop ((l arglist) (k arg-pos)) ; list-tail definition
(if (= k 0) l (loop (cdr l) (- k 1)))))
(define (add-arg-pos n)
(set! arg-pos (+ n arg-pos))
(set! %arg-pos arg-pos))
(define (anychar-dispatch) ; dispatches the format-string
(if (>= %pos format-string-len)
arg-pos ; used for ~? continuance
(let ((char (next-char)))
(cond
((char=? char #\~)
(set! modifier #f)
(set! params '())
(set! param-value-found #f)
(tilde-dispatch))
(else
(when (and (zero? conditional-nest)
(zero? iteration-nest))
(put-char char))
(anychar-dispatch))))))
(define (tilde-dispatch)
(cond
((>= %pos format-string-len)
(put-string "~") ; tilde at end of
; string is just
; output
arg-pos) ; used for ~?
; continuance
((and (or (zero? conditional-nest)
(memv (peek-next-char) ; find conditional
; directives
(append '(#\[ #\] #\; #\: #\@ #\^)
format:parameter-characters)))
(or (zero? iteration-nest)
(memv (peek-next-char) ; find iteration
; directives
(append '(#\{ #\} #\: #\@ #\^)
format:parameter-characters))))
(case (char-upcase (next-char))
;; format directives
((#\A) ; Any -- for humans
(set! format:read-proof
(memq modifier '(colon colon-at)))
(format:out-obj-padded (memq modifier '(at colon-at))
(next-arg) #f params)
(anychar-dispatch))
((#\S) ; Slashified -- for parsers
(set! format:read-proof
(memq modifier '(colon colon-at)))
(format:out-obj-padded (memq modifier '(at colon-at))
(next-arg) #t params)
(anychar-dispatch))
((#\D) ; Decimal
(format:out-num-padded modifier (next-arg) params 10)
(anychar-dispatch))
((#\H) ; Localized number
(let* ((num (next-arg))
(locale (case modifier
((colon) (next-arg))
(else %global-locale)))
(argc (length params))
(width (format:par params argc 0 #f "width"))
(decimals (format:par params argc 1 #t "decimals"))
(padchar (integer->char
(format:par params argc 2 format:space-ch
"padchar")))
(str (number->locale-string num decimals
locale)))
(put-string (if (and width
(< (string-length str) width))
(string-pad str width padchar)
str)))
(anychar-dispatch))
((#\X) ; Hexadecimal
(format:out-num-padded modifier (next-arg) params 16)
(anychar-dispatch))
((#\O) ; Octal
(format:out-num-padded modifier (next-arg) params 8)
(anychar-dispatch))
((#\B) ; Binary
(format:out-num-padded modifier (next-arg) params 2)
(anychar-dispatch))
((#\R)
(if (null? params)
(format:out-obj-padded ; Roman, cardinal,
; ordinal numerals
#f
((case modifier
((at) format:num->roman)
((colon-at) format:num->old-roman)
((colon) format:num->ordinal)
(else format:num->cardinal))
(next-arg))
#f params)
(format:out-num-padded ; any Radix
modifier (next-arg) (cdr params) (car params)))
(anychar-dispatch))
((#\F) ; Fixed-format floating-point
(format:out-fixed modifier (next-arg) params)
(anychar-dispatch))
((#\E) ; Exponential floating-point
(format:out-expon modifier (next-arg) params)
(anychar-dispatch))
((#\G) ; General floating-point
(format:out-general modifier (next-arg) params)
(anychar-dispatch))
((#\$) ; Dollars floating-point
(format:out-dollar modifier (next-arg) params)
(anychar-dispatch))
((#\I) ; Complex numbers
(let ((z (next-arg)))
(unless (complex? z)
(format-error "argument not a complex number"))
(format:out-fixed modifier (real-part z) params)
(format:out-fixed 'at (imag-part z) params)
(put-char #\i))
(anychar-dispatch))
((#\C) ; Character
(let ((ch (if (one-positive-integer? params)
(integer->char (car params))
(next-arg))))
(unless (char? ch)
(format-error "~~c expects a character"))
(case modifier
((at)
(put-string (object->string ch)))
((colon)
(let ((c (char->integer ch)))
(when (< c 0)
(set! c (+ c 256))) ; compensate
; complement
; impl.
(cond
((< c #x20) ; assumes that control
; chars are < #x20
(put-char #\^)
(put-char
(integer->char (+ c #x40))))
((>= c #x7f)
(put-string "#\\")
(put-string
(number->string c 8)))
(else
(put-char ch)))))
(else (put-char ch))))
(anychar-dispatch))
((#\P) ; Plural
(when (memq modifier '(colon colon-at))
(prev-arg))
(let ((arg (next-arg)))
(unless (number? arg)
(format-error "~~p expects a number argument"))
(if (= arg 1)
(when (memq modifier '(at colon-at))
(put-char #\y))
(if (memq modifier '(at colon-at))
(put-string "ies")
(put-char #\s))))
(anychar-dispatch))
((#\~) ; Tilde
(if (one-positive-integer? params)
(put-fill-chars (car params) #\~)
(put-char #\~))
(anychar-dispatch))
((#\%) ; Newline
(if (one-positive-integer? params)
(put-fill-chars (car params) #\newline)
(put-char #\newline))
(set! %output-col 0)
(anychar-dispatch))
((#\&) ; Fresh line
(if (one-positive-integer? params)
(begin
(when (> (car params) 0)
(put-fill-chars (- (car params)
(if (> %output-col 0) 0 1))
#\newline))
(set! %output-col 0))
(when (> %output-col 0)
(put-char #\newline)))
(anychar-dispatch))
((#\_) ; Space character
(if (one-positive-integer? params)
(put-fill-chars (car params) #\space)
(put-char #\space))
(anychar-dispatch))
((#\/) ; Tabulator character
(if (one-positive-integer? params)
(put-fill-chars (car params) #\tab)
(put-char #\tab))
(anychar-dispatch))
((#\|) ; Page seperator
(if (one-positive-integer? params)
(put-fill-chars (car params) #\page)
(put-char #\page))
(set! %output-col 0)
(anychar-dispatch))
((#\T) ; Tabulate
(format:tabulate modifier params)
(anychar-dispatch))
((#\Y) ; Structured print
(let ((width (if (one-positive-integer? params)
(car params)
79)))
(case modifier
((at)
(put-string
(call-with-output-string
(lambda (p)
(truncated-print (next-arg) p
#:width width)))))
((colon-at)
(put-string
(call-with-output-string
(lambda (p)
(truncated-print (next-arg) p
#:width
(max (- width
%output-col)
1))))))
((colon)
(format-error "illegal modifier in ~~?"))
(else
(pretty-print (next-arg) port
#:width width)
(set! %output-col 0))))
(anychar-dispatch))
((#\? #\K) ; Indirection (is "~K" in T-Scheme)
(cond
((memq modifier '(colon colon-at))
(format-error "illegal modifier in ~~?"))
((eq? modifier 'at)
(let* ((frmt (next-arg))
(args (rest-args)))
(add-arg-pos (format:format-work frmt args))))
(else
(let* ((frmt (next-arg))
(args (next-arg)))
(format:format-work frmt args))))
(anychar-dispatch))
((#\!) ; Flush output
(set! %flush-output? #t)
(anychar-dispatch))
((#\newline) ; Continuation lines
(when (eq? modifier 'at)
(put-char #\newline))
(if (< %pos format-string-len)
(do ((ch (peek-next-char) (peek-next-char)))
((or (not (char-whitespace? ch))
(= %pos (- format-string-len 1))))
(if (eq? modifier 'colon)
(put-char (next-char))
(next-char))))
(anychar-dispatch))
((#\*) ; Argument jumping
(case modifier
((colon) ; jump backwards
(if (one-positive-integer? params)
(do ((i 0 (+ i 1)))
((= i (car params)))
(prev-arg))
(prev-arg)))
((at) ; jump absolute
(set! arg-pos
(if (one-positive-integer? params) (car params) 0)))
((colon-at)
(format-error "illegal modifier `:@' in ~~* directive"))
(else ; jump forward
(if (one-positive-integer? params)
(do ((i 0 (+ i 1)))
((= i (car params)))
(next-arg))
(next-arg))))
(anychar-dispatch))
((#\() ; Case conversion begin
(set! %case-conversion
(case modifier
((at) string-capitalize-first)
((colon) string-capitalize)
((colon-at) string-upcase)
(else string-downcase)))
(anychar-dispatch))
((#\)) ; Case conversion end
(unless %case-conversion
(format-error "missing ~~("))
(set! %case-conversion #f)
(anychar-dispatch))
((#\[) ; Conditional begin
(set! conditional-nest (+ conditional-nest 1))
(cond
((= conditional-nest 1)
(set! clause-pos %pos)
(set! clause-default #f)
(set! clauses '())
(set! conditional-type
(case modifier
((at) 'if-then)
((colon) 'if-else-then)
((colon-at) (format-error "illegal modifier in ~~["))
(else 'num-case)))
(set! conditional-arg
(if (one-positive-integer? params)
(car params)
(next-arg)))))
(anychar-dispatch))
((#\;) ; Conditional separator
(when (zero? conditional-nest)
(format-error "~~; not in ~~[~~] conditional"))
(unless (null? params)
(format-error "no parameter allowed in ~~;"))
(when (= conditional-nest 1)
(let ((clause-str
(cond
((eq? modifier 'colon)
(set! clause-default #t)
(substring format-string clause-pos
(- %pos 3)))
((memq modifier '(at colon-at))
(format-error "illegal modifier in ~~;"))
(else
(substring format-string clause-pos
(- %pos 2))))))
(set! clauses (append clauses (list clause-str)))
(set! clause-pos %pos)))
(anychar-dispatch))
((#\]) ; Conditional end
(when (zero? conditional-nest)
(format-error "missing ~~["))
(set! conditional-nest (- conditional-nest 1))
(when modifier
(format-error "no modifier allowed in ~~]"))
(unless (null? params)
(format-error "no parameter allowed in ~~]"))
(cond
((zero? conditional-nest)
(let ((clause-str (substring format-string clause-pos
(- %pos 2))))
(if clause-default
(set! clause-default clause-str)
(set! clauses (append clauses (list clause-str)))))
(case conditional-type
((if-then)
(when conditional-arg
(format:format-work (car clauses)
(list conditional-arg))))
((if-else-then)
(add-arg-pos
(format:format-work (if conditional-arg
(cadr clauses)
(car clauses))
(rest-args))))
((num-case)
(when (or (not (integer? conditional-arg))
(< conditional-arg 0))
(format-error "argument not a positive integer"))
(unless (and (>= conditional-arg (length clauses))
(not clause-default))
(add-arg-pos
(format:format-work
(if (>= conditional-arg (length clauses))
clause-default
(list-ref clauses conditional-arg))
(rest-args))))))))
(anychar-dispatch))
((#\{) ; Iteration begin
(set! iteration-nest (+ iteration-nest 1))
(cond
((= iteration-nest 1)
(set! iteration-pos %pos)
(set! iteration-type
(case modifier
((at) 'rest-args)
((colon) 'sublists)
((colon-at) 'rest-sublists)
(else 'list)))
(set! max-iterations
(if (one-positive-integer? params)
(car params)
#f))))
(anychar-dispatch))
((#\}) ; Iteration end
(when (zero? iteration-nest) (format-error "missing ~~{"))
(set! iteration-nest (- iteration-nest 1))
(case modifier
((colon)
(unless max-iterations (set! max-iterations 1)))
((colon-at at) (format-error "illegal modifier")))
(unless (null? params)
(format-error "no parameters allowed in ~~}"))
(if (zero? iteration-nest)
(let ((iteration-str
(substring format-string iteration-pos
(- %pos (if modifier 3 2)))))
(when (string=? iteration-str "")
(set! iteration-str (next-arg)))
(case iteration-type
((list)
(let ((args (next-arg))
(args-len 0))
(unless (list? args)
(format-error "expected a list argument"))
(set! args-len (length args))
(do ((arg-pos 0 (+ arg-pos
(format:format-work
iteration-str
(list-tail args arg-pos))))
(i 0 (+ i 1)))
((or (>= arg-pos args-len)
(and max-iterations
(>= i max-iterations)))))))
((sublists)
(let ((args (next-arg))
(args-len 0))
(unless (list? args)
(format-error "expected a list argument"))
(set! args-len (length args))
(do ((arg-pos 0 (+ arg-pos 1)))
((or (>= arg-pos args-len)
(and max-iterations
(>= arg-pos max-iterations))))
(let ((sublist (list-ref args arg-pos)))
(unless (list? sublist)
(format-error "expected a list of lists argument"))
(format:format-work iteration-str sublist)))))
((rest-args)
(let* ((args (rest-args))
(args-len (length args))
(usedup-args
(do ((arg-pos 0 (+ arg-pos
(format:format-work
iteration-str
(list-tail
args arg-pos))))
(i 0 (+ i 1)))
((or (>= arg-pos args-len)
(and max-iterations
(>= i max-iterations)))
arg-pos))))
(add-arg-pos usedup-args)))
((rest-sublists)
(let* ((args (rest-args))
(args-len (length args))
(usedup-args
(do ((arg-pos 0 (+ arg-pos 1)))
((or (>= arg-pos args-len)
(and max-iterations
(>= arg-pos max-iterations)))
arg-pos)
(let ((sublist (list-ref args arg-pos)))
(unless (list? sublist)
(format-error "expected list arguments"))
(format:format-work iteration-str sublist)))))
(add-arg-pos usedup-args)))
(else (format-error "internal error in ~~}")))))
(anychar-dispatch))
((#\^) ; Up and out
(let* ((continue
(cond
((not (null? params))
(not
(case (length params)
((1) (zero? (car params)))
((2) (= (list-ref params 0) (list-ref params 1)))
((3) (<= (list-ref params 0)
(list-ref params 1)
(list-ref params 2)))
(else (format-error "too much parameters")))))
(%case-conversion ; if conversion stop conversion
(set! %case-conversion string-copy) #t)
((= iteration-nest 1) #t)
((= conditional-nest 1) #t)
((>= arg-pos arg-len)
(set! %pos format-string-len) #f)
(else #t))))
(when continue
(anychar-dispatch))))
;; format directive modifiers and parameters
((#\@) ; `@' modifier
(when (memq modifier '(at colon-at))
(format-error "double `@' modifier"))
(set! modifier (if (eq? modifier 'colon) 'colon-at 'at))
(tilde-dispatch))
((#\:) ; `:' modifier
(when (memq modifier '(colon colon-at))
(format-error "double `:' modifier"))
(set! modifier (if (eq? modifier 'at) 'colon-at 'colon))
(tilde-dispatch))
((#\') ; Character parameter
(when modifier
(format-error "misplaced modifier"))
(set! params (append params (list (char->integer (next-char)))))
(set! param-value-found #t)
(tilde-dispatch))
((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9 #\- #\+) ; num. paramtr
(when modifier
(format-error "misplaced modifier"))
(let ((num-str-beg (- %pos 1))
(num-str-end %pos))
(do ((ch (peek-next-char) (peek-next-char)))
((not (char-numeric? ch)))
(next-char)
(set! num-str-end (+ 1 num-str-end)))
(set! params
(append params
(list (string->number
(substring format-string
num-str-beg
num-str-end))))))
(set! param-value-found #t)
(tilde-dispatch))
((#\V) ; Variable parameter from next argum.
(when modifier
(format-error "misplaced modifier"))
(set! params (append params (list (next-arg))))
(set! param-value-found #t)
(tilde-dispatch))
((#\#) ; Parameter is number of remaining args
(when param-value-found
(format-error "misplaced '#'"))
(when modifier
(format-error "misplaced modifier"))
(set! params (append params (list (length (rest-args)))))
(set! param-value-found #t)
(tilde-dispatch))
((#\,) ; Parameter separators
(when modifier
(format-error "misplaced modifier"))
(unless param-value-found
(set! params (append params '(#f)))) ; append empty paramtr
(set! param-value-found #f)
(tilde-dispatch))
((#\Q) ; Inquiry messages
(if (eq? modifier 'colon)
(put-string format:version)
(let ((nl (string #\newline)))
(put-string
(string-append
"SLIB Common LISP format version " format:version nl
" (C) copyright 1992-1994 by Dirk Lutzebaeck" nl
" please send bug reports to `lutzeb@cs.tu-berlin.de'"
nl))))
(anychar-dispatch))
(else ; Unknown tilde directive
(format-error "unknown control character `~c'"
(string-ref format-string (- %pos 1))))))
(else (anychar-dispatch)))) ; in case of conditional
(set! %pos 0)
(set! %arg-pos 0)
(anychar-dispatch) ; start the formatting
(set! %pos recursive-pos-save)
arg-pos) ; return the position in the arg. list
;; when format:read-proof is true, format:obj->str will wrap
;; result strings starting with "#<" in an extra pair of double
;; quotes.
(define format:read-proof #f)
;; format:obj->str returns a R4RS representation as a string of
;; an arbitrary scheme object.
(define (format:obj->str obj slashify)
(let ((res (if slashify
(object->string obj)
(call-with-output-string (lambda (p) (display obj p))))))
(if (and format:read-proof (string-prefix? "#<" res))
(object->string res)
res)))
(define format:space-ch (char->integer #\space))
(define format:zero-ch (char->integer #\0))
(define (format:par pars length index default name)
(if (> length index)
(let ((par (list-ref pars index)))
(if par
(if name
(if (< par 0)
(format-error
"~s parameter must be a positive integer" name)
par)
par)
default))
default))
(define (format:out-obj-padded pad-left obj slashify pars)
(if (null? pars)
(put-string (format:obj->str obj slashify))
(let ((l (length pars)))
(let ((mincol (format:par pars l 0 0 "mincol"))
(colinc (format:par pars l 1 1 "colinc"))
(minpad (format:par pars l 2 0 "minpad"))
(padchar (integer->char
(format:par pars l 3 format:space-ch #f)))
(objstr (format:obj->str obj slashify)))
(unless pad-left
(put-string objstr))
(do ((objstr-len (string-length objstr))
(i minpad (+ i colinc)))
((>= (+ objstr-len i) mincol)
(put-fill-chars i padchar)))
(when pad-left
(put-string objstr))))))
(define (format:out-num-padded modifier number pars radix)
(unless (integer? number)
(format-error "argument not an integer"))
(let ((numstr (number->string number radix)))
(if (and (null? pars) (not modifier))
(put-string numstr)
(let ((l (length pars))
(numstr-len (string-length numstr)))
(let ((mincol (format:par pars l 0 #f "mincol"))
(padchar (integer->char
(format:par pars l 1 format:space-ch #f)))
(commachar (integer->char
(format:par pars l 2 (char->integer #\,) #f)))
(commawidth (format:par pars l 3 3 "commawidth")))
(when mincol
(let ((numlen numstr-len)) ; calc. the output len of number
(when (and (memq modifier '(at colon-at)) (>= number 0))
(set! numlen (+ numlen 1)))
(when (memq modifier '(colon colon-at))
(set! numlen (+ (quotient (- numstr-len
(if (< number 0) 2 1))
commawidth)
numlen)))
(when (> mincol numlen)
(put-fill-chars (- mincol numlen) padchar))))
(when (and (memq modifier '(at colon-at))
(>= number 0))
(put-char #\+))
(if (memq modifier '(colon colon-at)) ; insert comma character
(let ((start (remainder numstr-len commawidth))
(ns (if (< number 0) 1 0)))
(put-substring numstr 0 start)
(do ((i start (+ i commawidth)))
((>= i numstr-len))
(when (> i ns)
(put-char commachar))
(put-substring numstr i (+ i commawidth))))
(put-string numstr)))))))
(define (format:tabulate modifier pars)
(let ((l (length pars)))
(let ((colnum (format:par pars l 0 1 "colnum"))
(colinc (format:par pars l 1 1 "colinc"))
(padch (integer->char (format:par pars l 2 format:space-ch #f))))
(case modifier
((colon colon-at)
(format-error "unsupported modifier for ~~t"))
((at) ; relative tabulation
(put-fill-chars
(if (= colinc 0)
colnum ; colnum = colrel
(do ((c 0 (+ c colinc))
(col (+ %output-col colnum)))
((>= c col)
(- c %output-col))))
padch))
(else ; absolute tabulation
(put-fill-chars
(cond
((< %output-col colnum)
(- colnum %output-col))
((= colinc 0)
0)
(else
(do ((c colnum (+ c colinc)))
((>= c %output-col)
(- c %output-col)))))
padch))))))
;; roman numerals (from dorai@cs.rice.edu).
(define format:roman-alist
'((1000 #\M) (500 #\D) (100 #\C) (50 #\L)
(10 #\X) (5 #\V) (1 #\I)))
(define format:roman-boundary-values
'(100 100 10 10 1 1 #f))
(define (format:num->old-roman n)
(if (and (integer? n) (>= n 1))
(let loop ((n n)
(romans format:roman-alist)
(s '()))
(if (null? romans)
(list->string (reverse s))
(let ((roman-val (caar romans))
(roman-dgt (cadar romans)))
(do ((q (quotient n roman-val) (- q 1))
(s s (cons roman-dgt s)))
((= q 0)
(loop (remainder n roman-val)
(cdr romans) s))))))
(format-error "only positive integers can be romanized")))
(define (format:num->roman n)
(unless (and (integer? n) (> n 0))
(format-error "only positive integers can be romanized"))
(let loop ((n n)
(romans format:roman-alist)
(boundaries format:roman-boundary-values)
(s '()))
(if (null? romans)
(list->string (reverse s))
(let ((roman-val (caar romans))
(roman-dgt (cadar romans))
(bdry (car boundaries)))
(let loop2 ((q (quotient n roman-val))
(r (remainder n roman-val))
(s s))
(if (= q 0)
(if (and bdry (>= r (- roman-val bdry)))
(loop (remainder r bdry) (cdr romans)
(cdr boundaries)
(cons roman-dgt
(append
(cdr (assv bdry romans))
s)))
(loop r (cdr romans) (cdr boundaries) s))
(loop2 (- q 1) r (cons roman-dgt s))))))))
;; cardinals & ordinals (from dorai@cs.rice.edu)
(define format:cardinal-ones-list
'(#f "one" "two" "three" "four" "five"
"six" "seven" "eight" "nine" "ten" "eleven" "twelve" "thirteen"
"fourteen" "fifteen" "sixteen" "seventeen" "eighteen"
"nineteen"))
(define format:cardinal-tens-list
'(#f #f "twenty" "thirty" "forty" "fifty" "sixty" "seventy" "eighty"
"ninety"))
(define (format:num->cardinal999 n)
;; this procedure is inspired by the Bruno Haible's CLisp
;; function format-small-cardinal, which converts numbers
;; in the range 1 to 999, and is used for converting each
;; thousand-block in a larger number
(let* ((hundreds (quotient n 100))
(tens+ones (remainder n 100))
(tens (quotient tens+ones 10))
(ones (remainder tens+ones 10)))
(append
(if (> hundreds 0)
(append
(string->list
(list-ref format:cardinal-ones-list hundreds))
(string->list" hundred")
(if (> tens+ones 0) '(#\space) '()))
'())
(if (< tens+ones 20)
(if (> tens+ones 0)
(string->list
(list-ref format:cardinal-ones-list tens+ones))
'())
(append
(string->list
(list-ref format:cardinal-tens-list tens))
(if (> ones 0)
(cons #\-
(string->list
(list-ref format:cardinal-ones-list ones)))
'()))))))
(define format:cardinal-thousand-block-list
'("" " thousand" " million" " billion" " trillion" " quadrillion"
" quintillion" " sextillion" " septillion" " octillion" " nonillion"
" decillion" " undecillion" " duodecillion" " tredecillion"
" quattuordecillion" " quindecillion" " sexdecillion" " septendecillion"
" octodecillion" " novemdecillion" " vigintillion"))
(define (format:num->cardinal n)
(cond ((not (integer? n))
(format-error
"only integers can be converted to English cardinals"))
((= n 0) "zero")
((< n 0) (string-append "minus " (format:num->cardinal (- n))))
(else
(let ((power3-word-limit
(length format:cardinal-thousand-block-list)))
(let loop ((n n)
(power3 0)
(s '()))
(if (= n 0)
(list->string s)
(let ((n-before-block (quotient n 1000))
(n-after-block (remainder n 1000)))
(loop n-before-block
(+ power3 1)
(if (> n-after-block 0)
(append
(if (> n-before-block 0)
(string->list ", ")
'())
(format:num->cardinal999 n-after-block)
(if (< power3 power3-word-limit)
(string->list
(list-ref
format:cardinal-thousand-block-list
power3))
(append
(string->list " times ten to the ")
(string->list
(format:num->ordinal
(* power3 3)))
(string->list " power")))
s)
s)))))))))
(define format:ordinal-ones-list
'(#f "first" "second" "third" "fourth" "fifth"
"sixth" "seventh" "eighth" "ninth" "tenth" "eleventh" "twelfth"
"thirteenth" "fourteenth" "fifteenth" "sixteenth" "seventeenth"
"eighteenth" "nineteenth"))
(define format:ordinal-tens-list
'(#f #f "twentieth" "thirtieth" "fortieth" "fiftieth" "sixtieth"
"seventieth" "eightieth" "ninetieth"))
(define (format:num->ordinal n)
(cond ((not (integer? n))
(format-error
"only integers can be converted to English ordinals"))
((= n 0) "zeroth")
((< n 0) (string-append "minus " (format:num->ordinal (- n))))
(else
(let ((hundreds (quotient n 100))
(tens+ones (remainder n 100)))
(string-append
(if (> hundreds 0)
(string-append
(format:num->cardinal (* hundreds 100))
(if (= tens+ones 0) "th" " "))
"")
(if (= tens+ones 0)
""
(if (< tens+ones 20)
(list-ref format:ordinal-ones-list tens+ones)
(let ((tens (quotient tens+ones 10))
(ones (remainder tens+ones 10)))
(if (= ones 0)
(list-ref format:ordinal-tens-list tens)
(string-append
(list-ref format:cardinal-tens-list tens)
"-"
(list-ref format:ordinal-ones-list ones))))
)))))))
;; format inf and nan.
(define (format:out-inf-nan number width digits edigits overch padch)
;; inf and nan are always printed exactly as "+inf.0", "-inf.0" or
;; "+nan.0", suitably justified in their field. We insist on
;; printing this exact form so that the numbers can be read back in.
(let* ((str (number->string number))
(len (string-length str))
(dot (string-index str #\.))
(digits (+ (or digits 0)
(if edigits (+ edigits 2) 0))))
(if (and width overch (< width len))
(put-fill-chars width (integer->char overch))
(let* ((leftpad (if width
(max (- width (max len (+ dot 1 digits))) 0)
0))
(rightpad (if width
(max (- width leftpad len) 0)
0))
(padch (integer->char (or padch format:space-ch))))
(put-fill-chars leftpad padch)
(put-string str)
(put-fill-chars rightpad padch)))))
;; format fixed flonums (~F)
(define (format:out-fixed modifier number pars)
(unless (or (number? number) (string? number))
(format-error "argument is not a number or a number string"))
(let ((l (length pars)))
(let ((width (format:par pars l 0 #f "width"))
(digits (format:par pars l 1 #f "digits"))
(scale (format:par pars l 2 0 #f))
(overch (format:par pars l 3 #f #f))
(padch (format:par pars l 4 format:space-ch #f)))
(cond
((and (number? number)
(or (inf? number) (nan? number)))
(format:out-inf-nan number width digits #f overch padch))
(digits
(format:parse-float number #t scale)
(if (<= (- format:fn-len format:fn-dot) digits)
(format:fn-zfill #f (- digits (- format:fn-len format:fn-dot)))
(format:fn-round digits))
(if width
(let ((numlen (+ format:fn-len 1)))
(when (or (not format:fn-pos?) (eq? modifier 'at))
(set! numlen (+ numlen 1)))
(when (and (= format:fn-dot 0) (> width (+ digits 1)))
(set! numlen (+ numlen 1)))
(when (< numlen width)
(put-fill-chars (- width numlen) (integer->char padch)))
(if (and overch (> numlen width))
(put-fill-chars width (integer->char overch))
(format:fn-out modifier (> width (+ digits 1)))))
(format:fn-out modifier #t)))
(else
(format:parse-float number #t scale)
(format:fn-strip)
(if width
(let ((numlen (+ format:fn-len 1)))
(when (or (not format:fn-pos?) (eq? modifier 'at))
(set! numlen (+ numlen 1)))
(when (= format:fn-dot 0)
(set! numlen (+ numlen 1)))
(when (< numlen width)
(put-fill-chars (- width numlen) (integer->char padch)))
(if (> numlen width) ; adjust precision if possible
(let ((dot-index (- numlen
(- format:fn-len format:fn-dot))))
(if (> dot-index width)
(if overch ; numstr too big for required width
(put-fill-chars width (integer->char overch))
(format:fn-out modifier #t))
(begin
(format:fn-round (- width dot-index))
(format:fn-out modifier #t))))
(format:fn-out modifier #t)))
(format:fn-out modifier #t)))))))
;; format exponential flonums (~E)
(define (format:out-expon modifier number pars)
(unless (or (number? number) (string? number))
(format-error "argument is not a number"))
(let ((l (length pars)))
(let ((width (format:par pars l 0 #f "width"))
(digits (format:par pars l 1 #f "digits"))
(edigits (format:par pars l 2 #f "exponent digits"))
(scale (format:par pars l 3 1 #f))
(overch (format:par pars l 4 #f #f))
(padch (format:par pars l 5 format:space-ch #f))
(expch (format:par pars l 6 #f #f)))
(cond
((and (number? number)
(or (inf? number) (nan? number)))
(format:out-inf-nan number width digits edigits overch padch))
(digits ; fixed precision
(let ((digits (if (> scale 0)
(if (< scale (+ digits 2))
(+ (- digits scale) 1)
0)
digits)))
(format:parse-float number #f scale)
(if (<= (- format:fn-len format:fn-dot) digits)
(format:fn-zfill #f (- digits (- format:fn-len format:fn-dot)))
(format:fn-round digits))
(if width
(if (and edigits overch (> format:en-len edigits))
(put-fill-chars width (integer->char overch))
(let ((numlen (+ format:fn-len 3))) ; .E+
(when (or (not format:fn-pos?) (eq? modifier 'at))
(set! numlen (+ numlen 1)))
(when (and (= format:fn-dot 0) (> width (+ digits 1)))
(set! numlen (+ numlen 1)))
(set! numlen
(+ numlen
(if (and edigits (>= edigits format:en-len))
edigits
format:en-len)))
(when (< numlen width)
(put-fill-chars (- width numlen)
(integer->char padch)))
(if (and overch (> numlen width))
(put-fill-chars width (integer->char overch))
(begin
(format:fn-out modifier (> width (- numlen 1)))
(format:en-out edigits expch)))))
(begin
(format:fn-out modifier #t)
(format:en-out edigits expch)))))
(else
(format:parse-float number #f scale)
(format:fn-strip)
(if width
(if (and edigits overch (> format:en-len edigits))
(put-fill-chars width (integer->char overch))
(let ((numlen (+ format:fn-len 3))) ; .E+
(when (or (not format:fn-pos?) (eq? modifier 'at))
(set! numlen (+ numlen 1)))
(when (= format:fn-dot 0)
(set! numlen (+ numlen 1)))
(set! numlen
(+ numlen
(if (and edigits (>= edigits format:en-len))
edigits
format:en-len)))
(when (< numlen width)
(put-fill-chars (- width numlen)
(integer->char padch)))
(if (> numlen width) ; adjust precision if possible
(let ((f (- format:fn-len format:fn-dot))) ; fract len
(if (> (- numlen f) width)
(if overch ; numstr too big for required width
(put-fill-chars width
(integer->char overch))
(begin
(format:fn-out modifier #t)
(format:en-out edigits expch)))
(begin
(format:fn-round (+ (- f numlen) width))
(format:fn-out modifier #t)
(format:en-out edigits expch))))
(begin
(format:fn-out modifier #t)
(format:en-out edigits expch)))))
(begin
(format:fn-out modifier #t)
(format:en-out edigits expch))))))))
;; format general flonums (~G)
(define (format:out-general modifier number pars)
(unless (or (number? number) (string? number))
(format-error "argument is not a number or a number string"))
(let ((l (length pars)))
(let ((width (if (> l 0) (list-ref pars 0) #f))
(digits (if (> l 1) (list-ref pars 1) #f))
(edigits (if (> l 2) (list-ref pars 2) #f))
(overch (if (> l 4) (list-ref pars 4) #f))
(padch (if (> l 5) (list-ref pars 5) #f)))
(cond
((and (number? number)
(or (inf? number) (nan? number)))
;; FIXME: this isn't right.
(format:out-inf-nan number width digits edigits overch padch))
(else
(format:parse-float number #t 0)
(format:fn-strip)
(let* ((ee (if edigits (+ edigits 2) 4)) ; for the following algorithm
(ww (if width (- width ee) #f)) ; see Steele's CL book p.395
(n (if (= format:fn-dot 0) ; number less than (abs 1.0) ?
(- (format:fn-zlead))
format:fn-dot))
(d (if digits
digits
(max format:fn-len (min n 7)))) ; q = format:fn-len
(dd (- d n)))
(if (<= 0 dd d)
(begin
(format:out-fixed modifier number (list ww dd #f overch padch))
(put-fill-chars ee #\space)) ;~@T not implemented yet
(format:out-expon modifier number pars))))))))
;; format dollar flonums (~$)
(define (format:out-dollar modifier number pars)
(unless (or (number? number) (string? number))
(format-error "argument is not a number or a number string"))
(let ((l (length pars)))
(let ((digits (format:par pars l 0 2 "digits"))
(mindig (format:par pars l 1 1 "mindig"))
(width (format:par pars l 2 0 "width"))
(padch (format:par pars l 3 format:space-ch #f)))
(cond
((and (number? number)
(or (inf? number) (nan? number)))
(format:out-inf-nan number width digits #f #f padch))
(else
(format:parse-float number #t 0)
(if (<= (- format:fn-len format:fn-dot) digits)
(format:fn-zfill #f (- digits (- format:fn-len format:fn-dot)))
(format:fn-round digits))
(let ((numlen (+ format:fn-len 1)))
(when (or (not format:fn-pos?) (memq modifier '(at colon-at)))
(set! numlen (+ numlen 1)))
(when (and mindig (> mindig format:fn-dot))
(set! numlen (+ numlen (- mindig format:fn-dot))))
(when (and (= format:fn-dot 0) (not mindig))
(set! numlen (+ numlen 1)))
(if (< numlen width)
(case modifier
((colon)
(unless format:fn-pos?
(put-char #\-))
(put-fill-chars (- width numlen) (integer->char padch)))
((at)
(put-fill-chars (- width numlen) (integer->char padch))
(put-char (if format:fn-pos? #\+ #\-)))
((colon-at)
(put-char (if format:fn-pos? #\+ #\-))
(put-fill-chars (- width numlen) (integer->char padch)))
(else
(put-fill-chars (- width numlen) (integer->char padch))
(unless format:fn-pos?
(put-char #\-))))
(if format:fn-pos?
(when (memq modifier '(at colon-at))
(put-char #\+))
(put-char #\-))))
(when (and mindig (> mindig format:fn-dot))
(put-fill-chars (- mindig format:fn-dot) #\0))
(when (and (= format:fn-dot 0) (not mindig))
(put-char #\0))
(put-substring format:fn-str 0 format:fn-dot)
(put-char #\.)
(put-substring format:fn-str format:fn-dot format:fn-len))))))
; the flonum buffers
(define format:fn-max 400) ; max. number of number digits
(define format:fn-str (make-string format:fn-max)) ; number buffer
(define format:fn-len 0) ; digit length of number
(define format:fn-dot #f) ; dot position of number
(define format:fn-pos? #t) ; number positive?
(define format:en-max 10) ; max. number of exponent digits
(define format:en-str (make-string format:en-max)) ; exponent buffer
(define format:en-len 0) ; digit length of exponent
(define format:en-pos? #t) ; exponent positive?
(define (format:parse-float num fixed? scale)
(let ((num-str (if (string? num)
num
(number->string (exact->inexact num)))))
(set! format:fn-pos? #t)
(set! format:fn-len 0)
(set! format:fn-dot #f)
(set! format:en-pos? #t)
(set! format:en-len 0)
(do ((i 0 (+ i 1))
(left-zeros 0)
(mantissa? #t)
(all-zeros? #t)
(num-len (string-length num-str))
(c #f)) ; current exam. character in num-str
((= i num-len)
(unless format:fn-dot
(set! format:fn-dot format:fn-len))
(when all-zeros?
(set! left-zeros 0)
(set! format:fn-dot 0)
(set! format:fn-len 1))
;; now format the parsed values according to format's need
(if fixed?
(begin ; fixed format m.nnn or .nnn
(when (and (> left-zeros 0) (> format:fn-dot 0))
(if (> format:fn-dot left-zeros)
(begin ; norm 0{0}nn.mm to nn.mm
(format:fn-shiftleft left-zeros)
(set! format:fn-dot (- format:fn-dot left-zeros))
(set! left-zeros 0))
(begin ; normalize 0{0}.nnn to .nnn
(format:fn-shiftleft format:fn-dot)
(set! left-zeros (- left-zeros format:fn-dot))
(set! format:fn-dot 0))))
(when (or (not (= scale 0)) (> format:en-len 0))
(let ((shift (+ scale (format:en-int))))
(cond
(all-zeros? #t)
((> (+ format:fn-dot shift) format:fn-len)
(format:fn-zfill
#f (- shift (- format:fn-len format:fn-dot)))
(set! format:fn-dot format:fn-len))
((< (+ format:fn-dot shift) 0)
(format:fn-zfill #t (- (- shift) format:fn-dot))
(set! format:fn-dot 0))
(else
(if (> left-zeros 0)
(if (<= left-zeros shift) ; shift always > 0 here
(begin
(format:fn-shiftleft left-zeros)
(set! format:fn-dot (- shift left-zeros)))
(format:fn-shiftleft shift)) ; shift out 0s
(set! format:fn-dot (+ format:fn-dot shift))))))))
(let ((negexp ; expon format m.nnnEee
(if (> left-zeros 0)
(- left-zeros format:fn-dot -1)
(if (= format:fn-dot 0) 1 0))))
(if (> left-zeros 0)
(begin ; normalize 0{0}.nnn to n.nn
(format:fn-shiftleft left-zeros)
(set! format:fn-dot 1))
(when (= format:fn-dot 0)
(set! format:fn-dot 1)))
(format:en-set (- (+ (- format:fn-dot scale) (format:en-int))
negexp))
(cond
(all-zeros?
(format:en-set 0)
(set! format:fn-dot 1))
((< scale 0) ; leading zero
(format:fn-zfill #t (- scale))
(set! format:fn-dot 0))
((> scale format:fn-dot)
(format:fn-zfill #f (- scale format:fn-dot))
(set! format:fn-dot scale))
(else
(set! format:fn-dot scale)))))
#t)
;; do body
(set! c (string-ref num-str i)) ; parse the output of number->string
(cond ; which can be any valid number
((char-numeric? c) ; representation of R4RS except
(if mantissa? ; complex numbers
(begin
(if (char=? c #\0)
(when all-zeros?
(set! left-zeros (+ left-zeros 1)))
(begin
(set! all-zeros? #f)))
(string-set! format:fn-str format:fn-len c)
(set! format:fn-len (+ format:fn-len 1)))
(begin
(string-set! format:en-str format:en-len c)
(set! format:en-len (+ format:en-len 1)))))
((or (char=? c #\-) (char=? c #\+))
(if mantissa?
(set! format:fn-pos? (char=? c #\+))
(set! format:en-pos? (char=? c #\+))))
((char=? c #\.)
(set! format:fn-dot format:fn-len))
((char=? c #\e)
(set! mantissa? #f))
((char=? c #\E)
(set! mantissa? #f))
((char-whitespace? c) #t)
((char=? c #\d) #t) ; decimal radix prefix
((char=? c #\#) #t)
(else
(format-error "illegal character `~c' in number->string" c))))))
(define (format:en-int) ; convert exponent string to integer
(if (= format:en-len 0)
0
(do ((i 0 (+ i 1))
(n 0))
((= i format:en-len)
(if format:en-pos?
n
(- n)))
(set! n (+ (* n 10) (- (char->integer (string-ref format:en-str i))
format:zero-ch))))))
(define (format:en-set en) ; set exponent string number
(set! format:en-len 0)
(set! format:en-pos? (>= en 0))
(let ((en-str (number->string en)))
(do ((i 0 (+ i 1))
(en-len (string-length en-str))
(c #f))
((= i en-len))
(set! c (string-ref en-str i))
(when (char-numeric? c)
(string-set! format:en-str format:en-len c)
(set! format:en-len (+ format:en-len 1))))))
(define (format:fn-zfill left? n) ; fill current number string with 0s
(when (> (+ n format:fn-len) format:fn-max) ; from the left or right
(format-error "number is too long to format (enlarge format:fn-max)"))
(set! format:fn-len (+ format:fn-len n))
(if left?
(do ((i format:fn-len (- i 1))) ; fill n 0s to left
((< i 0))
(string-set! format:fn-str i
(if (< i n)
#\0
(string-ref format:fn-str (- i n)))))
(do ((i (- format:fn-len n) (+ i 1))) ; fill n 0s to the right
((= i format:fn-len))
(string-set! format:fn-str i #\0))))
(define (format:fn-shiftleft n) ; shift left current number n positions
(when (> n format:fn-len)
(format-error "internal error in format:fn-shiftleft (~d,~d)"
n format:fn-len))
(do ((i n (+ i 1)))
((= i format:fn-len)
(set! format:fn-len (- format:fn-len n)))
(string-set! format:fn-str (- i n) (string-ref format:fn-str i))))
(define (format:fn-round digits) ; round format:fn-str
(set! digits (+ digits format:fn-dot))
(do ((i digits (- i 1)) ; "099",2 -> "10"
(c 5)) ; "023",2 -> "02"
((or (= c 0) (< i 0)) ; "999",2 -> "100"
(if (= c 1) ; "005",2 -> "01"
(begin ; carry overflow
(set! format:fn-len digits)
(format:fn-zfill #t 1) ; add a 1 before fn-str
(string-set! format:fn-str 0 #\1)
(set! format:fn-dot (+ format:fn-dot 1)))
(set! format:fn-len digits)))
(set! c (+ (- (char->integer (string-ref format:fn-str i))
format:zero-ch) c))
(string-set! format:fn-str i (integer->char
(if (< c 10)
(+ c format:zero-ch)
(+ (- c 10) format:zero-ch))))
(set! c (if (< c 10) 0 1))))
(define (format:fn-out modifier add-leading-zero?)
(if format:fn-pos?
(when (eq? modifier 'at)
(put-char #\+))
(put-char #\-))
(if (= format:fn-dot 0)
(when add-leading-zero?
(put-char #\0))
(put-substring format:fn-str 0 format:fn-dot))
(put-char #\.)
(put-substring format:fn-str format:fn-dot format:fn-len))
(define (format:en-out edigits expch)
(put-char (if expch (integer->char expch) #\E))
(put-char (if format:en-pos? #\+ #\-))
(when (and edigits (< format:en-len edigits))
(put-fill-chars (- edigits format:en-len) #\0))
(put-substring format:en-str 0 format:en-len))
(define (format:fn-strip) ; strip trailing zeros but one
(string-set! format:fn-str format:fn-len #\0)
(do ((i format:fn-len (- i 1)))
((or (not (char=? (string-ref format:fn-str i) #\0))
(<= i format:fn-dot))
(set! format:fn-len (+ i 1)))))
(define (format:fn-zlead) ; count leading zeros
(do ((i 0 (+ i 1)))
((or (= i format:fn-len)
(not (char=? (string-ref format:fn-str i) #\0)))
(if (= i format:fn-len) ; found a real zero
0
i))))
;;; some global functions not found in SLIB
(define (string-capitalize-first str) ; "hello" -> "Hello"
(let ((cap-str (string-copy str)) ; "hELLO" -> "Hello"
(non-first-alpha #f) ; "*hello" -> "*Hello"
(str-len (string-length str))) ; "hello you" -> "Hello you"
(do ((i 0 (+ i 1)))
((= i str-len) cap-str)
(let ((c (string-ref str i)))
(when (char-alphabetic? c)
(if non-first-alpha
(string-set! cap-str i (char-downcase c))
(begin
(set! non-first-alpha #t)
(string-set! cap-str i (char-upcase c)))))))))
(define arg-pos (format:format-work format-string format-args))
(define arg-len (length format-args))
(cond
((> arg-pos arg-len)
(set! %arg-pos (+ arg-len 1))
(display %arg-pos)
(format-error "~a missing argument~:p" (- arg-pos arg-len)))
(else
(when %flush-output?
(force-output port))
(if destination
#t
(let ((str (get-output-string port)))
(close-port port)
str)))))
;; Thanks to Shuji Narazaki
(module-set! the-root-module 'format format)