/usr/share/scsh-0.6/scsh/rdelim.scm is in scsh-common-0.6 0.6.7-8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 | ;;; Delimited readers
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; These procedures ran their inner I/O loop in a C primitive in
;;; earlier versions of scsh. In a multi-threaded environment this
;;; causes lots of trouble in case the operation would
;;; block. Therefore the current implementation runs in Scheme but
;;; operates directly on the buffer of the port for speed. This also
;;; allows us to implement the push-back behaviour without a peek/read
;;; pair.
;;;
;;; (read-delimited delims [port delim-action])
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Returns a string or the EOF object. DELIM-ACTION determines what to do
;;; with the terminating delimiter:
;;; - PEEK
;;; Leave it in the input stream for later reading.
;;; - TRIM (the default)
;;; Drop it on the floor.
;;; - CONCAT
;;; Append it to the returned string.
;;; - SPLIT
;;; Return it as a second return value.
;;;
;;; We repeatedly allocate a buffer and fill it with READ-DELIMITED!
;;; until we hit a delimiter or EOF. Each time through the loop, we
;;; double the total buffer space, so the loop terminates with a log
;;; number of reads, but uses at most double the optimal buffer space.
(define (read-delimited delims . args)
(let-optionals args ((port (current-input-port))
(delim-action 'trim))
(let ((substr (lambda (s end) ; Smart substring.
(if (= end (string-length s)) s
(substring s 0 end))))
(delims (x->char-set delims))
(gobble? (not (eq? delim-action 'peek))))
;; BUFLEN is total amount of buffer space allocated to date.
(let lp ((strs '()) (buflen 80) (buf (make-string 80)))
(receive (terminator num-read)
(%read-delimited! delims buf gobble? port)
(if terminator
;; We are done. NUM-READ is either a read count or EOF.
(let ((retval (if (and (zero? num-read)
(eof-object? terminator)
(null? strs))
terminator ; EOF -- got nothing.
;; Got something. Stick all the strings
;; together, plus the terminator if the
;; client said 'CONCAT.
(let ((s (substr buf num-read)))
(cond ((and (eq? delim-action 'concat)
(char? terminator))
(apply string-append
(reverse `(,(string terminator)
,s . ,strs))))
((null? strs) s) ; Gratuitous opt.
(else (apply string-append
(reverse (cons s strs)))))))))
(if (eq? delim-action 'split)
(values retval terminator)
retval))
;; We are not done. Loop and read in some more.
(lp (cons buf strs)
(+ buflen buflen)
(make-string buflen))))))))
;;; (read-delimited! delims buf [port delim-action start end])
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Returns:
;;; - EOF if at end of file, and a non-zero read was requested.
;;; - Integer j if that many chars read into BUF.
;;; - #f if the buffer was filled w/o finding a delimiter.
;;;
;;; DELIM-ACTION determines what to do with the terminating delimiter;
;;; it is as in READ-DELIMITED.
;;;
;;; In determining the return value, there is an ambiguous case: when the
;;; buffer is full, *and* the following char is a delimiter char or EOF.
;;; Ties are broken favoring termination over #f -- after filling the buffer,
;;; READ-DELIMITED! won't return #f until it has peeked one past the end
;;; of the buffer to ensure the next char doesn't terminate input (or is EOF).
;;; However, this rule is relaxed with delim-action = CONCAT -- if the buffer
;;; is full, READ-DELIMITED! won't wait around trying to peek at the following
;;; char to determine whether or not it is a delimiter char, since it doesn't
;;; have space to store the character anyway. It simply immediately returns #f;
;;; a following read can pick up the delimiter char.
(define (read-delimited! delims buf . args) ; [port delim-action start end]
(let-optionals args ((port (current-input-port))
(delim-action 'trim)
(start 0)
(end (string-length buf)))
(receive (terminator num-read)
(%read-delimited! delims buf
(not (eq? delim-action 'peek)) ;Gobble delim?
port
start
(if (eq? delim-action 'concat)
(- end 1) ; Room for terminator.
end))
(if terminator ; Check for buffer overflow.
(let ((retval (if (and (zero? num-read)
(eof-object? terminator))
terminator ; EOF -- got nothing.
num-read))) ; Got something.
(case delim-action
((peek trim) retval)
((split) (values retval terminator))
((concat) (cond ((char? terminator)
(string-set! buf (+ start num-read) terminator)
(+ num-read 1))
(else retval)))))
;; Buffer overflow.
(case delim-action
((peek trim) #f)
((split) (values #f #f))
((concat) (let ((last (read-char port)))
(if (char? last)
(string-set! buf (+ start num-read) last))
(and (or (eof-object? last)
(char-set-contains? (x->char-set delims)
last))
(+ num-read 1)))))))))
;;; (%read-delimited! delims buf gobble? [port start end])
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; This low-level routine uses a different interface. It returns two values:
;;; - TERMINATOR: A value describing why the read was terminated:
;;; + character or eof-object => read terminated by this value;
;;; + #f => filled buffer w/o terminating read.
;;; - NUM-READ: Number of chars read into buf.
;;;
;;; Note:
;;; - Invariant: TERMINATOR = #f => NUM-READ = END - START.
;;; - Invariant: TERMINATOR = eof-object and NUM-READ = 0 => at EOF.
;;; - When determining the TERMINATOR return value, ties are broken
;;; favoring character or the eof-object over #f. That is, if the buffer
;;; fills up, %READ-DELIMITED! will peek at one more character from the
;;; input stream to determine if it terminates the input. If so, that
;;; is returned, not #f.
;;;
;;; If GOBBLE? is true, then a terminator character is removed from
;;; the input stream. Otherwise, it is left in place for a following input
;;; operation.
(define (port-buffer-read-delimited delims buf gobble? port start end)
(obtain-port-lock port)
(let ((the-port-limit (port-limit port)))
(let lp ((i start) (lp-port-index (port-index port)))
(cond ((port-pending-eof? port)
(set-port-index! port lp-port-index)
(release-port-lock port)
(values (eof-object) (- i start)))
((>= i end)
(set-port-index! port lp-port-index)
(release-port-lock port)
(values #f (- i start)))
((< lp-port-index the-port-limit)
(let ((the-read-char
(ascii->char (byte-vector-ref
(port-buffer port) lp-port-index))))
(if (char-set-contains? delims the-read-char)
(begin
(if gobble?
(set-port-index! port (+ lp-port-index 1))
(set-port-index! port lp-port-index))
(release-port-lock port)
(values the-read-char (- i start)))
(begin
(string-set! buf i the-read-char)
(lp (+ i 1) (+ lp-port-index 1))))))
(else (set-port-index! port 0)
(set-port-limit! port 0)
(release-port-lock port)
(values 'port-buffer-exhausted (- i start)))))))
(define (%read-delimited! delims buf gobble? . args)
(let-optionals args ((port (current-input-port))
(start 0)
(end (string-length buf)))
(if (immutable? buf)
(error "Immutable buffer argument to %read-delimited!" buf))
(let ((delims (x->char-set delims)))
(let lp ((start start) (total 0))
(receive (terminator num-read)
(port-buffer-read-delimited delims buf gobble? port start end)
(if (not (eq? terminator 'port-buffer-exhausted))
(values terminator (+ num-read total))
(begin (peek-char port) ; kludge to fill the buffer
(lp (+ start num-read) (+ total num-read)))))))))
; overwrites port-index :-(
(define (push-back port char)
(byte-vector-set! (port-buffer port) (port-index port) (char->ascii char))
(set-port-limit! port (+ (port-limit port) 1)))
(define (skip-char-set skip-chars . maybe-port)
(let ((port (:optional maybe-port (current-input-port)))
(cset (x->char-set skip-chars)))
(let lp ((total 0))
(receive (succ num-read) (buffer-skip-char-set cset port)
(if (not succ)
(+ total num-read) ; eof
(begin (peek-char port) ; kludge to fill the buffer
(lp (+ total num-read))))))))
(define (buffer-skip-char-set cset port)
(let ((the-port-limit (port-limit port)))
(let lp ((lp-port-index (port-index port)) (i 0))
(cond ((port-pending-eof? port)
(set-port-index! port lp-port-index)
(values #f i))
((< lp-port-index the-port-limit)
(let ((the-read-char
(ascii->char (byte-vector-ref
(port-buffer port) lp-port-index))))
(cond ((char-set-contains? cset the-read-char)
(lp (+ lp-port-index 1) (+ i 1)))
(else
(set-port-index! port lp-port-index)
(values #f i)))))
(else (set-port-index! port 0)
(set-port-limit! port 0)
(values 'port-buffer-exhausted i))))))
;;; (read-line [port delim-action])
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Read in a line of data. Input is terminated by either a newline or EOF.
;;; The newline is trimmed from the string by default.
(define charset:newline (char-set #\newline))
(define (read-line . rest) (apply read-delimited charset:newline rest))
;;; (read-paragraph [port handle-delim])
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define blank-line-regexp (rx bos (* white) #\newline eos))
(define (read-paragraph . args)
(let-optionals args ((port (current-input-port))
(handle-delim 'trim))
;; First, skip all blank lines.
(let lp ()
(let ((line (read-line port 'concat)))
(cond ((eof-object? line)
(if (eq? handle-delim 'split) (values line line) line))
((regexp-search? blank-line-regexp line) (lp))
;; Then, read in non-blank lines.
(else
(let lp ((lines (list line)))
(let ((line (read-line port 'concat)))
(if (and (string? line)
(not (regexp-search? blank-line-regexp line)))
(lp (cons line lines))
;; Return the paragraph
(let ((->str (lambda (lns) (apply string-append (reverse lns)))))
(case handle-delim
((trim) (->str lines))
((concat)
(->str (if (eof-object? line) lines (cons line lines))))
((split)
(values (->str lines) line))
(else (error "Illegal HANDLE-DELIM parameter to READ-PARAGRAPH")))))))))))))
|