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From: Vinay on 11 Mar 2010 22:06
i need to create a string containing the contents of a stream until i
reach eof. can anyone show me how this is done.

i found this in the cl cookbook ...

(with-open-file (stream "/etc/passwd")
(do ((line (read-line stream nil)
(read-line stream nil)))
((null line))
(print line)))

i need to accumulate the lines being read into a single string ...
From: Vassil Nikolov on 11 Mar 2010 22:53

On Thu, 11 Mar 2010 19:06:12 -0800, Vinay <vinay(a)vmmenon.org> said:

> i need to create a string containing the contents of a stream until i
> reach eof.
> ...
> (with-open-file (stream "/etc/passwd")
> (do ((line (read-line stream nil)
> (read-line stream nil)))
> ((null line))
> (print line)))

Do the above inside WITH-OUTPUT-TO-STRING, writing everything read
to the string output stream.

By the way, consider also something along the lines of

(loop for line = (read-line stream nil) while line
do (print line))

---Vassil.


--
No flies need shaving.
From: refun on 11 Mar 2010 22:58
Here's another way using a fill-pointer:

(defun read-stream-to-string (stream)
(let ((string (make-array (file-length stream)
:element-type 'character
:initial-element #\Space
:fill-pointer 0)))
(loop for char = (read-char stream nil 'done)
until (eql char 'done)
do (vector-push char string)
finally (return string))))

(with-open-file (s #p"path goes here")
(read-stream-to-string s))

It makes an array of file-length size, but keeps a fill-pointer of 0, then
pushes each character into the array.

Is this the way to keep down the consing and avoid copying the array data
pointlessly?
From: Vassil Nikolov on 11 Mar 2010 23:12

On Fri, 12 Mar 2010 03:58:53 +0000 (UTC), refun <refun(a)nospam.gmx.com> said:

> Here's another way using a fill-pointer:
> (defun read-stream-to-string (stream)
> (let ((string (make-array (file-length stream)
> :element-type 'character
> :initial-element #\Space
> :fill-pointer 0)))
> (loop for char = (read-char stream nil 'done)
> until (eql char 'done)
> do (vector-push char string)
> finally (return string))))

Change to ``(OR (FILE-LENGTH STREAM) 0)'', add ``:ADJUSTABLE T'',
and use VECTOR-PUSH-EXTEND to degrade gracefully when the input
stream's length cannot be determined or when the file grows while
being read.

---Vassil.


--
No flies need shaving.
From: milanj on 12 Mar 2010 03:10
what about using something like this:

(let ((string (make-array (file-stream stream) :element-type
'character)))
(read-sequence string stream)
(string))
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