I have a file: test.lisp
with this content:
( 3 3)
(let ((n 3)) ( n 1))
(let ((n 4))
( n 1))
(defun d (f)
(let ((n 3)
(f 4)
(g 3))
(if (= n 0)
( n f g)
(* n f g))))
I am trying to read the file like this:
(let ((in (open dd)))
(when in
(loop for line = (read-line in nil)
while line do (format t "~a~%" line))
(close in)))
which gives me the apparent correct output:
( 3 3)
(let ((n 3)) ( n 1))
(let ((n 4))
( n 1))
(defun d (f)
(let ((n 3)
(f 4)
(g 3))
(if (= n 0)
( n f g)
(* n f g))))
I want to call my function parse-exp
on each line of the file corresponding to each expression above.
From a different answer here on Stackoverflow I tried to do this:
* (defun get-file (filename)
(let ((in (open filename)))
(loop for line = (read-line in nil)
while line
collect line)))
GET-FILE
* (get-file dd)
("( 3 3)" "" "(let ((n 3)) ( n 1))" "" "(let ((n 4))" " ( n 1))" ""
"(defun d (f)" " (let ((n 3)" " (f 4)" " (g 3))" " (if (= n 0)"
" ( n f g)" " (* n f g))))")
which converts each line to a string and its not in the format that I want.
I also tried doing this:
(uiop:read-file-lines "file.txt")
but I get the same output as the previous example.
I want to be able to use each line/expression as input to parse-exp
- like this:
(parse-exp '( 3 3))
or
(parse-exp '(let ((n 3)) ( n 1)))
and so on.
How do I do this?
Thanks.
CodePudding user response:
What you search for is read
instead of read-line
which reads expression-wise (and is used by lisp interpreters).
(with-open-file (stream "test1.lisp")
(loop for expr = (read stream nil 'eof)
until (eq expr 'eof)
collect expr))
;; (( 3 3) (LET ((N 3)) ( N 1)) (LET ((N 4)) ( N 1))
;; (DEFUN D (F) (LET ((N 3) (F 4) (G 3)) (IF (= N 0) ( N F G) (* N F G)))))
;; every element is an expression.
If you want the expressions to be strings instead of list of symbols, use (format nil "~a" ...)
:
(with-open-file (stream "test1.lisp")
(loop for expr = (read stream nil 'eof)
until (eq expr 'eof)
collect (format nil "~a" expr)))
;; ("( 3 3)" "(LET ((N 3)) ( N 1))" "(LET ((N 4)) ( N 1))"
;; "(DEFUN D (F) (LET ((N 3) (F 4) (G 3)) (IF (= N 0) ( N F G) (* N F G))))")