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Fixes for unquote-splicing

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Justin Ethier 2015-05-28 22:39:21 -04:00
parent 49d6bc3213
commit 8ddce6b5bc
2 changed files with 25 additions and 24 deletions
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31
parser.scm
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@ -223,34 +223,35 @@
(in-port:set-buf! ptbl c)
(car (add-tok (->tok tok) toks quotes)))
(else
;; TODO: this is not good enough for unquote-splicing as
;; that construct requires reading two chars ,@
;; need a way of peeking at the next char here, either
;; via peek-char, or perhaps better by having a larger buffer
;; of input chars.
;; TODO:
; buffer must be empty now since it is only 1 char, so
; call read-char. then:
; - @ - unquote-splicing processing
; - eof - error
; - otherwise, add char back to buffer and do unquote processing
;
; can test this below for unquote by doing the read-char and adding
; back to the buffer
;; Read the next expression and wrap it in a quote
(letrec ((sub (parse fp '() '() #f #f #f 0 ptbl))
(letrec ((sub #f)
(next-c (read-char fp))
(unquote-sym (if (equal? next-c #\@) 'unquote-splicing 'unquote))
(new-toks
(new-toks #f))
;; Buffer read-ahead char, if unused
(cond
((eof-object? next-c)
(parse-error "unexpected end of file"
(in-port:get-lnum ptbl)
(in-port:get-cnum ptbl)))
((not (equal? next-c #\@))
(in-port:set-buf! ptbl next-c))
(else #f))
(set! sub (parse fp '() '() #f #f #f 0 ptbl))
(set! new-toks
(add-tok
(list unquote-sym sub)
(get-toks tok toks quotes)
quotes)))
;; Buffer read-ahead char, if unused
(if (not (equal? next-c #\@))
(in-port:set-buf! ptbl next-c))
quotes))
;; Keep going
(if all?

4
test.scm
View file

@ -3,5 +3,5 @@
(write `(read ,(+ 1 2 3)))
(write `(read ,(list 1 2 3)))
;(write `(read ,@(list 1 2 3)))
(write `(read ,@(list 1 2 3)))
;`(read ,