[cl-json-devel] patch to improve encode-json for lists

[Henrik Hjelte]

On Thu, 2007-03-22 at 08:56 -0400, Nathan Hawkins wrote:
> This fairly simple patch seems to enable encode-json to handle alists.
Thanks. I added your first example as a testcase,
test-encode-json-nathan-hawkins

(defvar *foo* '((a . 1) (b . 2) (c . 3)))
(encode-json-to-string *foo*)
--> "{\"a\":1,\"b\":2,\"c\":3}" 

When I added your patch several other tests broke. There is a problem
with you code that you guess the type of of the list from the first
element. So I instead made a solution that works with your code and
doesn't break any tests. It is in darcs now. 

Also, I have added Pascal Bourguignons patch to darcs, so beware that
json.asd is now renamed cl-json.asd.

Thanks,
Henrik 

> 
> ;; normal lists still work
> (defvar *bar* '(1 2 3 4 5))
> (encode-json-to-string *bar*)
> --> "[1,2,3,4,5]"
> 
> ;; messed up lists of alists which contain lists also works now
> (defvar *baz* '(((a . 1) (b .2) (c . 3) (d . (1 2 3 4 5))))) 
> (encode-json-to-string *baz*)
> --> "[{\"a\":1,\"b\":[0.2],\"c\":3,\"d\":[1,2,3,4,5]}]"
> 
> ;; even better, decode-json likes the output
> (decode-json-from-string "[{\"a\":1,\"b\":[ 0.2],\"c\":3,\"d
> \":[1,2,3,4,5]}]")
> --> (((:A . 1) (:B 0.2) (:C . 3) (:D 1 2 3 4 5)))
> 
> One thing you can't do is encode a list appended to an alist. That
> won't work, and I don't know how you'd 
> encode it in JSON anyway.
> 
> Someone who's had way more sleep than I have lately should test this
> as well. But I can now both encode
> and decode lists of alists, which scratches my particular itch...
> 
> Nathan
> 
> diff -rN -u old-cl-json/src/encoder.lisp new-cl-json/src/encoder.lisp
> --- old-cl-json/src/encoder.lisp    2007-03-21 23:29:22.000000000
> -0400
> +++ new-cl-json/src/encoder.lisp    2007-03-21 23:29:22.000000000
> -0400
> @@ -25,6 +25,12 @@
>      (t (write-json-string (funcall *symbol-to-string-fn* s)
> stream))))
>  
>  (defmethod encode-json((s sequence ) stream)
> +  (if (and (consp (car s))
> +           (atom (cdar s)))
> +    (encode-json-alist s stream)
> +    (encode-json-list s stream)))
> +
> +(defun encode-json-list (s stream)
>    (let ((first-element t))
>      (write-char #\[ stream)    
>      (map nil #'(lambda (element) 
> 
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