[no subject]

[Mark Oteiza]

Hi,

I wrote the following to get rid of the 'apply' here.  The
expansion is something that, according to how byte-switch is described,
should compile to a switch/jumptable, but it isn't happening.

Applying the following, doing M-x byte-compile-file, and inspecting the
.elc/disassembly I am seeing a series of goto-if-nil.  Am I doing
something wrong?

diff --git a/lisp/json.el b/lisp/json.el
index 64486258cc..6990ddd0f5 100644
--- a/lisp/json.el
+++ b/lisp/json.el
@@ -683,6 +683,23 @@ json-readtable
     table)
   "Readtable for JSON reader.")
 
+(defmacro json-readtable-dispatch (char)
+  "Dispatch reader function for CHAR."
+  (declare (debug (symbolp)))
+  (let ((table
+         '((?t json-read-keyword "true")
+           (?f json-read-keyword "false")
+           (?n json-read-keyword "null")
+           (?{ json-read-object)
+           (?\[ json-read-array)
+           (?\" json-read-string)))
+        res)
+    (dolist (c '(?- ?+ ?. ?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9))
+      (push (list c 'json-read-number) table))
+    (pcase-dolist (`(,c . ,rest) table)
+      (push `((= ,char ,c) (,@rest)) res))
+    `(cond ,@res (t (signal 'json-readtable-error ,char)))))
+
 (defun json-read ()
   "Parse and return the JSON object following point.
 Advances point just past JSON object."
@@ -690,10 +707,7 @@ json-read
   (let ((char (json-peek)))
     (if (zerop char)
         (signal 'json-end-of-file nil)
-      (let ((record (cdr (assq char json-readtable))))
-        (if (functionp (car record))
-            (apply (car record) (cdr record))
-          (signal 'json-readtable-error record))))))
+      (json-readtable-dispatch char))))
 
 ;; Syntactic sugar for the reader