json: support Lisp comments.

I've run into situations in which I wanted a comment in a
big JSON quasiliteral to explain some embedded piece of code.
We support only semicolon comments, and no #; ignore notation.

* parser.l (grammar): Recognize Lisp comments in the JSON
state also. That does it.

* tests/010/json.tl: One modest little test.

* txr.1: Documented.

* lex.yy.c.shipped: Regenerated.

1 files changed, 13 insertions, 0 deletions

diff --git a/txr.1 b/txr.1
index a0776343..053797bf 100644
--- a/txr.1
+++ b/txr.1
@@ -13074,6 +13074,13 @@ is accepted.
 \*(TL allows the circle notation to occur within JSON syntax. See the section
 Notation for Circular and Shared Structure.
 
+\*(TL supports the extension of Lisp comments in JSON. When the
+.code ;
+character (semicolon) occurs in the middle of JSON syntax, outside
+of a token, that character and all characters until the end of the line
+constitute a comment that is discarded. \*(TL never produces comments
+when printing JSON.
+
 \*(TL allows for JSON syntax to be quasiquoted, and provides two extensions
 for writing unquotes and splicing unquotes. Within a JSON quasiquote, the
 .code ~
@@ -13122,6 +13129,12 @@ symbols or structures. These objects have no representation in JSON syntax.
 
   (eval ^#J[~*(list 1.0 2.0 3.0), ~(* 2.0 2), 5.0])
   --> #(1.0 2.0 3.0 4.0 5.0)
+
+  ;; Comment extension
+  #J[1, ; Comment inside JSON.
+     2, ; Another one.
+     3] ; Lisp comment outside of JSON.
+  --> #(1.0 2.0 3.0)
 .brev
 
 .coNP The @ .. notation