From 38cf75733ec31e720c67f5be454ba524d37112f9 Mon Sep 17 00:00:00 2001
From: JeffBezanson <jeff.bezanson@gmail.com>
Date: Mon, 26 Jan 2009 02:03:37 +0000
Subject: [PATCH] adding #; datum comment allowing #||# comments to nest

---
 femtolisp/read.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/femtolisp/read.c b/femtolisp/read.c
index 8be80b8..96c52ac 100644
--- a/femtolisp/read.c
+++ b/femtolisp/read.c
@@ -2,7 +2,8 @@ enum {
     TOK_NONE, TOK_OPEN, TOK_CLOSE, TOK_DOT, TOK_QUOTE, TOK_SYM, TOK_NUM,
     TOK_BQ, TOK_COMMA, TOK_COMMAAT, TOK_COMMADOT,
     TOK_SHARPDOT, TOK_LABEL, TOK_BACKREF, TOK_SHARPQUOTE, TOK_SHARPOPEN,
-    TOK_OPENB, TOK_CLOSEB, TOK_SHARPSYM, TOK_GENSYM, TOK_DOUBLEQUOTE
+    TOK_OPENB, TOK_CLOSEB, TOK_SHARPSYM, TOK_GENSYM, TOK_DOUBLEQUOTE,
+    TOK_SHARPSEMI
 };
 
 // defines which characters are ordinary symbol characters.
@@ -221,21 +222,37 @@ static u_int32_t peek(ios_t *f)
         }
         else if ((char)ch == '|') {
             // multiline comment
+            int commentlevel=1;
             while (1) {
                 ch = ios_getc(f);
-            hashpipe_got:
+            hashpipe_gotc:
                 if (ch == IOS_EOF)
                     lerror(ParseError, "read: eof within comment");
                 if ((char)ch == '|') {
                     ch = ios_getc(f);
-                    if ((char)ch == '#')
-                        break;
-                    goto hashpipe_got;
+                    if ((char)ch == '#') {
+                        commentlevel--;
+                        if (commentlevel == 0)
+                            break;
+                        else
+                            continue;
+                    }
+                    goto hashpipe_gotc;
+                }
+                else if ((char)ch == '#') {
+                    ch = ios_getc(f);
+                    if ((char)ch == '|')
+                        commentlevel++;
+                    else
+                        goto hashpipe_gotc;
                 }
             }
             // this was whitespace, so keep peeking
             return peek(f);
         }
+        else if ((char)ch == ';') {
+            toktype = TOK_SHARPSEMI;
+        }
         else if ((char)ch == ':') {
             // gensym
             ch = ios_getc(f);
@@ -485,6 +502,10 @@ static value_t do_read_sexpr(ios_t *f, value_t label)
     case TOK_SHARPQUOTE:
         // femtoLisp doesn't need symbol-function, so #' does nothing
         return do_read_sexpr(f, label);
+    case TOK_SHARPSEMI:
+        // datum comment
+        (void)do_read_sexpr(f, UNBOUND); // skip one
+        return do_read_sexpr(f, label);
     case TOK_OPEN:
         PUSH(NIL);
         read_list(f, &Stack[SP-1], label);