Add new config options to support old-style table of contents links.

--with-id-anchor makes discount use `id=` instead of `a name=`, and
--with-anchor-default=C makes discount use the character C instead of
`.` for illegal characters in anchors.

configure.sh

@@ -10,6 +10,8 @@
 ac_help='--enable-amalloc	Enable memory allocation debugging
 --with-tabstops=N	Set tabstops to N characters (default is 4)
 --with-dl=X		Use Discount, Extra, or Both types of definition list
+--with-id-anchor	Use id= anchors for table-of-contents links
+--with-anchor-default=C	Use C instead of illegal characters in anchors
 --enable-all-features	Turn on all stable optional features
 --shared		Build shared libraries (default is static)'
 
@@ -51,6 +53,9 @@ BOTH)          AC_DEFINE 'USE_EXTRA_DL' 1
 *)             AC_FAIL "Unknown value <$WITH_DL> for --with-dl (want 'discount', 'extra', or 'both')" ;;
 esac
 
+test "$WITH_ID_ANCHOR" && AC_DEFINE 'WITH_ID_ANCHOR' 1
+AC_DEFINE 'ANCHOR_DEFAULT_CHAR' "'${WITH_ANCHOR_DEFAULT:-.}'"
+
 AC_PROG_CC
 
 test "$TRY_SHARED" && AC_COMPILER_PIC && AC_CC_SHLIBS

generate.c

@@ -1353,6 +1353,17 @@ text(MMIOT *f)
 static void
 printheader(Paragraph *pp, MMIOT *f)
 {
+#if WITH_ID_ANCHOR
+    Qprintf(f, "<h%d", pp->hnumber);
+    if ( f->flags & MKD_TOC ) {
+	Qstring(" id=\"", f);
+	mkd_string_to_anchor(T(pp->text->text),
+			     S(pp->text->text),
+			     (mkd_sta_function_t)Qchar, f, 1);
+	Qchar('"', f);
+    }
+    Qchar('>', f);
+#else
     if ( f->flags & MKD_TOC ) {
 	Qstring("<a name=\"", f);
 	mkd_string_to_anchor(T(pp->text->text),
@@ -1361,6 +1372,7 @@ printheader(Paragraph *pp, MMIOT *f)
 	Qstring("\"></a>\n", f);
     }
     Qprintf(f, "<h%d>", pp->hnumber);
+#endif
     push(T(pp->text->text), S(pp->text->text), f);
     text(f);
     Qprintf(f, "</h%d>", pp->hnumber);

mkdio.c

@@ -233,7 +233,7 @@ mkd_string_to_anchor(char *s, int len, mkd_sta_function_t outchar,
 	    if ( isalnum(c) || (c == '_') || (c == ':') || (c == '-') || (c == '.' ) )
 		(*outchar)(c, out);
 	    else
-		(*outchar)('.',out);
+		(*outchar)(ANCHOR_DEFAULT_CHAR, out);
 	}
 	else
 	    (*outchar)(c,out);

tests/toc.t

@@ -1,5 +1,10 @@
 . tests/functions.sh
 
+# don't bother to test the table of contents code
+# if we're using id= for labelling things
+#
+./markdown -V | grep ID-ANCHOR >/dev/null && exit 0
+
 title "table-of-contents support"
 
 rc=0

version.c.in

@@ -18,5 +18,7 @@ char markdown_version[] = VERSION
 #else
 		" DL=NONE"
 #endif
-
+#if WITH_ID_ANCHOR
+		" ID-ANCHOR"
+#endif
 		;