PATCH: fix extension checking in termquery

[Oliver Kiddle <opk@xxxxxxx>]

Mikael pointed out to me that the extension_enabled() function was not
properly checking for the dash in the name of the extensions (thanks!).
This fixes that.

Also when looking at the code again, it occurred to me that using
"class" as a variable name is not a great idea as someone might use a
C++ compiler on it.

And when testing the changes, I found that the cursor extension
check would not apply for the next command after an assignment to
.term.extensions. This is because the assignment hasn't yet happened
when zlerefresh() is called with trashedzle set. Checking that at all
is done as an opitmisation. Having that act as a reset so the next
zlerefresh() will apply the changes works better.

It was also possible to remove some negations that were cancelling each
other out.

Oliver

diff --git a/Src/Zle/termquery.c b/Src/Zle/termquery.c
index bd601735f..f61870c29 100644
--- a/Src/Zle/termquery.c
+++ b/Src/Zle/termquery.c
@@ -659,16 +659,17 @@ system_clipput(char clip, char *content, size_t clen)
 
 /**/
 static int
-extension_enabled(const char *class, const char *ext, unsigned clen, int def)
+extension_enabled(const char *prefix, const char *ext, unsigned plen, int def)
 {
-    char **e, **elist = getaparam(EXTVAR);
+    char dash, **e, **elist = getaparam(EXTVAR);
 
     for (e = elist; e && *e; e++) {
 	int negate = (**e == '-');
-	if (strncmp(*e + negate, class, clen))
+	if (strncmp(*e + negate, prefix, plen))
 	    continue;
 
-	if (!*(*e + negate + clen) || !strcmp(*e + negate + clen + 1, ext))
+	if (!(dash = *(*e + negate + plen)) ||
+		(dash == '-' && !strcmp(*e + negate + plen + 1, ext)))
 	    return !negate;
     }
     return def;
@@ -677,7 +678,7 @@ extension_enabled(const char *class, const char *ext, unsigned clen, int def)
 
 struct extension {
     char *key, *seq[2];
-    int class, enabled;
+    int prefix, enabled;
 };
 
 static const struct extension editext[] = {
@@ -707,11 +708,11 @@ collate_seq(int sindex, int dir)
 	    int negate = (**e == '-');
 	    if (negate != enabled)
 		continue;
-	    if ((editext[i].class &&
-                !strncmp(*e + negate, editext[i].key, editext[i].class) &&
-		!*(*e + negate + editext[i].class)) ||
-		!strcmp(*e + negate + editext[i].class,
-                    editext[i].key + editext[i].class))
+	    if ((editext[i].prefix &&
+                !strncmp(*e + negate, editext[i].key, editext[i].prefix) &&
+		!*(*e + negate + editext[i].prefix)) ||
+		!strcmp(*e + negate + editext[i].prefix,
+                    editext[i].key + editext[i].prefix))
 	    {
                 enabled = !negate;
 		break;
@@ -906,12 +907,14 @@ zle_set_cursorform(void)
 	}
     }
 
-    if (!setup || trashedzle) {
+    if (trashedzle)
+	setup = 0;
+    else if (!setup) {
 	cursor_enabled_mask = 0;
 	setup = 1;
-	if (!extension_enabled("cursor", "shape", 6, 1))
+	if (extension_enabled("cursor", "shape", 6, 1))
 	    cursor_enabled_mask |= CURF_SHAPE_MASK | CURF_BLINK | CURF_STEADY;
-	if (!extension_enabled("cursor", "color", 6, 1))
+	if (extension_enabled("cursor", "color", 6, 1))
 	    cursor_enabled_mask |= CURF_COLOR_MASK;
     }
 }
@@ -953,7 +956,7 @@ cursor_form(void)
     } else
 	context = invicmdmode() ? CURC_COMMAND : (vichgflag ? CURC_INSERT : CURC_EDIT);
     want = (context == CURC_DEFAULT) ? CURF_DEFAULT : cursor_forms[context];
-    if (!(changed = (want ^ state) & ~cursor_enabled_mask))
+    if (!(changed = (want ^ state) & cursor_enabled_mask))
 	return;
 
     if (changed & CURF_HIDDEN)