[PATCH 6/7] lib/index.cc: generalize filter state machine

[David Bremner <david@tethera.net>]

To match things more complicated than fixed strings, we need states
with multiple out arrows.
---
 lib/index.cc | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/lib/index.cc b/lib/index.cc
index 3bb1ac1c..fd66762c 100644
--- a/lib/index.cc
+++ b/lib/index.cc
@@ -122,23 +122,25 @@ do_filter (const scanner_state_t states[],
     register const char *inptr = inbuf;
     const char *inend = inbuf + inlen;
     char *outptr;
-    int next;
+    int next, current;
     (void) prespace;
 
 
     g_mime_filter_set_size (gmime_filter, inlen, FALSE);
     outptr = gmime_filter->outbuf;
 
+    current = filter->state;
     while (inptr < inend) {
-	if (*inptr >= states[filter->state].a &&
-	    *inptr <= states[filter->state].b)
-	{
-	    next = states[filter->state].next_if_match;
-	}
-	else
-	{
-	    next = states[filter->state].next_if_not_match;
-	}
+	/* do "fake transitions" until we fire a rule, or run out of rules */
+	do {
+	    if (*inptr >= states[current].a && *inptr <= states[current].b)  {
+		next = states[current].next_if_match;
+	    } else  {
+		next = states[current].next_if_not_match;
+	    }
+
+	    current = next;
+	} while (next != states[next].state);
 
 	if (filter->state < first_skipping_state)
 	    *outptr++ = *inptr;
-- 
2.11.0