Add the EXACT selector.

README.rst

@@ -161,7 +161,7 @@ INT xset.which(ENUM select)
 ::
 
       INT xset.which(
-            ENUM {UNIQUE, FIRST, LAST, SHORTEST, LONGEST} select=UNIQUE
+            ENUM {UNIQUE, EXACT, FIRST, LAST, SHORTEST, LONGEST} select=UNIQUE
       )
 
 Returns ...

src/patricia.c

@@ -278,6 +278,10 @@ pt_search(const struct pt_y * const restrict y,
 			match->min = y->idx;
 		if (y->idx > match->max)
 			match->max = y->idx;
+		if (*c == '\0') {
+			match->exact = y->idx;
+			return (0);
+		}
 	}
 
 	if (i < y->len)
@@ -306,6 +310,7 @@ PT_Prefixes(const struct pt_y * const restrict root,
 	match->n = 0;
 	match->min = UINT_MAX;
 	match->max = 0;
+	match->exact = UINT_MAX;
 
 	return (pt_search(root, strings, (unsigned char *)subject, match));
 }

src/patricia.h

@@ -40,6 +40,7 @@ struct match_data {
 	unsigned	*indices;
 	unsigned	limit;
 	unsigned	n;
+	unsigned	exact;
 	unsigned	min;
 	unsigned	max;
 };

src/vmod_selector.c

@@ -387,6 +387,8 @@ select(VRT_CTX, const struct match_data * const restrict match,
 		}
 		return match->indices[0];
 	}
+	if (selects == vmod_enum_EXACT)
+		return match->exact;
 	if (selects == vmod_enum_FIRST)
 		return match->min;
 	if (selects == vmod_enum_LAST)

src/vmod_selector.vcc

@@ -94,7 +94,8 @@ Example::
      # ...
   }
 
-$Method INT .which(ENUM {UNIQUE, FIRST, LAST, SHORTEST, LONGEST} select=UNIQUE)
+$Method INT .which(ENUM {UNIQUE, EXACT, FIRST, LAST, SHORTEST, LONGEST}
+		   select=UNIQUE)
 
 Returns ...