fix leftmost rotation

diff --git a/libdm/regex/parse_rx.c b/libdm/regex/parse_rx.c
index fb9406de495bf1f35fa7d75d4bb1e85d2931231f..66e16a35aed0be6f96fec959b953aab2a0ad0491 100644 (file)
--- a/libdm/regex/parse_rx.c
+++ b/libdm/regex/parse_rx.c
@@ -16,6 +16,8 @@
 #include "dmlib.h"
 #include "parse_rx.h"
 
+#include <ctype.h>
+
 struct parse_sp {              /* scratch pad for the parsing process */
        struct dm_pool *mem;
        int type;               /* token type, 0 indicates a charset */
@@ -413,24 +415,36 @@ static int _find_leftmost_common(struct rx_node *or,
        return 0;
 }
 
-static struct rx_node *_exchange_nodes(struct dm_pool *mem, struct rx_node *r, struct rx_node *left_cat, struct rx_node *right_cat, unsigned leftmost)
+/* If top node is OR, rotate from ((ab)|((ac)|d)) to (((ab)|(ac))|d) */
+static int _rotate_ors(struct rx_node *r)
+{
+       struct rx_node *old_r_right;
+
+       if (r->type == OR && r->right->type == OR) {
+               old_r_right = r->right;
+               r->right = old_r_right->right;
+               old_r_right->right = old_r_right->left;
+               old_r_right->left = r->left;
+               r->left = old_r_right;
+               return 1;
+       }
+
+       return 0;
+}
+
+static struct rx_node *_exchange_nodes(struct dm_pool *mem, struct rx_node *r,
+                                      struct rx_node *left_cat, struct rx_node *right_cat,
+                                      unsigned leftmost)
 {
-       struct rx_node *new_r, *new_cat;
+       struct rx_node *new_r;
 
-       /* FIXME Clean up leftmost */
        if (leftmost) {
-               new_r = r->right;
-               new_cat = _node(mem, CAT, left_cat->left, r);
-               if (!new_cat)
+               new_r = _node(mem, CAT, left_cat->left, r);
+               if (!new_r)
                        return_NULL;
-               new_r->left = new_cat;
 
                memcpy(left_cat, left_cat->right, sizeof(*left_cat));
-               r->right = right_cat->right;
-
-               /* FIXME Avoid this */
-               if (new_r->right == right_cat->right)
-                       new_r = new_r->left;
+               memcpy(right_cat, right_cat->right, sizeof(*right_cat));
        } else {
                new_r = _node(mem, CAT, r, right_cat->right);
                if (!new_r)
@@ -447,6 +461,8 @@ static struct rx_node *_pass(struct dm_pool *mem,
                              struct rx_node *r,
                              int *changed)
 {
+       struct rx_node *left, *right;
+
        /*
         * walk the tree, optimising every 'or' node.
         */
@@ -475,18 +491,17 @@ static struct rx_node *_pass(struct dm_pool *mem,
                if (!(r->right = _pass(mem, r->right, changed)))
                        return_NULL;
 
-               {
-                       struct rx_node *left, *right;
-
-                       if (_find_leftmost_common(r, &left, &right, 1)) {
+               if (_find_leftmost_common(r, &left, &right, 1)) {
+                       /*
+                        * If rotate_ors changes the tree, left and right are stale,
+                        * so just set 'changed' to repeat the search.
+                        */
+                       if (!_rotate_ors(r))
                                r = _exchange_nodes(mem, r, left, right, 1);
-
-                               *changed = 1;
-                       } else if (_find_leftmost_common(r, &left, &right, 0)) {
-                               r = _exchange_nodes(mem, r, left, right, 0);
-
-                               *changed = 1;
-                       }
+                       *changed = 1;
+               } else if (_find_leftmost_common(r, &left, &right, 0)) {
+                       r = _exchange_nodes(mem, r, left, right, 0);
+                       *changed = 1;
                }
                break;