abstract checks into a macro

diff --git a/src/lib/rbtree.c b/src/lib/rbtree.c
index f55945793f17c7ef7c346eb60e7f0dff5077b25e..0602c9dcb17d214ba04701ca14c25e329483a542 100644 (file)
--- a/src/lib/rbtree.c
+++ b/src/lib/rbtree.c
@@ -51,6 +51,8 @@ struct rbnode_t {
 #define NIL &sentinel     /* all leafs are sentinels */
 static rbnode_t sentinel = { NIL, NIL, NULL, BLACK, NULL};
 
+#define NOT_AT_ROOT(_node) ((_node) != NULL)
+
 struct rbtree_t {
 #ifndef NDEBUG
        uint32_t                magic;
@@ -149,7 +151,7 @@ static void rotate_left(rbtree_t *tree, rbnode_t *x)
 
        /* establish y->parent link */
        if (y != NIL) y->parent = x->parent;
-       if (x->parent) {
+       if (NOT_AT_ROOT(x->parent)) {
                if (x == x->parent->left) {
                        x->parent->left = y;
                } else {
@@ -177,7 +179,7 @@ static void rotate_right(rbtree_t *tree, rbnode_t *x)
 
        /* establish y->parent link */
        if (y != NIL) y->parent = x->parent;
-       if (x->parent) {
+       if (NOT_AT_ROOT(x->parent)) {
                if (x == x->parent->right) {
                        x->parent->right = y;
                } else {
@@ -308,7 +310,7 @@ rbnode_t *rbtree_insert_node(rbtree_t *tree, void *data)
        x->colour = RED;
 
        /* insert node in tree */
-       if (parent) {
+       if (NOT_AT_ROOT(parent)) {
                if (tree->compare(data, parent->data) <= 0) {
                        parent->left = x;
                } else {
@@ -432,7 +434,7 @@ static void rbtree_delete_internal(rbtree_t *tree, rbnode_t *z, bool skiplock)
        parent = y->parent;
        if (x != NIL) x->parent = parent;
 
-       if (parent) {
+       if (NOT_AT_ROOT(parent)) {
                if (y == parent->left) {
                        parent->left = x;
                } else {
@@ -447,7 +449,7 @@ static void rbtree_delete_internal(rbtree_t *tree, rbnode_t *z, bool skiplock)
                z->data = y->data;
                y->data = NULL;
 
-               if ((y->colour == BLACK) && parent) {
+               if ((y->colour == BLACK) && NOT_AT_ROOT(parent)) {
                        delete_fixup(tree, x, parent);
                }
 
@@ -460,7 +462,7 @@ static void rbtree_delete_internal(rbtree_t *tree, rbnode_t *z, bool skiplock)
                 */
                memcpy(y, z, sizeof(*y));
 
-               if (y->parent) {
+               if (NOT_AT_ROOT(y->parent)) {
                        if (y->parent->left == z) y->parent->left = y;
                        if (y->parent->right == z) y->parent->right = y;
                } else {
@@ -671,7 +673,7 @@ static int walk_delete_order(rbtree_t *tree, rb_walker_t compare, void *context)
                        x = x->right;
                        goto descend;
                }
-               while (x->parent) {
+               while (NOT_AT_ROOT(x->parent)) {
                        if (x->parent->left == x) {
                                x = x->parent;
                                goto visit;