tree: change type and size of the extra field

Instead of using a bool, let's use a 2-bit unsigned int.  Having two bits
will clearly be enough for red-black trees, but it will also allow AVL trees
(which need to store 3 states per node) to be implemented later on.

Signed-off-by: Josef 'Jeff' Sipek <[email protected]>

Author: jeffpc

include/jeffpc/tree_private.h

@@ -30,7 +30,7 @@
 struct tree_node {
 	struct tree_node *children[2];
 	struct tree_node *_parent;
-	bool _extra;
+	unsigned int _extra:2;
 };
 
 struct tree_tree {

tree.c

@@ -141,7 +141,7 @@ static inline void __swap_nodes(struct tree_tree *tree,
 	const enum tree_dir right = 1 - left;
 	const bool root = tree->root == x;
 	enum tree_dir dir_to_orig_x;
-	bool tmp;
+	unsigned int tmp;
 
 	ASSERT3P(x, !=, y);
 	ASSERT3P(y->children[left], ==, NULL);

tree_impl.h

@@ -51,12 +51,12 @@ static inline void set_parent(struct tree_node *node, struct tree_node *parent)
 	node->_parent = parent;
 }
 
-static inline bool get_extra(struct tree_node *node)
+static inline unsigned int get_extra(struct tree_node *node)
 {
 	return node->_extra;
 }
 
-static inline void set_extra(struct tree_node *node, bool extra)
+static inline void set_extra(struct tree_node *node, unsigned int extra)
 {
 	node->_extra = extra;
 }