registry: avoid negating INT32_MIN

[wimlib] / src / avl_tree.c

diff --git a/src/avl_tree.c b/src/avl_tree.c
index d3afae4e2114e7de667113b433d905af98dc6c24..50ed1777cf9f52e4e78ae1dfa35d5eb51f1ba57c 100644 (file)
--- a/src/avl_tree.c
+++ b/src/avl_tree.c
@@ -4,7 +4,7 @@
  *
  * The following copying information applies to this specific source code file:
  *
- * Written in 2014 by Eric Biggers <ebiggers3@gmail.com>
+ * Written in 2014-2016 by Eric Biggers <ebiggers3@gmail.com>
  *
  * To the extent possible under law, the author(s) have dedicated all copyright
  * and related and neighboring rights to this software to the public domain
@@ -25,39 +25,80 @@
 
 #include "wimlib/avl_tree.h"
 
-/* Starts an in-order traversal of the tree: returns the least-valued node, or
- * NULL if the tree is empty.  */
-struct avl_tree_node *
-avl_tree_first_in_order(const struct avl_tree_node *root)
+/* Returns the left child (sign < 0) or the right child (sign > 0) of the
+ * specified AVL tree node.
+ * Note: for all calls of this, 'sign' is constant at compilation time,
+ * so the compiler can remove the conditional.  */
+static AVL_INLINE struct avl_tree_node *
+avl_get_child(const struct avl_tree_node *parent, int sign)
+{
+       if (sign < 0)
+               return parent->left;
+       else
+               return parent->right;
+}
+
+static AVL_INLINE struct avl_tree_node *
+avl_tree_first_or_last_in_order(const struct avl_tree_node *root, int sign)
 {
        const struct avl_tree_node *first = root;
 
        if (first)
-               while (first->left)
-                       first = first->left;
+               while (avl_get_child(first, +sign))
+                       first = avl_get_child(first, +sign);
        return (struct avl_tree_node *)first;
 }
 
-/* Continues an in-order traversal of the tree: returns the next-greatest-valued
- * node, or NULL if there is none.  */
+/* Starts an in-order traversal of the tree: returns the least-valued node, or
+ * NULL if the tree is empty.  */
+struct avl_tree_node *
+avl_tree_first_in_order(const struct avl_tree_node *root)
+{
+       return avl_tree_first_or_last_in_order(root, -1);
+}
+
+/* Starts a *reverse* in-order traversal of the tree: returns the
+ * greatest-valued node, or NULL if the tree is empty.  */
 struct avl_tree_node *
-avl_tree_next_in_order(const struct avl_tree_node *prev)
+avl_tree_last_in_order(const struct avl_tree_node *root)
+{
+       return avl_tree_first_or_last_in_order(root, 1);
+}
+
+static AVL_INLINE struct avl_tree_node *
+avl_tree_next_or_prev_in_order(const struct avl_tree_node *node, int sign)
 {
        const struct avl_tree_node *next;
 
-       if (prev->right)
-               for (next = prev->right;
-                    next->left;
-                    next = next->left)
+       if (avl_get_child(node, +sign))
+               for (next = avl_get_child(node, +sign);
+                    avl_get_child(next, -sign);
+                    next = avl_get_child(next, -sign))
                        ;
        else
-               for (next = avl_get_parent(prev);
-                    next && prev == next->right;
-                    prev = next, next = avl_get_parent(next))
+               for (next = avl_get_parent(node);
+                    next && node == avl_get_child(next, +sign);
+                    node = next, next = avl_get_parent(next))
                        ;
        return (struct avl_tree_node *)next;
 }
 
+/* Continues an in-order traversal of the tree: returns the next-greatest-valued
+ * node, or NULL if there is none.  */
+struct avl_tree_node *
+avl_tree_next_in_order(const struct avl_tree_node *node)
+{
+       return avl_tree_next_or_prev_in_order(node, 1);
+}
+
+/* Continues a *reverse* in-order traversal of the tree: returns the
+ * previous-greatest-valued node, or NULL if there is none.  */
+struct avl_tree_node *
+avl_tree_prev_in_order(const struct avl_tree_node *node)
+{
+       return avl_tree_next_or_prev_in_order(node, -1);
+}
+
 /* Starts a postorder traversal of the tree.  */
 struct avl_tree_node *
 avl_tree_first_in_postorder(const struct avl_tree_node *root)
@@ -89,19 +130,6 @@ avl_tree_next_in_postorder(const struct avl_tree_node *prev,
        return (struct avl_tree_node *)next;
 }
 
-/* Returns the left child (sign < 0) or the right child (sign > 0) of the
- * specified AVL tree node.
- * Note: for all calls of this, 'sign' is constant at compilation time,
- * so the compiler can remove the conditional.  */
-static AVL_INLINE struct avl_tree_node *
-avl_get_child(const struct avl_tree_node *parent, int sign)
-{
-       if (sign < 0)
-               return parent->left;
-       else
-               return parent->right;
-}
-
 /* Sets the left child (sign < 0) or the right child (sign > 0) of the
  * specified AVL tree node.
  * Note: for all calls of this, 'sign' is constant at compilation time,
@@ -705,8 +733,7 @@ avl_tree_swap_with_successor(struct avl_tree_node **root_ptr,
  *     remove from the tree.
  *
  * Note: This function *only* removes the node and rebalances the tree.
- * It does not free any memory, nor does it do the equivalent of
- * avl_tree_node_set_unlinked().
+ * It does not free any memory.
  */
 void
 avl_tree_remove(struct avl_tree_node **root_ptr, struct avl_tree_node *node)