diff options
| -rw-r--r-- | libiberty/ChangeLog | 7 | ||||
| -rw-r--r-- | libiberty/splay-tree.c | 191 |
2 files changed, 87 insertions, 111 deletions
diff --git a/libiberty/ChangeLog b/libiberty/ChangeLog index eeae1e3..6fdeba3 100644 --- a/libiberty/ChangeLog +++ b/libiberty/ChangeLog @@ -1,3 +1,10 @@ +2005-11-06 Richard Guenther <rguenther@suse.de> + + * splay-tree.c (rotate_left): New function. + (rotate_right): Likewise. + (splay_tree_splay_helper): Remove. + (splay_tree_splay): Re-implement. + 2005-10-31 Mark Kettenis <kettenis@gnu.org> * floatformat.c (floatformat_vax_aingle, floatformat_vax_double): diff --git a/libiberty/splay-tree.c b/libiberty/splay-tree.c index 311b49e..060f900 100644 --- a/libiberty/splay-tree.c +++ b/libiberty/splay-tree.c @@ -38,12 +38,11 @@ Boston, MA 02110-1301, USA. */ #include "splay-tree.h" static void splay_tree_delete_helper (splay_tree, splay_tree_node); +static inline void rotate_left (splay_tree_node *, + splay_tree_node, splay_tree_node); +static inline void rotate_right (splay_tree_node *, + splay_tree_node, splay_tree_node); static void splay_tree_splay (splay_tree, splay_tree_key); -static splay_tree_node splay_tree_splay_helper (splay_tree, - splay_tree_key, - splay_tree_node*, - splay_tree_node*, - splay_tree_node*); static int splay_tree_foreach_helper (splay_tree, splay_tree_node, splay_tree_foreach_fn, void*); @@ -107,116 +106,33 @@ splay_tree_delete_helper (splay_tree sp, splay_tree_node node) #undef VDEL } -/* Help splay SP around KEY. PARENT and GRANDPARENT are the parent - and grandparent, respectively, of NODE. */ +/* Rotate the edge joining the left child N with its parent P. PP is the + grandparents pointer to P. */ -static splay_tree_node -splay_tree_splay_helper (splay_tree sp, splay_tree_key key, - splay_tree_node *node, splay_tree_node *parent, - splay_tree_node *grandparent) +static inline void +rotate_left (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) { - splay_tree_node *next; - splay_tree_node n; - int comparison; - - n = *node; - - if (!n) - return *parent; - - comparison = (*sp->comp) (key, n->key); - - if (comparison == 0) - /* We've found the target. */ - next = 0; - else if (comparison < 0) - /* The target is to the left. */ - next = &n->left; - else - /* The target is to the right. */ - next = &n->right; - - if (next) - { - /* Continue down the tree. */ - n = splay_tree_splay_helper (sp, key, next, node, parent); - - /* The recursive call will change the place to which NODE - points. */ - if (*node != n) - return n; - } - - if (!parent) - /* NODE is the root. We are done. */ - return n; - - /* First, handle the case where there is no grandparent (i.e., - *PARENT is the root of the tree.) */ - if (!grandparent) - { - if (n == (*parent)->left) - { - *node = n->right; - n->right = *parent; - } - else - { - *node = n->left; - n->left = *parent; - } - *parent = n; - return n; - } + splay_tree_node tmp; + tmp = n->right; + n->right = p; + p->left = tmp; + *pp = n; +} - /* Next handle the cases where both N and *PARENT are left children, - or where both are right children. */ - if (n == (*parent)->left && *parent == (*grandparent)->left) - { - splay_tree_node p = *parent; - - (*grandparent)->left = p->right; - p->right = *grandparent; - p->left = n->right; - n->right = p; - *grandparent = n; - return n; - } - else if (n == (*parent)->right && *parent == (*grandparent)->right) - { - splay_tree_node p = *parent; - - (*grandparent)->right = p->left; - p->left = *grandparent; - p->right = n->left; - n->left = p; - *grandparent = n; - return n; - } +/* Rotate the edge joining the right child N with its parent P. PP is the + grandparents pointer to P. */ - /* Finally, deal with the case where N is a left child, but *PARENT - is a right child, or vice versa. */ - if (n == (*parent)->left) - { - (*parent)->left = n->right; - n->right = *parent; - (*grandparent)->right = n->left; - n->left = *grandparent; - *grandparent = n; - return n; - } - else - { - (*parent)->right = n->left; - n->left = *parent; - (*grandparent)->left = n->right; - n->right = *grandparent; - *grandparent = n; - return n; - } +static inline void +rotate_right (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) +{ + splay_tree_node tmp; + tmp = n->left; + n->left = p; + p->right = tmp; + *pp = n; } -/* Splay SP around KEY. */ +/* Bottom up splay of key. */ static void splay_tree_splay (splay_tree sp, splay_tree_key key) @@ -224,8 +140,61 @@ splay_tree_splay (splay_tree sp, splay_tree_key key) if (sp->root == 0) return; - splay_tree_splay_helper (sp, key, &sp->root, - /*grandparent=*/0, /*parent=*/0); + do { + int cmp1, cmp2; + splay_tree_node n, c; + + n = sp->root; + cmp1 = (*sp->comp) (key, n->key); + + /* Found. */ + if (cmp1 == 0) + return; + + /* Left or right? If no child, then we're done. */ + if (cmp1 < 0) + c = n->left; + else + c = n->right; + if (!c) + return; + + /* Next one left or right? If found or no child, we're done + after one rotation. */ + cmp2 = (*sp->comp) (key, c->key); + if (cmp2 == 0 + || (cmp2 < 0 && !c->left) + || (cmp2 > 0 && !c->right)) + { + if (cmp1 < 0) + rotate_left (&sp->root, n, c); + else + rotate_right (&sp->root, n, c); + return; + } + + /* Now we have the four cases of double-rotation. */ + if (cmp1 < 0 && cmp2 < 0) + { + rotate_left (&n->left, c, c->left); + rotate_left (&sp->root, n, n->left); + } + else if (cmp1 > 0 && cmp2 > 0) + { + rotate_right (&n->right, c, c->right); + rotate_right (&sp->root, n, n->right); + } + else if (cmp1 < 0 && cmp2 > 0) + { + rotate_right (&n->left, c, c->right); + rotate_left (&sp->root, n, n->left); + } + else if (cmp1 > 0 && cmp2 < 0) + { + rotate_left (&n->right, c, c->left); + rotate_right (&sp->root, n, n->right); + } + } while (1); } /* Call FN, passing it the DATA, for every node below NODE, all of |