/* libavl - library for manipulation of binary trees. Copyright (C) 1998-2002, 2004 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. The author may be contacted at on the Internet, or write to Ben Pfaff, Stanford University, Computer Science Dept., 353 Serra Mall, Stanford CA 94305, USA. */ #include #include #include #include "tbst.h" /* Creates and returns a new table with comparison function |compare| using parameter |param| and memory allocator |allocator|. Returns |NULL| if memory allocation failed. */ struct tbst_table * tbst_create (tbst_comparison_func *compare, void *param, struct libavl_allocator *allocator) { struct tbst_table *tree; assert (compare != NULL); if (allocator == NULL) allocator = &tbst_allocator_default; tree = allocator->libavl_malloc (allocator, sizeof *tree); if (tree == NULL) return NULL; tree->tbst_root = NULL; tree->tbst_compare = compare; tree->tbst_param = param; tree->tbst_alloc = allocator; tree->tbst_count = 0; return tree; } /* Search |tree| for an item matching |item|, and return it if found. Otherwise return |NULL|. */ void * tbst_find (const struct tbst_table *tree, const void *item) { const struct tbst_node *p; assert (tree != NULL && item != NULL); p = tree->tbst_root; if (p == NULL) return NULL; for (;;) { int cmp, dir; cmp = tree->tbst_compare (item, p->tbst_data, tree->tbst_param); if (cmp == 0) return p->tbst_data; dir = cmp > 0; if (p->tbst_tag[dir] == TBST_CHILD) p = p->tbst_link[dir]; else return NULL; } } /* Inserts |item| into |tree| and returns a pointer to |item|'s address. If a duplicate item is found in the tree, returns a pointer to the duplicate without inserting |item|. Returns |NULL| in case of memory allocation failure. */ void ** tbst_probe (struct tbst_table *tree, void *item) { struct tbst_node *p; /* Traverses tree to find insertion point. */ struct tbst_node *n; /* New node. */ int dir; /* Side of |p| on which |n| is inserted. */ assert (tree != NULL && item != NULL); if (tree->tbst_root != NULL) for (p = tree->tbst_root; ; p = p->tbst_link[dir]) { int cmp = tree->tbst_compare (item, p->tbst_data, tree->tbst_param); if (cmp == 0) return &p->tbst_data; dir = cmp > 0; if (p->tbst_tag[dir] == TBST_THREAD) break; } else { p = (struct tbst_node *) &tree->tbst_root; dir = 0; } n = tree->tbst_alloc->libavl_malloc (tree->tbst_alloc, sizeof *n); if (n == NULL) return NULL; tree->tbst_count++; n->tbst_data = item; n->tbst_tag[0] = n->tbst_tag[1] = TBST_THREAD; n->tbst_link[dir] = p->tbst_link[dir]; if (tree->tbst_root != NULL) { p->tbst_tag[dir] = TBST_CHILD; n->tbst_link[!dir] = p; } else n->tbst_link[1] = NULL; p->tbst_link[dir] = n; return &n->tbst_data; } /* Inserts |item| into |table|. Returns |NULL| if |item| was successfully inserted or if a memory allocation error occurred. Otherwise, returns the duplicate item. */ void * tbst_insert (struct tbst_table *table, void *item) { void **p = tbst_probe (table, item); return p == NULL || *p == item ? NULL : *p; } /* Inserts |item| into |table|, replacing any duplicate item. Returns |NULL| if |item| was inserted without replacing a duplicate, or if a memory allocation error occurred. Otherwise, returns the item that was replaced. */ void * tbst_replace (struct tbst_table *table, void *item) { void **p = tbst_probe (table, item); if (p == NULL || *p == item) return NULL; else { void *r = *p; *p = item; return r; } } /* Deletes from |tree| and returns an item matching |item|. Returns a null pointer if no matching item found. */ void * tbst_delete (struct tbst_table *tree, const void *item) { struct tbst_node *p; /* Node to delete. */ struct tbst_node *q; /* Parent of |p|. */ int dir; /* Index into |q->tbst_link[]| that leads to |p|. */ assert (tree != NULL && item != NULL); if (tree->tbst_root == NULL) return NULL; p = tree->tbst_root; q = (struct tbst_node *) &tree->tbst_root; dir = 0; for (;;) { int cmp = tree->tbst_compare (item, p->tbst_data, tree->tbst_param); if (cmp == 0) break; dir = cmp > 0; if (p->tbst_tag[dir] == TBST_THREAD) return NULL; q = p; p = p->tbst_link[dir]; } item = p->tbst_data; if (p->tbst_tag[1] == TBST_THREAD) { if (p->tbst_tag[0] == TBST_CHILD) { struct tbst_node *t = p->tbst_link[0]; while (t->tbst_tag[1] == TBST_CHILD) t = t->tbst_link[1]; t->tbst_link[1] = p->tbst_link[1]; q->tbst_link[dir] = p->tbst_link[0]; } else { q->tbst_link[dir] = p->tbst_link[dir]; if (q != (struct tbst_node *) &tree->tbst_root) q->tbst_tag[dir] = TBST_THREAD; } } else { struct tbst_node *r = p->tbst_link[1]; if (r->tbst_tag[0] == TBST_THREAD) { r->tbst_link[0] = p->tbst_link[0]; r->tbst_tag[0] = p->tbst_tag[0]; if (r->tbst_tag[0] == TBST_CHILD) { struct tbst_node *t = r->tbst_link[0]; while (t->tbst_tag[1] == TBST_CHILD) t = t->tbst_link[1]; t->tbst_link[1] = r; } q->tbst_link[dir] = r; } else { struct tbst_node *s; for (;;) { s = r->tbst_link[0]; if (s->tbst_tag[0] == TBST_THREAD) break; r = s; } if (s->tbst_tag[1] == TBST_CHILD) r->tbst_link[0] = s->tbst_link[1]; else { r->tbst_link[0] = s; r->tbst_tag[0] = TBST_THREAD; } s->tbst_link[0] = p->tbst_link[0]; if (p->tbst_tag[0] == TBST_CHILD) { struct tbst_node *t = p->tbst_link[0]; while (t->tbst_tag[1] == TBST_CHILD) t = t->tbst_link[1]; t->tbst_link[1] = s; s->tbst_tag[0] = TBST_CHILD; } s->tbst_link[1] = p->tbst_link[1]; s->tbst_tag[1] = TBST_CHILD; q->tbst_link[dir] = s; } } tree->tbst_alloc->libavl_free (tree->tbst_alloc, p); tree->tbst_count--; return (void *) item; } /* Initializes |trav| for use with |tree| and selects the null node. */ void tbst_t_init (struct tbst_traverser *trav, struct tbst_table *tree) { trav->tbst_table = tree; trav->tbst_node = NULL; } /* Initializes |trav| for |tree|. Returns data item in |tree| with the least value, or |NULL| if |tree| is empty. */ void * tbst_t_first (struct tbst_traverser *trav, struct tbst_table *tree) { assert (tree != NULL && trav != NULL); trav->tbst_table = tree; trav->tbst_node = tree->tbst_root; if (trav->tbst_node != NULL) { while (trav->tbst_node->tbst_tag[0] == TBST_CHILD) trav->tbst_node = trav->tbst_node->tbst_link[0]; return trav->tbst_node->tbst_data; } else return NULL; } /* Initializes |trav| for |tree|. Returns data item in |tree| with the greatest value, or |NULL| if |tree| is empty. */ void * tbst_t_last (struct tbst_traverser *trav, struct tbst_table *tree) { assert (tree != NULL && trav != NULL); trav->tbst_table = tree; trav->tbst_node = tree->tbst_root; if (trav->tbst_node != NULL) { while (trav->tbst_node->tbst_tag[1] == TBST_CHILD) trav->tbst_node = trav->tbst_node->tbst_link[1]; return trav->tbst_node->tbst_data; } else return NULL; } /* Searches for |item| in |tree|. If found, initializes |trav| to the item found and returns the item as well. If there is no matching item, initializes |trav| to the null item and returns |NULL|. */ void * tbst_t_find (struct tbst_traverser *trav, struct tbst_table *tree, void *item) { struct tbst_node *p; assert (trav != NULL && tree != NULL && item != NULL); trav->tbst_table = tree; trav->tbst_node = NULL; p = tree->tbst_root; if (p == NULL) return NULL; for (;;) { int cmp, dir; cmp = tree->tbst_compare (item, p->tbst_data, tree->tbst_param); if (cmp == 0) { trav->tbst_node = p; return p->tbst_data; } dir = cmp > 0; if (p->tbst_tag[dir] == TBST_CHILD) p = p->tbst_link[dir]; else return NULL; } } /* Attempts to insert |item| into |tree|. If |item| is inserted successfully, it is returned and |trav| is initialized to its location. If a duplicate is found, it is returned and |trav| is initialized to its location. No replacement of the item occurs. If a memory allocation failure occurs, |NULL| is returned and |trav| is initialized to the null item. */ void * tbst_t_insert (struct tbst_traverser *trav, struct tbst_table *tree, void *item) { void **p; assert (trav != NULL && tree != NULL && item != NULL); p = tbst_probe (tree, item); if (p != NULL) { trav->tbst_table = tree; trav->tbst_node = ((struct tbst_node *) ((char *) p - offsetof (struct tbst_node, tbst_data))); return *p; } else { tbst_t_init (trav, tree); return NULL; } } /* Initializes |trav| to have the same current node as |src|. */ void * tbst_t_copy (struct tbst_traverser *trav, const struct tbst_traverser *src) { assert (trav != NULL && src != NULL); trav->tbst_table = src->tbst_table; trav->tbst_node = src->tbst_node; return trav->tbst_node != NULL ? trav->tbst_node->tbst_data : NULL; } /* Returns the next data item in inorder within the tree being traversed with |trav|, or if there are no more data items returns |NULL|. */ void * tbst_t_next (struct tbst_traverser *trav) { assert (trav != NULL); if (trav->tbst_node == NULL) return tbst_t_first (trav, trav->tbst_table); else if (trav->tbst_node->tbst_tag[1] == TBST_THREAD) { trav->tbst_node = trav->tbst_node->tbst_link[1]; return trav->tbst_node != NULL ? trav->tbst_node->tbst_data : NULL; } else { trav->tbst_node = trav->tbst_node->tbst_link[1]; while (trav->tbst_node->tbst_tag[0] == TBST_CHILD) trav->tbst_node = trav->tbst_node->tbst_link[0]; return trav->tbst_node->tbst_data; } } /* Returns the previous data item in inorder within the tree being traversed with |trav|, or if there are no more data items returns |NULL|. */ void * tbst_t_prev (struct tbst_traverser *trav) { assert (trav != NULL); if (trav->tbst_node == NULL) return tbst_t_last (trav, trav->tbst_table); else if (trav->tbst_node->tbst_tag[0] == TBST_THREAD) { trav->tbst_node = trav->tbst_node->tbst_link[0]; return trav->tbst_node != NULL ? trav->tbst_node->tbst_data : NULL; } else { trav->tbst_node = trav->tbst_node->tbst_link[0]; while (trav->tbst_node->tbst_tag[1] == TBST_CHILD) trav->tbst_node = trav->tbst_node->tbst_link[1]; return trav->tbst_node->tbst_data; } } /* Returns |trav|'s current item. */ void * tbst_t_cur (struct tbst_traverser *trav) { assert (trav != NULL); return trav->tbst_node != NULL ? trav->tbst_node->tbst_data : NULL; } /* Replaces the current item in |trav| by |new| and returns the item replaced. |trav| must not have the null item selected. The new item must not upset the ordering of the tree. */ void * tbst_t_replace (struct tbst_traverser *trav, void *new) { void *old; assert (trav != NULL && trav->tbst_node != NULL && new != NULL); old = trav->tbst_node->tbst_data; trav->tbst_node->tbst_data = new; return old; } /* Creates a new node as a child of |dst| on side |dir|. Copies data from |src| into the new node, applying |copy()|, if non-null. Returns nonzero only if fully successful. Regardless of success, integrity of the tree structure is assured, though failure may leave a null pointer in a |tbst_data| member. */ static int copy_node (struct tbst_table *tree, struct tbst_node *dst, int dir, const struct tbst_node *src, tbst_copy_func *copy) { struct tbst_node *new = tree->tbst_alloc->libavl_malloc (tree->tbst_alloc, sizeof *new); if (new == NULL) return 0; new->tbst_link[dir] = dst->tbst_link[dir]; new->tbst_tag[dir] = TBST_THREAD; new->tbst_link[!dir] = dst; new->tbst_tag[!dir] = TBST_THREAD; dst->tbst_link[dir] = new; dst->tbst_tag[dir] = TBST_CHILD; if (copy == NULL) new->tbst_data = src->tbst_data; else { new->tbst_data = copy (src->tbst_data, tree->tbst_param); if (new->tbst_data == NULL) return 0; } return 1; } /* Destroys |new| with |tbst_destroy (new, destroy)|, first initializing the right link in |new| that has not yet been initialized. */ static void copy_error_recovery (struct tbst_node *p, struct tbst_table *new, tbst_item_func *destroy) { new->tbst_root = p; if (p != NULL) { while (p->tbst_tag[1] == TBST_CHILD) p = p->tbst_link[1]; p->tbst_link[1] = NULL; } tbst_destroy (new, destroy); } /* Copies |org| to a newly created tree, which is returned. If |copy != NULL|, each data item in |org| is first passed to |copy|, and the return values are inserted into the tree, with |NULL| return values taken as indications of failure. On failure, destroys the partially created new tree, applying |destroy|, if non-null, to each item in the new tree so far, and returns |NULL|. If |allocator != NULL|, it is used for allocation in the new tree. Otherwise, the same allocator used for |org| is used. */ struct tbst_table * tbst_copy (const struct tbst_table *org, tbst_copy_func *copy, tbst_item_func *destroy, struct libavl_allocator *allocator) { struct tbst_table *new; const struct tbst_node *p; struct tbst_node *q; struct tbst_node rp, rq; assert (org != NULL); new = tbst_create (org->tbst_compare, org->tbst_param, allocator != NULL ? allocator : org->tbst_alloc); if (new == NULL) return NULL; new->tbst_count = org->tbst_count; if (new->tbst_count == 0) return new; p = &rp; rp.tbst_link[0] = org->tbst_root; rp.tbst_tag[0] = TBST_CHILD; q = &rq; rq.tbst_link[0] = NULL; rq.tbst_tag[0] = TBST_THREAD; for (;;) { if (p->tbst_tag[0] == TBST_CHILD) { if (!copy_node (new, q, 0, p->tbst_link[0], copy)) { copy_error_recovery (rq.tbst_link[0], new, destroy); return NULL; } p = p->tbst_link[0]; q = q->tbst_link[0]; } else { while (p->tbst_tag[1] == TBST_THREAD) { p = p->tbst_link[1]; if (p == NULL) { q->tbst_link[1] = NULL; new->tbst_root = rq.tbst_link[0]; return new; } q = q->tbst_link[1]; } p = p->tbst_link[1]; q = q->tbst_link[1]; } if (p->tbst_tag[1] == TBST_CHILD) if (!copy_node (new, q, 1, p->tbst_link[1], copy)) { copy_error_recovery (rq.tbst_link[0], new, destroy); return NULL; } } } /* Frees storage allocated for |tree|. If |destroy != NULL|, applies it to each data item in inorder. */ void tbst_destroy (struct tbst_table *tree, tbst_item_func *destroy) { struct tbst_node *p; /* Current node. */ struct tbst_node *n; /* Next node. */ p = tree->tbst_root; if (p != NULL) while (p->tbst_tag[0] == TBST_CHILD) p = p->tbst_link[0]; while (p != NULL) { n = p->tbst_link[1]; if (p->tbst_tag[1] == TBST_CHILD) while (n->tbst_tag[0] == TBST_CHILD) n = n->tbst_link[0]; if (destroy != NULL && p->tbst_data != NULL) destroy (p->tbst_data, tree->tbst_param); tree->tbst_alloc->libavl_free (tree->tbst_alloc, p); p = n; } tree->tbst_alloc->libavl_free (tree->tbst_alloc, tree); } static void tree_to_vine (struct tbst_table *tree) { struct tbst_node *p; if (tree->tbst_root == NULL) return; p = tree->tbst_root; while (p->tbst_tag[0] == TBST_CHILD) p = p->tbst_link[0]; for (;;) { struct tbst_node *q = p->tbst_link[1]; if (p->tbst_tag[1] == TBST_CHILD) { while (q->tbst_tag[0] == TBST_CHILD) q = q->tbst_link[0]; p->tbst_tag[1] = TBST_THREAD; p->tbst_link[1] = q; } if (q == NULL) break; q->tbst_tag[0] = TBST_CHILD; q->tbst_link[0] = p; p = q; } tree->tbst_root = p; } /* Performs a nonthreaded compression operation |nonthread| times, then a threaded compression operation |thread| times, starting at |root|. */ static void compress (struct tbst_node *root, unsigned long nonthread, unsigned long thread) { assert (root != NULL); while (nonthread--) { struct tbst_node *red = root->tbst_link[0]; struct tbst_node *black = red->tbst_link[0]; root->tbst_link[0] = black; red->tbst_link[0] = black->tbst_link[1]; black->tbst_link[1] = red; root = black; } while (thread--) { struct tbst_node *red = root->tbst_link[0]; struct tbst_node *black = red->tbst_link[0]; root->tbst_link[0] = black; red->tbst_link[0] = black; red->tbst_tag[0] = TBST_THREAD; black->tbst_tag[1] = TBST_CHILD; root = black; } } /* Converts |tree|, which must be in the shape of a vine, into a balanced tree. */ static void vine_to_tree (struct tbst_table *tree) { unsigned long vine; /* Number of nodes in main vine. */ unsigned long leaves; /* Nodes in incomplete bottom level, if any. */ int height; /* Height of produced balanced tree. */ leaves = tree->tbst_count + 1; for (;;) { unsigned long next = leaves & (leaves - 1); if (next == 0) break; leaves = next; } leaves = tree->tbst_count + 1 - leaves; compress ((struct tbst_node *) &tree->tbst_root, 0, leaves); vine = tree->tbst_count - leaves; height = 1 + (leaves > 0); if (vine > 1) { unsigned long nonleaves = vine / 2; leaves /= 2; if (leaves > nonleaves) { leaves = nonleaves; nonleaves = 0; } else nonleaves -= leaves; compress ((struct tbst_node *) &tree->tbst_root, leaves, nonleaves); vine /= 2; height++; } while (vine > 1) { compress ((struct tbst_node *) &tree->tbst_root, vine / 2, 0); vine /= 2; height++; } } /* Balances |tree|. */ void tbst_balance (struct tbst_table *tree) { assert (tree != NULL); tree_to_vine (tree); vine_to_tree (tree); } /* Allocates |size| bytes of space using |malloc()|. Returns a null pointer if allocation fails. */ void * tbst_malloc (struct libavl_allocator *allocator, size_t size) { assert (allocator != NULL && size > 0); return malloc (size); } /* Frees |block|. */ void tbst_free (struct libavl_allocator *allocator, void *block) { assert (allocator != NULL && block != NULL); free (block); } /* Default memory allocator that uses |malloc()| and |free()|. */ struct libavl_allocator tbst_allocator_default = { tbst_malloc, tbst_free }; #undef NDEBUG #include /* Asserts that |tbst_insert()| succeeds at inserting |item| into |table|. */ void (tbst_assert_insert) (struct tbst_table *table, void *item) { void **p = tbst_probe (table, item); assert (p != NULL && *p == item); } /* Asserts that |tbst_delete()| really removes |item| from |table|, and returns the removed item. */ void * (tbst_assert_delete) (struct tbst_table *table, void *item) { void *p = tbst_delete (table, item); assert (p != NULL); return p; }