| /* A splay-tree datatype. |
| Copyright (C) 1998-2021 Free Software Foundation, Inc. |
| Contributed by Mark Mitchell (mark@markmitchell.com). |
| |
| This file is part of GNU CC. |
| |
| GNU CC 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, or (at your option) |
| any later version. |
| |
| GNU CC 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 GNU CC; see the file COPYING. If not, write to |
| the Free Software Foundation, 51 Franklin Street - Fifth Floor, |
| Boston, MA 02110-1301, USA. */ |
| |
| /* For an easily readable description of splay-trees, see: |
| |
| Lewis, Harry R. and Denenberg, Larry. Data Structures and Their |
| Algorithms. Harper-Collins, Inc. 1991. */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #ifdef HAVE_STDLIB_H |
| #include <stdlib.h> |
| #endif |
| #ifdef HAVE_STRING_H |
| #include <string.h> |
| #endif |
| |
| #include <stdio.h> |
| |
| #include "libiberty.h" |
| #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 int splay_tree_foreach_helper (splay_tree_node, |
| splay_tree_foreach_fn, void*); |
| |
| /* Deallocate NODE (a member of SP), and all its sub-trees. */ |
| |
| static void |
| splay_tree_delete_helper (splay_tree sp, splay_tree_node node) |
| { |
| splay_tree_node pending = 0; |
| splay_tree_node active = 0; |
| |
| if (!node) |
| return; |
| |
| #define KDEL(x) if (sp->delete_key) (*sp->delete_key)(x); |
| #define VDEL(x) if (sp->delete_value) (*sp->delete_value)(x); |
| |
| KDEL (node->key); |
| VDEL (node->value); |
| |
| /* We use the "key" field to hold the "next" pointer. */ |
| node->key = (splay_tree_key)pending; |
| pending = (splay_tree_node)node; |
| |
| /* Now, keep processing the pending list until there aren't any |
| more. This is a little more complicated than just recursing, but |
| it doesn't toast the stack for large trees. */ |
| |
| while (pending) |
| { |
| active = pending; |
| pending = 0; |
| while (active) |
| { |
| splay_tree_node temp; |
| |
| /* active points to a node which has its key and value |
| deallocated, we just need to process left and right. */ |
| |
| if (active->left) |
| { |
| KDEL (active->left->key); |
| VDEL (active->left->value); |
| active->left->key = (splay_tree_key)pending; |
| pending = (splay_tree_node)(active->left); |
| } |
| if (active->right) |
| { |
| KDEL (active->right->key); |
| VDEL (active->right->value); |
| active->right->key = (splay_tree_key)pending; |
| pending = (splay_tree_node)(active->right); |
| } |
| |
| temp = active; |
| active = (splay_tree_node)(temp->key); |
| (*sp->deallocate) ((char*) temp, sp->allocate_data); |
| } |
| } |
| #undef KDEL |
| #undef VDEL |
| } |
| |
| /* Rotate the edge joining the left child N with its parent P. PP is the |
| grandparents' pointer to P. */ |
| |
| static inline void |
| rotate_left (splay_tree_node *pp, splay_tree_node p, splay_tree_node n) |
| { |
| splay_tree_node tmp; |
| tmp = n->right; |
| n->right = p; |
| p->left = tmp; |
| *pp = n; |
| } |
| |
| /* Rotate the edge joining the right child N with its parent P. PP is the |
| grandparents' pointer to P. */ |
| |
| 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; |
| } |
| |
| /* Bottom up splay of key. */ |
| |
| static void |
| splay_tree_splay (splay_tree sp, splay_tree_key key) |
| { |
| if (sp->root == 0) |
| return; |
| |
| 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 |
| which are from SP, following an in-order traversal. If FN every |
| returns a non-zero value, the iteration ceases immediately, and the |
| value is returned. Otherwise, this function returns 0. */ |
| |
| static int |
| splay_tree_foreach_helper (splay_tree_node node, |
| splay_tree_foreach_fn fn, void *data) |
| { |
| int val; |
| splay_tree_node *stack; |
| int stack_ptr, stack_size; |
| |
| /* A non-recursive implementation is used to avoid filling the stack |
| for large trees. Splay trees are worst case O(n) in the depth of |
| the tree. */ |
| |
| #define INITIAL_STACK_SIZE 100 |
| stack_size = INITIAL_STACK_SIZE; |
| stack_ptr = 0; |
| stack = XNEWVEC (splay_tree_node, stack_size); |
| val = 0; |
| |
| for (;;) |
| { |
| while (node != NULL) |
| { |
| if (stack_ptr == stack_size) |
| { |
| stack_size *= 2; |
| stack = XRESIZEVEC (splay_tree_node, stack, stack_size); |
| } |
| stack[stack_ptr++] = node; |
| node = node->left; |
| } |
| |
| if (stack_ptr == 0) |
| break; |
| |
| node = stack[--stack_ptr]; |
| |
| val = (*fn) (node, data); |
| if (val) |
| break; |
| |
| node = node->right; |
| } |
| |
| XDELETEVEC (stack); |
| return val; |
| } |
| |
| /* An allocator and deallocator based on xmalloc. */ |
| static void * |
| splay_tree_xmalloc_allocate (int size, void *data ATTRIBUTE_UNUSED) |
| { |
| return (void *) xmalloc (size); |
| } |
| |
| static void |
| splay_tree_xmalloc_deallocate (void *object, void *data ATTRIBUTE_UNUSED) |
| { |
| free (object); |
| } |
| |
| |
| /* Allocate a new splay tree, using COMPARE_FN to compare nodes, |
| DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate |
| values. Use xmalloc to allocate the splay tree structure, and any |
| nodes added. */ |
| |
| splay_tree |
| splay_tree_new (splay_tree_compare_fn compare_fn, |
| splay_tree_delete_key_fn delete_key_fn, |
| splay_tree_delete_value_fn delete_value_fn) |
| { |
| return (splay_tree_new_with_allocator |
| (compare_fn, delete_key_fn, delete_value_fn, |
| splay_tree_xmalloc_allocate, splay_tree_xmalloc_deallocate, 0)); |
| } |
| |
| |
| /* Allocate a new splay tree, using COMPARE_FN to compare nodes, |
| DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate |
| values. */ |
| |
| splay_tree |
| splay_tree_new_with_allocator (splay_tree_compare_fn compare_fn, |
| splay_tree_delete_key_fn delete_key_fn, |
| splay_tree_delete_value_fn delete_value_fn, |
| splay_tree_allocate_fn allocate_fn, |
| splay_tree_deallocate_fn deallocate_fn, |
| void *allocate_data) |
| { |
| return |
| splay_tree_new_typed_alloc (compare_fn, delete_key_fn, delete_value_fn, |
| allocate_fn, allocate_fn, deallocate_fn, |
| allocate_data); |
| } |
| |
| /* |
| |
| @deftypefn Supplemental splay_tree splay_tree_new_with_typed_alloc @ |
| (splay_tree_compare_fn @var{compare_fn}, @ |
| splay_tree_delete_key_fn @var{delete_key_fn}, @ |
| splay_tree_delete_value_fn @var{delete_value_fn}, @ |
| splay_tree_allocate_fn @var{tree_allocate_fn}, @ |
| splay_tree_allocate_fn @var{node_allocate_fn}, @ |
| splay_tree_deallocate_fn @var{deallocate_fn}, @ |
| void * @var{allocate_data}) |
| |
| This function creates a splay tree that uses two different allocators |
| @var{tree_allocate_fn} and @var{node_allocate_fn} to use for allocating the |
| tree itself and its nodes respectively. This is useful when variables of |
| different types need to be allocated with different allocators. |
| |
| The splay tree will use @var{compare_fn} to compare nodes, |
| @var{delete_key_fn} to deallocate keys, and @var{delete_value_fn} to |
| deallocate values. Keys and values will be deallocated when the |
| tree is deleted using splay_tree_delete or when a node is removed |
| using splay_tree_remove. splay_tree_insert will release the previously |
| inserted key and value using @var{delete_key_fn} and @var{delete_value_fn} |
| if the inserted key is already found in the tree. |
| |
| @end deftypefn |
| |
| */ |
| |
| splay_tree |
| splay_tree_new_typed_alloc (splay_tree_compare_fn compare_fn, |
| splay_tree_delete_key_fn delete_key_fn, |
| splay_tree_delete_value_fn delete_value_fn, |
| splay_tree_allocate_fn tree_allocate_fn, |
| splay_tree_allocate_fn node_allocate_fn, |
| splay_tree_deallocate_fn deallocate_fn, |
| void * allocate_data) |
| { |
| splay_tree sp = (splay_tree) (*tree_allocate_fn) |
| (sizeof (struct splay_tree_s), allocate_data); |
| |
| sp->root = 0; |
| sp->comp = compare_fn; |
| sp->delete_key = delete_key_fn; |
| sp->delete_value = delete_value_fn; |
| sp->allocate = node_allocate_fn; |
| sp->deallocate = deallocate_fn; |
| sp->allocate_data = allocate_data; |
| |
| return sp; |
| } |
| |
| /* Deallocate SP. */ |
| |
| void |
| splay_tree_delete (splay_tree sp) |
| { |
| splay_tree_delete_helper (sp, sp->root); |
| (*sp->deallocate) ((char*) sp, sp->allocate_data); |
| } |
| |
| /* Insert a new node (associating KEY with DATA) into SP. If a |
| previous node with the indicated KEY exists, its data is replaced |
| with the new value. Returns the new node. */ |
| |
| splay_tree_node |
| splay_tree_insert (splay_tree sp, splay_tree_key key, splay_tree_value value) |
| { |
| int comparison = 0; |
| |
| splay_tree_splay (sp, key); |
| |
| if (sp->root) |
| comparison = (*sp->comp)(sp->root->key, key); |
| |
| if (sp->root && comparison == 0) |
| { |
| /* If the root of the tree already has the indicated KEY, delete |
| the old key and old value, and replace them with KEY and VALUE. */ |
| if (sp->delete_key) |
| (*sp->delete_key) (sp->root->key); |
| if (sp->delete_value) |
| (*sp->delete_value)(sp->root->value); |
| sp->root->key = key; |
| sp->root->value = value; |
| } |
| else |
| { |
| /* Create a new node, and insert it at the root. */ |
| splay_tree_node node; |
| |
| node = ((splay_tree_node) |
| (*sp->allocate) (sizeof (struct splay_tree_node_s), |
| sp->allocate_data)); |
| node->key = key; |
| node->value = value; |
| |
| if (!sp->root) |
| node->left = node->right = 0; |
| else if (comparison < 0) |
| { |
| node->left = sp->root; |
| node->right = node->left->right; |
| node->left->right = 0; |
| } |
| else |
| { |
| node->right = sp->root; |
| node->left = node->right->left; |
| node->right->left = 0; |
| } |
| |
| sp->root = node; |
| } |
| |
| return sp->root; |
| } |
| |
| /* Remove KEY from SP. It is not an error if it did not exist. */ |
| |
| void |
| splay_tree_remove (splay_tree sp, splay_tree_key key) |
| { |
| splay_tree_splay (sp, key); |
| |
| if (sp->root && (*sp->comp) (sp->root->key, key) == 0) |
| { |
| splay_tree_node left, right; |
| |
| left = sp->root->left; |
| right = sp->root->right; |
| |
| /* Delete the root node itself. */ |
| if (sp->delete_key) |
| (*sp->delete_key) (sp->root->key); |
| if (sp->delete_value) |
| (*sp->delete_value) (sp->root->value); |
| (*sp->deallocate) (sp->root, sp->allocate_data); |
| |
| /* One of the children is now the root. Doesn't matter much |
| which, so long as we preserve the properties of the tree. */ |
| if (left) |
| { |
| sp->root = left; |
| |
| /* If there was a right child as well, hang it off the |
| right-most leaf of the left child. */ |
| if (right) |
| { |
| while (left->right) |
| left = left->right; |
| left->right = right; |
| } |
| } |
| else |
| sp->root = right; |
| } |
| } |
| |
| /* Lookup KEY in SP, returning VALUE if present, and NULL |
| otherwise. */ |
| |
| splay_tree_node |
| splay_tree_lookup (splay_tree sp, splay_tree_key key) |
| { |
| splay_tree_splay (sp, key); |
| |
| if (sp->root && (*sp->comp)(sp->root->key, key) == 0) |
| return sp->root; |
| else |
| return 0; |
| } |
| |
| /* Return the node in SP with the greatest key. */ |
| |
| splay_tree_node |
| splay_tree_max (splay_tree sp) |
| { |
| splay_tree_node n = sp->root; |
| |
| if (!n) |
| return NULL; |
| |
| while (n->right) |
| n = n->right; |
| |
| return n; |
| } |
| |
| /* Return the node in SP with the smallest key. */ |
| |
| splay_tree_node |
| splay_tree_min (splay_tree sp) |
| { |
| splay_tree_node n = sp->root; |
| |
| if (!n) |
| return NULL; |
| |
| while (n->left) |
| n = n->left; |
| |
| return n; |
| } |
| |
| /* Return the immediate predecessor KEY, or NULL if there is no |
| predecessor. KEY need not be present in the tree. */ |
| |
| splay_tree_node |
| splay_tree_predecessor (splay_tree sp, splay_tree_key key) |
| { |
| int comparison; |
| splay_tree_node node; |
| |
| /* If the tree is empty, there is certainly no predecessor. */ |
| if (!sp->root) |
| return NULL; |
| |
| /* Splay the tree around KEY. That will leave either the KEY |
| itself, its predecessor, or its successor at the root. */ |
| splay_tree_splay (sp, key); |
| comparison = (*sp->comp)(sp->root->key, key); |
| |
| /* If the predecessor is at the root, just return it. */ |
| if (comparison < 0) |
| return sp->root; |
| |
| /* Otherwise, find the rightmost element of the left subtree. */ |
| node = sp->root->left; |
| if (node) |
| while (node->right) |
| node = node->right; |
| |
| return node; |
| } |
| |
| /* Return the immediate successor KEY, or NULL if there is no |
| successor. KEY need not be present in the tree. */ |
| |
| splay_tree_node |
| splay_tree_successor (splay_tree sp, splay_tree_key key) |
| { |
| int comparison; |
| splay_tree_node node; |
| |
| /* If the tree is empty, there is certainly no successor. */ |
| if (!sp->root) |
| return NULL; |
| |
| /* Splay the tree around KEY. That will leave either the KEY |
| itself, its predecessor, or its successor at the root. */ |
| splay_tree_splay (sp, key); |
| comparison = (*sp->comp)(sp->root->key, key); |
| |
| /* If the successor is at the root, just return it. */ |
| if (comparison > 0) |
| return sp->root; |
| |
| /* Otherwise, find the leftmost element of the right subtree. */ |
| node = sp->root->right; |
| if (node) |
| while (node->left) |
| node = node->left; |
| |
| return node; |
| } |
| |
| /* Call FN, passing it the DATA, for every node in SP, following an |
| in-order traversal. If FN every returns a non-zero value, the |
| iteration ceases immediately, and the value is returned. |
| Otherwise, this function returns 0. */ |
| |
| int |
| splay_tree_foreach (splay_tree sp, splay_tree_foreach_fn fn, void *data) |
| { |
| return splay_tree_foreach_helper (sp->root, fn, data); |
| } |
| |
| /* Splay-tree comparison function, treating the keys as ints. */ |
| |
| int |
| splay_tree_compare_ints (splay_tree_key k1, splay_tree_key k2) |
| { |
| if ((int) k1 < (int) k2) |
| return -1; |
| else if ((int) k1 > (int) k2) |
| return 1; |
| else |
| return 0; |
| } |
| |
| /* Splay-tree comparison function, treating the keys as pointers. */ |
| |
| int |
| splay_tree_compare_pointers (splay_tree_key k1, splay_tree_key k2) |
| { |
| if ((char*) k1 < (char*) k2) |
| return -1; |
| else if ((char*) k1 > (char*) k2) |
| return 1; |
| else |
| return 0; |
| } |
| |
| /* Splay-tree comparison function, treating the keys as strings. */ |
| |
| int |
| splay_tree_compare_strings (splay_tree_key k1, splay_tree_key k2) |
| { |
| return strcmp ((char *) k1, (char *) k2); |
| } |
| |
| /* Splay-tree delete function, simply using free. */ |
| |
| void |
| splay_tree_delete_pointers (splay_tree_value value) |
| { |
| free ((void *) value); |
| } |