diff options
Diffstat (limited to 'libiberty')
| -rw-r--r-- | libiberty/ChangeLog | 5 | ||||
| -rw-r--r-- | libiberty/ternary.c | 157 |
2 files changed, 162 insertions, 0 deletions
diff --git a/libiberty/ChangeLog b/libiberty/ChangeLog index 79bef79..6816e7f 100644 --- a/libiberty/ChangeLog +++ b/libiberty/ChangeLog @@ -1,3 +1,8 @@ +2001-04-15 Daniel Berlin <dan@cgsoftware.com> + + * ternary.c: New file - Ternary search tree implementation. + + 2001-04-03 Zack Weinberg <zackw@stanford.edu> * make-temp-file.c (try): Inline. diff --git a/libiberty/ternary.c b/libiberty/ternary.c new file mode 100644 index 0000000..c5ef3a5 --- /dev/null +++ b/libiberty/ternary.c @@ -0,0 +1,157 @@ +/* ternary.c - Ternary Search Trees + Copyright (C) 2001 Free Software Foundation, Inc. + + Contributed by Daniel Berlin (dan@cgsoftware.com) + + 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, 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. */ +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#ifdef HAVE_STDLIB_H +#include <stdlib.h> +#endif + +#include <stdio.h> + +#include "libiberty.h" +#include "ternary.h" + +/* Non-recursive so we don't waste stack space/time on large + insertions. */ + +void * +ternary_insert (ternary_tree * root, char *s, void *data, int replace) +{ + int diff; + ternary_tree curr, *pcurr; + + /* Start at the root. */ + pcurr = root; + /* Loop until we find the right position */ + while ((curr = *pcurr)) + { + /* Calculate the difference */ + diff = *s - curr->splitchar; + /* Handle current char equal to node splitchar */ + if (diff == 0) + { + /* Handle the case of a string we already have */ + if (*s++ == 0) + { + if (replace) + curr->eqkid = (ternary_tree) data; + return (void *) curr->eqkid; + } + pcurr = &(curr->eqkid); + } + /* Handle current char less than node splitchar */ + else if (diff < 0) + { + pcurr = &(curr->lokid); + } + /* Handle current char greater than node splitchar */ + else + { + pcurr = &(curr->hikid); + } + } + /* It's not a duplicate string, and we should insert what's left of + the string, into the tree rooted at curr */ + for (;;) + { + /* Allocate the memory for the node, and fill it in */ + *pcurr = (ternary_tree) xmalloc (sizeof (ternary_node)); + curr = *pcurr; + curr->splitchar = *s; + curr->lokid = curr->hikid = curr->eqkid = 0; + + /* Place nodes until we hit the end of the string. + When we hit it, place the data in the right place, and + return. + */ + if (*s++ == 0) + { + curr->eqkid = (ternary_tree) data; + return data; + } + pcurr = &(curr->eqkid); + } +} + +/* Free the ternary search tree rooted at p. */ +void +ternary_cleanup (ternary_tree p) +{ + if (p) + { + ternary_cleanup (p->lokid); + if (p->splitchar) + ternary_cleanup (p->eqkid); + ternary_cleanup (p->hikid); + free (p); + } +} + +/* Non-recursive find of a string in the ternary tree */ +void * +ternary_search (ternary_tree p, char *s) +{ + ternary_tree curr; + int diff, spchar; + spchar = *s; + curr = p; + /* Loop while we haven't hit a NULL node or returned */ + while (curr) + { + /* Calculate the difference */ + diff = spchar - curr->splitchar; + /* Handle the equal case */ + if (diff == 0) + { + if (spchar == 0) + return (void *) curr->eqkid; + spchar = *++s; + curr = curr->eqkid; + } + /* Handle the less than case */ + else if (diff < 0) + curr = curr->lokid; + /* All that's left is greater than */ + else + curr = curr->hikid; + } + return NULL; +} + +/* For those who care, the recursive version of the search. Useful if + you want a starting point for pmsearch or nearsearch. */ +static void * +ternary_recursivesearch (ternary_tree p, char *s) +{ + if (!p) + return 0; + if (*s < p->splitchar) + return ternary_recursivesearch (p->lokid, s); + else if (*s > p->splitchar) + return ternary_recursivesearch (p->hikid, s); + else + { + if (*s == 0) + return (void *) p->eqkid; + return ternary_recursivesearch (p->eqkid, ++s); + } +} |