570 lines
15 KiB
C
570 lines
15 KiB
C
/* Copyright (c) 2013-2017, David Anderson
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All rights reserved.
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Redistribution and use in source and binary forms, with
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or without modification, are permitted provided that the
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following conditions are met:
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Redistributions of source code must retain the above
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copyright notice, this list of conditions and the following
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disclaimer.
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Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials
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provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* The interfaces follow tsearch (See the Single
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Unix Specification) but the implementation is
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written without reference to the source of any
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version of tsearch.
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See http://www.prevanders.net/tsearch.html
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for information and an example of use.
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Based on Knuth, chapter 6.2.2, algorithm T and
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Algorithm D.
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Algorithm D here is with Eppinger's left/right reflection
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in delete (J L Eppinger CACM26 (1983),663-669, 27 (1984),235).
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*/
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#include "config.h"
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#include "dwarf_incl.h"
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#include "stdlib.h" /* for free() */
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#include <stdio.h> /* for printf */
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#include "dwarf_tsearch.h"
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/* INVARIANT: The head node has no user data.
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head->llink is null, head->rlink points to the real user
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top node (root of the user tree).
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So the physical top node we call 'head'. No user data.
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The user top node we call 'root' here. It has a user key.
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Though we intend that head->rlink be non-NULL
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except briefly when a tdelete removes the last
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node (in which case we remove the head too before
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returning) the code is a bit cautious and tests
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for a non-NULL head->rlink.
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*/
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struct ts_entry {
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/* Keyptr points to a pointer to a record the user saved, the
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user record contains the user's key itself
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and perhaps more. */
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const void *keyptr;
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struct ts_entry * llink;
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struct ts_entry * rlink;
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};
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/* Not needed for this set of functions. */
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void *
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dwarf_initialize_search_hash( void **treeptr,
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DW_TSHASHTYPE(*hashfunc)(const void *key),
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unsigned long size_estimate)
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{
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return *treeptr;
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}
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/* For debugging. Prints the level number and indents 1 space
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per level. That won't work very well for a deep tree, so perhaps
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we should clamp at some number of indent spaces? */
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static void printlevel(int level)
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{
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int len = 0;
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int targetlen = 4 + level;
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int shownlen = 0;
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char number[10];
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len = snprintf(number,sizeof(number),"<%d>",level);
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printf("%s",number);
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shownlen = len;
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while(shownlen < targetlen) {
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putchar(' ');
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++shownlen;
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}
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}
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/* For debugging */
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static void
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dumptree_inner(const struct ts_entry *t,
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char *(* keyprint)(const void *),
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const char *descr, int level)
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{
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char *v = "";
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if(!t) {
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return;
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}
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dumptree_inner(t->rlink,keyprint,"left ",level+1);
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if(t->keyptr) {
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v = keyprint(t->keyptr);
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}
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printlevel(level);
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printf("0x%08x <keyptr 0x%08x> <%s %s> <l 0x%08x> <r 0x%08x> %s\n",
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(unsigned)t,
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(unsigned)t->keyptr,
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t->keyptr?"key ":"null",
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v,
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(unsigned)t->llink,(unsigned)t->rlink,
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descr);
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dumptree_inner(t->llink,keyprint,"right",level+1);
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}
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static struct ts_entry*
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getlink(struct ts_entry*t,int a)
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{
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if(a < 0) {
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return(t->llink);
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}
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return(t->rlink);
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}
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/* Dumping the tree to stdout. */
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void
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dwarf_tdump(const void*rootin,
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char *(* keyprint)(const void *),
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const char *msg)
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{
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const struct ts_entry *head = (const struct ts_entry *)rootin;
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const struct ts_entry *root = 0;
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if(!head) {
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printf("dwarf_tdump null tree ptr : %s\n",msg);
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return;
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}
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root = head->rlink;
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if(!root) {
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printf("dwarf_tdump empty tree : %s\n",msg);
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return;
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}
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printf("dwarf_tdump tree head : 0x%08lx %s\n",(unsigned long)head,msg);
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printf("dwarf_tdump tree root : 0x%08lx %s\n",(unsigned long)root,msg);
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dumptree_inner(root,keyprint,"top",0);
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}
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static struct ts_entry *
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allocate_ts_entry(const void *key)
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{
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struct ts_entry *e = (struct ts_entry *)
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malloc(sizeof(struct ts_entry));
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if(!e) {
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return NULL;
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}
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e->keyptr = key;
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e->llink = 0;
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e->rlink = 0;
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return e;
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}
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/* Knuth step T5, the insert. */
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static struct ts_entry *
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tsearch_insert_k(const void *key,int kc,
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struct ts_entry *p)
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{
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struct ts_entry *e = allocate_ts_entry(key);
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if (!e) {
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/* out of memory */
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return NULL;
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}
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if( kc < 0) {
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p->llink = e;
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} else {
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p->rlink = e;
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}
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/* Non-NULL means inserted. */
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return e;
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}
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/* Knuth step T5. */
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static struct ts_entry *
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tsearch_inner_do_insert(const void *key,
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int kc,
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int * inserted,
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struct ts_entry* p)
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{
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struct ts_entry *q = 0;
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q = tsearch_insert_k(key,kc,p);
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if(q) {
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*inserted = 1;
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}
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return q;
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}
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/* Algorithm T of Knuth 6.2.2.2
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key is pointer to a user data area containing the key
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and possibly more.
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We iterate like Knuth does, but using for(;;) instead
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of go-to. */
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static struct ts_entry *
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tsearch_inner( const void *key, struct ts_entry* localrootp,
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int (*compar)(const void *, const void *),
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int*inserted)
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{
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struct ts_entry* p = localrootp;
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for(;;) {
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struct ts_entry *r = 0;
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/* T2. */
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int kc = compar(key,p->keyptr);
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if(kc < 0) {
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/* T3. */
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struct ts_entry *l = p->llink;
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if (l) {
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p = l;
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continue;
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}
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/* T5 */
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r = tsearch_inner_do_insert(key,kc,inserted,p);
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return r;
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} else if (kc > 0 ) {
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/* T4. */
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struct ts_entry *r2 = p->rlink;
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if (r2) {
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p = r2;
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continue;
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}
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/* T5 */
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r = tsearch_inner_do_insert(key,kc,inserted,p);
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return r;
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}
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/* K = KEY(P) in Knuth. */
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/* kc == 0, we found the entry we search for. */
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return p;
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}
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return 0;
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}
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/* Search and, if missing, insert. */
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void *
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dwarf_tsearch(const void *key, void **headpin,
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int (*compar)(const void *, const void *))
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{
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struct ts_entry *head = 0;
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struct ts_entry *root = 0;
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struct ts_entry *r = 0;
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int inserted = 0;
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if(!headpin) {
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return NULL;
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}
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head = (struct ts_entry *)*headpin;
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if(head) {
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root = head->rlink;
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}
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if(!head || !root) {
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int allocatedhead = 0;
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if(!head) {
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head = allocate_ts_entry(0);
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allocatedhead = 1
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}
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if(!head) {
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return NULL;
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}
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root = allocate_ts_entry(key);
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if(!root) {
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if (allocatedhead) {
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free(head);
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}
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return NULL;
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}
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head->rlink = root;
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*headpin = head;
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return (void *)(&(root->keyptr));
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}
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root = head->rlink;
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r = tsearch_inner(key,root,compar,&inserted);
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if (!r) {
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return NULL;
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}
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/* Was this found or inserted?
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Value is the same either way, but the pointer to return
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is not the same! */
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/* Discards const. Required by the interface definition. */
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return (void *)&(r->keyptr);
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}
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/* Search. */
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void *
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dwarf_tfind(const void *key, void *const*headppin,
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int (*compar)(const void *, const void *))
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{
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struct ts_entry *head = (struct ts_entry *)*headppin;
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struct ts_entry **proot = 0;
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struct ts_entry *root = 0;
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struct ts_entry *p = 0;
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if(!headppin) {
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return NULL;
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}
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head = (struct ts_entry *)*headppin;
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if(!head) {
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return NULL;
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}
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proot = &head->rlink;
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root = *proot;
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if(!root) {
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return NULL;
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}
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p = root;
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while(p) {
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int kc = compar(key,p->keyptr);
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if (!kc) {
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return (void *)&(p->keyptr);
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}
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p = getlink(p,kc);
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}
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return NULL;
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}
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void *
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dwarf_tdelete(const void *key, void **headin,
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int (*compar)(const void *, const void *))
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{
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struct ts_entry *phead = 0;
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struct ts_entry **rootp = 0;
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struct ts_entry *root = 0;
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struct ts_entry * p= 0;
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/* If a leaf is found, we have to null a parent link
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or the root */
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struct ts_entry * parentp = 0;
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int parentcomparv = 0;
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int done = 0;
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/* We don't really care much if multiple tree
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tables use this simultaneously. This left/right
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is a practical thing not supported by known theory,
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according to Knuth.
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We start with eppingerleftr=1 because that happens to
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show a different tree than standard knuth
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in one of our standard tsearch regression test sequences.
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*/
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static unsigned eppingerleft = 1;
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if (!headin) {
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return NULL;
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}
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phead = (struct ts_entry *)*headin;
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if (!phead) {
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return NULL;
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}
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rootp = &phead->rlink;
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root = phead->rlink;
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if (!root) {
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return NULL;
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}
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p = root;
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while(p) {
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int kc = compar(key,p->keyptr);
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if (!kc) {
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break;
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}
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parentp = p;
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parentcomparv = kc;
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p = getlink(p,kc);
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}
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if(!p) {
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return NULL;
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}
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{
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struct ts_entry **q = 0;
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struct ts_entry *t = 0;
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struct ts_entry *s = 0;
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int emptied_a_leaf = 0;
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/* Either we found root (to remove) or we
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have a parentp and the parent mismatched the key so
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parentcomparv is != 0 */
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if (p == root) {
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q = rootp;
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} else if (parentcomparv < 0) {
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q = &parentp->llink;
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} else /* (parentcomparv > 0) */ {
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q = &parentp->rlink;
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}
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/* D1. *q is what Knuth calls q. */
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t = *q;
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if(!eppingerleft) {
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struct ts_entry *r = 0;
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eppingerleft = 1;
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r = t->rlink;
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if (!r) {
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*q = t->llink;
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done = 1;
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} else {
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/* D2. */
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if (!r->llink) {
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r->llink = t->llink;
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*q = r;
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done = 1;
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}
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}
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while (!done) {
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/* D3. */
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s = r->llink;
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if(s->llink) {
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r = s;
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continue;
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}
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s->llink = t->llink;
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r->llink = s->rlink;
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s->rlink = t->rlink;
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*q = s;
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done = 1;
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}
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} else {
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struct ts_entry *l = 0;
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eppingerleft = 0;
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l = t->llink;
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if (!l) {
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*q = t->rlink;
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done = 1;
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} else {
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/* D2. */
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if (!l->rlink) {
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l->rlink = t->rlink;
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*q = l;
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done = 1;
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}
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}
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while (!done) {
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/* D3. */
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s = l->rlink;
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if(s->rlink) {
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l = s;
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continue;
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}
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s->rlink = t->rlink;
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l->rlink = s->llink;
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s->llink = t->llink;
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*q = s;
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done = 1;
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}
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}
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/* Step D4. */
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if(!t->llink && !t->rlink) {
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emptied_a_leaf = 1;
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}
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free(t);
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if(emptied_a_leaf) {
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if (p == root) {
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/* The tree is completely empty now.
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Free the special head node.
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Notify the caller. */
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free(phead);
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*headin = 0;
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return NULL;
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}
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}
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if(!parentp) {
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/* The item we found was at top of tree,
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found == root.
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We have a new root node.
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We return it, there is no parent. */
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return (void *)(&(root->keyptr));
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}
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return (void *)(&(parentp->keyptr));
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}
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return NULL;
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}
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static void
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dwarf_twalk_inner(const struct ts_entry *p,
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void (*action)(const void *nodep, const DW_VISIT which, const int depth),
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unsigned level)
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{
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if (!p->llink && !p->rlink) {
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action((const void *)(&(p->keyptr)),dwarf_leaf,level);
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return;
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}
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action((const void *)(&(p->keyptr)),dwarf_preorder,level);
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if(p->llink) {
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dwarf_twalk_inner(p->llink,action,level+1);
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}
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action((const void *)(&(p->keyptr)),dwarf_postorder,level);
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if(p->rlink) {
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dwarf_twalk_inner(p->rlink,action,level+1);
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}
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action((const void *)(&(p->keyptr)),dwarf_endorder,level);
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}
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void
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dwarf_twalk(const void *headin,
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void (*action)(const void *nodep, const DW_VISIT which, const int depth))
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{
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const struct ts_entry *head = (const struct ts_entry *)headin;
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const struct ts_entry *root = 0;
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if(!head) {
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return;
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}
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root = head->rlink;
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if(!root) {
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return;
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}
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dwarf_twalk_inner(root,action,0);
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}
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static void
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dwarf_tdestroy_inner(struct ts_entry*p,
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void (*free_node)(void *nodep),
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int depth)
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{
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if(p->llink) {
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dwarf_tdestroy_inner(p->llink,free_node,depth+1);
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p->llink = 0;
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}
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if(p->rlink) {
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dwarf_tdestroy_inner(p->rlink,free_node,depth+1);
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p->rlink = 0;
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}
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/* Discards const. Required by the interface definition. */
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free_node((void *)p->keyptr);
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free(p);
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}
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/* Walk the tree, freeing all space in the tree
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and calling the user's callback function on each node.
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The user must zero out the head node, we have no
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way to do that in the defined interface.
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*/
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void
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dwarf_tdestroy(void *headin, void (*free_node)(void *nodep))
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{
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struct ts_entry *head = (struct ts_entry *)headin;
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struct ts_entry *root = 0;
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if(!head) {
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return;
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}
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root = head->rlink;
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if(head) {
|
|
dwarf_tdestroy_inner(root,free_node,0);
|
|
}
|
|
free(head);
|
|
}
|
|
|
|
|
|
|