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512 lines
10 KiB
C
512 lines
10 KiB
C
/* as_tree - tree library for as
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* vix 14dec85 [written]
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* vix 02feb86 [added tree balancing from wirth "a+ds=p" p. 220-221]
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* vix 06feb86 [added tree_mung()]
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* vix 20jun86 [added tree_delete per wirth a+ds (mod2 v.) p. 224]
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* vix 23jun86 [added delete uar to add for replaced nodes]
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*/
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/* This program text was created by Paul Vixie using examples from the book:
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* "Algorithms & Data Structures," Niklaus Wirth, Prentice-Hall, 1986, ISBN
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* 0-13-022005-1. This code and associated documentation is hereby placed
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* in the public domain.
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*/
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/*#define DEBUG "tree"*/
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#include <stdio.h>
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#include "vixie.h"
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#include "tree.h"
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#ifdef DEBUG
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#define MSG(msg) printf("DEBUG: '%s'\n", msg);
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#else
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#define MSG(msg)
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#endif
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void tree_init(ppr_tree)
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tree **ppr_tree;
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{
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ENTER("tree_init")
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*ppr_tree = NULL;
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EXITV
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}
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char *tree_srch(ppr_tree, pfi_compare, pc_user)
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tree **ppr_tree;
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int (*pfi_compare)();
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char *pc_user;
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{
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register int i_comp;
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register tree *pr_new;
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ENTER("tree_srch")
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if (*ppr_tree)
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{
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i_comp = (*pfi_compare)(pc_user, (**ppr_tree).tree_p);
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if (i_comp > 0)
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EXIT(tree_srch(
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&(**ppr_tree).tree_r,
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pfi_compare,
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pc_user
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))
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if (i_comp < 0)
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EXIT(tree_srch(
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&(**ppr_tree).tree_l,
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pfi_compare,
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pc_user
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))
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/* not higher, not lower... this must be the one.
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*/
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EXIT((**ppr_tree).tree_p)
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}
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/* grounded. NOT found.
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*/
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EXIT(NULL)
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}
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void tree_add(ppr_tree, pfi_compare, pc_user, pfi_delete)
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tree **ppr_tree;
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int (*pfi_compare)();
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char *pc_user;
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int (*pfi_delete)();
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{
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void sprout();
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int i_balance = FALSE;
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ENTER("tree_add")
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sprout(ppr_tree, pc_user, &i_balance, pfi_compare, pfi_delete);
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EXITV
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}
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static void sprout(ppr, pc_data, pi_balance, pfi_compare, pfi_delete)
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tree **ppr;
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char *pc_data;
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int *pi_balance;
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int (*pfi_compare)();
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int (*pfi_delete)();
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{
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tree *p1, *p2;
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int cmp;
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ENTER("sprout")
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/* are we grounded? if so, add the node "here" and set the rebalance
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* flag, then exit.
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*/
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if (!*ppr) {
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MSG("grounded. adding new node, setting h=true")
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*ppr = (tree *) malloc(sizeof(tree));
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(*ppr)->tree_l = NULL;
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(*ppr)->tree_r = NULL;
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(*ppr)->tree_b = 0;
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(*ppr)->tree_p = pc_data;
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*pi_balance = TRUE;
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EXITV
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}
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/* compare the data using routine passed by caller.
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*/
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cmp = (*pfi_compare)(pc_data, (*ppr)->tree_p);
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/* if LESS, prepare to move to the left.
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*/
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if (cmp < 0) {
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MSG("LESS. sprouting left.")
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sprout(&(*ppr)->tree_l, pc_data, pi_balance,
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pfi_compare, pfi_delete);
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if (*pi_balance) { /* left branch has grown longer */
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MSG("LESS: left branch has grown")
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switch ((*ppr)->tree_b)
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{
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case 1: /* right branch WAS longer; balance is ok now */
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MSG("LESS: case 1.. balnce restored implicitly")
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(*ppr)->tree_b = 0;
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*pi_balance = FALSE;
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break;
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case 0: /* balance WAS okay; now left branch longer */
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MSG("LESS: case 0.. balnce bad but still ok")
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(*ppr)->tree_b = -1;
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break;
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case -1:
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/* left branch was already too long. rebalnce */
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MSG("LESS: case -1: rebalancing")
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p1 = (*ppr)->tree_l;
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if (p1->tree_b == -1) { /* LL */
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MSG("LESS: single LL")
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(*ppr)->tree_l = p1->tree_r;
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p1->tree_r = *ppr;
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(*ppr)->tree_b = 0;
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*ppr = p1;
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}
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else { /* double LR */
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MSG("LESS: double LR")
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p2 = p1->tree_r;
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p1->tree_r = p2->tree_l;
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p2->tree_l = p1;
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(*ppr)->tree_l = p2->tree_r;
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p2->tree_r = *ppr;
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if (p2->tree_b == -1)
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(*ppr)->tree_b = 1;
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else
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(*ppr)->tree_b = 0;
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if (p2->tree_b == 1)
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p1->tree_b = -1;
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else
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p1->tree_b = 0;
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*ppr = p2;
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} /*else*/
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(*ppr)->tree_b = 0;
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*pi_balance = FALSE;
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} /*switch*/
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} /*if*/
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EXITV
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} /*if*/
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/* if MORE, prepare to move to the right.
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*/
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if (cmp > 0) {
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MSG("MORE: sprouting to the right")
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sprout(&(*ppr)->tree_r, pc_data, pi_balance,
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pfi_compare, pfi_delete);
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if (*pi_balance) { /* right branch has grown longer */
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MSG("MORE: right branch has grown")
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switch ((*ppr)->tree_b)
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{
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case -1:MSG("MORE: balance was off, fixed implicitly")
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(*ppr)->tree_b = 0;
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*pi_balance = FALSE;
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break;
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case 0: MSG("MORE: balance was okay, now off but ok")
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(*ppr)->tree_b = 1;
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break;
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case 1: MSG("MORE: balance was off, need to rebalance")
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p1 = (*ppr)->tree_r;
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if (p1->tree_b == 1) { /* RR */
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MSG("MORE: single RR")
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(*ppr)->tree_r = p1->tree_l;
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p1->tree_l = *ppr;
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(*ppr)->tree_b = 0;
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*ppr = p1;
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}
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else { /* double RL */
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MSG("MORE: double RL")
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p2 = p1->tree_l;
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p1->tree_l = p2->tree_r;
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p2->tree_r = p1;
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(*ppr)->tree_r = p2->tree_l;
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p2->tree_l = *ppr;
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if (p2->tree_b == 1)
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(*ppr)->tree_b = -1;
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else
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(*ppr)->tree_b = 0;
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if (p2->tree_b == -1)
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p1->tree_b = 1;
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else
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p1->tree_b = 0;
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*ppr = p2;
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} /*else*/
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(*ppr)->tree_b = 0;
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*pi_balance = FALSE;
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} /*switch*/
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} /*if*/
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EXITV
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} /*if*/
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/* not less, not more: this is the same key! replace...
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*/
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MSG("I found it! Replacing data value")
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*pi_balance = FALSE;
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if (pfi_delete)
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(*pfi_delete)((*ppr)->tree_p);
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(*ppr)->tree_p = pc_data;
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EXITV
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}
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int tree_delete(ppr_p, pfi_compare, pc_user, pfi_uar)
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tree **ppr_p;
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int (*pfi_compare)();
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char *pc_user;
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int (*pfi_uar)();
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{
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int i_balance = FALSE, i_uar_called = FALSE;
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ENTER("tree_delete");
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EXIT(delete(ppr_p, pfi_compare, pc_user, pfi_uar,
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&i_balance, &i_uar_called))
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}
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static int delete(ppr_p, pfi_compare, pc_user, pfi_uar,
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pi_balance, pi_uar_called)
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tree **ppr_p;
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int (*pfi_compare)();
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char *pc_user;
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int (*pfi_uar)();
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int *pi_balance;
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int *pi_uar_called;
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{
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void del(), balanceL(), balanceR();
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tree *pr_q;
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int i_comp, i_ret;
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ENTER("delete")
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if (*ppr_p == NULL) {
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MSG("key not in tree")
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EXIT(FALSE)
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}
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i_comp = (*pfi_compare)((*ppr_p)->tree_p, pc_user);
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if (i_comp > 0) {
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MSG("too high - scan left")
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i_ret = delete(&(*ppr_p)->tree_l, pfi_compare, pc_user, pfi_uar,
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pi_balance, pi_uar_called);
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if (*pi_balance)
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balanceL(ppr_p, pi_balance);
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}
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else if (i_comp < 0) {
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MSG("too low - scan right")
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i_ret = delete(&(*ppr_p)->tree_r, pfi_compare, pc_user, pfi_uar,
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pi_balance, pi_uar_called);
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if (*pi_balance)
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balanceR(ppr_p, pi_balance);
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}
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else {
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MSG("equal")
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pr_q = *ppr_p;
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if (pr_q->tree_r == NULL) {
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MSG("right subtree null")
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*ppr_p = pr_q->tree_l;
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*pi_balance = TRUE;
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}
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else if (pr_q->tree_l == NULL) {
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MSG("right subtree non-null, left subtree null")
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*ppr_p = pr_q->tree_r;
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*pi_balance = TRUE;
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}
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else {
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MSG("neither subtree null")
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del(&pr_q->tree_l, pi_balance, &pr_q, pfi_uar,
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pi_uar_called);
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if (*pi_balance)
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balanceL(ppr_p, pi_balance);
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}
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free(pr_q);
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if (!*pi_uar_called && *pfi_uar)
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(*pfi_uar)(pr_q->tree_p);
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i_ret = TRUE;
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}
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EXIT(i_ret)
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}
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static void del(ppr_r, pi_balance, ppr_q, pfi_uar, pi_uar_called)
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tree **ppr_r;
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int *pi_balance;
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tree **ppr_q;
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int (*pfi_uar)();
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int *pi_uar_called;
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{
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void balanceR();
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ENTER("del")
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if ((*ppr_r)->tree_r != NULL) {
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del(&(*ppr_r)->tree_r, pi_balance, ppr_q, pfi_uar,
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pi_uar_called);
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if (*pi_balance)
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balanceR(ppr_r, pi_balance);
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} else {
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if (pfi_uar)
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(*pfi_uar)((*ppr_q)->tree_p);
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*pi_uar_called = TRUE;
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(*ppr_q)->tree_p = (*ppr_r)->tree_p;
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*ppr_q = *ppr_r;
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*ppr_r = (*ppr_r)->tree_l;
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*pi_balance = TRUE;
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}
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EXITV
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}
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static void balanceL(ppr_p, pi_balance)
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tree **ppr_p;
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int *pi_balance;
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{
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tree *p1, *p2;
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int b1, b2;
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ENTER("balanceL")
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MSG("left branch has shrunk")
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switch ((*ppr_p)->tree_b)
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{
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case -1: MSG("was imbalanced, fixed implicitly")
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(*ppr_p)->tree_b = 0;
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break;
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case 0: MSG("was okay, is now one off")
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(*ppr_p)->tree_b = 1;
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*pi_balance = FALSE;
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break;
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case 1: MSG("was already off, this is too much")
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p1 = (*ppr_p)->tree_r;
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b1 = p1->tree_b;
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if (b1 >= 0) {
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MSG("single RR")
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(*ppr_p)->tree_r = p1->tree_l;
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p1->tree_l = *ppr_p;
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if (b1 == 0) {
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MSG("b1 == 0")
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(*ppr_p)->tree_b = 1;
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p1->tree_b = -1;
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*pi_balance = FALSE;
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} else {
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MSG("b1 != 0")
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(*ppr_p)->tree_b = 0;
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p1->tree_b = 0;
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}
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*ppr_p = p1;
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} else {
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MSG("double RL")
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p2 = p1->tree_l;
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b2 = p2->tree_b;
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p1->tree_l = p2->tree_r;
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p2->tree_r = p1;
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(*ppr_p)->tree_r = p2->tree_l;
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p2->tree_l = *ppr_p;
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if (b2 == 1)
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(*ppr_p)->tree_b = -1;
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else
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(*ppr_p)->tree_b = 0;
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if (b2 == -1)
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p1->tree_b = 1;
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else
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p1->tree_b = 0;
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*ppr_p = p2;
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p2->tree_b = 0;
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}
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}
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EXITV
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}
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static void balanceR(ppr_p, pi_balance)
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tree **ppr_p;
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int *pi_balance;
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{
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tree *p1, *p2;
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int b1, b2;
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ENTER("balanceR")
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MSG("right branch has shrunk")
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switch ((*ppr_p)->tree_b)
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{
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case 1: MSG("was imbalanced, fixed implicitly")
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(*ppr_p)->tree_b = 0;
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break;
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case 0: MSG("was okay, is now one off")
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(*ppr_p)->tree_b = -1;
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*pi_balance = FALSE;
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break;
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case -1: MSG("was already off, this is too much")
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p1 = (*ppr_p)->tree_l;
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b1 = p1->tree_b;
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if (b1 <= 0) {
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MSG("single LL")
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(*ppr_p)->tree_l = p1->tree_r;
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p1->tree_r = *ppr_p;
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if (b1 == 0) {
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MSG("b1 == 0")
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(*ppr_p)->tree_b = -1;
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p1->tree_b = 1;
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*pi_balance = FALSE;
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} else {
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MSG("b1 != 0")
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(*ppr_p)->tree_b = 0;
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p1->tree_b = 0;
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}
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*ppr_p = p1;
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} else {
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MSG("double LR")
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p2 = p1->tree_r;
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b2 = p2->tree_b;
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p1->tree_r = p2->tree_l;
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p2->tree_l = p1;
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(*ppr_p)->tree_l = p2->tree_r;
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p2->tree_r = *ppr_p;
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if (b2 == -1)
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(*ppr_p)->tree_b = 1;
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else
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(*ppr_p)->tree_b = 0;
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if (b2 == 1)
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p1->tree_b = -1;
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else
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p1->tree_b = 0;
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*ppr_p = p2;
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p2->tree_b = 0;
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}
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}
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EXITV
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}
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int tree_trav(ppr_tree, pfi_uar)
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tree **ppr_tree;
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int (*pfi_uar)();
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{
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ENTER("tree_trav")
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if (!*ppr_tree)
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EXIT(TRUE)
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if (!tree_trav(&(**ppr_tree).tree_l, pfi_uar))
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EXIT(FALSE)
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if (!(*pfi_uar)((**ppr_tree).tree_p))
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EXIT(FALSE)
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if (!tree_trav(&(**ppr_tree).tree_r, pfi_uar))
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EXIT(FALSE)
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EXIT(TRUE)
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}
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void tree_mung(ppr_tree, pfi_uar)
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tree **ppr_tree;
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int (*pfi_uar)();
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{
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ENTER("tree_mung")
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if (*ppr_tree)
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{
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tree_mung(&(**ppr_tree).tree_l, pfi_uar);
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tree_mung(&(**ppr_tree).tree_r, pfi_uar);
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if (pfi_uar)
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(*pfi_uar)((**ppr_tree).tree_p);
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free(*ppr_tree);
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*ppr_tree = NULL;
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}
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EXITV
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}
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