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qpkg: simplify jrb_delete_node and more whitespace cleanup

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- jrb.c (recolor, jrb_delete_node, jrb_nblack, jrb_free_tree): add space
  to while(...
- jrb.c (jrb_delete_node): flatten deletion of internal node
- rbtest.c (main): add test of jrb_delete_node
This commit is contained in:
Werner Almesberger 2010-11-19 20:30:24 -03:00
parent 5a422a470d
commit a463773c12
2 changed files with 46 additions and 45 deletions
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85
qpkg/jrb.c
View File

@ -272,7 +272,7 @@ static void recolor(JRB n)
JRB p, gp, s; JRB p, gp, s;
int done = 0; int done = 0;
while(!done) { while (!done) {
if (isroot(n)) { if (isroot(n)) {
setblack(n); setblack(n);
return; return;
@ -360,8 +360,8 @@ static void single_rotate(JRB y, int l)
void jrb_delete_node(JRB n) void jrb_delete_node(JRB n)
{ {
JRB s, p, gp; JRB s, p, gp, x, z;
char ir; char ir, il;
if (isint(n)) { if (isint(n)) {
fprintf(stderr, "Cannot delete an internal node: %p\n", n); fprintf(stderr, "Cannot delete an internal node: %p\n", n);
@ -430,7 +430,7 @@ void jrb_delete_node(JRB n)
n = s; n = s;
p = n->parent; p = n->parent;
s = sibling(n); s = sibling(n);
while(isblack(p) && isblack(s) && isint(s) && while (isblack(p) && isblack(s) && isint(s) &&
isblack(s->flink) && isblack(s->blink)) { isblack(s->flink) && isblack(s->blink)) {
setred(s); setred(s);
n = p; n = p;
@ -447,49 +447,46 @@ void jrb_delete_node(JRB n)
s = sibling(n); s = sibling(n);
} }
{ if (isext(s)) {
JRB x, z; char il; fprintf(stderr, "DELETION ERROR: sibling not internal\n");
exit(1);
}
if (isext(s)) { il = isleft(n);
x = il ? s->flink : s->blink;
z = sibling(x);
if (isred(z)) { /* Rotation 2.3f */
single_rotate(p, !il);
setblack(z);
if (isred(p))
setred(s);
else
setblack(s);
setblack(p);
return;
}
if (isblack(x)) { /* Recoloring only (2.3c) */
if (isred(s) || isblack(p)) {
fprintf(stderr, fprintf(stderr,
"DELETION ERROR: sibling not internal\n"); "DELETION ERROR: 2.3c not quite right\n");
exit(1); exit(1);
} }
setblack(p);
il = isleft(n); setred(s);
x = il ? s->flink : s->blink; return;
z = sibling(x);
if (isred(z)) { /* Rotation 2.3f */
single_rotate(p, !il);
setblack(z);
if (isred(p))
setred(s);
else
setblack(s);
setblack(p);
} else if (isblack(x)) { /* Recoloring only (2.3c) */
if (isred(s) || isblack(p)) {
fprintf(stderr,
"DELETION ERROR: 2.3c not quite right\n");
exit(1);
}
setblack(p);
setred(s);
return;
} else if (isred(p)) { /* 2.3d */
single_rotate(s, il);
single_rotate(p, !il);
setblack(x);
setred(s);
return;
} else { /* 2.3e */
single_rotate(s, il);
single_rotate(p, !il);
setblack(x);
return;
}
} }
if (isred(p)) { /* 2.3d */
single_rotate(s, il);
single_rotate(p, !il);
setblack(x);
setred(s);
return;
}
/* 2.3e */
single_rotate(s, il);
single_rotate(p, !il);
setblack(x);
} }
@ -503,7 +500,7 @@ int jrb_nblack(JRB n)
exit(1); exit(1);
} }
nb = 0; nb = 0;
while(!ishead(n)) { while (!ishead(n)) {
if (isblack(n)) nb++; if (isblack(n)) nb++;
n = n->parent; n = n->parent;
} }
@ -537,7 +534,7 @@ void jrb_free_tree(JRB n)
exit(1); exit(1);
} }
while(jrb_first(n) != jrb_nil(n)) while (jrb_first(n) != jrb_nil(n))
jrb_delete_node(jrb_first(n)); jrb_delete_node(jrb_first(n));
free(n); free(n);

4
qpkg/rbtest.c
View File

@ -21,6 +21,7 @@ int main(void)
JRB p; JRB p;
INSERT("ab", "have"); INSERT("ab", "have");
INSERT("ac", "NOT");
INSERT("d", "little"); INSERT("d", "little");
INSERT("c", "this"); INSERT("c", "this");
INSERT("b", "passed"); INSERT("b", "passed");
@ -29,6 +30,9 @@ int main(void)
INSERT("aa", "We"); INSERT("aa", "We");
INSERT("ff", "!"); INSERT("ff", "!");
p = jrb_find(tree, "ac", cmp);
jrb_delete_node(p);
jrb_traverse(p, tree) jrb_traverse(p, tree)
printf("%s ", (char *) jrb_val(p)); printf("%s ", (char *) jrb_val(p));
printf("\n"); printf("\n");