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ziplistPrev should return the tail when the argument is ZIP_END

This commit is contained in:
Pieter Noordhuis 2010-05-31 20:17:21 +02:00
parent 3fbf9001ce
commit 8632fb3040
2 changed files with 25 additions and 11 deletions
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32
ziplist.c
View File

@ -428,14 +428,27 @@ unsigned char *ziplistIndex(unsigned char *zl, int index) {
}
/* Return pointer to next entry in ziplist. */
unsigned char *ziplistNext(unsigned char *p) {
unsigned char *ziplistNext(unsigned char *zl, unsigned char *p) {
((void) zl);
return (p[0] == ZIP_END) ? NULL : p+zipRawEntryLength(p);
}
/* Return pointer to previous entry in ziplist. */
unsigned char *ziplistPrev(unsigned char *p) {
zlentry entry = zipEntry(p);
return (entry.prevrawlen == 0) ? NULL : p-entry.prevrawlen;
unsigned char *ziplistPrev(unsigned char *zl, unsigned char *p) {
zlentry entry;
/* Iterating backwards from ZIP_END should return the tail. When "p" is
* equal to the first element of the list, we're already at the head,
* and should return NULL. */
if (p[0] == ZIP_END) {
p = ZIPLIST_ENTRY_TAIL(zl);
return (p[0] == ZIP_END) ? NULL : p;
} else if (p == ZIPLIST_ENTRY_HEAD(zl)) {
return NULL;
} else {
entry = zipEntry(p);
return p-entry.prevrawlen;
}
}
/* Get entry pointer to by 'p' and store in either 'e' or 'v' depending
@ -709,7 +722,7 @@ int main(int argc, char **argv) {
} else {
printf("%lld", value);
}
p = ziplistNext(p);
p = ziplistNext(zl,p);
printf("\n");
}
printf("\n");
@ -726,7 +739,7 @@ int main(int argc, char **argv) {
} else {
printf("%lld", value);
}
p = ziplistNext(p);
p = ziplistNext(zl,p);
printf("\n");
}
printf("\n");
@ -743,7 +756,7 @@ int main(int argc, char **argv) {
} else {
printf("%lld", value);
}
p = ziplistNext(p);
p = ziplistNext(zl,p);
printf("\n");
}
printf("\n");
@ -772,7 +785,7 @@ int main(int argc, char **argv) {
} else {
printf("%lld", value);
}
p = ziplistPrev(p);
p = ziplistPrev(zl,p);
printf("\n");
}
printf("\n");
@ -789,7 +802,8 @@ int main(int argc, char **argv) {
} else {
printf("%lld", value);
}
zl = ziplistDelete(zl, &p, ZIPLIST_HEAD);
zl = ziplistDelete(zl,&p);
p = ziplistPrev(zl,p);
printf("\n");
}
printf("\n");

4
ziplist.h
View File

@ -5,8 +5,8 @@ unsigned char *ziplistNew(void);
unsigned char *ziplistPush(unsigned char *zl, char *s, unsigned int slen, int where);
unsigned char *ziplistPop(unsigned char *zl, sds *target, int where);
unsigned char *ziplistIndex(unsigned char *zl, int index);
unsigned char *ziplistNext(unsigned char *p);
unsigned char *ziplistPrev(unsigned char *p);
unsigned char *ziplistNext(unsigned char *zl, unsigned char *p);
unsigned char *ziplistPrev(unsigned char *zl, unsigned char *p);
unsigned int ziplistGet(unsigned char *p, char **sstr, unsigned int *slen, long long *sval);
unsigned char *ziplistInsert(unsigned char *zl, unsigned char *p, char *s, unsigned int slen);
unsigned char *ziplistDelete(unsigned char *zl, unsigned char **p, int direction);