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[svn] Switch to binary search for find_tag.

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hniksic 2003-10-08 09:00:10 -07:00
parent 72820b092f
commit a9c3c58c9f
2 changed files with 21 additions and 11 deletions
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4
src/ChangeLog
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@ -1,3 +1,7 @@
2003-10-08 Hrvoje Niksic <hniksic@xemacs.org>
* html-url.c (find_tag): Switch to binary search.
2003-10-08 Hrvoje Niksic <hniksic@xemacs.org>
* main.c (print_help): Fix typo; stured -> stored.

28
src/html-url.c
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@ -270,30 +270,36 @@ init_interesting (void)
}
}
/* Find tag with name TAG_NAME in KNOWN_TAGS and return its index. */
static int
find_tag (const char *tag_name)
{
int i;
/* Originally implemented as linear search. In Wget 1.9 known_tags
contains 21 elements, for which binary search requires max. 5
comparisons, whereas linear search performs 10 on average. */
/* This is linear search; if the number of tags grow, we can switch
to binary search. */
int lo = 0, hi = countof (known_tags) - 1;
for (i = 0; i < countof (known_tags); i++)
while (lo <= hi)
{
int cmp = strcasecmp (known_tags[i].name, tag_name);
/* known_tags are sorted alphabetically, so we can
micro-optimize. */
if (cmp > 0)
break;
else if (cmp == 0)
return i;
int mid = (lo + hi) >> 1;
int cmp = strcasecmp (tag_name, known_tags[mid].name);
if (cmp < 0)
hi = mid - 1;
else if (cmp > 0)
lo = mid + 1;
else
return mid;
}
return -1;
}
/* Find the value of attribute named NAME in the taginfo TAG. If the
attribute is not present, return NULL. If ATTRIND is non-NULL, the
index of the attribute in TAG will be stored there. */
static char *
find_attr (struct taginfo *tag, const char *name, int *attrind)
{