From a9c3c58c9fb22e71e0878d4da1d3de0cd9e36445 Mon Sep 17 00:00:00 2001
From: hniksic <devnull@localhost>
Date: Wed, 8 Oct 2003 09:00:10 -0700
Subject: [PATCH] [svn] Switch to binary search for find_tag.
---
src/ChangeLog | 4 ++++
src/html-url.c | 28 +++++++++++++++++-----------
2 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/src/ChangeLog b/src/ChangeLog
index 85b0f3da..baa4c581 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -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.
diff --git a/src/html-url.c b/src/html-url.c
index 756bf2ab..abaa2f8e 100644
--- a/src/html-url.c
+++ b/src/html-url.c
@@ -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)
{