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* string.c (rb_str_rindex): performance improvement by using

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memrchr(3).

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42269 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
glass 2013-07-31 08:47:13 +00:00
parent 8b126d59b3
commit 867876ab9b
3 changed files with 67 additions and 16 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
Wed Jul 31 17:45:39 2013 Masaki Matsushita <glass.saga@gmail.com>
* string.c (rb_str_rindex): performance improvement by using
memrchr(3).
Wed Jul 31 16:43:30 2013 Masaki Matsushita <glass.saga@gmail.com>
* string.c (rb_str_rindex): refactoring and avoid to call str_nth() if

1
configure.in
View file

@ -1789,6 +1789,7 @@ AC_CHECK_FUNCS(log2)
AC_CHECK_FUNCS(lstat)
AC_CHECK_FUNCS(mblen)
AC_CHECK_FUNCS(memalign)
AC_CHECK_FUNCS(memrchr)
AC_CHECK_FUNCS(mktime)
AC_CHECK_FUNCS(pipe2)
AC_CHECK_FUNCS(poll)

77
string.c
View file

@ -2667,11 +2667,68 @@ rb_str_index_m(int argc, VALUE *argv, VALUE str)
return LONG2NUM(pos);
}
#if HAVE_MEMRCHR
static long
str_rindex(VALUE str, VALUE sub, const char *s, rb_encoding *enc)
{
char *hit, *adjusted;
int c;
long slen, searchlen;
char *sbeg, *e, *t;
sbeg = RSTRING_PTR(str);
e = RSTRING_END(str);
t = RSTRING_PTR(sub);
slen = RSTRING_LEN(sub);
c = *t & 0xff;
searchlen = s - sbeg + 1;
do {
/* printf("\"%s\" \"%s\" %ld %ld %d\n", hit, t, slen, searchlen, memcmp(hit, t, slen)); */
hit = memrchr(sbeg, c, searchlen);
if (!hit) break;
adjusted = rb_enc_left_char_head(sbeg, hit, e, enc);
if (hit != adjusted) {
searchlen = adjusted - sbeg;
continue;
}
if (memcmp(hit, t, slen) == 0)
return rb_str_sublen(str, hit - sbeg);
searchlen = adjusted - sbeg;
} while (searchlen > 0);
return -1;
}
#else
static long
str_rindex(VALUE str, VALUE sub, const char *s, rb_encoding *enc)
{
long slen;
char *sbeg, *e, *t;
sbeg = RSTRING_PTR(str);
e = RSTRING_END(str);
t = RSTRING_PTR(sub);
slen = RSTRING_LEN(sub);
while (s) {
if (memcmp(s, t, slen) == 0) {
return pos;
}
if (pos == 0) break;
pos--;
s = rb_enc_prev_char(sbeg, s, e, enc);
}
return -1;
}
#endif
static long
rb_str_rindex(VALUE str, VALUE sub, long pos)
{
long len, slen;
char *s, *sbeg, *e, *t;
char *sbeg, *s;
rb_encoding *enc;
int singlebyte;
@ -2687,28 +2744,16 @@ rb_str_rindex(VALUE str, VALUE sub, long pos)
if (len == 0) return pos;
sbeg = RSTRING_PTR(str);
e = RSTRING_END(str);
t = RSTRING_PTR(sub);
slen = RSTRING_LEN(sub);
if (pos == 0) {
if (memcmp(sbeg, t, slen) == 0)
if (memcmp(sbeg, RSTRING_PTR(sub), RSTRING_LEN(sub)) == 0)
return 0;
else
return -1;
}
s = str_nth(sbeg, e, pos, enc, singlebyte);
while (s) {
if (memcmp(s, t, slen) == 0) {
return pos;
}
if (pos == 0) break;
pos--;
s = rb_enc_prev_char(sbeg, s, e, enc);
}
return -1;
s = str_nth(sbeg, RSTRING_END(str), pos, enc, singlebyte);
return str_rindex(str, sub, s, enc);
}