Re: [PATCHES] TODO item: Implement Boyer-Moore searching (First time hacker)

"David Rowley" <dgrowley(at)gmail(dot)com> writes:
> I've made the discussed changes. Also updated the benchmark results.
> http://www.unixbeast.com/~fat/8.3_test_v1.3.xls

Applied with revisions; mostly cosmetic except for one point. I
realized after studying the code a bit more that B-M cannot possibly win
for a single-character pattern (needle), since the skip distance must
always be 1 in that case. The fact that it seemed to keep up at that
length has to be because the original coding included a strncmp call
inside the innermost loop, which likely prevents the compiler from
optimizing that loop really tightly. But the strncmp wasn't doing
anything anyway for the case of pattern length = 1. So what I committed
special-cases pattern length 1 to be a naive search with a *very* tight
inner loop. I think it's worth troubling over this case because a
common usage is split_to_array and suchlike with single-character
delimiters.

regards, tom lane