Simpler (and a bit faster) keyword matcher

Simpler (and a bit faster) keyword matcher.

Replaced the keyword matching state machine with a switch on the first char followed up by inlined char comparisons.


R=lrn@chromium.org
TEST=cctest/test-parsing/ScanKeywords

Committed: http://code.google.com/p/v8/source/detail?r=8866

[Lasse Reichstein, 2011-08-09 12:47:56]

LGTM!

http://codereview.chromium.org/7558017/diff/1004/src/scanner-base.cc
File src/scanner-base.cc (right):

http://codereview.chromium.org/7558017/diff/1004/src/scanner-base.cc#newcode738
src/scanner-base.cc:738: ASSERT(input_length >= 1);
I think this assert can be omitted. You just returned if input_length <= 1.

http://codereview.chromium.org/7558017/diff/1004/src/scanner-base.cc#newcode746
src/scanner-base.cc:746: const int keyword_length = sizeof(keyword) - 1;        
\
Add a comment saying sizeof(keyword) == strlen(keyword)+1

http://codereview.chromium.org/7558017/diff/1004/test/cctest/test-parsing.cc
File test/cctest/test-parsing.cc (right):

http://codereview.chromium.org/7558017/diff/1004/test/cctest/test-parsing.cc#...
test/cctest/test-parsing.cc:83: memmove(buffer, keyword, length);
Could you try appending all three of a letter, a digit and an underscore?

[Vitaly Repeshko, 2011-08-09 13:08:00]

Thanks!

http://codereview.chromium.org/7558017/diff/1004/src/scanner-base.cc
File src/scanner-base.cc (right):

http://codereview.chromium.org/7558017/diff/1004/src/scanner-base.cc#newcode738
src/scanner-base.cc:738: ASSERT(input_length >= 1);
On 2011/08/09 12:48:02, Lasse Reichstein wrote:
> I think this assert can be omitted. You just returned if input_length <= 1.

I wanted to catch bad inputs. Moved the assert to be the first line in the
function.

http://codereview.chromium.org/7558017/diff/1004/src/scanner-base.cc#newcode746
src/scanner-base.cc:746: const int keyword_length = sizeof(keyword) - 1;        
\
On 2011/08/09 12:48:02, Lasse Reichstein wrote:
> Add a comment saying sizeof(keyword) == strlen(keyword)+1

Done.

http://codereview.chromium.org/7558017/diff/1004/test/cctest/test-parsing.cc
File test/cctest/test-parsing.cc (right):

http://codereview.chromium.org/7558017/diff/1004/test/cctest/test-parsing.cc#...
test/cctest/test-parsing.cc:83: memmove(buffer, keyword, length);
On 2011/08/09 12:48:02, Lasse Reichstein wrote:
> Could you try appending all three of a letter, a digit and an underscore?

Done.