Jim: I was referring to the rest of the process (the calls to
toCodePoint/toUpperCase/toLowerCase), not isHighSurrogate itself. But
Roger has a more comprehensive review on performance, and Naoto is
planning on preparing a JMH test.
-Joe
On 7/15/2020 11:46 AM, Jim Laskey wrote:
Joe: This is a defensive approach that I believe has minimal cost.
public static boolean isHighSurrogate(char ch) {
// Help VM constant-fold; MAX_HIGH_SURROGATE + 1 == MIN_LOW_SURROGATE
return ch >= MIN_HIGH_SURROGATE && ch < (MAX_HIGH_SURROGATE + 1);
}
On Jul 15, 2020, at 3:32 PM, naoto.s...@oracle.com wrote:
Hi Joe,
Thank you for your review.
On 7/15/20 10:57 AM, Joe Wang wrote:
Hi Naoto,
In StringUTF16.java, if one is isHighSurrogate and the other not, you may
quickly return without going through the rest of the process, probably not
significant as cp1 and cp2 and/or u1 and u2 won't be equal anyways. But it
could skip a couple of toCodePoint/toUpperCase/toLowerCase calls.
Yes, that is correct as of now, which is based on the assumption that case
mappings do not cross BMP and supplementary planes boundary. I could not find
any description where that's given or not. So I just took it to be safe.
Naoto
-Joe
On 7/15/20 9:00 AM, naoto.s...@oracle.com wrote:
Hello,
Please review the fix to the following issues:
https://bugs.openjdk.java.net/browse/JDK-8248655
https://bugs.openjdk.java.net/browse/JDK-8248434
The proposed changeset and its CSR are located at:
https://cr.openjdk.java.net/~naoto/8248655.8248434/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8248664
A bug was filed against SimpleDateFormat (8248434) where case-insensitive date
format/parse failed in some of the new locales in JDK15. The root cause was that
case-insensitive String.regionMatches() method did not work with supplementary
characters. The problem is that the method's spec does not expect case mappings of
supplementary characters, possibly because it was overlooked in the first place, JSR 204
- "Unicode Supplementary Character support". Similar behavior is observed in
other two case-insensitive methods, i.e., compareToIgnoreCase() and equalsIgnoreCase().
The fix is straightforward to compare strings by code point basis, instead of code unit
(16bit "char") basis. Technically this change will introduce a backward
incompatibility, but I believe it is an incompatibility to wrong behavior, not true to
the meaning of those methods' expectations.
Naoto
