Iterating a HashMap<String, X> involves a string equality comparison to check for the empty value
https://bugs.webkit.org/show_bug.cgi?id=84524
Reviewed by Antti Koivisto.
Added a new algorithm for checking for empty buckets that can be specialized.
Specialized it for String. We may later want to do the same thing for KURL.
It's not important to do it for AtomicString, since AtomicString's == function
is already a simple pointer equality compare.
* wtf/HashTable.h:
(WTF::HashTable::isEmptyBucket): Call the new isHashTraitsEmptyValue function, which
will do something more efficient for String.
* wtf/HashTraits.h: Added hasIsEmptyValueFunction to hash traits, with a default value
of false. This allows us to continue to get automatic comparison with the appropriate
emptyValue result for all existing traits, but supply a custom isEmptyValue function
for HashTraits<String>. Putting an isEmptyValue function into the traits would require
overriding it in every class that has a custom value for emptyValue. Specialized
HashTraits for String to add hasIsEmptyValueFunction and declare, but not define, the
isEmptyValue function.
(WTF::isHashTraitsEmptyValue): Added a function that uses the HashTraitsEmptyValueChecker
struct to use either == combined with the emptyValue function or the isEmptyValue function.
(PairHashTraits): Define hasIsEmptyValueFunction and isEmptyValue.
* wtf/text/StringHash.h: Removed unneeded includes and sorted the using statements at
the bottom of the file.
(WTF::HashTraits<String>::isEmptyValue): Define this function here, since here we have
included the WTFString.h header; the HashTraits.h header compiles without WTFString.h.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114914 268f45cc-cd09-0410-ab3c-d52691b4dbfc
4 files changed
