As part of the work to deploy efficient string patterns [1] throughout WebKit, Benjamin and I noticed a bunch of very inefficient code that uses operator+= with Strings:
String foo; for (...) foo += [...]; return foo; This pattern is particularly inefficient because += mallocs an entirely new buffer for the result and copies the the string into the new buffer. That means that this pattern makes O(n) calls to malloc and does O(n^2) work. A more efficient pattern is to use StringBuilder: StringBuilder foo; for (...) foo.append([...]); return foo.toString(); I'm in the process of going through WebCore and removing all callers of WTF::String::operator+=. Once that's complete, my plan is to remove WTF::String::operator+= from WTFString.h. Hopefully that will nudge contributors and reviewers towards more efficient string patterns. Removing operator+= will likely require changes to a number of port-specific files. I'll do my best to remove these, but I might need some help from maintainers of individual ports. If you're interested in helping out, please let me know. Many thanks, Adam [1] http://trac.webkit.org/wiki/EfficientStrings _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo/webkit-dev
