On Nov 15, 2012, at 12:41 PM, "Phil Endecott" <spam_from_boost_dev@chezphil.org> wrote:
Marshall Clow wrote:
I'm about to check in some new functionality into the string_algo library; an implementation of string_ref.
A string_ref is a non-owning reference to a string. It is implemented as a {pointer, length} pair, and is exceedingly useful when parsing, and manipulating strings in "read-only" ways.
I mistyped: A string_ref is a non-owning reference to a contiguous sequence of characters.
I did something like this once. I called mine const_string_facade - I also had a mutable version - and it was a template that took an iterator pair. This lets you adapt something like a vector<char> into a string.
BUT, I think my feeling is that this is actually taking us in the wrong direction: my current coding style tries to avoid the "special" features of std::string and prefers the things that are common to other containers, and std::algorithms.
Yes. And No. ;-) When you're writing generic code (and many of us do), you want to be as general as possible. In that case, you want a pair of iterators, or .. a range!. However, when you are dealing with contiguous runs of characters (a a surprisingly large set of cases), then a specific solution (like string_ref) can give you a significant performance boost. The LLVM experience has been quite enlightening about this, and while I don't have first-hand knowledge of what happened inside of Google, the reports I get from people there say the same thing. -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki