[llvm-commits] [llvm] r120984 - in /llvm/trunk/include/llvm/ADT: SmallString.h SmallVector.h

[Michael Spencer]

On Mon, Dec 6, 2010 at 4:03 PM, Chris Lattner <clattner at apple.com> wrote:
>
> On Dec 5, 2010, at 9:44 PM, Michael Spencer wrote:
>
>>> I don't think this makes sense, why not just cast data?  With wchar_t you usually need a multibyte 0 anyway.
>>>
>>> -Chris
>>
>> c_str() as implemented uses push_back to add the 0, thus we get a
>> sizeof(wchar_t) byte null terminator. The reason this is needed is
>> because I kept running into bugs trying to keep track of when I needed
>> to add a null terminator. This way I can use c_str() exactly when
>> passing the string to a Windows API function.
>
> Oh right, but why add this to SmallVector?  It doesn't seem to make sense there.  If there are weird clients that want this in the system library, can't they either take a smallstring, or just do push_back(0) + pop_back() manually?
>
> -Chris

They can't take a small string because that requires specifying the
size, or templating on the size. And SmallString is char only.

Doing push/pop manually is what I was doing before. The problem is
that it ends up littered all throughout the function before every
system API call. The major difference is that the null termination is
explicit and obvious in the function call when using .c_str().

If this is undesired, I'm also happy with adding a free-standing
template <class T> typename
SmallVectorImpl<T>::SuperClass::const_pointer c_str(SmallVectorImpl<T>
&) function someplace and using that.

- Michael Spencer