Re: [PATCH 1/4] msvcp90: Added basic_string<char>::swap implementation.

[Piotr Caban]

On 11/11/10 18:55, Vincas Miliūnas wrote:
> This implementation handles cases when basic_strings are allocated using different allocators, however WINE's implementation seems to ignore allocators.
> It's not ignoring allocators (but it's not setting allocator field). 
> There's no legal way of accessing it by end user, so there's no point of 
> setting it, unless it's needed internally (and it's not needed for 
> correct implementation of basic_string_char_swap function).

+/* Helper function for MSVCP_basic_string_char_swap */
+void basic_string_char_swap_bufxptr_same_alloc(basic_string_char * lhs, 
basic_string_char * rhs)
+{
+    char * const ptr = rhs->data.ptr;
+    const size_t size = rhs->size;
+    const size_t res = rhs->res;
+
+    memcpy(rhs->data.buf, lhs->data.buf, lhs->size * sizeof(char));
This function should work in constant time. It should only swap pointers 
and lengths.

+/* Helper function for MSVCP_basic_string_char_swap */
+MSVCP_BOOL basic_string_char_swap_bufxptr_diff_alloc(basic_string_char 
* lhs, basic_string_char * rhs)
+{
+    char tmp[BUF_SIZE_CHAR];
+    const size_t size = lhs->size;
+    const size_t res = lhs->res;
+    memcpy(tmp, lhs->data.buf, lhs->size * sizeof(char));
+
+    char * const ptr = MSVCP_allocator_char_allocate(lhs->allocator, 
rhs->res);
You can't pass unknown data to MSVCP_allocator_char_allocate, this is 
the implementation of default char allocator. When other allocators are 
in use compiler will use templates.

The function you're implementing is only used when two basic_string_char 
are swapped, because there's no legal way of modifying allocator field 
there's only one case - the same allocators are used.

Cheers,
Piotr