Re: Specialising for iterators over contiguous memory (e.g. vector, string)

From:

Abhishek Padmanabh <abhishek.padmanabh@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 20 Feb 2008 07:17:13 -0800 (PST)

Message-ID:

<b8a7f617-7fa9-4694-a160-52d432a8c1e4@u10g2000prn.googlegroups.com>

On Feb 20, 7:54 pm, Phil Endecott <spam_from_usenet_0...@chezphil.org>
wrote:

So presumably I could specifically detect basic_string and vector, and
invoke the char* specialisation on the address of the element:

template <>
void func(std::basic_string<char>::iterator i)
<std::basic_string<char>::iterator> {
func<char*>(&(*i));

}

template <>
void func(std::basic_string<char>::iterator i)
<std::basic_string<char>::iterator> {
func<char*>(&(*i));

}

Question: does that work?

Fixing the compiler errors, it should work. The iterators are
implementation defined typedefs so they could be pointers or not. You
cannot reliably assume that. But dereferencing and applying address-of
should give you the pointer to the element.

But I'd really like to be able to detect any container, including
user-defined ones, where the elements are stored contiguously in memory.
Is there some way to enable the specialisation in these cases?

I don't know how you could possibly specialize for containers
detecting if they hold contiguous memory or not. But possibly, you can
provide non-template overloads to take the start and end pointers
(using the same trick above). This, however, does cause change the
call of the function func from user code.