String view

[Daniel Keep]

Lionello Lunesu wrote:
> char* p = ....;
> char[] stringview = p[0..strlen(p)];
> assert( stringview.ptr is p );
> 
> "NN" <nn-mail at bk.ru> wrote in message 
> news:ep0ic7$1a9c$1 at digitaldaemon.com...
> 
>>Why there is no string view in D ?
>>
>>Assume I have pointer in memory pointing to zero ending string:
>>char* p;
>>
>>I want to create a string from it but i do not want to copy it.
>>Assume I have a special class for this:
>>StringView s(p);
>>
>>But what would I do if function receives char[] ? There will be a copy.
>>What if I do not want a copy ?
>>
>>Thanx. 

A more in-depth explanation:

D has "slices" which are a combination of a pointer and a length (number 
of elements).  Slices are effectively the same thing as arrays (they 
work in precisely the same way).

You can take a slice of an array, *or* a pointer using the

   ptr[first..(last+1)]

syntax.  The reason you use the last index you want to slice + 1 is that 
this allows things like

   ptr[0..0]

for an empty slice and

   arr[0..$]

which is a slice over an entire array (where "$" is the array's length).

So, in your example, to convert a null-terminated C string into a D 
array (WITHOUT copying), you would use the code Lionello posted.  Just 
note that by doing so, you strip off the trailing NULL (D doesn't use 
trailing NULLs since all arrays know their own bounds).

	-- Daniel