std.Stream.InputStream convenience functions

[bitwise via Digitalmars-d]

On Saturday, 5 September 2015 at 23:00:43 UTC, BBasile wrote:
> On Saturday, 5 September 2015 at 19:59:03 UTC, bitwise wrote:
>> On Saturday, 5 September 2015 at 06:15:17 UTC, Jonathan M 
>> Davis wrote:
>>> [...]
>>
>> Thanks for the explanation, but could you give an example of 
>> how Stream would be rangified?
>
> this was not addressed to me but here is how it should be done:
>
> ---
> module runnable;
>
> import std.stdio;
> import std.stream;
> import std.algorithm;
>
> class RangifiedStream: MemoryStream
> {
>     auto range()
>     {
>         return Range(this);
>     }
>
>     private struct Range
>     {
>         MemoryStream _str;
>         ulong _curr;
>
>         this(MemoryStream str)
>         {
>             _str = str;
>         }
>
>         void popFront()
>         {
>             _curr += 1;
>         }
>
>         @property ubyte front()
>         {
>             ubyte result;
>             _str.position = _curr;
>             _str.read(result);
>             _str.position = _str.position - 1;
>             return result;
>         }
>
>         @property bool empty()
>         {
>             return _curr == _str.size;
>         }
>     }
> }
>
> void main(string[] args)
> {
>
>     import std.range;
>     assert( isInputRange!(RangifiedStream.Range));
>
>     RangifiedStream str = new RangifiedStream;
>     ubyte[] src = [0,1,2,3,4,5,6,7,8,9];
>     str.write(src);
>
>     str.range.each!(a => a.writeln);
> }
> ---
>
> The range has a reference to a stream. The range uses its own 
> position and this is important since several ranges may 
> co-exist at the same time. Here you just have a byte InputRange 
> but it works...
>
> For FileStream the performances will be terrible (bad), because 
> the position is hold by a a structure specific to the OS...
>
> I think I'll add this to my iz streams classes.

If all we had was a flat array of bytes(or any uniform type), 
then we wouldn't need a stream at all.

My typical usage is something like this:

int a = 1;
float b = 2;
string s = "3";

MemoryStream ms = new MemoryStream();
ms.write(a);
ms.write(b);
ms.write(s);

// stash ms in a file, or send/receive over socket..

int a = ms.readInt();
float b = ms.readFloat();
string s = ms.readString();

doSomething(a, b, s);

I'm not sure how you would go about rangifying something like 
this.