Re: Disjoint slices of an array as reference

[Ali Çehreli via Digitalmars-d-learn]

On 8/19/20 9:11 PM, data pulverizer wrote:
On Thursday, 20 August 2020 at 03:47:15 UTC, Paul Backus wrote:
double[][] y;
y ~= x[0..5];

Thanks. I might go for a design like this:

```
struct View(T){
   T* data;
   long[2][] ranges;
}
```
The ranges are were the slices are stored and T* (maybe even 
immutable(T*)) is a pointer is to the start of the original array. I'll 
use an opIndex that calculates the correct index in the original array 
to obtain the right data.


I implemented the same idea recently; it's a fun exercise. :) I didn't 
bother with opIndex because my use case was happy with just the 
InputRange primitives (and .length I think).

And I had to implement it because std.range.chain works only with 
statically known number of sub-ranges. :/ If the number of ranges are 
known, then this works:

import std.stdio;
import std.range;

void main() {
  auto x = [1,  2,  3, 4,  5,
            6,  7,  8, 9,  10,
            11, 12, 13, 14, 15];
  auto y = chain(x[0..5], x[9..14]);
  writeln(y);
}

[1, 2, 3, 4, 5, 10, 11, 12, 13, 14]

Ali