Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Saturday, 18 November 2017 at 05:24:30 UTC, Tony wrote:

Forgot to handle pre-mature foreach exit:

import std.stdio : writeln;

class RefRange {
    int foreach_index;
    int[] items;
    this(int[] src)
    {
       items = src;
    }

    bool empty()
    {
       if (foreach_index == items.length)
       {
          foreach_index = 0; // reset for another foreach
          return true;
       }
       return false;
    }
    int front() { return items[foreach_index]; }
    void popFront() { foreach_index++; }
    void resetIteration() { foreach_index = 0; }
}

void main() {

    int[] ints = [1, 2, 3];
    auto refRange = new RefRange(ints);

    writeln("Ref 1st Run:");
    foreach(i; refRange)
    {
       writeln(i);
       if ( i == 2 )
       {
          refRange.resetIteration();
          break;
       }
    }
    assert( ! refRange.empty);
    writeln("Ref 2nd Run:");
    foreach(i; refRange) writeln(i); // works
}
-------------------------------
Ref 1st Run:
1
2
Ref 2nd Run:
1
2
3