[Issue 7839] New: std.range.count() too

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=7839

           Summary: std.range.count() too
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: nobody at puremagic.com
        ReportedBy: bearophile_hugs at eml.cc


--- Comment #0 from bearophile_hugs at eml.cc 2012-04-05 17:59:57 PDT ---
I'd like a count() in std.range. It's similar to the generator with the same
name in the Python itertools module:
http://docs.python.org/library/itertools.html#itertools.count

a count() is also useful with bigints, where you can't replace it with
iota(BigInt.max).


A bare-bones implementation that shows it basic semantics (but it's useful to
add few more methods):


struct Count(T) {
    T n;
    this(T n_) { this.n = n_; }
    const bool empty = false;
    @property T front() { return n; }
    void popFront() { /* n++; */ n += 1; }
}

// Two helper functions
Count!T count(T)(T start) { return Count!T(start); }
Count!T count(T)() { return Count!T(cast(T)0); }

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