module count;

import std.algorithm;
import std.array;
import std.stdio;
import std.range;
import std.traits;
import std.datetime;

alias std.array.replicate replicate;

void main()
{
    auto arr = array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10].replicate(100));

    auto r = benchmark!({splitLengthOld(arr, 2);}, {splitLengthNew(arr, 2);})(10_000);
    writefln("splitLengthOld 10_000 times: %s msecs.", r[0].to!("msecs", int));
    writefln("splitLengthNew 10_000 times: %s msecs.", r[1].to!("msecs", int));
}

T[] splitLengthOld(T)(T arr, size_t count) if (isArray!T)
{
    T[] result;

    while (arr.length)
    {
        result ~= arr.take(count);
        arr.popFrontN(count);
    }

    return result;
}

T[] splitLengthNew(T)(T arr, size_t count) if (isArray!T)
{
    T[] result;
    assert(count > 0);

    result.reserve((arr.length + count - 1) / count);

    while (arr.length > count)
    {
        result ~= arr[0..count];
        arr = arr[count..$];
    }

    if (arr.length)
        result ~= arr;
    
    return result;
}