// released into public domain

import std.stdio;


template Tuple(T...)
{
    alias T Tuple;
}

void main()
{
    alias Tuple!(int, double) T;
    T t;
    t[0] = 5;
    t[1] = 15.0;

    mixin(Foreach( "x", "t", `x *= 3;` ));

    writefln("%s %s", t); // prints 15 45
}

string Foreach(string param, string tuple, string code)
{
    return "mixin(genForeachCode(`" ~ param ~ "`, " ~ tuple ~ ".length, `" ~ tuple ~ "`, `" ~ code ~ "`));";
}

string itoa(uint val)
{
    if (val > 9)
        return itoa(val / 10) ~ itoa(val % 10);
    char[] s = " ".dup;
    s[0] = cast(char) (val + '0');
    return s;
}


string genForeachCode(string param, uint len, string tuple, string code)
{
    string val = "";

    for (int i = 0; i < len; i++)
    {
        string tupleElem = tuple ~ "[" ~ itoa(i) ~ "]";
        val ~= "{  auto " ~ param ~ " = " ~ tupleElem ~ "; " ~ code ~ \n ~ tupleElem ~ " = " ~ param ~ "; }\n";
    }
    
    return val;
}