cmb

#COMB
##the simple combination generator

$3

Given a set and the number of elements you want to have in a
combination, comb returns an iterator object, with the methods
next and rewind.

``
var c = new Comb([1,2,3], 2);
c.next() // {done: false, value: [1,2]}
c.next() // {done: false, value: [1,3]}
c.next() // {done: false, value: [2,3]}
c.next() // {done: true}
c.rewind() // true
c.next() // {done: false, value: [1,2]}
`

If a callback function is given, it is
executed for each element right away.

`
Comb([1,2,3,4,5], 2, console.log.bind(console));
[ 1, 2 ]
[ 1, 3 ]
[ 1, 4 ]
[ 1, 5 ]
[ 2, 3 ]
[ 2, 4 ]
[ 2, 5 ]
[ 3, 4 ]
[ 3, 5 ]
[ 4, 5 ]
`

You can also use each to iterate over each combination. You can stop
the iteration by returning the generators own break property from within
the function. The generator is not rewinded implicitely, so you can resume
where you left off, if you want.

`
var cmb = new Comb([1,2,3,4], 2);
cmb.each(function (val) {
console.log(val);
if (val[1] === 3) return cmb.break;
});
console.log("");
cmb.each(function (val) {
console.log(val);
});

[1,2]
[1,3]

[1,4]
[2,3]
[2,4]
[3,4]
`

$3

Node.js is pretty strong on streams, so here you have a stream of
combinations:

`
var cstr = Comb.Stream([1,2,3,4,5], 2);

cstr.read() // [ 1, 2 ]
cstr.read() // [ 1, 3 ]
cstr.on('end', console.log.bind(console, 'FIN'));
cstr.on('data', console.log.bind(console));
[ 1, 4 ]
[ 1, 5 ]
[ 2, 3 ]
[ 2, 4 ]
[ 2, 5 ]
[ 3, 4 ]
[ 3, 5 ]
[ 4, 5 ]
null
``