iterUnshift

Create an iterator which prepends values to the beginning of a provided iterator.

Usage

var iterUnshift = require( '@stdlib/iter/unshift' );

iterUnshift( iterator, ...items )

Returns an iterator which prepends values to the beginning of a provided iterator.

var array2iterator = require( '@stdlib/array/to-iterator' );

var it = iterUnshift( array2iterator( [ 1, 2 ] ), 3, 4 );
// returns <Object>

var v = it.next().value;
// returns 3

v = it.next().value;
// returns 4

v = it.next().value;
// returns 1

v = it.next().value;
// returns 2

var bool = it.next().done;
// returns true

The returned iterator protocol-compliant object has the following properties:

next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

Notes

If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

var randu = require( '@stdlib/random/iter/randu' );
var iterUnshift = require( '@stdlib/iter/unshift' );

// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
    'seed': 1234,
    'iter': 10
});

// Create an iterator with prepended values:
var it = iterUnshift( rand, 'beep', 'boop' );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( v.done ) {
        break;
    }
    console.log( v.value );
}