Add mapWithKeys()

[judahnator]

#64 caught my eye. I noticed that changing how the existing methods worked would cause issues, so I made a new mapWithKeys() method that passes the iterator key in addition to its value to the callback.

Here is a copy/paste of the test I wrote for it, to see it in action:

$mapped = mapWithKeys(func\operator('*'), range(0, 5));
$this->assertSame([0, 1, 4, 9, 16, 25], toArray($mapped));

$mapped = mapWithKeys(
    function ($v, $k) { return sprintf('%s%s', $k, $v); },
    ['foo' => 'bar', 'bing' => 'baz']
);
$this->assertSame(
    ['foo' => 'foobar', 'bing' => 'bingbaz'],
    toArrayWithKeys($mapped)
);

[SamMousa]

LGTM, would definitely use this if it gets merged...

[nikic]

Looks reasonable to me as well. I think it needs to be added to the rewindable namespace as well.

[SamMousa]

Since this PR is pretty old, what about merging this one and either: creating an issue for the rewindable version, or implementing that ourselves?

[judahnator]

Oh hey! I had given up hope on this PR, glad to see it is not quite dead yet.

I looked at how the rewindable stuff was laid out and did my best to copy the implementation and test for it. Let me know if anything is amiss!

[nikic]

Thanks!