Improve float/double hash values

[rvanvelzen]

Right now the hash value for floats is their integer component. Instead, use dark magic to map the bits to an int.

Simple test script:

<?php
$map = new \Ds\Map();

for ($ii = 0, $max = 100000; $ii < $max; ++$ii) {
    $map[($ii / $max)] = $ii;
}

Time before patch: 16.721446990967
Time with patch: 0.012161016464233

[nikic]

Not sure how exactly ds defines floating point equality for the purpose of HT lookups, but most likely 0. === -0., which would not be handled correctly by this hash.

[rvanvelzen]

Good catch - 0.0 and -0.0 are mapped to the same value on master.

[rtheunissen]

@nikic === is used.

[rtheunissen]

Looks good, if this passes we can merge. ✨

[rvanvelzen]

(Closing and re-opening to bump Travis)

[rtheunissen]

Hah I restarted the build on Travis as well 😂

[rvanvelzen]

It's still stuck 😞

[rtheunissen]

Well this obviously isn't right.
https://travis-ci.org/php-ds/extension/jobs/438563025

[rtheunissen]

I'll merge this now and sort the test suite out tomorrow.