for PHP: validate input and support integers up to PHP_INT_MAX

[divinity76]

use regular php division if safe (<=0x7FFFFFFF ), else use bcdiv if available (because it's faster), and finally fallback to an userland php division based on an algorithm from http://justinparrtech.com/JustinParr-Tech/an-algorithm-for-arbitrary-precision-integer-division

i can't guarantee that the algorithm is flawless, but it passes all my own tests (without using bcmath), i can't get it to fail, i have tested a lot of large integers, including PHP_INT_MAX.

note, i have not extensively tested 32bit php support, due to the fact that i dont have a 32bit system. ( i have barely tested it using ideone.com , which uses 32bit php), but because i use normal PHP division if the $num <= 0x7FFFFFFF , i can't imagine it making any difference.

[divinity76]

if you wonder about all the (int) casts, it's because the algorithm was SUPPOSED to be implemented using integer types, but PHP likes to automatically convert ints to float/double's during potential overflows or potential loss of precision, i had to make sure that didn't happen (and indeed, removing the int casts breaks the algorithm)

[ocram]

Thanks for this!

I'm not really sure about the custom implementation of the division. I'd rather add BC Math or GMP as a mandatory dependency, I guess.

Alternatively, we could add those as recommended dependencies and explain that they allow for the conversion of larger integers, together with your conditional check for the availability of BC Math or GMP.

[divinity76]

@ocram i made an alternative implementation which makes BCMath or GMP a mandatory dependency for integers above 0x7FFFFFFF , see https://github.com/delight-im/ShortURL/pull/12