Port Python's strtod implementation

[fermian]

This pull request includes a port of Python's strtod implementation for parsing floating point numbers in Wren's source code parser. Using a separate strtod function should remove locale dependency from using the one provided by the standard library.

[mhermier]

Could someone with more knowledge than me verify licencing of it. The python licence seems troublesome too add to the project.

[clsource]

https://docs.python.org/3/license.html

2. Subject to the terms and conditions of this License Agreement, PSF hereby grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce, analyze, test, perform and/or display publicly, prepare derivative works, distribute, and otherwise use Python 3.9.2 alone or in any derivative version, provided, however, that PSF's License Agreement and PSF's notice of copyright, i.e., "Copyright © 2001-2021 Python Software Foundation; All Rights Reserved" are retained in Python 3.9.2 alone or in any derivative version prepared by Licensee.

3. In the event Licensee prepares a derivative work that is based on or incorporates Python 3.9.2 or any part thereof, and wants to make the derivative work available to others as provided herein, then Licensee hereby agrees to include in any such work a brief summary of the changes made to Python 3.9.2.

Im no lawyer but it seems it would need adding a copyright notice

[fermian]

I added the PSF copyright notice, is that enough?

[mhermier]

The real question is will that contaminate the MIT Licencing of the project ?

[ruby0x1]

fwiw if we do go down this road (it is not determined yet) there are also MIT implementations available https://git.musl-libc.org/cgit/musl/tree/src/stdlib and I found a public domain one here but I have not verified any of these as this is a rather large rabbit hole. https://gist.github.com/mattn/1890186/

[PureFox48]

Personally, if I'm looking for something to copy/translate, I don't even consider anything that isn't either MIT licensed (as Wren is itself) or in the public domain. Licensing is just too much of a can of worms to do otherwise in my view.

[mhermier]

I will probably hate myself later for proposing that, but maybe we should implement it ourself, by augmenting our own functions. That way we could do token scanning and parsing in one pass...

[p0nce]

locale dependency in strtod in Wren caused problems for us in wren-port. I would recommend replacing double parsing in Wren by something indenpendent from C stdlib locale.

[mhermier]

Maybe we can conditionally support strtod_l. It seems supported on a a fair amount of systems now with some kind of limitations on some like #define _GNU_SOURCE on glibc. Dunno if it is a no go for the MIT licence though...