lossless float support

[samuelcolvin]

fix #80.

Example usage:

import jiter

f = jiter.from_json(b'123.456789123456789e45', lossless_floats=True)
assert isinstance(f, jiter.LosslessFloat)
assert 123e45 < float(f) < 124e45
assert f.as_decimal() == Decimal('1.23456789123456789E+47')
assert bytes(f) == b'123.456789123456789e45'
assert str(f) == '123.456789123456789e45'
assert repr(f) == 'LosslessFloat(123.456789123456789e45)'

[codspeed-hq]

CodSpeed Performance Report

Merging #98 will not alter performance

_{Comparing py-float (9ed4360) with main (1fbedbf)}

Summary

✅ 73 untouched benchmarks

[davidhewitt]

This is quite big brain 🧠. Is it worth considering a lower-level function to just try to parse the float as a number range and fail if it doesn't successfully consume the whole string?

[samuelcolvin]

I think it's good as is.