Incorrect parsing of decibel units

[jcarrillo-oai]

Seems like logarithmic units are not correctly handled in the parser

>>> reg.from_ucum("dB")
<Quantity(1, 'decibyte')>
>>> reg.from_ucum("dB[W]")
<Quantity(1, 'decibyte * watt')>
>>> reg.from_ucum("dB[mW]")
...
 raise UnexpectedCharacters(stream, i, text_line, text_column, {item.expect.name for item in to_scan},
lark.exceptions.UnexpectedCharacters: No terminal matches '[' in the current parser context, at line 1 col 3

dB[mW]
  ^

[dalito]

"db[mW]" seems to be an invalid UCUM code. Also https://ucum.nlm.nih.gov/ucum-lhc/demo.html does not accept it. However, B[W] is an accepted logarithmic unit so it can be parsed (see "§46 levels" in https://ucum.org/ucum#section-Other-Legacy-Units).

Do you have other sources that made you expect that dB[mW] is valid?

[jcarrillo-oai]

@dalito Ah sorry that part came from a conversation with ChatGPT after I hit the error. My original issue was sparked by the incorrect parsing of dB as decibyte rather than decibel. dB[V], dB[mV], and dB[kW] also parse incorrectly. They are all accepted by the online validator as well.

>>> reg = ucumvert.PintUcumRegistry()
>>> reg.from_ucum("dB")
<Quantity(1, 'decibyte')>
>>> reg.from_ucum("dB[V]")
<Quantity(1, 'decibyte * volt')>
>>> reg.from_ucum("dB[mV]")
<Quantity(1, 'decibyte * millivolt')>
>>> reg.from_ucum("dB[kW]")
<Quantity(1, 'decibyte * kilowatt')>

[dalito]

Ok - There is something wrong. I have to look in detail which may take a few days.