Support multiple abbreviations for kilo, mega and other prefixes of units

[angularsen]

Problem

Currently, it is not possible to support parsing both Area.Parse("1 km²") and Area.Parse("1 km^2") due to a limitation in the JSON structure for prefix units (kilo, mega etc.) and how we parse it in powershell script.

Background

We support defining multiple abbreviations for a unit in JSON on the Abbreviations property, but many units add prefixes such as kilo, mega etc to generate those extra units by simply adding k and M prefix to the unit abbreviation. However, this design currently has two limitations:

1. Only the first abbreviation in Abbreviations is used when creating abbreviations for prefix units. Ex: Area may have "Abbreviations": [ "m²", "m^2" ] and "Prefixes": [ "Kilo" ], but it only generates km² for the square kilometer unit.

2. If AbbreviationsWithPrefixes is defined, then this should be used instead of adding k and M prefixes. This is a list of abbreviations fully typed out and each position in the array matches the array Prefixes. This is useful for languages such as Russian where a different character should be used or where it's not as simple as prefixing a string. However, currently this is an array of strings and thus only supports 1 abbreviation per prefix. I propose to extend this to support an array of a mix of strings and arrays of strings.

Proposal

Support defining multiple strings per prefix unit in JSON, but keep it backwards compatible so we can either define an array of strings (as we already do) or an array of arrays of strings.

The following (silly) example would create the following abbreviations: m², m^2, km², km^2, Mm²
I think in most cases it would be either an array of string OR an array of arrays of strings - and not a mix as in this example, but implementing it this way makes it flexible and should be a matter of checking each item in AbbreviationsWithPrefixes whether it is a string or an array.

"Localization": [
          {
            "Culture": "en-US",
            "Abbreviations": [ "m²", "m^2" ],
            "Prefixes": [ "Kilo", "Mega" ],
            "AbbreviationsWithPrefixes": [ ["km²", "km^2"], "Mm²" ] // contrived example
          }
  ]

[angularsen]

Closing this due to inactivity.

[angularsen]

Reopening this due to blocking #646 .

[lipchev]

Here is what I tried with (first time PS):

Localization=$unit.Localization | % { 
   					foreach ($abbrSyno in $_.Abbreviations) {
   						$abbrev = $prefixAbbreviation + $abbrSyno
   						if ($_.AbbreviationsWithPrefixes) {
   							if($_.AbbreviationsWithPrefixes[$prefixIndex] -isnot [System.String]){
   								foreach($synoWithPrefix in $_.AbbreviationsWithPrefixes[$prefixIndex]){		
   									New-Object PsObject -Property @{
   										Culture=$_.Culture
   										Abbreviations= $synoWithPrefix
   									}
   								}
   								continue
   							}
   							else{
   								$abbrev = $_.AbbreviationsWithPrefixes[$prefixIndex]
   							}
   						}
   						New-Object PsObject -Property @{
   							Culture=$_.Culture
   							Abbreviations= $abbrev
   						}
   					}
   				}

It seems to work for

{
     "Prefixes": [ "Pico", "Nano", "Micro", "Milli", "Centi", "Deci" ],
     "Localization": [
       {
         "Culture": "en-US",
         "Abbreviations": [ "mol/L", "M"]
       }
     ]
   }

However when I tried to alter the mass with ..

"Localization": [
        {
          "Culture": "en-US",
          "Abbreviations": [ "g" ]
        },
        {
          "Culture": "ru-RU",
          "Abbreviations": [ "г" ],
          "AbbreviationsWithPrefixes": [ "нг", "мкг", "мг", "сг", "дг", "даг", "гг", [ "кг", "кг." ] ]
        }

.. I got a list of strings and no arrays (the AbbrWithPrefix is array condition is never reached).
Any tips?

[angularsen]

I don't immediately see the error her, and I kind of struggle to read the above code snippet and the flow.
Do you have a branch I can checkout and look at the code locally with an IDE?

[angularsen]

Just create a pull request and we can discuss there.

[lipchev]

Ok I figured it out- it works if you change the Localization.AbbreviationsWithPrefixes to [object[]]. Was that your intention?
Also found an issue(not related to the abbreviations) with (for example) Mass.Parse("1 кг", RussianCulture) - here the format provider gets lost..
Does it merit a separate issue?

[angularsen]

1. object[] seems reasonable since we want it to be an array of items either string or string[] yes.
2. I don't fully understand, I believe in your example you try to parse 1 kg in Russian. Are you saying that it fails to parse that? How does it fail?

[angularsen]

@lipchev A heads up, but yesterday I decided to rewrite the codegen scripts from PowerShell to C# in #656. Too many papercuts with the limited type system in PS over the years.
Depending on what PR is merged first, one of us will have a merge conflict to deal with.