feat: fully implemented amount formats as per hledger spec

[darylwright]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

  • Introduces support for more amount formats, which include inversions of commodity and sign order, and alternate digit group and decimal marks.
  • Whitespace is a significant token in amounts and are stored during lexing and parsing.
  • The plus (+) has been added as a valid sign in amounts and behaves the same as the dash (-).

• What is the current behavior? (You can also link to an open issue here)

  • Currently, hledger-parser only supports negative numbers and implicitly positive numbers (without the plus).
  • Additionally, whitespace in amounts is ignored when it should be considered a significant token.
  • No support for the plus (+) in amounts.
  • No support for alternate digit group and decimal marks.

• What is the new behavior (if this is a feature change)?

  • See above description.

• Other information:

  • N/A

fixes #6

[darylwright]

Prod build currently fails, still have some cleanup to do.

Edit: Completed.

[jonestristand]

Sorry - had an interesting CPU hardware issue that was preventing me from running the test suite without getting segfaults. Item replaced now and I'll have a look at this and merge. Thanks for all your work!

[darylwright]

Thanks! The parsing algorithm for the amount is particularly complex as you'll see in the diagram. I think I got it right, but could use a bit of scrutiny. Also, I tried to represent the amount in the raw type as simply as possible, but I'm open to suggestions on how to communicate the location of whitespace, commodity, and signs. For now, I just ensure the number, commodity, and sign are stored in their own respective fields, while the full expression of the amount with whitespace is just a single string field.

[jonestristand]

You weren't kidding :-)

[jonestristand]

This looks actually spot on to me. Well done!

[darylwright]

Awesome, thanks for the merge! This will make it easier to implement the commodity directive. It was during development of that feature where I realized I needed the correct amount parsing algorithm.