Refactor Content.rec(..) function to support tail-optimisation

[dmytroDragan]

What is the context for this pull request?

• Tracking Issue: #400
• Parent Issue: N/A
• Dependencies: N/A

What changes were proposed in this pull request?

Refactor Content.rec(..) function to support tail-optimisation

Does this PR introduce any user-facing change?

No

How was this patch tested?

Existing unit tests should be enough, because it is just refactoring without changing functionality.

[ghost]

All CLA requirements met.

[dmytroDragan]

Hi @andrei-ionescu ,

1. Sure (might make sense to add also scalafmt version for alignment)
2. There are already tests for Content class like "Content.files api lists all files from Content object" which rely on it, but I could move rec function to Content object and add more.

[sezruby]

@dmytroDragan Sorry but, could you revert unnecessary changes from scalafmt to reduce the diff? It can be handled with a different PR (would be appreciated if you could push a new PR!), so that we could review & merge only required change for tailrec.

[dmytroDragan]

Hi @sezruby! I can revert changes from scalafmt, but it makes a usage of scalafmt useless in first place.

I`m using 2.7.5 (latest) scalamft with dev conf:

# The following configs are taken from https://github.com/apache/spark/blob/master/dev/.scalafmt.conf
align = none
align.openParenDefnSite = false
align.openParenCallSite = false
align.tokens = []
optIn = {
  configStyleArguments = false
}
danglingParentheses = false
docstrings = JavaDoc
maxColumn = 98

# The following are specific to Hyperspace.
importSelectors = singleLine

If anyone gets different result for this files (like old once), please reach out to me and we could try to figure out.

I could make a PR with only scalafmt of this two files, so my PR will cover only my changes after merge. What do you think?

[andrei-ionescu]

@dmytroDragan, Here is my scalafmt setup in IntelliJ Idea (I have 1.5.1 version):

I usually do Command+Shift+Alt+L to reformat the file and use the following options in the dialog box:

The formatting is correct, the only annoying thing is that it order the functions by name too. I will be great if you could double check the diffs before pushing the changes.

[dmytroDragan]

Thank you @andrei-ionescu. I have rechecked my configuration and applied result formatting. I have created PR with just scalafmt formated code for this 2 files, so reviewing it could be easier: https://github.com/microsoft/hyperspace/pull/412

[dmytroDragan]

Th problem was with 1.5.1 vs 2.7.5 scalafmt. Fixed version is done as new PR: https://github.com/microsoft/hyperspace/pull/417