Add support for patterns that accept empty data

[ddaspit]

This change is 

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 70.52%. Comparing base (29246ef) to head (0bd5aca).

Files with missing lines	Patch %	Lines
.../FiniteState/NondeterministicFstTraversalMethod.cs	0.00%	1 Missing ⚠️
src/SIL.Machine/FiniteState/TraversalMethodBase.cs	97.43%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #298      +/-   ##
==========================================
+ Coverage   70.46%   70.52%   +0.05%     
==========================================
  Files         386      386              
  Lines       32260    32299      +39     
  Branches     4539     4543       +4     
==========================================
+ Hits        22733    22779      +46     
+ Misses       8479     8472       -7     
  Partials     1048     1048              

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[johnml1135]

@ddaspit - having a meaningful review would be fairly challenging without understanding the ins and outs of the finite state machine. Here are two things that I would like:

• An affirmation that the tests fail before the changes made
• An issue opened up (and linked to the pull request) that describes why this is an issue now (how it came up) and more exactly what capability is being added.

With the affirmation and new issue (even if I don't understand it), I will be happy to approve the pull request.

[jtmaxwell3]

@johnml1135:
This pull request fixes https://jira.sil.org/browse/LT-21867.
The root cause of LT-21867 was the inability of FSTs to accept the empty string.
I proposed a superficial fix in #296.
Damien preferred to fix the root problem in this pull request.
The modified test in RewriteRuleTests.cs fails without one of these changes (the modification should be a NOOP, but the test fails without one of the fixes).

[ddaspit]

@jtmaxwell3 Thanks for providing the full context.

[jtmaxwell3]

@ddaspit I tested this pull request against https://jira.sil.org/browse/LT-21867, and it fixes the problem.

[Enkidu93]

Do you just need someone to approve this, @ddaspit?

[ddaspit]

Yes, this hasn't been merged, because it hasn't been reviewed. And, to be honest, I forgot about it.

[Enkidu93]

Yes, this hasn't been merged, because it hasn't been reviewed. And, to be honest, I forgot about it.

Who should review it? I wasn't sure if @jtmaxwell3's admission that it fixes the issue was sufficient.

[ddaspit]

That is probably sufficient. It would be helpful for you to do at least a cursory review for any obvious issues.

Reviewable status: 0 of 11 files reviewed, all discussions resolved

[Enkidu93]

Nothing jumps out at me

Reviewed 11 of 11 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ddaspit)