Fix float exponents when writing a TDB file (TC ERROR DatabaseUtils)

[ricardonpa]

Hi, this is a small fix to '_print_Piecewise' function in the io.tdb module to improve compatibility with TC. I'm using this module to parse some of my tdbs and TC complains about float exponents (A constant integer must be used as the exponent in exponential TDB expressions). Thank you.

Edit on 03/07: I updated my previous fix to change only the exponents in '_stringify_expr' and added some extra rules where to break lines in 'reflow_text'. I did a couple of tests with different tdbs and TC is reading it with no errors now.

Checklist

• [N/A] If any dependencies have changed, the changes are reflected in the
  • [N/A] setup.py (runtime requirements)
  • [N/A] pyproject.toml (build requirements)
  • [N/A] requirements-dev.txt (build and development requirements)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.46%. Comparing base (1c79c0c) to head (1dc5cc1).

❗ Current head 1dc5cc1 differs from pull request most recent head 7bf0bd4

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Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #516      +/-   ##
===========================================
- Coverage    90.47%   90.46%   -0.02%     
===========================================
  Files           50       50              
  Lines         7878     7868      -10     
===========================================
- Hits          7128     7118      -10     
  Misses         750      750              

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[richardotis]

Only one test is failing, and I think it's safe for you to modify the pass condition for that test to match this new behavior, since it only differs in the amount of whitespace.

[ricardonpa]

Hi Richard, I’ve updated ‘test_database.py’, and the test should pass now. I’ve also generalized my previous rules to allow line breaks before any number addition/subtraction that isn’t part of an EXP or LN/LOG operation. The previous rules already accounted for that, but were overlooking some permissible break points.

[richardotis]

Please pull and merge the latest develop into this branch to resolve the conflict with #522

I think it should be an easy merge, just adopting the new code and changing the ' * ' to '*' as you've already done.

[ricardonpa]

Hi @richardotis. This regex basically matches any addition and subtraction of any number, ie. [+-][0-9], since they are not preceded by 'E' or '('. This should prevent breaking lines inside EXP or LN/LOG or power expression: '6.14599E-07', 'T**(-3)', and 'LOG(-3)', hence splitting these could lead to errors in TC. In practice, this makes the functions being breakable at the linebreak_chars plus at [+-][0-9], since they are not preceded by 'E' or '('.

I'll add a comment on the code about this implementation and merge it to #522

[richardotis]

The test failures are unrelated and will be fixed once #530 is merged.

Can you add a test for reflow_text to confirm the line-breaking behavior for floating-point exponents is correct now?

[ricardonpa]

Sure, I'll add it and let you know.

[ricardonpa]

Hi @richardotis, just added a new test test_reflow_text_for_line_breaks for testing the line breaks and updated test_tc_printer_exp for testing if floating-point exponents are being returned.