experiment: rascal formatter based on Box and layoutDiff

[jurgenvinju]

Rascal is a pretty big language so this pushes the new toBox and format and layoutDiff functions to the max.

• For now the goal is to formulate toBox rules such that the formatter produces beautiful layout, and
• We identify bugs and efficiency issues in toBox, format and layoutDiff for later fixing.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47%. Comparing base (6cfa756) to head (a7ad1a3).

Additional details and impacted files

@@           Coverage Diff           @@
##              main   #2346   +/-   ##
=======================================
  Coverage       47%     47%           
- Complexity    6626    6627    +1     
=======================================
  Files          783     783           
  Lines        64703   64698    -5     
  Branches      9688    9683    -5     
=======================================
+ Hits         30724   30732    +8     
+ Misses       31580   31562   -18     
- Partials      2399    2404    +5     

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[toinehartman]

In the spirit of eat your own dog food, I gave it a spin

rascal>formatRascalFile(|file:///c:/Users/toine/swat/projects/Rascal/rascal/src/org/rascalmpl/library/lang/rascal/format/Rascal.rsc|);
|TODO:///|: ParseError(|file:///c:/Users/toine/swat/projects/Rascal/rascal/src/org/rascalmpl/library/lang/rascal/format/Rascal.rsc|(2734,1,<67,73>,<67,74>))

The error is not in the original file:

rascal>parse(#start[Module], |file:///c:/Users/toine/swat/projects/Rascal/rascal/src/org/rascalmpl/library/lang/rascal/format/Rascal.rsc|);
start[Module]: (start[Module]) `@license{
Copyright (c) 2022, NWO-I Centrum Wiskunde & Informatica (CWI)
All rights reserved.
...

I did not investigate further, but it might very well be introduced by our toBox rules.

[toinehartman]

Nice! Really cool to test declarative formatting on a mature languge.

I think finding a formatting for Rascal that's commonly agreed on might be controversial...