Enhancement

Description

As discussed in various places, including atom/atom#10384 (comment), there is an opportunity to implement a new indentation logic that heavily exploits the output from the new tree-sitter parser. This makes it possible to address a number of issues users have been seeing with indentation, including in other languages, e.g., atom/atom#6655.

Status

I've started developing this in my sane-indentation package, and version 0.9.3 already use it. It works very well so far and without having gone through the above linked list of issues in detail, it seems to fix a good number of them already. I'm showing an example of its current indentation below.

Proposed Approach

I plan to complete the work for this new logic in the package for JavaScript. Once that is done, i.e., it fixes all known indentation issues, so long as they are not mutually exclusive (for instance, because they were just a matter of opinion), then I propose we discuss porting that code into this package (language-javascript). If and when that is completed, i.e., we all agree that this is the right approach, then it should be relatively simple to port this to other languages as well.

Example

foo({
    sd,
    sdf
  },
  4
);

foo( 2, {
    sd,
    sdf
  },
  4
);

foo( 2,
  {
    sd,
    sdf
  });

foo(2,
  4);

var x = [
  3,
  4
];

if (true) {
  foo();
  bar();
} else {
  foo();
  bar();
}

if (true)
  foo();
else
  bar();

const jsx = (
  <div
    title='start'
    >
    good
    <a>
      link
    </a>
    <i>
      sdfg
    </i>
    <div>
      sdf
    </div>
  </div>
);

const two = (
  <div>
    <b>
      test
    </b>
    <b>
      test
    </b>
  </div>
);

const x = {
  g: {
    a: 1,
    b: 2
  },
  h: {
    c: 3
  }
}

/* multi-line expressions */
req
  .shouldBeOne();
too.
  more.
  shouldBeOneToo;

const a =
  long_expression;

b =
  long;

b =
  3 + 5;

/**
  Comments
*/

while (mycondition) {
  sdfsdfg();
}