Add rule to remove blank lines between chained functions

[mannylopez]

Summary

This PR proposes adding a rule that removes spaces between chained functions (blankLinesBetweenChainedFunctions )

Reasoning

Improves readability and maintainability, making it easier to see the sequence of functions that are applied to the object.

Examples

// WRONG
var innerPlanetNames: [String] {
  planets
    .filter { $0.isInnerPlanet }

    .map { $0.name }
}

// RIGHT
 var innerPlanetNames: [String] {
  planets
    .filter { $0.isInnerPlanet }
    .map { $0.name }
}

Note

After nicklockwood/SwiftFormat#1723 merges, the rule will also apply to cases where there is a comment between chained functions.

// WRONG
var innerPlanetNames: [String] {
  planets
    .filter { $0.isInnerPlanet }

    // Gets the name of the inner planet
    .map { $0.name }
}

// RIGHT
var innerPlanetNames: [String] {
  planets
    .filter { $0.isInnerPlanet }
    // Gets the name of the inner planet
    .map { $0.name }
}

Test

Confirmed that running the linter with --rules blankLinesBetweenChainedFunctions turned on does remove the extra space

[calda]

The rule does not remove this empty space if there is a comment in between chained functions. Running the linter will leave this code as-is.

let planets = ["Mercury", "Venus", "Earth", "Mars"]

var transformedPlanetNames: [String] {
   planets
     .map { $0.uppercased() } // Making names uppercase

     // Adding excitement with an exclamation mark
     .map { $0 + "!" }
}

Is this exception necessary? I'd prefer we not allow this, and for consistency remove the blank line here as well.

Looking at the PR that introduced this SwiftFormat rule, I don't see any indication that this behavior was implemented intentionally. It would be easy to update the SwiftFormat rule to handle this case and remove this blank line as well.

What do you think @mannylopez?

[mannylopez]

Thanks for the help updating the rule. Here's the SwiftFormat PR to get rid of this exception: nicklockwood/SwiftFormat#1723

[mannylopez]

@calda nicklockwood/SwiftFormat#1723 merged overnight. Do you think this PR is ready to merge as well?

[calda]

We currently wait to merge until about one week after announcing the proposal review so everyone has a chance to share their feedback (so, we can merge this on Thursday or Friday). We'll also want to update the SwiftFormat version in this repo to include your bug fix. I'm working on instructions for how to do that, which I'll share in a bit.

[mannylopez]

We currently wait to merge until about one week after announcing the proposal review so everyone has a chance to share their feedback (so, we can merge this on Thursday or Friday). We'll also want to update the SwiftFormat version in this repo to include your bug fix. I'm working on instructions for how to do that, which I'll share in a bit.

ah, that's right! Thanks.

[calda]

Thanks! Looks great, and very strong support on Slack.