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https://github.com/swift-emacs/swift-mode

Emacs support for Apple's Swift programming language.
https://github.com/swift-emacs/swift-mode

elisp emacs emacs-lisp emacs-mode swift swift-programming-language

Last synced: 29 days ago
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Emacs support for Apple's Swift programming language.

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README 

        
[![License GPL 3][badge-license]][copying]

[![Run Tests][badge-run-test]][action-run-test]

[![MELPA](https://melpa.org/packages/swift-mode-badge.svg)](https://melpa.org/#/swift-mode)

[![MELPA](https://stable.melpa.org/packages/swift-mode-badge.svg)](https://melpa.org/#/swift-mode)



# swift-mode



Major-mode for Apple's [Swift programming language](https://developer.apple.com/swift/).



## Installation



Install `swift-mode` package from MELPA.



To install without MELPA, download [latest release](https://github.com/swift-emacs/swift-mode/releases) and execute `M-x package-install-file` for the .tar archive.



## Features



- Font Lock

- Indentation



  ```swift

  switch foo {

  case let .P1(x)

         where

           x > 0,

       let .P2(x)

         where

           x > 0:

      bar()

        .then { x in

            return baz(x)

        }

        .then {(

                 x,

                 y

               ) in

            return moo(x + y)

        }

  }



  // Hanging brace

  let x = [

    1,

    2,

    3

  ]



  // Brace on its own line

  let y =

    [

      1,

      2,

      3

    ]



  // Utrecht style

  let z =

    [ 1

    , 2

    , 3

    ]

  ```

- `forward-sexp`

- `beginning-of-defun`, `end-of-defun`, `mark-defun`, and `narrow-to-defun`.

- `beginning-of-sentence`, `end-of-sentence`, `kill-sentence`, `backward-kill-sentence`, `mark-sentence`, and `narrow-to-sentence`.

  A sentence is a statement outside comments or strings, or an ordinal sentence inside comments or strings.

- `indent-new-comment-line`

- [Imenu](https://www.gnu.org/software/emacs/manual/html_node/emacs/Imenu.html)

- Running Swift REPL in a buffer (`M-x run-swift`)

- Build Swift module (`M-x swift-mode:build-swift-module`)

- Build iOS app (`M-x swift-mode:build-ios-app`)

- Running debugger on Swift module (`M-x swift-mode:debug-swift-module`)

- Running debugger on iOS app in simulator or device (`M-x swift-mode:debug-ios-app`)

  ([`ios-deploy`](https://github.com/ios-control/ios-deploy) is required to debug on device).



This package does not provide flycheck. See [flycheck-swift](https://github.com/swift-emacs/flycheck-swift).



## Limitations



Some syntax constructs removed from Swift 3.0 are not supported:



- C-style for-loop: `for var i = 1; i < 10; i++ { }`

- Multiple assignments in single `if let`:

  ```swift

  if let x = x,

         y = y {

  }

  ```



  Use multiple `let` instead:

  ```swift

  if let x = x,

     let y = y {

  }

  ```



Indentation may not accurate. For example, `foo(Bar < A, B > (c))` can be indented like either

```swift

foo(Bar < A,

    B > (c)) // Passing two Boolean arguments to foo

```

or

```swift

foo(Bar < A,

          B > (c)) // Passing a new Bar with two type arguments and a value

```

The Swift compiler disambiguates this case using tokens after `>`, but those tokens may not available at editing time. We use some heuristic for this.



Another example is difficulty of handling of colons. We have to pair all `?` and `:` of conditional operators to decide indentation of the below snippet. This is a future work.



```swift

switch foo {

  case let P(x) where x is Foo? ? a ? b : c ?? d : e ? f : g :

    h ? i?.j() : k()

}



switch foo {

  case let P(x) where (x is Foo?) ? (a ? b : c ?? d) : (e ? f : g) :

    h ? i?.j() : k()

}

```



Yet another difficult case is consistency of blocks. We want to indent method chains like this:

```swift

var x = foo

  .then { x in

      aaa

  }

  .then { x in

      aaa

  }

```



while we also want to indent the body of `if` like this:



```swift

if anotherVeryLongVariableName

     .veryLongPropertyName {

    aaa

}

```



That is, we have to indent the closing brace with offset if it is a part of expressions while it should be aligned with the beginning of the statement/declaration if it is a part of a statement/declaration.



Then, how should we indent the following code when the cursor is before `@`?



```swift

var x = foo

  .bar {

    @

```



This could be

```swift

var x = foo

  .bar {

    @abc willSet {

        aaa

    }

}

// property declaration

```

or

```swift

var x = foo

  .bar {

      @abc var x = 1

      x

  }

// property initialization

```



Both are syntactically correct code. We cannot handle this case properly. This is also a future work.



Other example is regex literals and custom operators.  The following example is valid Swift code with regex literals and custom operators.



```swift

let x = /^/ /^/ /^/

```



We parse them as regex literals rather than custom operators for now.



## Hacking



To build the package locally, run `make package`.



To install the built package, run `make install`.



To run tests, run `make test`.



For other commands, run `make help`.



## Related projects



- [Official swift-mode.el by Apple](https://github.com/apple/swift/blob/master/utils/swift-mode.el): Seems still in very early stage for now. We cannot contribute to it due to the license incompatibility.

- [sourcekit-lsp](https://github.com/apple/sourcekit-lsp): Language Server Protocol implementation for Swift and C-based languages.

- [lsp-sourcekit](https://github.com/emacs-lsp/lsp-sourcekit): Emacs client for lsp-sourcekit.

- [swift-helpful](https://github.com/danielmartin/swift-helpful): Shows documentation about Swift keywords, attributes, and API.

- [company-sourcekit](https://github.com/nathankot/company-sourcekit): Completion for Swift projects via SourceKit with the help of SourceKitten.

- [flycheck-swift](https://github.com/swift-emacs/flycheck-swift): Flycheck extensions for Swift.

- [swift-playground-mode](https://gitlab.com/michael.sanders/swift-playground-mode): Emacs support for Swift playgrounds.

- [swift-format](https://github.com/apple/swift-format): Formatter for Swift by Apple (`swift format` command).

- [SwiftRewriter](https://github.com/inamiy/SwiftRewriter): Formatter for Swift using SwiftSyntax.

- [SwiftFormat](https://github.com/nicklockwood/SwiftFormat): Formatter for Swift.



## Contributing



Yes, please do! See [CONTRIBUTING](./CONTRIBUTING.md) for guidelines.



## Acknowledgements



The REPL code is based on [js-comint](http://js-comint-el.sourceforge.net/).



Thanks to the following original developer and users for their contributions:



- [@chrisbarrett](https://github.com/chrisbarrett) (Chris Barrett)

- [@ap4y](https://github.com/ap4y) (Arthur Evstifeev)

- [@bbatsov](https://github.com/bbatsov) (Bozhidar Batsov)

- [@ckruse](https://github.com/ckruse) (Christian Kruse)

- [@syohex](https://github.com/syohex) (Syohei Yoshida)

- [@uk-ar](https://github.com/uk-ar) (Yuuki Arisawa)

- [@msanders](https://github.com/msanders) (Michael Sanders)



You can find a [full list of those people here](https://github.com/swift-emacs/swift-mode/graphs/contributors).



Thanks to [@purcell](https://github.com/purcell) (Steve Purcell) for advices on the code and arrangement for merging `swift3-mode` and `swift-mode`.



## License



GPLv3. See [COPYING][] for details. Copyright (C) 2014-2021 taku0, Chris Barrett, Bozhidar Batsov, Arthur Evstifeev.



[badge-license]: https://img.shields.io/badge/license-GPL_3-green.svg

[badge-run-test]: https://github.com/swift-emacs/swift-mode/workflows/Run%20Tests/badge.svg

[action-run-test]: https://github.com/swift-emacs/swift-mode/actions?query=workflow%3A%22Run+Tests%22

[COPYING]: ./COPYING