tASTe: The AST Editor

Editing code often involves dealing with low-level textual representations, which can be tedious and error-prone.

tASTe is a vscode extension to edit code based on its structure, allowing you to interact more directly with the elements that make up your language.

For example, when your cursor is inside a for loop, you can invoke a command to select the whole loop at once.

Or, if you have a list of elements, tASTe gives you a command to jump from one element to the next, or expand the current selection from one element to te next. This works equally well with strings in a list as it does with other syntactic elements of many languages; you can for instance jump between code blocks (to jump from one function to the next for example), or select markdown paragraphs one after the other.

The theme of this plugin is to do away with some of the tediousness of editing code by raising the level of abstraction, so as to end up a little closer to manipulating the concepts inherent to your programming language instead of characters. Hopefully resulting in less errors and more fun :)

Commands

Expand and Contract Selection

• taste.ExpandSelection
• taste.ContractSelection

Grow and Shrink Selection

• taste.SelectForward
• taste.SelectBackward

Move Cursor

• taste.MoveCursorBackward
• taste.MoveCursorForward

Select Top Level

• taste.selectTopLevel

Raise

• taste.Raise

Swap

• taste.SwapForward
• taste.SwapBackward

Slurp / Barf

• taste.SlurpForward
• taste.BarfForward

Install instructions

1. Install from here
2. Add the keyboard shortcuts you are interested in to your editor config from the Command Palette (⇧⌘P) with the "Preferences: Open Keyboard Shortcuts (JSON) command." (docs)

Here's some suggested ones:

{
  "key": "cmd+e",
  "command": "taste.ExpandSelection"
},
{
  "key": "cmd+shift+e",
  "command": "taste.ContractSelection"
},
{
  "key": "shift+cmd+left",
  "command": "taste.SelectBackward"
},
{
  "key": "shift+cmd+right",
  "command": "taste.SelectForward"
},
{
  "key": "cmd+right",
  "command": "taste.MoveCursorForward"
},
{
  "key": "cmd+left",
  "command": "taste.MoveCursorBackward"
}

Supported languages

• Bash
• C
• C Sharp
• Common Lisp
• C++
• Cap'n Proto
• CSV
• CSS
• Dart
• Dockerfile
• DOT
• Elixir
• Erlang
• Fish
• Go
• Graphql
• Hack
• Haskell
• HCL (Terraform)
• HTML
• Java
• Javascript
• JSON
• Julia
• Kotlin
• Lua
• Markdown
• Matlab
• Nix
• Objective C
• PHP
• Python
• QML
• R
• Racket
• Rust
• Ruby
• Scala
• Scheme
• SCSS
• Scheme
• SQL
• Swift
• Toml
• TSV
• Typescript
• XML
• YAML
• Zig

Troubleshooting

Unrecognized language

If you get the message "The language ... is not yet supported by tASTe" but the language of my file listed as supported in this readme, it could be that vscode cannot auto-detect the language in question. You can verify this by checking that the language is shown correctly in the bottom-right corner of vscode.

In case it's not shown correctly, you might need to install an extension that enables support for your language.

If the language is already recognized correctly and you still get the "language not supported" error, the problem is probably that the languageId assigned by vscode to your language does not coincide with the one used by tree-sitter. Please open an issue!

Credits

Credit for this idea goes to the long lineage of lisp structured editors, with a special shoutout to Emac's paredit and vscode's Calva. A special thank you also to the developers of Tree-sitter and its many parsers, without which this wouldn't be possible.

Dev HOWTOs

Bringup development environment

1. Make sure you have installed the following:

• emscripten compiler
• nodejs
• docker (optional)
• gnu parallel (optional)

2. npm install
3. npm build-parsers
4. npm run build-watch
5. In the "Run and Debug" menu of vscode, Start debugging the "Run Extension" target

Publish

1. npm run check
2. Bump version number in package.json
3. Write changelog
4. git commit -m 'Bump'
5. npm run tag-n-push
6. npm run clean
7. npm run build-parsers
8. npm run publish

Get Personal access token

This only applies if you are the extension publisher (simonacca).

Instructions, PAT tab.

Rebuild parsers

1. npm build-parsers

Configure a new language

1. Check open and closed issues first tagged with language-support, that's where unsuccessful attempts at adding languages are documented.
2. Install the parser npm i tree-sitter-mylanguage
3. Add a line to the build_wasm.sh script to generate the grammar
4. List the language in languageID2ParserName
5. Add an entry to excludeNodeTypes corresponding to the language

A language is installed and built but not recognized

Add an entry in src/languages.ts -> languageIDTranslation mapping the vscode languageID to the wasm name (see build-parsers.sh -> build_parser <node_module_name> <wasm_name>).