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

Install from here
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

Make sure you have installed the following:

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

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

Publish

npm run check
Bump version number in package.json
Write changelog
git commit -m 'Bump'
npm run tag-n-push
npm run clean
npm run build-parsers
npm run publish

Get Personal access token

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

Instructions, PAT tab.

Rebuild parsers

npm build-parsers

Configure a new language

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

simonacca / tASTe