@hyrious/lezer-fmt

Code formatter based on Lezer Parser.

Important

This package is still in experiment stage. It isn't published.
To play with it, clone this repo and do:

pnpm install
Edit src/cli.ts
npx @hyrious/esbuild-dev src/cli.ts

Usage

import {definePrinter, format, space} from '@hyrious/lezer-fmt'

let code = await format('foo ( bar )', {
  parser: await import('@lezer/javascript').then(m => m.parser),
  spec: definePrinter({
    spec: {}
  })
})

`definePrinter({ spec })`

The spec is a list of rules to match tokens and return the spaces rule. For example,

definePrinter({
  spec: {
    // If the token is '=', add spaces around.
    'Equals, ArithOp': space.around,
    // The `ArithOp` matched later takes higher precedence.
    'UnaryExpression/ArithOp': space.none,
  },
  // Default rule if none of the spec above matched.
  defaultSpec: space.after,
})

You can view each token's scope names in debug mode.

Plus it can be written with operators - & | ():

'Equals' // match '='
'VariableName - ForStatement' // match a variable not in for-statement
'^-' // match '-', the '^' is used to escape the next character

License

MIT @ hyrious