AST操作でコメント付与の実験

add-comment.js

const template = require('babel-template')
const {parse} = require('babylon')
const {transform} = require('@babel/core')
const prettier = require('prettier')

const src =
`function hoge() {
}
`

const addLeadingComment = (nodePath, comment) => {
  const temp = `${comment}\n${nodePath.getSource()}`
  const ast = template(temp, {preserveComments: true})()
  nodePath.replaceWith(ast)
}

const addJsDoc = (nodePath, text) => {
  const comments = ['/**', ...text.split('\n').map(line => ` * ${line}`), ' */\n']
  return addLeadingComment(nodePath, comments.join('\n'))
}

const plugin = (babel) => {
  const visitor = {
    Function: {
      exit: (nodePath, state) => {
        if (nodePath.node.leadingComments) {
          return
        }
        addJsDoc(nodePath, 'hoge')
      }
    }
  }
  return {
    visitor    
  }
}


let {code} = transform(src, {plugins: [plugin]})
// code = prettier.format(code)
console.log(code)