index.js

const codeblocks = (tree, options) => {
  options = options || {}

  const lang = options.lang || 'all'
  const name = options.name || 'codeblocks'
  const formatter = options.formatter || (v => v)

  const { children } = tree
  let data = {}
  let i = -1
  let child

  if (lang === 'all') {
    data[name] = {}
  } else {
    data[name] = []
  }

  while (++i < children.length) {
    child = children[i]

    if (child.type === 'code' && child.value) {
      if (lang === 'all') {
        child.lang = child.lang || '_'
        data[name][child.lang] = data[name][child.lang] || []
        data[name][child.lang].push(formatter(child.value))
      } else {
        if (child.lang === lang) {
          data[name].push(formatter(child.value))
        }
      }
    }
  }

  return data
}

module.exports = options => (tree, file) => {
  const data = codeblocks(tree, options)
  file.data = Object.assign({}, file.data, data)
}

module.exports.codeblocks = (tree, options) => codeblocks(tree, options)