postcss-modules-sync

import CSSModulesSync from 'postcss-modules-sync'
import postcss from 'postcss'

const css = `
  :global .text {
    color: white;
    background-color: gray;
  }

  .green {
    background-color: green;
  }

  .blue {
    background-color: blue;
  }

  .default {
    composes: green;
    display: flex;
  }
`

let exportedTokens = {}
const styles = postcss([
  CSSModulesSync({
    getTokens: tokens => exportedTokens = tokens
  })
]).process(css).css

console.log('styles', styles)
console.log('tokens', exportedTokens)