css string to styled components theme

css-string-theme.js

import flow from 'lodash.flow';
import set from 'lodash.set';

export const cssString = `
  :root {
    --root: #a;
    --sub-theme__variable: #a;
    --sub-theme__variable2: #a1;
    --sub-theme__variable3__a2: #cecea2;
    --sub-theme__variable3__a3: #cecea3;
  }
`

export const cssToTheme = flow(
  str => str.replace(/[\s\n\t]+/g, ''),
  str => /:root.*\{(.*)\}/gm.exec(str)[1],
  str => str.split(';'),
  arr => arr.filter(el => el !== ''),
  arr => arr.map(flow( 
    value => value.split(':'),
    ([key, value ]) => [key.replace('--', ''), value],
    ([key, value ]) => [key.replace(/__/g, '.'), value]
  )),
  arr => arr.reduce ((object, [key, value]) => {
      set(object, key, value)
      return object;
  }
  ,{})
)