Transducer composed

transducer_composed.js

// Stripped straight from the good Dan Abramov
// https://gist.github.com/gaearon/ffd88b0e4f00b22c3159
function compose(...functions) {
  return function (arg) {
    return functions.reduceRight(function (composed, f) {
      return f(composed);
    }, arg);
  };
};

// we need a function to consistenly provide the same type
// expect(ingest([], 1)).toEqual([1]);
// expect(ingest([1], 2)).toEqual([1, 2]);
function ingest(accum, value) {
  return accum.concat(value);
}

// expect(getSelectedClass(/--solarized/)('btn--solarized')).toBe(true)
function getSelectedClass(classRegex) {
  return function(classStr) {
    classRegex.test(classStr);
  }
}

// expect(addClassModifier('active')('btn')).toBe("btn--active");
function addClassModifier(className) {
  return function (classStr) {
    return classStr.concat('--').concat(className);
  }
}

const transducer = compose(
  mapReduce(addClassModifier('active')),
  filterReduce(getSelectedClass(/--solarized/)),
)(ingest);

ClassList.of([
    'btn__background--solarized',
    'btn__text--solarized',
    'btn__overlay--solarized',
    'btn__icon',
    'btn__placeholder'
]).reduce(transducer, []);

// ClassList.of([
//   "btn__background--solarized--active",
//   "btn__text--solarized--active",
//   "btn__overlay--solarized--active"
// ]);