flow-runtime/lib/makeUnion.js

import UnionType from './types/UnionType';


export default function makeUnion(context, types) {
  var length = types.length;
  var merged = [];
  for (var i = 0; i < length; i++) {
    var type = types[i];
    if (type instanceof UnionType) {
      mergeUnionTypes(merged, type.types);
    } else {
      merged.push(type);
    }
  }
  var union = new UnionType(context);
  union.types = merged;
  return union;
}

function mergeUnionTypes(aTypes, bTypes) {
  loop: for (var i = 0; i < bTypes.length; i++) {
    var bType = bTypes[i];
    for (var j = 0; j < aTypes.length; j++) {
      var aType = aTypes[j];
      if (aType.acceptsType(bType)) {
        continue loop;
      }
    }
    aTypes.push(bType);
  }
}