Function parseParameters

docs/tests/v2/es6/js/sanddance.js:131418–131430

* Parse a set of operator parameters.

(spec, ctx, params)

 * Parse a set of operator parameters.
 */
function parseParameters(spec, ctx, params) {
  params = params || {};
  var key, value;

  for (key in spec) {
    value = spec[key];
    params[key] = (0, _vegaUtil.isArray)(value) ? value.map(function (v) {
      return parseParameter(v, ctx, params);
    }) : parseParameter(value, ctx, params);
  }

  return params;
}
/**
 * Parse a single parameter.
 */