Function getExpression

docs/tests/v2/es6/js/sanddance.js:131492–131500

* Resolve an expression reference.

(_, ctx, params)

function getExpression(_, ctx, params) {
  if (_.$params) {
    // parse expression parameters
    parseParameters(_.$params, ctx, params);
  }

  var k = 'e:' + _.$expr + '_' + _.$name;
  return ctx.fn[k] || (ctx.fn[k] = (0, _vegaUtil.accessor)((0, _expression.parameterExpression)(_.$expr, ctx), _.$fields, _.$name));
}
/**
 * Resolve a key accessor reference.
 */