Function parameterValue

docs/tests/v2/es6/js/sanddance.js:135374–135383

* Parse a single parameter value.

(def, value, scope)

function parameterValue(def, value, scope) {
  var type = def.type;

  if ((0, _util.isSignal)(value)) {
    return isExpr(type) ? (0, _vegaUtil.error)('Expression references can not be signals.') : isField(type) ? scope.fieldRef(value) : isCompare(type) ? scope.compareRef(value) : scope.signalRef(value.signal);
  } else {
    var expr = def.expr || isField(type);
    return expr && outerExpr(value) ? scope.exprRef(value.expr, value.as) : expr && outerField(value) ? (0, _util.fieldRef)(value.field, value.as) : isExpr(type) ? (0, _expression.default)(value, scope) : isData(type) ? (0, _util.ref)(scope.getData(value).values) : isField(type) ? (0, _util.fieldRef)(value) : isCompare(type) ? scope.compareRef(value) : value;
  }
}
/**
 * Parse parameter for accessing an index of another data set.
 */