// EvalFrom evaluates the From clause on the input record. It only
// applies to JSON input data format (currently).
func (e *SelectStatement) EvalFrom(format string, input Record) ([]*Record, error) {
	if !e.selectAST.From.HasKeypath() {
		return []*Record{&input}, nil
	}
	_, rawVal := input.Raw()

	if format != "json" {
		return nil, errDataSource(errors.New("path not supported"))
	}
	switch rec := rawVal.(type) {