Function PrependToMaybeNullArray

pkg/sql/sem/tree/eval.go:230–243

PrependToMaybeNullArray prepends an element in the front of an arrray. If the argument is NULL, an array of one element is created.

(typ *types.T, left Datum, right Datum)

// PrependToMaybeNullArray prepends an element in the front of an arrray.
// If the argument is NULL, an array of one element is created.
func PrependToMaybeNullArray(typ *types.T, left Datum, right Datum) (Datum, error) {
	result := NewDArray(typ)
	if err := result.Append(left); err != nil {
		return nil, err
	}
	if right != DNull {
		for _, e := range MustBeDArray(right).Array {
			if err := result.Append(e); err != nil {
				return nil, err
			}
		}
	}
	return result, nil
}

// TODO(justin): these might be improved by making arrays into an interface and
// then introducing a ConcatenatedArray implementation which just references two