32 lines
966 B
PL/PgSQL
32 lines
966 B
PL/PgSQL
begin;
|
|
|
|
create function wt_is_sentinel(string text) returns bool
|
|
as $$
|
|
select length(trim(leading u&'\fffe ' from string)) > 0 AND starts_with(string, u&'\fffe');
|
|
$$ language sql
|
|
immutable
|
|
returns null on null input;
|
|
comment on function wt_is_sentinel is
|
|
'wt_is_sentinel returns true if string is a sentinel value';
|
|
|
|
create domain wt_sentinel as text
|
|
constraint wt_sentinel_not_valid
|
|
check(
|
|
wt_is_sentinel(value)
|
|
or
|
|
length(trim(u&'\fffe ' from value)) > 0
|
|
);
|
|
comment on domain wt_sentinel is
|
|
'A non-empty string with a Unicode prefix of U+FFFE to indicate it is a sentinel value';
|
|
|
|
create function wt_to_sentinel(string text) returns text
|
|
as $$
|
|
select concat(u&'\fffe', trim(ltrim(string, u&'\fffe ')));
|
|
$$ language sql
|
|
immutable
|
|
returns null on null input;
|
|
comment on function wt_to_sentinel is
|
|
'wt_to_sentinel takes string and returns it as a wt_sentinel';
|
|
|
|
commit;
|