type-wildcard.sql

-- A custom base type 'wildcard' that returns true on < comparisons,
-- no matter what.  Otherwise acts like a 4-byte integer.

DROP TYPE IF EXISTS wildcard CASCADE;
CREATE TYPE wildcard;

CREATE FUNCTION wildcard_in(s cstring) RETURNS wildcard
LANGUAGE internal IMMUTABLE AS 'int4in';
CREATE FUNCTION wildcard_out(d wildcard) RETURNS cstring
LANGUAGE internal IMMUTABLE AS 'int4out';

CREATE TYPE wildcard (
  INPUT  = wildcard_in,
  OUTPUT = wildcard_out,
  LIKE   = integer
);


CREATE FUNCTION wildcard_eq(wildcard, wildcard)
RETURNS boolean LANGUAGE internal IMMUTABLE AS 'int4eq';

CREATE FUNCTION wildcard_ne(wildcard, wildcard)
RETURNS boolean LANGUAGE internal IMMUTABLE AS 'int4ne';

-- ⚠️
CREATE FUNCTION wildcard_lt(wildcard, wildcard) RETURNS boolean AS
$$
  SELECT true;
$$  LANGUAGE SQL IMMUTABLE STRICT;

CREATE FUNCTION wildcard_le(wildcard, wildcard)
RETURNS boolean LANGUAGE internal IMMUTABLE AS 'int4le';

CREATE FUNCTION wildcard_gt(wildcard, wildcard)
RETURNS boolean LANGUAGE internal IMMUTABLE AS 'int4gt';

CREATE FUNCTION wildcard_ge(wildcard, wildcard)
RETURNS boolean LANGUAGE internal IMMUTABLE AS 'int4ge';

-- ⚠️
CREATE FUNCTION wildcard_cmp(wildcard, wildcard) RETURNS integer AS
$$
  SELECT -1;
$$ LANGUAGE SQL IMMUTABLE STRICT;

CREATE OPERATOR = (
  LEFTARG = wildcard,
  RIGHTARG = wildcard,
  PROCEDURE = wildcard_eq,
  COMMUTATOR = '=',
  NEGATOR = '<>',
  RESTRICT = eqsel,
  JOIN = eqjoinsel,
  HASHES, MERGES
);

CREATE OPERATOR <> (
  LEFTARG = wildcard,
  RIGHTARG = wildcard,
  PROCEDURE = wildcard_ne,
  COMMUTATOR = '<>',
  NEGATOR = '=',
  RESTRICT = neqsel,
  JOIN = neqjoinsel
);

CREATE OPERATOR < (
  LEFTARG = wildcard,
  RIGHTARG = wildcard,
  PROCEDURE = wildcard_lt,
  COMMUTATOR = > ,
  NEGATOR = >= ,
  RESTRICT = scalarltsel,
  JOIN = scalarltjoinsel
);

CREATE OPERATOR <= (
  LEFTARG = wildcard,
  RIGHTARG = wildcard,
  PROCEDURE = wildcard_le,
  COMMUTATOR = >= ,
  NEGATOR = > ,
  RESTRICT = scalarltsel,
  JOIN = scalarltjoinsel
);

CREATE OPERATOR > (
  LEFTARG = wildcard,
  RIGHTARG = wildcard,
  PROCEDURE = wildcard_gt,
  COMMUTATOR = < ,
  NEGATOR = <= ,
  RESTRICT = scalargtsel,
  JOIN = scalargtjoinsel
);

CREATE OPERATOR >= (
  LEFTARG = wildcard,
  RIGHTARG = wildcard,
  PROCEDURE = wildcard_ge,
  COMMUTATOR = <= ,
  NEGATOR = < ,
  RESTRICT = scalargtsel,
  JOIN = scalargtjoinsel
);

CREATE OPERATOR CLASS btree_wildcard_ops
DEFAULT FOR TYPE wildcard USING btree
AS
        OPERATOR        1       <  ,
        OPERATOR        2       <= ,
        OPERATOR        3       =  ,
        OPERATOR        4       >= ,
        OPERATOR        5       >  ,
        FUNCTION        1       wildcard_cmp(wildcard, wildcard);

CREATE OPERATOR CLASS hash_wildcard_ops
    DEFAULT FOR TYPE wildcard USING hash AS
        OPERATOR        1       = ,
        FUNCTION        1       hashint4;

CREATE CAST (integer AS wildcard) WITHOUT FUNCTION AS IMPLICIT;
CREATE CAST (wildcard AS integer) WITHOUT FUNCTION AS IMPLICIT;