Postgres 10

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CREATE TABLE the_rule (
   value1 text NOT NULL
 , op1    regoperator NOT NULL
 , value2 text NOT NULL
 , op2    regoperator NOT NULL
);

INSERT INTO the_rule VALUES
   ('foo', '=(text,text)', 'bar', '<(text,text)')
 , ('baz', '<(text,text)', 'bam', '>(text,text)');

CREATE FUNCTION rule_eval(_val text, _opr regoperator, _arg text
                        , OUT _pass bool) AS
$func$
BEGIN
   EXECUTE format('SELECT %L OPERATOR(%s) %L', _val, _opr::regoper, _arg)
   INTO _pass;
END
$func$  LANGUAGE plpgsql;
2 rows affected

SELECT rule_eval('foo', '=(text,text)', 'foo');


rule_eval


t


SELECT rule_eval('foo', '=(text,text)', 'bar');


rule_eval


f


SELECT * FROM the_rule
WHERE  rule_eval(value1, op1, 'foo')
AND    rule_eval(value2, op2, 'aaa');


value1
op1
value2
op2


baz
<(text,text)
bam
>(text,text)