Ur/Web: demo/broadcast.ur annotate

UNIQUE constraints

author	Adam Chlipala <adamc@hcoop.net>
date	Tue, 07 Apr 2009 12:24:31 -0400
parents	4e260887d8f2
children	1a317a707d71

rev	line source
adamc@699	1 functor Make(M : sig type t end) = struct
adamc@699	2 sequence s
adamc@699	3 table t : {Id : int, Client : client, Channel : channel M.t}
adamc@699	4
adamc@699	5 type topic = int
adamc@699	6
adamc@699	7 val inj : sql_injectable topic = _
adamc@699	8
adamc@699	9 val create = nextval s
adamc@699	10
adamc@699	11 fun subscribe id =
adamc@699	12 cli <- self;
adamc@699	13 ro <- oneOrNoRows (SELECT t.Channel FROM t WHERE t.Id = {[id]} AND t.Client = {[cli]});
adamc@699	14 case ro of
adamc@699	15 None =>
adamc@699	16 ch <- channel;
adamc@699	17 dml (INSERT INTO t (Id, Client, Channel) VALUES ({[id]}, {[cli]}, {[ch]}));
adamc@699	18 return ch
adamc@699	19 \| Some r => return r.T.Channel
adamc@699	20
adamc@699	21 fun send id msg =
adamc@699	22 queryI (SELECT t.Channel FROM t WHERE t.Id = {[id]})
adamc@699	23 (fn r => Basis.send r.T.Channel msg)
adamc@699	24
adamc@699	25 fun subscribers id =
adamc@699	26 r <- oneRow (SELECT COUNT( * ) AS N FROM t WHERE t.Id = {[id]});
adamc@699	27 return r.N
adamc@699	28 end

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