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open Utilities.Result
let page_limit = 16
(* [mg:rel] names a relation on the session's branch; a bare name, one the session created. *)
let path_of (ctx : Sublanguage_context.t) name =
match String.index_opt name ':' with
| None -> ctx.session#namespace ^ "\\" ^ name
| Some i ->
String.concat "\\"
[ "";
"branch";
ctx.session#branch;
"multigroup";
String.sub name 0 i;
"relation";
String.sub name (i + 1) (String.length name - i - 1) ]
let rec compile ctx = function
| Ast.Base name -> RNT.Base (path_of ctx name)
| Ast.Project (attributes, query) -> RNT.Project (compile ctx query, attributes)
let execute (ctx : Sublanguage_context.t) query =
let* relation = RNT.execute ctx.kernel (compile ctx query) in
Fun.protect
~finally:(fun () -> RNT.release relation)
(fun () ->
let* cursor = RNT.enumerate relation in
Fun.protect
~finally:(fun () -> RNT.release cursor)
(fun () ->
let* {RNT.tuples; exhausted} = RNT.fetch cursor page_limit in
Ok (Sublanguage_types.Cursor {rows= tuples; has_more= not exhausted}) ) )
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