Introduce Multigroups (#65)

2 files changed, 55 insertions, 0 deletions

diff --git a/lib/qualified_name.ml b/lib/qualified_name.ml
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+++ b/lib/qualified_name.ml
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+(** Fully qualified relation name: [multigroup:schema:relation].
+
+    Splits on [:], fills defaults for missing parts.
+    - ["relation"]             -> { multigroup=""; schema="public"; relation }
+    - ["schema:relation"]      -> { multigroup=""; schema; relation }
+    - ["mg:schema:relation"]   -> { multigroup=mg; schema; relation }
+*)
+
+type t = {
+  multigroup : string;
+  schema : string;
+  relation : string;
+}
+
+let default_schema = "public"
+
+let parse s =
+  match String.split_on_char ':' s with
+  | [ rel ] -> { multigroup = ""; schema = default_schema; relation = rel }
+  | [ schema; rel ] -> { multigroup = ""; schema; relation = rel }
+  | [ mg; schema; rel ] -> { multigroup = mg; schema; relation = rel }
+  | _ -> { multigroup = ""; schema = default_schema; relation = s }
+
+let make ?(multigroup = "") ?(schema = default_schema) relation =
+  { multigroup; schema; relation }
+
+let to_string { multigroup; schema; relation } =
+  if multigroup = "" then schema ^ ":" ^ relation
+  else multigroup ^ ":" ^ schema ^ ":" ^ relation
+
+let to_key { schema; relation; _ } = schema ^ ":" ^ relation
diff --git a/lib/qualified_name.mli b/lib/qualified_name.mli
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+++ b/lib/qualified_name.mli
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+(** Fully qualified relation name: [multigroup:schema:relation].
+
+    Unqualified names fill in defaults: empty multigroup, ["public"] schema. *)
+
+type t = {
+  multigroup : string;
+  schema : string;
+  relation : string;
+}
+
+val default_schema : string
+
+(** Split on [:] with default filling.
+    - ["rel"]           -> multigroup="", schema="public", relation="rel"
+    - ["s:rel"]         -> multigroup="", schema="s",      relation="rel"
+    - ["mg:s:rel"]      -> multigroup="mg", schema="s",    relation="rel" *)
+val parse : string -> t
+
+val make : ?multigroup:string -> ?schema:string -> string -> t
+val to_string : t -> string
+
+(** Composite key for [RelationMap] lookup within a single database:
+    ["schema:relation"]. *)
+val to_key : t -> string