add an example extracted from a bench

src/examples/dune

@@ -65,3 +65,15 @@
  (modules file_server) ; just check that it compiles
  (package pbrt_services)
  (libraries pbrt pbrt_yojson pbrt_services))
+
+(rule
+ (targets orgchart.ml orgchart.mli)
+ (deps orgchart.proto)
+ (action
+  (run ocaml-protoc --pp --binary --ml_out ./ %{deps})))
+
+(test
+ (name orgchart_ml)
+ (modules orgchart orgchart_ml)
+ (package pbrt)
+ (libraries pbrt))

src/examples/orgchart.proto

@@ -0,0 +1,19 @@
+
+syntax = "proto3";
+
+message Person {
+  string name = 1;
+  sint64 age = 2;
+}
+
+message Store {
+  string address = 1;
+  repeated Person employees = 2;
+  repeated Person clients = 3;
+}
+
+message Company {
+  string name = 1;
+  repeated Store stores = 2;
+  repeated Company subsidiaries = 3;
+}

src/examples/orgchart_ml.ml

@@ -0,0 +1,81 @@
+open Orgchart
+
+let spf = Printf.sprintf
+
+(* company, with [n] stores and [2^depth] subsidiaries *)
+let rec mk_company ~n ~depth : company =
+  {
+    name = "bigcorp";
+    subsidiaries =
+      (if depth = 0 then
+        []
+      else (
+        let c = mk_company ~n ~depth:(depth - 1) in
+        [ c; c ]
+      ));
+    stores =
+      List.init n (fun i ->
+          {
+            address = spf "%d foobar street" i;
+            clients =
+              List.init 2 (fun j ->
+                  {
+                    name = spf "client_%d_%d" i j;
+                    age = Int64.of_int ((j mod 30) + 15);
+                  });
+            employees =
+              List.init 2 (fun j ->
+                  {
+                    name = spf "employee_%d_%d" i j;
+                    age = Int64.of_int ((j mod 30) + 18);
+                  });
+          });
+  }
+
+let test ~n ~depth () : unit =
+  let c = mk_company ~n ~depth in
+  let enc = Pbrt.Encoder.create () in
+  encode_pb_company c enc;
+  let str = Pbrt.Encoder.to_string enc in
+  let c2 =
+    let dec = Pbrt.Decoder.of_string str in
+    decode_pb_company dec
+  in
+
+  if c <> c2 then (
+    Format.eprintf "c=%a@." pp_company c;
+    Format.eprintf "dec(enc(c))=%a@." pp_company c2;
+    failwith @@ spf "failed for n=%d, depth=%d" n depth
+  )
+(* else Printf.eprintf "ok for n=%d, depth=%d\n%!" n depth *)
+
+let () =
+  List.iter
+    (fun (n, depth) -> test ~n ~depth ())
+    [
+      1, 1;
+      1, 1;
+      1, 4;
+      1, 6;
+      1, 10;
+      2, 1;
+      2, 4;
+      2, 6;
+      2, 10;
+      5, 1;
+      5, 4;
+      5, 6;
+      10, 1;
+      10, 2;
+      10, 3;
+      10, 4;
+      20, 1;
+      50, 1;
+      20, 3;
+      20, 4;
+      50, 1;
+      50, 3;
+      50, 4;
+      100, 1;
+      100, 3;
+    ]