Adds naive collection generator.

1 files changed, 28 insertions, 2 deletions

diff --git a/src/shared/util/shr_lists_util.erl b/src/shared/util/shr_lists_util.erl
index 0568692..348d002 100644
--- a/src/shared/util/shr_lists_util.erl
+++ b/src/shared/util/shr_lists_util.erl
@@ -11,13 +11,35 @@
    [
       %%% Gentoo hasn't marked Erlang/OTP 21 as stable yet, but I'd like to
       %%% use this function.
-      %%% TODO: remove once lists:search/2 is available. 
-      search/2
+      %%% TODO: remove once lists:search/2 is available.
+      search/2,
+      product/3
    ]
 ).
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-spec product_internals
+   (
+      list(A),
+      list(B),
+      fun((A, B) -> C),
+      list(C)
+   )
+   -> list(C).
+product_internals ([], _ListB, _Fun, Result) ->
+   Result;
+product_internals ([A|Next], ListB, Fun, Result) ->
+   product_internals
+   (
+      Next,
+      ListB,
+      Fun,
+      (
+         lists:map(fun (B) -> Fun(A, B) end, ListB)
+         ++ Result
+      )
+   ).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -30,3 +52,7 @@ search (Pred, [Hd|Tail]) ->
    end;
 search (Pred, []) when is_function(Pred, 1) ->
    false.
+
+-spec product (fun((A, B) -> C), list(A), list(B)) -> list(C).
+product (Fun, ListA, ListB) ->
+   product_internals(ListA, ListB, Fun, []).