otpbp_binary: add join/2

Ledest · Nov 7, 2024 · 8bdb7be · 8bdb7be
1 parent 8c7a10c
commit 8bdb7be
Show file tree

Hide file tree

Showing 4 changed files with 33 additions and 0 deletions.
diff --git a/rebar.config.script b/rebar.config.script
@@ -34,6 +34,7 @@ Funs = [{application, get_supervisor, 1},
         {binary, decode_hex, 1},
         {binary, encode_hex, 1},
         {binary, encode_hex, 2},
+        {binary, join, 2},
         {c, c, 3},
         {c, erlangrc, 1},
         {c, h, 1},

diff --git a/src/otpbp_binary.erl b/src/otpbp_binary.erl
@@ -12,6 +12,10 @@
 % OTP 25.3
 -export([encode_hex/2]).
 -endif.
+-ifndef(HAVE_binary__join_2).
+% OTP 28.0
+-export([join/2]).
+-endif.
 
 -ifndef(HAVE_binary__decode_hex_1).
 decode_hex(Bin) when byte_size(Bin) rem 2 =:= 0 ->
@@ -51,3 +55,19 @@ encode_hex_digit(Char, uppercase) -> Char + ($A - 10);
 encode_hex_digit(Char, _lowercase) -> Char + ($a - 10).
 -endif.
 -endif.
+
+-ifndef(HAVE_binary__join_2).
+join([], Separator) when is_binary(Separator) -> <<>>;
+join([H], Separator) when is_binary(H), is_binary(Separator) -> H;
+join([H|T] = List, Separator) when is_binary(Separator) ->
+    Acc = <<>>, %Enable private-append optimization
+    try
+        join(T, Separator, <<Acc/binary, H/binary>>)
+    catch
+        error:_ -> error(badarg, [List, Separator])
+    end;
+join(Arg, Separator) -> error(badarg, [Arg, Separator]).
+
+join([], _Separator, Acc) -> Acc;
+join([H|T], Separator, Acc) -> join(T, Separator, <<Acc/binary, Separator/binary, H/binary>>).
+-endif.
diff --git a/src/otpbp_pt.erl b/src/otpbp_pt.erl
@@ -37,6 +37,7 @@
          {{beam_lib, [strip, strip_files, strip_release], 2}, otpbp_beam_lib},
          {{binary, decode_hex, 1}, otpbp_binary},
          {{binary, encode_hex, [1, 2]}, otpbp_binary},
+         {{binary, join, 2}, otpbp_binary},
          {{c, c, 3}, otpbp_c},
          {{c, erlangrc, 1}, otpbp_c},
          {{c, [h, hcb, ht], [1, 2, 3]}, otpbp_c},

diff --git a/test/stdlib_tests.erl b/test/stdlib_tests.erl
@@ -543,6 +543,17 @@ binary_test() ->
     ?assertEqual(<<"fooba">>, binary:decode_hex(<<"666f6f6261">>)),
     ?assertEqual(<<"foobar">>, binary:decode_hex(<<"666f6f626172">>)),
     ?assertEqual(<<"foobar">>, binary:decode_hex(<<"666f6F626172">>)),
+    % join/2
+    ?assertEqual(<<"a, b, c">>, binary:join([<<"a">>, <<"b">>, <<"c">>], <<", ">>)),
+    ?assertEqual(<<"a">>, binary:join([<<"a">>], <<", ">>)),
+    ?assertEqual(<<>>, binary:join([], <<", ">>)),
+    ?assertError(badarg, maps:merge_with(not_a_fun, #{}, #{})),
+    ?assertError(badarg, binary:join(<<"">>, ",")),
+    ?assertError(badarg, binary:join([""], <<",">>)),
+    ?assertError(badarg, binary:join([123], <<",">>)),
+    ?assertError(badarg, binary:join(123, <<",">>)),
+    ?assertError(badarg, binary:join(#{}, <<",">>)),
+    ?assertError(badarg, binary:join(foo, <<",">>)),
     ok.
 
 ets_test() ->