From f951b3fcc69c195ce04ae1022fa53272cb74f71b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Wed, 6 Mar 2019 15:28:30 +0100
Subject: erts: Add enif_term_type

This helps avoid long sequences of enif_is_xxx in code that
serializes terms (such as JSON encoders) by letting the user
switch on the type.
---
 erts/emulator/test/nif_SUITE.erl              | 43 +++++++++++++++++++++++++--
 erts/emulator/test/nif_SUITE_data/nif_SUITE.c | 33 +++++++++++++++++++-
 2 files changed, 73 insertions(+), 3 deletions(-)

(limited to 'erts/emulator/test')

diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 4a0ad9c1d5..2309f844b9 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -65,7 +65,8 @@
          nif_whereis/1, nif_whereis_parallel/1,
          nif_whereis_threaded/1, nif_whereis_proxy/1,
          nif_ioq/1,
-         pid/1
+         pid/1,
+         nif_term_type/1
 	]).
 
 -export([many_args_100/100]).
@@ -105,7 +106,8 @@ all() ->
      nif_phash2,
      nif_whereis, nif_whereis_parallel, nif_whereis_threaded,
      nif_ioq,
-     pid].
+     pid,
+     nif_term_type].
 
 groups() ->
     [{G, [], api_repeaters()} || G <- api_groups()]
@@ -3392,6 +3394,41 @@ pid(Config) ->
     {false, _} = get_local_pid_nif(undefined),
     ok.
 
+nif_term_type(Config) ->
+    ensure_lib_loaded(Config),
+
+    atom = term_type_nif(atom),
+
+    bitstring = term_type_nif(<<1:1>>),
+    bitstring = term_type_nif(<<1:8>>),
+
+    float = term_type_nif(0.0),
+
+    'fun' = term_type_nif(fun external:function/1),
+    'fun' = term_type_nif(fun(A) -> A end),
+    'fun' = term_type_nif(fun id/1),
+
+    integer = term_type_nif(1 bsl 1024),        %Bignum.
+    integer = term_type_nif(1),
+
+    list = term_type_nif([list]),
+    list = term_type_nif([]),
+
+    LargeMap = maps:from_list([{N, N} || N <- lists:seq(1, 256)]),
+    map = term_type_nif(LargeMap),
+    map = term_type_nif(#{ small => map }),
+
+    pid = term_type_nif(self()),
+
+    Port = open_port({spawn,echo_drv},[eof]),
+    port = term_type_nif(Port),
+    port_close(Port),
+
+    reference = term_type_nif(make_ref()),
+
+    tuple = term_type_nif({}),
+
+    ok.
 
 id(I) -> I.
 
@@ -3507,5 +3544,7 @@ set_pid_undefined_nif() -> ?nif_stub.
 is_pid_undefined_nif(_) -> ?nif_stub.
 compare_pids_nif(_, _) -> ?nif_stub.
 
+term_type_nif(_) -> ?nif_stub.
+
 nif_stub_error(Line) ->
     exit({nif_not_loaded,module,?MODULE,line,Line}).
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 0d5d900d31..1906384af4 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -3583,6 +3583,36 @@ static ERL_NIF_TERM compare_pids_nif(ErlNifEnv* env, int argc, const ERL_NIF_TER
     return enif_make_int(env, enif_compare_pids(&a, &b));
 }
 
+static ERL_NIF_TERM term_type_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    switch (enif_term_type(env, argv[0])) {
+    case ERL_NIF_TERM_TYPE_ATOM:
+        return enif_make_atom(env, "atom");
+    case ERL_NIF_TERM_TYPE_BITSTRING:
+        return enif_make_atom(env, "bitstring");
+    case ERL_NIF_TERM_TYPE_FLOAT:
+        return enif_make_atom(env, "float");
+    case ERL_NIF_TERM_TYPE_FUN:
+        return enif_make_atom(env, "fun");
+    case ERL_NIF_TERM_TYPE_INTEGER:
+        return enif_make_atom(env, "integer");
+    case ERL_NIF_TERM_TYPE_LIST:
+        return enif_make_atom(env, "list");
+    case ERL_NIF_TERM_TYPE_MAP:
+        return enif_make_atom(env, "map");
+    case ERL_NIF_TERM_TYPE_PID:
+        return enif_make_atom(env, "pid");
+    case ERL_NIF_TERM_TYPE_PORT:
+        return enif_make_atom(env, "port");
+    case ERL_NIF_TERM_TYPE_REFERENCE:
+        return enif_make_atom(env, "reference");
+    case ERL_NIF_TERM_TYPE_TUPLE:
+        return enif_make_atom(env, "tuple");
+    default:
+        return enif_make_badarg(env);
+    }
+}
+
 static ErlNifFunc nif_funcs[] =
 {
     {"lib_version", 0, lib_version},
@@ -3690,7 +3720,8 @@ static ErlNifFunc nif_funcs[] =
     {"make_pid_nif", 1, make_pid_nif},
     {"set_pid_undefined_nif", 0, set_pid_undefined_nif},
     {"is_pid_undefined_nif", 1, is_pid_undefined_nif},
-    {"compare_pids_nif", 2, compare_pids_nif}
+    {"compare_pids_nif", 2, compare_pids_nif},
+    {"term_type_nif", 1, term_type_nif}
 };
 
 ERL_NIF_INIT(nif_SUITE,nif_funcs,load,NULL,upgrade,unload)
-- 
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