erts: Rename ErlNifMapIteratorEntry enums

To differentiate between first/last map entry
and head/tail which is before/after first/last map entry.

3 files changed, 12 insertions, 8 deletions

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 426a00304e..4df34e4a06 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -2024,8 +2024,8 @@ int enif_map_iterator_create(ErlNifEnv *env,
 	size_t offset;
 
 	switch (entry) {
-	    case ERL_NIF_MAP_ITERATOR_HEAD: offset = 0; break;
-	    case ERL_NIF_MAP_ITERATOR_TAIL: offset = flatmap_get_size(mp) - 1; break;
+	    case ERL_NIF_MAP_ITERATOR_FIRST: offset = 0; break;
+	    case ERL_NIF_MAP_ITERATOR_LAST: offset = flatmap_get_size(mp) - 1; break;
 	    default: goto error;
 	}
 
@@ -2048,12 +2048,12 @@ int enif_map_iterator_create(ErlNifEnv *env,
         WSTACK_INIT(iter->u.hash.wstack, ERTS_ALC_T_NIF);
 
         switch (entry) {
-	    case ERL_NIF_MAP_ITERATOR_HEAD:
+	    case ERL_NIF_MAP_ITERATOR_FIRST:
                 iter->idx = 1;
                 hashmap_iterator_init(&iter->u.hash.wstack->ws, map, 0);
                 iter->u.hash.kv = hashmap_iterator_next(&iter->u.hash.wstack->ws);
                 break;
-	    case ERL_NIF_MAP_ITERATOR_TAIL:
+	    case ERL_NIF_MAP_ITERATOR_LAST:
                 iter->idx = hashmap_size(map);
                 hashmap_iterator_init(&iter->u.hash.wstack->ws, map, 1);
                 iter->u.hash.kv = hashmap_iterator_prev(&iter->u.hash.wstack->ws);
diff --git a/erts/emulator/beam/erl_nif.h b/erts/emulator/beam/erl_nif.h
index c4fdfd4187..af806736fd 100644
--- a/erts/emulator/beam/erl_nif.h
+++ b/erts/emulator/beam/erl_nif.h
@@ -218,8 +218,12 @@ typedef struct /* All fields all internal and may change */
 } ErlNifMapIterator;
 
 typedef enum {
-    ERL_NIF_MAP_ITERATOR_HEAD = 1,
-    ERL_NIF_MAP_ITERATOR_TAIL = 2
+    ERL_NIF_MAP_ITERATOR_FIRST = 1,
+    ERL_NIF_MAP_ITERATOR_LAST = 2,
+
+    /* deprecated synonyms (undocumented in 17 and 18-rc) */
+    ERL_NIF_MAP_ITERATOR_HEAD = ERL_NIF_MAP_ITERATOR_FIRST,
+    ERL_NIF_MAP_ITERATOR_TAIL = ERL_NIF_MAP_ITERATOR_LAST
 } ErlNifMapIteratorEntry;
 
 #if (defined(__WIN32__) || defined(_WIN32) || defined(_WIN32_))
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 3cc9f51ef8..d964ae338e 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -1802,7 +1802,7 @@ static ERL_NIF_TERM sorted_list_from_maps_nif(ErlNifEnv* env, int argc, const ER
     if (argc != 1 && !enif_is_map(env, map))
 	return enif_make_int(env, __LINE__);
 
-    if(!enif_map_iterator_create(env, map, &iter_f, ERL_NIF_MAP_ITERATOR_HEAD))
+    if(!enif_map_iterator_create(env, map, &iter_f, ERL_NIF_MAP_ITERATOR_FIRST))
 	return enif_make_int(env, __LINE__);
 
     cnt = 0;
@@ -1817,7 +1817,7 @@ static ERL_NIF_TERM sorted_list_from_maps_nif(ErlNifEnv* env, int argc, const ER
     if (cnt && next_ret)
 	return enif_make_int(env, __LINE__);
 
-    if(!enif_map_iterator_create(env, map, &iter_b, ERL_NIF_MAP_ITERATOR_TAIL))
+    if(!enif_map_iterator_create(env, map, &iter_b, ERL_NIF_MAP_ITERATOR_LAST))
 	return enif_make_int(env, __LINE__);
 
     cnt = 0;