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authorBjörn-Egil Dahlberg <egil@erlang.org>2017-02-22 16:52:29 +0100
committerBjörn-Egil Dahlberg <egil@erlang.org>2017-02-23 10:10:54 +0100
commitd8c0f76c800051629cd9cf7279bf075435708a1c (patch)
tree04156d46a4fa8a433e4314ab812590d7590b94e1
parent82b184fee07c78583a7198f1da022a9da7e87260 (diff)
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erts: Introduce erts_internal:maps_to_list/2
-rw-r--r--erts/emulator/beam/bif.tab1
-rw-r--r--erts/emulator/beam/erl_map.c66
-rw-r--r--erts/preloaded/src/erts_internal.erl12
3 files changed, 71 insertions, 8 deletions
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index a6510ace81..ce2cffa498 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -671,3 +671,4 @@ bif math:floor/1
bif math:ceil/1
bif math:fmod/2
bif os:set_signal/2
+bif erts_internal:maps_to_list/2
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 9062e44b10..a80f5d6a16 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -91,7 +91,7 @@ static BIF_RETTYPE hashmap_merge(Process *p, Eterm nodeA, Eterm nodeB, int swap_
static Export hashmap_merge_trap_export;
static BIF_RETTYPE maps_merge_trap_1(BIF_ALIST_1);
static Uint hashmap_subtree_size(Eterm node);
-static Eterm hashmap_to_list(Process *p, Eterm map);
+static Eterm hashmap_to_list(Process *p, Eterm map, Sint n);
static Eterm hashmap_keys(Process *p, Eterm map);
static Eterm hashmap_values(Process *p, Eterm map);
static Eterm hashmap_delete(Process *p, Uint32 hx, Eterm key, Eterm node, Eterm *value);
@@ -161,13 +161,58 @@ BIF_RETTYPE maps_to_list_1(BIF_ALIST_1) {
BIF_RET(res);
} else if (is_hashmap(BIF_ARG_1)) {
- return hashmap_to_list(BIF_P, BIF_ARG_1);
+ return hashmap_to_list(BIF_P, BIF_ARG_1, -1);
}
BIF_P->fvalue = BIF_ARG_1;
BIF_ERROR(BIF_P, BADMAP);
}
+/* erts_internal:maps_to_list/2
+ *
+ * This function should be removed once iterators are in place.
+ * Never document it.
+ * Never encourage its usage.
+ *
+ * A negative value in ARG 2 means the entire map.
+ */
+
+BIF_RETTYPE erts_internal_maps_to_list_2(BIF_ALIST_2) {
+ Sint m;
+ if (term_to_Sint(BIF_ARG_2, &m)) {
+ if (is_flatmap(BIF_ARG_1)) {
+ Uint n;
+ Eterm* hp;
+ Eterm *ks,*vs, res, tup;
+ flatmap_t *mp = (flatmap_t*)flatmap_val(BIF_ARG_1);
+
+ ks = flatmap_get_keys(mp);
+ vs = flatmap_get_values(mp);
+ n = flatmap_get_size(mp);
+
+ if (m >= 0) {
+ n = m < n ? m : n;
+ }
+
+ hp = HAlloc(BIF_P, (2 + 3) * n);
+ res = NIL;
+
+ while(n--) {
+ tup = TUPLE2(hp, ks[n], vs[n]); hp += 3;
+ res = CONS(hp, tup, res); hp += 2;
+ }
+
+ BIF_RET(res);
+ } else if (is_hashmap(BIF_ARG_1)) {
+ return hashmap_to_list(BIF_P, BIF_ARG_1, m);
+ }
+ BIF_P->fvalue = BIF_ARG_1;
+ BIF_ERROR(BIF_P, BADMAP);
+ }
+ BIF_ERROR(BIF_P, BADARG);
+}
+
+
/* maps:find/2
* return value if key *matches* a key in the map
*/
@@ -1917,15 +1962,22 @@ BIF_RETTYPE maps_values_1(BIF_ALIST_1) {
BIF_ERROR(BIF_P, BADMAP);
}
-static Eterm hashmap_to_list(Process *p, Eterm node) {
+static Eterm hashmap_to_list(Process *p, Eterm node, Sint m) {
DECLARE_WSTACK(stack);
Eterm *hp, *kv;
- Eterm res = NIL;
+ Eterm tup, res = NIL;
+ Uint n = hashmap_size(node);
- hp = HAlloc(p, hashmap_size(node) * (2 + 3));
+ if (m >= 0) {
+ n = m < n ? m : n;
+ }
+
+ hp = HAlloc(p, n * (2 + 3));
hashmap_iterator_init(&stack, node, 0);
- while ((kv=hashmap_iterator_next(&stack)) != NULL) {
- Eterm tup = TUPLE2(hp, CAR(kv), CDR(kv));
+ while (n--) {
+ kv = hashmap_iterator_next(&stack);
+ ASSERT(kv != NULL);
+ tup = TUPLE2(hp, CAR(kv), CDR(kv));
hp += 3;
res = CONS(hp, tup, res);
hp += 2;
diff --git a/erts/preloaded/src/erts_internal.erl b/erts/preloaded/src/erts_internal.erl
index a27cb2ba38..bcc779e6f6 100644
--- a/erts/preloaded/src/erts_internal.erl
+++ b/erts/preloaded/src/erts_internal.erl
@@ -31,7 +31,8 @@
-export([await_port_send_result/3]).
-export([cmp_term/2]).
--export([map_to_tuple_keys/1, term_type/1, map_hashmap_children/1]).
+-export([map_to_tuple_keys/1, term_type/1, map_hashmap_children/1,
+ maps_to_list/2]).
-export([open_port/2, port_command/3, port_connect/2, port_close/1,
port_control/3, port_call/3, port_info/1, port_info/2]).
@@ -369,6 +370,15 @@ map_hashmap_children(_M) ->
Multi :: boolean(),
Res :: term().
+%% return a list of key value pairs, at most of length N
+-spec maps_to_list(M,N) -> Pairs when
+ M :: map(),
+ N :: integer(),
+ Pairs :: list().
+
+maps_to_list(_M, _N) ->
+ erlang:nif_error(undefined).
+
%% erlang:demonitor(Ref, [flush]) traps to
%% erts_internal:flush_monitor_messages(Ref, Res) when
%% it needs to flush monitor messages.