Merge branch 'map-get-bif' of git://github.com/michalmuskala/otp

* 'map-get-bif' of git://github.com/michalmuskala/otp:
  Introduce map_get guard-safe function

OTP-15037

8 files changed, 102 insertions, 10 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index d4d4dd7f31..f561413fab 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -2965,6 +2965,25 @@ os_prompt%</pre>
     </func>
 
     <func>
+      <name name="map_get" arity="2" />
+      <fsummary>Extract a value from a map</fsummary>
+      <desc>
+        <p>Returns value <c><anno>Value</anno></c> associated with
+          <c><anno>Key</anno></c> if <c><anno>Map</anno></c> contains
+          <c><anno>Key</anno></c>.</p>
+        <p>The call fails with a <c>{badmap,Map}</c> exception if
+          <c><anno>Map</anno></c> is not a map, or with a <c>{badkey,Key}</c>
+          exception if no value is associated with <c><anno>Key</anno></c>.</p>
+        <p><em>Example:</em></p>
+        <code type="none">
+> Key = 1337,
+  Map = #{42 => value_two,1337 => "value one","a" => 1},
+  map_get(Key,Map).
+"value one"</code>
+      </desc>
+    </func>
+
+    <func>
       <name name="map_size" arity="1"/>
       <fsummary>Return the size of a map.</fsummary>
       <desc>
@@ -10999,4 +11018,3 @@ true</pre>
     </func>
   </funcs>
 </erlref>
-
diff --git a/erts/doc/src/match_spec.xml b/erts/doc/src/match_spec.xml
index 6cf0a0e677..888366b239 100644
--- a/erts/doc/src/match_spec.xml
+++ b/erts/doc/src/match_spec.xml
@@ -110,7 +110,8 @@
       </item>
       <item>GuardFunction ::= BoolFunction | <c><![CDATA[abs]]></c> |
         <c><![CDATA[element]]></c> | <c><![CDATA[hd]]></c> |
-        <c><![CDATA[length]]></c> | <c><![CDATA[node]]></c> |
+        <c><![CDATA[length]]></c> | <c><![CDATA[map_get]]></c> |
+        <c><![CDATA[map_size]]></c> | <c><![CDATA[node]]></c> |
         <c><![CDATA[round]]></c> | <c><![CDATA[size]]></c> |
         <c><![CDATA[tl]]></c> | <c><![CDATA[trunc]]></c> |
         <c><![CDATA['+']]></c> | <c><![CDATA['-']]></c> |
@@ -189,7 +190,8 @@
       </item>
       <item>GuardFunction ::= BoolFunction | <c><![CDATA[abs]]></c> |
         <c><![CDATA[element]]></c> | <c><![CDATA[hd]]></c> |
-        <c><![CDATA[length]]></c> | <c><![CDATA[node]]></c> |
+        <c><![CDATA[length]]></c> | <c><![CDATA[map_get]]></c> |
+        <c><![CDATA[map_size]]></c> | <c><![CDATA[node]]></c> |
         <c><![CDATA[round]]></c> | <c><![CDATA[size]]></c> |
         <c><![CDATA[tl]]></c> | <c><![CDATA[trunc]]></c> |
         <c><![CDATA['+']]></c> | <c><![CDATA['-']]></c> |
@@ -865,4 +867,3 @@
       can be useful for testing complicated ETS matches.</p>
   </section>
 </chapter>
-
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index bcaf9277bf..276bef2bbb 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -695,3 +695,4 @@ bif erts_internal:map_next/3
 bif ets:whereis/1
 bif erts_internal:gather_alloc_histograms/1
 bif erts_internal:gather_carrier_info/1
+ubif erlang:map_get/2
diff --git a/erts/emulator/beam/erl_db_util.c b/erts/emulator/beam/erl_db_util.c
index 3836f28aa4..6354abfd1f 100644
--- a/erts/emulator/beam/erl_db_util.c
+++ b/erts/emulator/beam/erl_db_util.c
@@ -638,6 +638,12 @@ static DMCGuardBif guard_tab[] =
 	DBIF_ALL
     },
     {
+        am_map_get,
+        &map_get_2,
+        2,
+        DBIF_ALL
+    },
+    {
 	am_bit_size,
 	&bit_size_1,
 	1,
@@ -5737,5 +5743,3 @@ void db_match_dis(Binary *bp)
 }
 
 #endif /* DMC_DEBUG */
-
-
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 4ec6960997..f577b017c3 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -44,6 +44,7 @@
  * DONE:
  * - erlang:is_map/1
  * - erlang:map_size/1
+ * - erlang:map_get/2
  *
  * - maps:find/2
  * - maps:from_list/1
@@ -202,7 +203,7 @@ BIF_RETTYPE maps_find_2(BIF_ALIST_2) {
     BIF_ERROR(BIF_P, BADMAP);
 }
 
-/* maps:get/2
+/* maps:get/2 and erlang:map_get/2
  * return value if key *matches* a key in the map
  * exception badkey if none matches
  */
@@ -223,6 +224,10 @@ BIF_RETTYPE maps_get_2(BIF_ALIST_2) {
     BIF_ERROR(BIF_P, BADMAP);
 }
 
+BIF_RETTYPE map_get_2(BIF_ALIST_2) {
+    BIF_RET(maps_get_2(BIF_CALL_ARGS));
+}
+
 /* maps:from_list/1
  * List may be unsorted [{K,V}]
  */
diff --git a/erts/emulator/test/map_SUITE.erl b/erts/emulator/test/map_SUITE.erl
index c9e971af8a..43807b4388 100644
--- a/erts/emulator/test/map_SUITE.erl
+++ b/erts/emulator/test/map_SUITE.erl
@@ -36,6 +36,7 @@
          t_map_equal/1,
          t_map_compare/1,
          t_map_size/1,
+         t_map_get/1,
          t_is_map/1,
 
          %% Specific Map BIFs
@@ -124,7 +125,7 @@ all() -> [t_build_and_match_literals, t_build_and_match_literals_large,
           %% erlang
           t_erlang_hash, t_map_encode_decode,
           t_gc_rare_map_overflow,
-          t_map_size, t_is_map,
+          t_map_size, t_map_get, t_is_map,
 
           %% non specific BIF related
           t_bif_build_and_check,
@@ -680,6 +681,48 @@ t_map_size(Config) when is_list(Config) ->
               end),
     ok.
 
+t_map_get(Config) when is_list(Config) ->
+    %% small map
+    1    = map_get(a, id(#{a=>1})),
+    2    = map_get(b, id(#{a=>1, b=>2})),
+    "hi" = map_get("hello", id(#{a=>1, "hello"=>"hi"})),
+    "tuple hi" = map_get({1,1.0}, id(#{a=>a, {1,1.0}=>"tuple hi"})),
+
+    M0    = id(#{ k1=>"v1", <<"k2">> => <<"v3">> }),
+    "v4" = map_get(<<"k2">>, M0#{<<"k2">> => "v4"}),
+
+    %% large map
+    M1   = maps:from_list([{I,I}||I<-lists:seq(1,100)] ++
+			  [{a,1},{b,2},{"hello","hi"},{{1,1.0},"tuple hi"},
+			   {k1,"v1"},{<<"k2">>,"v3"}]),
+    1    = map_get(a, M1),
+    2    = map_get(b, M1),
+    "hi" = map_get("hello", M1),
+    "tuple hi" = map_get({1,1.0}, M1),
+    "v3" = map_get(<<"k2">>, M1),
+
+    %% error cases
+    do_badmap(fun(T) ->
+		      {'EXIT',{{badmap,T},[{erlang,map_get,_,_}|_]}} =
+			  (catch map_get(a, T))
+	      end),
+
+    {'EXIT',{{badkey,{1,1}},[{erlang,map_get,_,_}|_]}} =
+	(catch map_get({1,1}, id(#{{1,1.0}=>"tuple"}))),
+    {'EXIT',{{badkey,a},[{erlang,map_get,_,_}|_]}} = (catch map_get(a, id(#{}))),
+    {'EXIT',{{badkey,a},[{erlang,map_get,_,_}|_]}} =
+	(catch map_get(a, id(#{b=>1, c=>2}))),
+
+    %% in guards
+    M2 = id(#{a=>1}),
+    true = if map_get(a, M2) =:= 1 -> true; true -> false end,
+    false = if map_get(x, M2) =:= 1 -> true; true -> false end,
+    do_badmap(fun
+        (T) when map_get(T, x) =:= 1 -> ok;
+        (T) -> false = is_map(T)
+    end),
+    ok.
+
 build_and_check_size([K|Ks],N,M0) ->
     N = map_size(M0),
     M1 = M0#{ K => K },
diff --git a/erts/emulator/test/match_spec_SUITE.erl b/erts/emulator/test/match_spec_SUITE.erl
index 08a7b4560c..c1bc01f01e 100644
--- a/erts/emulator/test/match_spec_SUITE.erl
+++ b/erts/emulator/test/match_spec_SUITE.erl
@@ -885,6 +885,19 @@ maps(Config) when is_list(Config) ->
         erlang:match_spec_test(#{<<"b">> =>"camembert","c"=>"cabécou", "wat"=>"hi", b=><<"other">>},
                                [{#{<<"b">> => '$1',"wat" => '$2'},[],[#{a=>'$1',b=>'$2'}]}],
                                table),
+
+    {ok,1,[],[]} = erlang:match_spec_test(#{a => 1}, [{'$1',[],[{map_size,'$1'}]}],table),
+    {ok,'EXIT',[],[]} = erlang:match_spec_test(not_a_map, [{'$1',[],[{map_size,'$1'}]}], table),
+    {ok,false,[],[]} = erlang:match_spec_test(not_a_map, [{'$1',[{map_size,'$1'}],['$_']}], table),
+    {ok,true,[],[]} = erlang:match_spec_test(#{a => 1}, [{'$1',[{'=:=',{map_size,'$1'},1}],[true]}], table),
+
+    {ok,1,[],[]} = erlang:match_spec_test(#{a => 1}, [{'$1',[],[{map_get,a,'$1'}]}], table),
+    {ok,'EXIT',[],[]} = erlang:match_spec_test(#{a => 1}, [{'$1',[],[{map_get,b,'$1'}]}], table),
+    {ok,'EXIT',[],[]} = erlang:match_spec_test(not_a_map, [{'$1',[],[{map_get,b,'$1'}]}], table),
+    {ok,false,[],[]} = erlang:match_spec_test(#{a => 1}, [{'$1',[{map_get,b,'$1'}],['$_']}], table),
+    {ok,false,[],[]} = erlang:match_spec_test(not_a_map, [{'$1',[{map_get,b,'$1'}],['$_']}], table),
+    {ok,true,[],[]} = erlang:match_spec_test(#{a => true}, [{'$1',[{map_get,a,'$1'}],[true]}], table),
+
     %% large maps
 
     Ls0 = [{I,<<I:32>>}||I <- lists:seq(1,415)],
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 6fad5adde8..53e90a4f2d 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -141,7 +141,7 @@
 -export([list_to_integer/1, list_to_integer/2]).
 -export([list_to_pid/1, list_to_port/1, list_to_ref/1, list_to_tuple/1, loaded/0]).
 -export([localtime/0, make_ref/0]).
--export([map_size/1, match_spec_test/3, md5/1, md5_final/1]).
+-export([map_size/1, map_get/2, match_spec_test/3, md5/1, md5_final/1]).
 -export([md5_init/0, md5_update/2, module_loaded/1, monitor/2]).
 -export([monitor_node/2, monitor_node/3, nif_error/1, nif_error/2]).
 -export([node/0, node/1, now/0, phash/2, phash2/1, phash2/2]).
@@ -1230,6 +1230,14 @@ make_ref() ->
 map_size(_Map) ->
     erlang:nif_error(undefined).
 
+%% Shadowed by erl_bif_types: erlang:map_get/2
+-spec map_get(Key, Map) -> Value when
+      Map :: map(),
+      Key :: any(),
+      Value :: any().
+map_get(_Key, _Map) ->
+    erlang:nif_error(undefined).
+
 %% match_spec_test/3
 -spec erlang:match_spec_test(MatchAgainst, MatchSpec, Type) -> TestResult when
       MatchAgainst :: [term()] | tuple(),
@@ -3938,4 +3946,3 @@ gc_info(Ref, N, {OrigColls,OrigRecl}) ->
 	{Ref, {_,Colls, Recl}} -> 
 	    gc_info(Ref, N-1, {Colls+OrigColls,Recl+OrigRecl})
     end.
-