stdlib: Pretty print maps

Pretty printing behaviour mimic records.

This commit requires Map enabled bootstrap compiler.

1 files changed, 32 insertions, 0 deletions

diff --git a/lib/stdlib/src/io_lib_pretty.erl b/lib/stdlib/src/io_lib_pretty.erl
index 7637ad7a3d..f02a7921f8 100644
--- a/lib/stdlib/src/io_lib_pretty.erl
+++ b/lib/stdlib/src/io_lib_pretty.erl
@@ -101,6 +101,7 @@ print(Term, Col, Ll, D, M, RecDefFun, Enc, Str) when Col =< 0 ->
     print(Term, 1, Ll, D, M, RecDefFun, Enc, Str);
 print(Term, Col, Ll, D, M0, RecDefFun, Enc, Str) when is_tuple(Term);
                                                       is_list(Term);
+                                                      is_map(Term);
                                                       is_bitstring(Term) ->
     If = {_S, Len} = print_length(Term, D, RecDefFun, Enc, Str),
     M = max_cs(M0, Len),
@@ -137,6 +138,10 @@ pp({{tuple,true,L}, _Len}, Col, Ll, M, TInd, Ind, LD, W) ->
     [${, pp_tag_tuple(L, Col, Ll, M, TInd, Ind, LD, W + 1), $}];
 pp({{tuple,false,L}, _Len}, Col, Ll, M, TInd, Ind, LD, W) ->
     [${, pp_list(L, Col + 1, Ll, M, TInd, indent(1, Ind), LD, $,, W + 1), $}];
+pp({{map,Pairs},_Len}, Col, Ll, M, TInd, Ind, LD, W) ->
+    [$#,${, pp_list(Pairs, Col + 2, Ll, M, TInd, indent(2, Ind), LD, $,, W + 1), $}];
+pp({{map_pair,K,V},_Len}, Col, Ll, M, TInd, Ind, LD, W) ->
+    [pp(K, Col, Ll, M, TInd, Ind, LD, W), " => ", pp(V, Col, Ll, M, TInd, Ind, LD, W)];
 pp({{record,[{Name,NLen} | L]}, _Len}, Col, Ll, M, TInd, Ind, LD, W) ->
     [Name, ${, pp_record(L, NLen, Col, Ll, M, TInd, Ind, LD, W + NLen+1), $}];
 pp({{bin,S}, _Len}, Col, Ll, M, _TInd, Ind, LD, W) ->
@@ -283,6 +288,10 @@ write({{tuple, _IsTagged, L}, _}) ->
     [${, write_list(L, $,), $}];
 write({{list, L}, _}) ->
     [$[, write_list(L, $|), $]];
+write({{map, Pairs}, _}) ->
+    [$#,${, write_list(Pairs, $,), $}];
+write({{map_pair, K, V}, _}) ->
+    [write(K)," => ",write(V)];
 write({{record, [{Name,_} | L]}, _}) ->
     [Name, ${, write_fields(L), $}];
 write({{bin, S}, _}) ->
@@ -331,6 +340,8 @@ print_length([], _D, _RF, _Enc, _Str) ->
     {"[]", 2};
 print_length({}, _D, _RF, _Enc, _Str) ->
     {"{}", 2};
+print_length(#{}=M, _D, _RF, _Enc, _Str) when map_size(M) =:= 0 ->
+    {"#{}", 3};
 print_length(List, D, RF, Enc, Str) when is_list(List) ->
     case Str andalso printable_list(List, D, Enc) of
         true ->
@@ -356,6 +367,8 @@ print_length(R, D, RF, Enc, Str) when is_atom(element(1, R)),
     end;
 print_length(Tuple, D, RF, Enc, Str) when is_tuple(Tuple) ->
     print_length_tuple(Tuple, D, RF, Enc, Str);
+print_length(Map, D, RF, Enc, Str) when is_map(Map) ->
+    print_length_map(Map, D, RF, Enc, Str);
 print_length(<<>>, _D, _RF, _Enc, _Str) ->
     {"<<>>", 4};
 print_length(<<_/bitstring>>, 1, _RF, _Enc, _Str) ->
@@ -389,6 +402,25 @@ print_length(Term, _D, _RF, _Enc, _Str) ->
     S = io_lib:write(Term),
     {S, lists:flatlength(S)}.
 
+print_length_map(_Map, 1, _RF, _Enc, _Str) ->
+    {"#{...}", 6};
+print_length_map(Map, D, RF, Enc, Str) when is_map(Map) ->
+    Pairs = print_length_map_pairs(maps:to_list(Map), D, RF, Enc, Str),
+    {{map, Pairs}, list_length(Pairs, 3)}.
+
+print_length_map_pairs([], _D, _RF, _Enc, _Str) ->
+    [];
+print_length_map_pairs(_Pairs, 1, _RF, _Enc, _Str) ->
+    {dots, 3};
+print_length_map_pairs([{K,V}|Pairs], D, RF, Enc, Str) ->
+    [print_length_map_pair(K,V,D-1,RF,Enc,Str) |
+     print_length_map_pairs(Pairs,D-1,RF,Enc,Str)].
+
+print_length_map_pair(K, V, D, RF, Enc, Str) ->
+    {KS, KL} = print_length(K, D, RF, Enc, Str),
+    {VS, VL} = print_length(V, D, RF, Enc, Str),
+    {{map_pair, {KS,KL}, {VS,VL}}, KL + VL}.
+
 print_length_tuple(_Tuple, 1, _RF, _Enc, _Str) ->
     {"{...}", 5};
 print_length_tuple(Tuple, D, RF, Enc, Str) ->