stdlib: Improve Erlang shell's tab-completion of long names

2 files changed, 140 insertions, 34 deletions

diff --git a/lib/stdlib/src/edlin_expand.erl b/lib/stdlib/src/edlin_expand.erl
index 5f821caef0..a1a97af4c5 100644
--- a/lib/stdlib/src/edlin_expand.erl
+++ b/lib/stdlib/src/edlin_expand.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% Copyright Ericsson AB 2005-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -101,44 +101,77 @@ match(Prefix, Alts, Extra0) ->
 
 %% Return the list of names L in multiple columns.
 format_matches(L) ->
-    S = format_col(lists:sort(L), []),
+    {S1, Dots} = format_col(lists:sort(L), []),
+    S = case Dots of
+            true ->
+                {_, Prefix} = longest_common_head(vals(L)),
+                PrefixLen = length(Prefix),
+                case PrefixLen =< 3 of
+                    true -> S1; % Do not replace the prefix with "...".
+                    false ->
+                        LeadingDotsL = leading_dots(L, PrefixLen),
+                        {S2, _} = format_col(lists:sort(LeadingDotsL), []),
+                        S2
+                end;
+            false -> S1
+        end,
     ["\n" | S].
 
 format_col([], _) -> [];
-format_col(L, Acc) -> format_col(L, field_width(L), 0, Acc).
-
-format_col(X, Width, Len, Acc) when Width + Len > 79 ->
-    format_col(X, Width, 0, ["\n" | Acc]);
-format_col([A|T], Width, Len, Acc0) ->
-    H = case A of
- 	    %% If it's a tuple {string(), integer()}, we assume it's an
- 	    %% arity, and meant to be printed.
-	    {H0, I} when is_integer(I) ->
-		H0 ++ "/" ++ integer_to_list(I);
-	    {H1, _} -> H1;
- 	    H2 -> H2
- 	end,
-    Acc = [io_lib:format("~-*ts", [Width,H]) | Acc0],
-    format_col(T, Width, Len+Width, Acc);
-format_col([], _, _, Acc) ->
-    lists:reverse(Acc, "\n").
-
-field_width(L) -> field_width(L, 0).
-
-field_width([{H,_}|T], W) ->
+format_col(L, Acc) ->
+    LL = 79,
+    format_col(L, field_width(L, LL), 0, Acc, LL, false).
+
+format_col(X, Width, Len, Acc, LL, Dots) when Width + Len > LL ->
+    format_col(X, Width, 0, ["\n" | Acc], LL, Dots);
+format_col([A|T], Width, Len, Acc0, LL, Dots) ->
+    {H0, R} = format_val(A),
+    Hmax = LL - length(R),
+    {H, NewDots} =
+        case length(H0) > Hmax of
+            true -> {io_lib:format("~-*ts", [Hmax - 3, H0]) ++ "...", true};
+            false -> {H0, Dots}
+        end,
+    Acc = [io_lib:format("~-*ts", [Width, H ++ R]) | Acc0],
+    format_col(T, Width, Len+Width, Acc, LL, NewDots);
+format_col([], _, _, Acc, _LL, Dots) ->
+    {lists:reverse(Acc, "\n"), Dots}.
+
+format_val({H, I}) when is_integer(I) ->
+    %% If it's a tuple {string(), integer()}, we assume it's an
+    %% arity, and meant to be printed.
+    {H, "/" ++ integer_to_list(I)};
+format_val({H, _}) ->
+    {H, ""};
+format_val(H) ->
+    {H, ""}.
+
+field_width(L, LL) -> field_width(L, 0, LL).
+
+field_width([{H,_}|T], W, LL) ->
     case length(H) of
- 	L when L > W -> field_width(T, L);
- 	_ -> field_width(T, W)
+        L when L > W -> field_width(T, L, LL);
+        _ -> field_width(T, W, LL)
     end;
-field_width([H|T], W) ->
+field_width([H|T], W, LL) ->
     case length(H) of
- 	L when L > W -> field_width(T, L);
- 	_ -> field_width(T, W)
+        L when L > W -> field_width(T, L, LL);
+        _ -> field_width(T, W, LL)
     end;
-field_width([], W) when W < 40 ->
+field_width([], W, LL) when W < LL - 3 ->
     W + 4;
-field_width([], _) ->
-    40.
+field_width([], _, LL) ->
+    LL.
+
+vals([]) -> [];
+vals([{S, _}|L]) -> [S|vals(L)];
+vals([S|L]) -> [S|vals(L)].
+
+leading_dots([], _Len) -> [];
+leading_dots([{H, I}|L], Len) ->
+    [{"..." ++ nthtail(Len, H), I}|leading_dots(L, Len)];
+leading_dots([H|L], Len) ->
+    ["..." ++ nthtail(Len, H)|leading_dots(L, Len)].
 
 longest_common_head([]) ->
     no;
diff --git a/lib/stdlib/test/edlin_expand_SUITE.erl b/lib/stdlib/test/edlin_expand_SUITE.erl
index 718d91c6a3..1f694ea549 100644
--- a/lib/stdlib/test/edlin_expand_SUITE.erl
+++ b/lib/stdlib/test/edlin_expand_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2016. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -21,7 +21,8 @@
 -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
 	 init_per_testcase/2, end_per_testcase/2,
 	 init_per_group/2,end_per_group/2]).
--export([normal/1, quoted_fun/1, quoted_module/1, quoted_both/1, erl_1152/1]).
+-export([normal/1, quoted_fun/1, quoted_module/1, quoted_both/1, erl_1152/1,
+         erl_352/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -36,7 +37,7 @@ suite() ->
      {timetrap,{minutes,1}}].
 
 all() -> 
-    [normal, quoted_fun, quoted_module, quoted_both, erl_1152].
+    [normal, quoted_fun, quoted_module, quoted_both, erl_1152, erl_352].
 
 groups() -> 
     [].
@@ -153,6 +154,78 @@ erl_1152(Config) when is_list(Config) ->
     "\n"++"foo"++"    "++[1089]++_ = do_format(["foo",[1089]]),
     ok.
 
+erl_352(Config) when is_list(Config) ->
+    erl_352_test(3, 3),
+
+    erl_352_test(3, 75),
+    erl_352_test(3, 76, [trailing]),
+    erl_352_test(4, 74),
+    erl_352_test(4, 75, [leading]),
+    erl_352_test(4, 76, [leading, trailing]),
+
+    erl_352_test(75, 3),
+    erl_352_test(76, 3, [leading]),
+    erl_352_test(74, 4),
+    erl_352_test(75, 4, [leading]),
+    erl_352_test(76, 4, [leading]),
+
+    erl_352_test(74, 74, [leading]),
+    erl_352_test(74, 75, [leading]),
+    erl_352_test(74, 76, [leading, trailing]).
+
+erl_352_test(PrefixLen, SuffixLen) ->
+    erl_352_test(PrefixLen, SuffixLen, []).
+
+erl_352_test(PrefixLen, SuffixLen, Dots) ->
+    io:format("\nPrefixLen = ~w, SuffixLen = ~w\n", [PrefixLen, SuffixLen]),
+
+    PrefixM = lists:duplicate(PrefixLen, $p),
+    SuffixM = lists:duplicate(SuffixLen, $s),
+    LM = [PrefixM ++ S ++ SuffixM || S <- ["1", "2"]],
+    StrM = do_format(LM),
+    check_leading(StrM, "", PrefixM, SuffixM, Dots),
+
+    PrefixF = lists:duplicate(PrefixLen, $p),
+    SuffixF = lists:duplicate(SuffixLen-2, $s),
+    LF = [{PrefixF ++ S ++ SuffixF, 1} || S <- ["1", "2"]],
+    StrF = do_format(LF),
+    true = check_leading(StrF, "/1", PrefixF, SuffixF, Dots),
+
+    ok.
+
+check_leading(FormStr, ArityStr, Prefix, Suffix, Dots) ->
+    List = string:tokens(FormStr, "\n "),
+    io:format("~p\n", [List]),
+    true = lists:all(fun(L) -> length(L) < 80 end, List),
+    case lists:member(leading, Dots) of
+        true ->
+            true = lists:all(fun(L) ->
+                                     {"...", Rest} = lists:split(3, L),
+                                     check_trailing(Rest, ArityStr,
+                                                    Suffix, Dots)
+                             end, List);
+        false ->
+            true = lists:all(fun(L) ->
+                                     {Prefix, Rest} =
+                                         lists:split(length(Prefix), L),
+                                     check_trailing(Rest, ArityStr,
+                                                    Suffix, Dots)
+                             end, List)
+    end.
+
+check_trailing([I|Str], ArityStr, Suffix, Dots) ->
+    true = lists:member(I, [$1, $2]),
+    case lists:member(trailing, Dots) of
+        true ->
+            {Rest, "..." ++ ArityStr} =
+                lists:split(length(Str) - (3 + length(ArityStr)), Str),
+            true = lists:prefix(Rest, Suffix);
+        false ->
+            {Rest, ArityStr} =
+                lists:split(length(Str) - length(ArityStr), Str),
+            Rest =:= Suffix
+    end.
+
 do_expand(String) ->
     edlin_expand:expand(lists:reverse(String)).