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authorHans Bolinder <[email protected]>2019-02-26 10:11:59 +0100
committerHans Bolinder <[email protected]>2019-03-05 12:02:25 +0100
commitcd5dbd5204a783743c72116d81e993ec041b7396 (patch)
tree16673271f8c9e97b2aafd41f2c6287358f56f9a1
parent23c33d5b8d5234a159b0dc39e2fe6aa99dadaed2 (diff)
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stdlib: Correct and optimize pretty printing of strings
Avoid traversing all of the list/string when only part of it will be used. An explicit check that the list is flat is needed since string:slice() accepts deep lists and more.
-rw-r--r--lib/stdlib/src/io_lib_pretty.erl46
-rw-r--r--lib/stdlib/test/io_SUITE.erl39
2 files changed, 72 insertions, 13 deletions
diff --git a/lib/stdlib/src/io_lib_pretty.erl b/lib/stdlib/src/io_lib_pretty.erl
index 5483ea87b5..8f2fd7ea8f 100644
--- a/lib/stdlib/src/io_lib_pretty.erl
+++ b/lib/stdlib/src/io_lib_pretty.erl
@@ -721,7 +721,7 @@ printable_list(_L, 1, _T, _Enc) ->
printable_list(L, _D, T, latin1) when T < 0 ->
io_lib:printable_latin1_list(L);
printable_list(L, _D, T, Enc) when T >= 0 ->
- case slice(L, tsub(T, 2)) of
+ case slice(L, tsub(T, 2), Enc) of
false ->
false;
{prefix, Prefix} when Enc =:= latin1 ->
@@ -737,20 +737,46 @@ printable_list(L, _D, T, Enc) when T >= 0 ->
printable_list(L, _D, T, _Uni) when T < 0->
io_lib:printable_list(L).
-slice(L, N) ->
- try io_lib:chars_length(L) =< N of
- true ->
+slice(L, N, latin1) ->
+ try lists:split(N, L) of
+ {_, []} ->
all;
- false ->
- case string:slice(L, 0, N) of
- "" ->
- false;
- Prefix ->
- {prefix, Prefix}
+ {[], _} ->
+ false;
+ {L1, _} ->
+ {prefix, L1}
+ catch
+ _:_ ->
+ all
+ end;
+slice(L, N, _Uni) ->
+ %% Be careful not to traverse more of L than necessary.
+ try string:slice(L, 0, N) of
+ "" ->
+ false;
+ Prefix ->
+ %% Assume no binaries are introduced by string:slice().
+ case is_flat(L, lists:flatlength(Prefix)) of
+ true ->
+ case string:equal(Prefix, L) of
+ true ->
+ all;
+ false ->
+ {prefix, Prefix}
+ end;
+ false ->
+ false
end
catch _:_ -> false
end.
+is_flat(_L, 0) ->
+ true;
+is_flat([C|Cs], N) when is_integer(C) ->
+ is_flat(Cs, N - 1);
+is_flat(_, _N) ->
+ false.
+
printable_bin0(Bin, D, T, Enc) ->
Len = case D >= 0 of
true ->
diff --git a/lib/stdlib/test/io_SUITE.erl b/lib/stdlib/test/io_SUITE.erl
index f097552e8c..824f5d19f2 100644
--- a/lib/stdlib/test/io_SUITE.erl
+++ b/lib/stdlib/test/io_SUITE.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1999-2018. All Rights Reserved.
+%% Copyright Ericsson AB 1999-2019. 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.
@@ -32,7 +32,7 @@
io_with_huge_message_queue/1, format_string/1,
maps/1, coverage/1, otp_14178_unicode_atoms/1, otp_14175/1,
otp_14285/1, limit_term/1, otp_14983/1, otp_15103/1, otp_15076/1,
- otp_15159/1]).
+ otp_15159/1, otp_15639/1]).
-export([pretty/2, trf/3]).
@@ -64,7 +64,8 @@ all() ->
io_lib_print_binary_depth_one, otp_10302, otp_10755, otp_10836,
io_lib_width_too_small, io_with_huge_message_queue,
format_string, maps, coverage, otp_14178_unicode_atoms, otp_14175,
- otp_14285, limit_term, otp_14983, otp_15103, otp_15076, otp_15159].
+ otp_14285, limit_term, otp_14983, otp_15103, otp_15076, otp_15159,
+ otp_15639].
%% Error cases for output.
error_1(Config) when is_list(Config) ->
@@ -2647,3 +2648,35 @@ otp_15076(_Config) ->
{'EXIT', {badarg, _}} = (catch io_lib:build_text(L)),
{'EXIT', {badarg, _}} = (catch io_lib:build_text(L, [])),
ok.
+
+otp_15639(_Config) ->
+ L = lists:duplicate(10, "a"),
+ LOpts = [{encoding, latin1}, {chars_limit, 10}],
+ UOpts = [{encoding, unicode}, {chars_limit, 10}],
+ "[[...]|...]" = pretty(L, LOpts),
+ "[[...]|...]" = pretty(L, UOpts),
+ "[\"a\",[...]|...]" =
+ pretty(L, [{chars_limit, 12}, {encoding, latin1}]),
+ "[\"a\",[...]|...]" =
+ pretty(L, [{chars_limit, 12}, {encoding, unicode}]),
+
+ %% Latin-1
+ "\"12345678\"" = pretty("12345678", LOpts),
+ "\"12345678\"..." = pretty("123456789", LOpts),
+ "\"\\r\\n123456\"..." = pretty("\r\n1234567", LOpts),
+ "\"\\r1234567\"..." = pretty("\r12345678", LOpts),
+ "\"\\r\\n123456\"..." = pretty("\r\n12345678", LOpts),
+ "\"12345678\"..." = pretty("12345678"++[x], LOpts),
+ "[49,50|...]" = pretty("1234567"++[x], LOpts),
+ "[49,x]" = pretty("1"++[x], LOpts),
+ "[[...]|...]" = pretty(["1","2","3","4","5","6","7","8"], LOpts),
+ %% Unicode
+ "\"12345678\"" = pretty("12345678", UOpts),
+ "\"12345678\"..." = pretty("123456789", UOpts),
+ "\"\\r\\n1234567\"" = pretty("\r\n1234567", UOpts),
+ "\"\\r1234567\"..." = pretty("\r12345678", UOpts),
+ "\"\\r\\n1234567\"..." = pretty("\r\n12345678", UOpts),
+ "[49,50|...]" = pretty("12345678"++[x], UOpts),
+ "\"12345678\"..." = pretty("123456789"++[x], UOpts),
+ "[[...]|...]" = pretty(["1","2","3","4","5","6","7","8"], UOpts),
+ ok.