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authorBjörn Gustavsson <[email protected]>2016-08-15 15:34:06 +0200
committerBjörn Gustavsson <[email protected]>2016-09-02 14:24:36 +0200
commit0baa07cdf2754748bbc2d969bf83f08c0976fb78 (patch)
treeb5d649dbe4778d8488ae09a99e68435adc216342 /lib/debugger/test/overridden_bif_SUITE.erl
parent8a04dd4dd2d479efe488b0bed118e10559835fb6 (diff)
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Fix overridden BIFs
The filters in a list comprehension can be guard expressions or an ordinary expressions. If a guard expression is used as a filter, an exception will basically mean the same as 'false': t() -> L = [{some_tag,42},an_atom], [X || X <- L, element(1, X) =:= some_tag] %% Returns [{some_tag,42}] On the other hand, if an ordinary expression is used as a filter, there will be an exception: my_element(N, T) -> element(N, T). t() -> L = [{some_tag,42},an_atom], [X || X <- L, my_element(1, X) =:= some_tag] %% Causes a 'badarg' exception when element(1, an_atom) is evaluated It has been allowed for several releases to override a BIF with a local function. Thus, if we define a function called element/2, it will be called instead of the BIF element/2 within the module. We must use the "erlang:" prefix to call the BIF. Therefore, the following code is expected to work the same way as in our second example above: -compile({no_auto_import,[element/2]}). element(N, T) -> erlang:element(N, T). t() -> L = [{some_tag,42},an_atom], [X || X <- L, element(1, X) =:= some_tag]. %% Causes a 'badarg' exception when element(1, an_atom) is evaluated But the compiler refuses to compile the code with the following diagnostic: call to local/imported function element/2 is illegal in guard
Diffstat (limited to 'lib/debugger/test/overridden_bif_SUITE.erl')
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1 files changed, 99 insertions, 0 deletions
diff --git a/lib/debugger/test/overridden_bif_SUITE.erl b/lib/debugger/test/overridden_bif_SUITE.erl
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+++ b/lib/debugger/test/overridden_bif_SUITE.erl
@@ -0,0 +1,99 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2001-2016. 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.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(overridden_bif_SUITE).
+-compile({no_auto_import,[is_reference/1,size/1]}).
+
+-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
+ init_per_group/2,end_per_group/2,
+ init_per_testcase/2,end_per_testcase/2,
+ overridden_bif/1]).
+
+-include_lib("common_test/include/ct.hrl").
+
+%% Used by overridden_bif/1.
+-import(gb_sets, [size/1]).
+-import(test_lib, [binary/1]).
+
+suite() ->
+ [{ct_hooks,[ts_install_cth]},
+ {timetrap,{minutes,1}}].
+
+all() ->
+ [overridden_bif].
+
+groups() ->
+ [].
+
+init_per_suite(Config) ->
+ test_lib:interpret(?MODULE),
+ Config.
+
+end_per_suite(_Config) ->
+ ok.
+
+init_per_group(_GroupName, Config) ->
+ Config.
+
+end_per_group(_GroupName, Config) ->
+ Config.
+
+
+init_per_testcase(Case, Config) when is_atom(Case), is_list(Config) ->
+ Config.
+
+end_per_testcase(Case, Config) when is_atom(Case), is_list(Config) ->
+ ok.
+
+overridden_bif(_Config) ->
+ L = [-3,-2,-1,0,1,2,3,4],
+ [-3,0,3] = do_overridden_bif_1(L),
+ [-2,0,2,4] = do_overridden_bif_2(L),
+ [3] = do_overridden_bif_3(L),
+ [2,4] = do_overridden_bif_4(L),
+
+ Set = gb_sets:from_list(L),
+ [Set] = do_overridden_bif_5([gb_sets:singleton(42),Set]),
+
+ [100,0] = do_overridden_bif_6([100|L]),
+ ok.
+
+do_overridden_bif_1(L) ->
+ [E || E <- L, is_reference(E)].
+
+do_overridden_bif_2(L) ->
+ [E || E <- L, port(E)].
+
+do_overridden_bif_3(L) ->
+ [E || E <- L, (is_reference(E) andalso E > 0)].
+
+do_overridden_bif_4(L) ->
+ [E || E <- L, (port(E) andalso E > 0)].
+
+do_overridden_bif_5(L) ->
+ [E || E <- L, size(E) > 1].
+
+do_overridden_bif_6(L) ->
+ [E || E <- L, binary(E)].
+
+is_reference(N) ->
+ N rem 3 =:= 0.
+
+port(N) ->
+ N rem 2 =:= 0.