Add stub for xref support; not yet done

1 files changed, 184 insertions, 0 deletions

diff --git a/src/rebar_xref.erl b/src/rebar_xref.erl
new file mode 100644
index 0000000..b5e6d8a
--- /dev/null
+++ b/src/rebar_xref.erl
@@ -0,0 +1,184 @@
+%% -*- tab-width: 4;erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 et
+%% -------------------------------------------------------------------
+%%
+%% rebar: Erlang Build Tools
+%%
+%% Copyright (c) 2009 Dave Smith (dizzyd@dizzyd.com)
+%%
+%% Permission is hereby granted, free of charge, to any person obtaining a copy
+%% of this software and associated documentation files (the "Software"), to deal
+%% in the Software without restriction, including without limitation the rights
+%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+%% copies of the Software, and to permit persons to whom the Software is
+%% furnished to do so, subject to the following conditions:
+%%
+%% The above copyright notice and this permission notice shall be included in
+%% all copies or substantial portions of the Software.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+%% THE SOFTWARE.
+%%
+%% -------------------------------------------------------------------
+
+%% -------------------------------------------------------------------
+%% This module borrows heavily from http://github.com/etnt/exrefcheck project as
+%% written by Torbjorn Tornkvist <tobbe@kreditor.se>, Daniel Luna and others.
+%% -------------------------------------------------------------------
+-module(rebar_xref).
+
+-include("rebar.hrl").
+
+-export([xref/2]).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+
+xref(Config, _) ->
+    %% Spin up xref
+    xref:start(xref),
+    ok = xref:set_library_path(xref, code_path()),
+    xref:set_default(xref, [{warnings, rebar_config:get(Config, xref_warnings, false)},
+                            {verbose, rebar_config:is_verbose()}]),
+    {ok, _} = xref:add_directory(xref, "ebin"),
+
+    %% Get list of xref checks we want to run
+    XrefChecks = rebar_config:get(Config, xref_checks, [exports_not_used,
+                                                        undefined_function_calls]),
+
+    %% Look for exports that are unused by anything
+    case lists:member(exports_not_used, XrefChecks) of
+        true ->
+            check_exports_not_used(Config);
+        false ->
+            ok
+    end,
+
+    %% Look for calls to undefined functions
+    case lists:member(undefined_function_calls, XrefChecks) of
+        true ->
+            check_undefined_function_calls(Config);
+        false ->
+            ok
+    end,
+
+    ok.
+
+foobar() ->
+    ok.
+
+%% ===================================================================
+%% Internal functions
+%% ===================================================================
+
+check_exports_not_used(_Config) ->
+    {ok, UnusedExports0} = xref:analyze(xref, exports_not_used),
+    UnusedExports = filter_away_ignored(UnusedExports0),
+
+    %% Report all the unused functions
+    display_mfas(UnusedExports, "is unused export (Xref)"),
+    ok.
+
+check_undefined_function_calls(_Config) ->
+    {ok, UndefinedCalls0} = xref:analyze(xref, undefined_function_calls),
+
+    UndefinedCalls = [{find_mfa_source(Caller), format_fa(Caller), format_mfa(Target)} ||
+                         {Caller, Target} <- UndefinedCalls0],
+    [?CONSOLE("~s:~w: Warning ~s calls undefined function ~s\n",
+              [Source, Line, FunStr, Target]) ||
+        {{Source, Line}, FunStr, Target} <- UndefinedCalls],
+    ok.
+
+
+code_path() ->
+    [P || P <- code:get_path(),
+          filelib:is_dir(P)].
+
+%%
+%% Ignore behaviour functions, and explicitly marked functions
+%%
+filter_away_ignored(UnusedExports) ->
+    %% Functions can be ignored by using
+    %% -ignore_xref([{F, A}, ...]).
+
+    %% Setup a filter function that build a list of behaviour callbacks and/or
+    %% any functions marked to ignore. We then use this list to mask any functions
+    %% marked as unused exports by xref
+    F = fun(Mod) ->
+                Attrs  = ks(attributes, Mod:module_info()),
+                Ignore = ks(ignore_xref, Attrs),
+                Callbacks = [B:behaviour_info(callbacks) || B <- ks(behaviour, Attrs)],
+                [{Mod, F, A} || {F, A} <- Ignore ++ lists:flatten(Callbacks)]
+        end,
+    AttrIgnore = lists:flatten(lists:map(F, lists:usort([M || {M, _, _} <- UnusedExports]))),
+    [X || X <- UnusedExports, not(lists:member(X, AttrIgnore))].
+
+
+
+ks(Key, List) ->
+    case lists:keysearch(Key, 1, List) of
+        {value, {Key, Value}} ->
+            Value;
+        false ->
+            []
+    end.
+
+display_mfas([], _Message) ->
+    ok;
+display_mfas([{Mod, Fun, Args} = MFA | Rest], Message) ->
+    {Source, Line} = find_mfa_source(MFA),
+    ?CONSOLE("~s:~w: Warning: function ~s/~w ~s\n", [Source, Line, Fun, Args, Message]),
+    display_mfas(Rest, Message).
+
+format_mfa({M, F, A}) ->
+    ?FMT("~s:~s/~w", [M, F, A]).
+
+format_fa({_M, F, A}) ->
+    ?FMT("~s/~w", [F, A]).
+
+%%
+%% Extract an element from a tuple, or undefined if N > tuple size
+safe_element(N, Tuple) ->
+    case catch(element(N, Tuple)) of
+        {'EXIT', {badarg, _}} ->
+            undefined;
+        Value ->
+            Value
+    end.
+
+%%
+%% Extract the line number for a given function def
+%%
+abstract_code_function_line(Code, Name, Args) ->
+    [{function, Line, Name, _, _}] = [E || E <- Code,
+                                           safe_element(1, E) == function,
+                                           safe_element(3, E) == Name,
+                                           safe_element(4, E) == Args],
+    Line.
+
+%%
+%% Extract the original source filename from the abstract code
+%%
+abstract_code_source_file(Code) ->
+    [{attribute, 1, file, {Name, _}} | _] = Code,
+    Name.
+
+
+%%
+%% Given a MFA, find the file and LOC where it's defined. Note that
+%% xref doesn't work if there is no abstract_code, so we can avoid
+%% being too paranoid here.
+%%
+find_mfa_source({M, F, A}) ->
+    {M, Bin, _} = code:get_object_code(M),
+    {ok, {M, [{abstract_code, AbstractCode}]}} = beam_lib:chunks(Bin, [abstract_code]),
+    {raw_abstract_v1, Code} = AbstractCode,
+    Source = abstract_code_source_file(Code),
+    Line = abstract_code_function_line(Code, F, A),
+    {Source, Line}.