allow plugins to add project builders and compilers

src/rebar_app_info.erl

@@ -71,7 +71,10 @@
 -include("rebar.hrl").
 -include_lib("providers/include/providers.hrl").
 
--export_type([t/0]).
+-export_type([t/0,
+              project_type/0]).
+
+-type project_type() :: rebar3 | mix | undefined.
 
 -record(app_info_t, {name               :: binary() | undefined,
                      app_file_src       :: file:filename_all() | undefined,
@@ -93,7 +96,7 @@
                      is_lock=false      :: boolean(),
                      is_checkout=false  :: boolean(),
                      valid              :: boolean() | undefined,
-                     project_type       :: rebar3 | mix | undefined,
+                     project_type       :: project_type(),
                      is_available=false :: boolean()}).
 
 %%============================================================================

src/rebar_otp_app.erl

@@ -60,7 +60,8 @@ compile(State, App) ->
 format_error({missing_app_file, Filename}) ->
     io_lib:format("App file is missing: ~ts", [Filename]);
 format_error({file_read, AppName, File, Reason}) ->
-    io_lib:format("Failed to read required ~ts file for processing the application '~ts': ~ts", [File, AppName, file:format_error(Reason)]);
+    io_lib:format("Failed to read required ~ts file for processing the application '~ts': ~ts",
+                  [File, AppName, file:format_error(Reason)]);
 format_error({invalid_name, File, AppName}) ->
     io_lib:format("Invalid ~ts: name of application (~p) must match filename.", [File, AppName]).
 

src/rebar_packages.erl

@@ -60,7 +60,7 @@ get_all_names(State) ->
 get_package_versions(Dep, Repo, Table, State) ->
     ?MODULE:verify_table(State),
     AllowPreRelease = rebar_state:get(State, deps_allow_prerelease, false),
-    ets:select(Table, [{#package{key={Dep,{'$1', '$2'}, Repo},
+    ets:select(Table, [{#package{key={Dep, {'$1', '$2'}, Repo},
                                  _='_'},
                         [{'==', '$2', {{[],[]}}} || not AllowPreRelease], [{{'$1', '$2'}}]}]).
 

src/rebar_prv_compile.erl

@@ -198,22 +198,20 @@ compile(State, Providers, AppInfo) ->
 
 build_app(AppInfo, State) ->
     case rebar_app_info:project_type(AppInfo) of
-        T when T =:= rebar3 ; T =:= undefined ->
+        Type when Type =:= rebar3 ; Type =:= undefined ->
             Compilers = rebar_state:compilers(State),
             rebar_compiler:compile_all(Compilers, AppInfo);
-        T ->
-            ProjectBuilders = rebar_state:get(State, project_builders, []),
-            case lists:keyfind(T, 1, ProjectBuilders) of
+        Type ->
+            ProjectBuilders = rebar_state:project_builders(State),
+            case lists:keyfind(Type, 1, ProjectBuilders) of
                 {_, Module} ->
-                    _ = code:ensure_loaded(Module),
-                    case erlang:function_exported(Module, build, 1) of
-                        true ->
-                            Module:build(AppInfo);
-                        false ->
-                            throw(?PRV_ERROR({bad_project_builder, rebar_app_info:name(AppInfo), T, Module}))
-                    end;
+                    %% load plugins since thats where project builders would be
+                    PluginDepsPaths = rebar_state:code_paths(State, all_plugin_deps),
+                    code:add_pathsa(PluginDepsPaths),
+                    Module:build(AppInfo),
+                    rebar_utils:remove_from_code_path(PluginDepsPaths);
                 _ ->
-                    throw(?PRV_ERROR({unknown_project_type, rebar_app_info:name(AppInfo), T}))
+                    throw(?PRV_ERROR({unknown_project_type, rebar_app_info:name(AppInfo), Type}))
             end
     end.
 update_code_paths(State, ProjectApps, DepsPaths) ->

src/rebar_state.erl

@@ -39,6 +39,9 @@
          to_list/1,
 
          compilers/1, compilers/2,
+         prepend_compilers/2, append_compilers/2,
+
+         project_builders/1, add_project_builder/3,
 
          create_resources/2,
          resources/1, resources/2, add_resource/2,
@@ -69,6 +72,7 @@
                   all_deps            = []          :: [rebar_app_info:t()],
 
                   compilers           = []          :: [{compiler_type(), extension(), extension(), compile_fun()}],
+                  project_builders    = []          :: [{rebar_app_info:project_type(), module()}],
                   resources           = [],
                   providers           = [],
                   allow_provider_overrides = false  :: boolean()}).
@@ -402,9 +406,29 @@ warn_old_resource(ResourceModule) ->
 compilers(#state_t{compilers=Compilers}) ->
     Compilers.
 
+prepend_compilers(State=#state_t{compilers=Compilers}, NewCompilers) ->
+    State#state_t{compilers=NewCompilers++Compilers}.
+
+append_compilers(State=#state_t{compilers=Compilers}, NewCompilers) ->
+    State#state_t{compilers=Compilers++NewCompilers}.
+
 compilers(State, Compilers) ->
     State#state_t{compilers=Compilers}.
 
+project_builders(#state_t{project_builders=ProjectBuilders}) ->
+    ProjectBuilders.
+
+add_project_builder(State=#state_t{project_builders=ProjectBuilders}, Type, Module) ->
+    _ = code:ensure_loaded(Module),
+    case erlang:function_exported(Module, build, 1) of
+        true ->
+            State#state_t{project_builders=[{Type, Module} | ProjectBuilders]};
+        false ->
+            ?WARN("Unable to add project builder for type ~s, required function ~s:build/1 not found.",
+                  [Type, Module]),
+            State
+    end.
+
 create_resources(Resources, State) ->
     lists:foldl(fun(R, StateAcc) ->
                         add_resource(StateAcc, R)