Fix #267, refactor as/do/namespace interactions

Breaking up initial call to parse from the ones deep inside the provider
parsing to do smarter namespace detection, added 'as' the ability to
look into these also, and cleaned up the code a whole lot that would
depend on implicit assumptions.

A side-effect is that 'do' is now valid for all namespaces, although it
can be overriden.

src/rebar3.erl

@@ -133,7 +133,7 @@ run_aux(State, GlobalPluginProviders, RawArgs) ->
 
     {Task, Args} = parse_args(RawArgs),
 
-    rebar_core:process_command(rebar_state:command_args(State6, Args), Task).
+    rebar_core:init_command(rebar_state:command_args(State6, Args), Task).
 
 init_config() ->
     %% Initialize logging system

src/rebar_core.erl

@@ -26,69 +26,61 @@
 %% -------------------------------------------------------------------
 -module(rebar_core).
 
--export([process_command/2]).
+-export([init_command/2, process_namespace/2, process_command/2]).
 
 -include("rebar.hrl").
 
+init_command(State, do) ->
+    process_command(rebar_state:namespace(State, default), do);
+init_command(State, as) ->
+    process_command(rebar_state:namespace(State, default), as);
+init_command(State, Command) ->
+    case process_namespace(State, Command) of
+        {ok, State1, Command1} ->
+            process_command(State1, Command1);
+        {error, Reason} ->
+            {error, Reason}
+    end.
+
+process_namespace(_State, as) ->
+    {error, "Namespace 'as' is forbidden"};
+process_namespace(State, Command) ->
+    Providers = rebar_state:providers(State),
+    CommandProvider = providers:get_provider(Command, Providers, default),
+    case CommandProvider of
+        not_found ->
+            case providers:get_providers_by_namespace(Command, Providers) of
+                [] ->
+                    {error, io_lib:format("Command ~p not found", [Command])};
+                _ ->
+                    %% Replay 'do' as a command of that namespace
+                    {ok, rebar_state:namespace(State, Command), do}
+            end;
+        _ ->
+            {ok, rebar_state:namespace(State, default), Command}
+    end.
+
 -spec process_command(rebar_state:t(), atom()) -> {ok, rebar_state:t()} | {error, string()}.
 process_command(State, Command) ->
     %% ? rebar_prv_install_deps:setup_env(State),
     Providers = rebar_state:providers(State),
     Namespace = rebar_state:namespace(State),
-    {TargetProviders, CommandProvider} =
-        case Namespace of
-            undefined ->
-                %% undefined namespace means 'default', but on the first run;
-                %% it is used as an implicit counter for the first vs. subsequent
-                %% runs.
-                {providers:get_target_providers(Command, Providers, default),
-                 providers:get_provider(Command, Providers, default)};
-            _ ->
-                {providers:get_target_providers(Command, Providers, Namespace),
-                 providers:get_provider(Command, Providers, Namespace)}
-        end,
-
+    TargetProviders = providers:get_target_providers(Command, Providers, Namespace),
+    CommandProvider = providers:get_provider(Command, Providers, Namespace),
     case CommandProvider of
-        not_found ->
+        not_found when Command =/= do ->
             case Namespace of
-                undefined ->
-                    %% On the first run (Namespace = undefined), we use the
-                    %% unfound command name to be a namespace.
-                    case providers:get_providers_by_namespace(Command, Providers) of
-                        [] ->
-                            {error, io_lib:format("Command ~p not found", [Command])};
-                        _ ->
-                            do([{default, do} | TargetProviders],
-                               rebar_state:namespace(State, Command))
-                    end;
                 default ->
                     {error, io_lib:format("Command ~p not found", [Command])};
                 _ ->
                     {error, io_lib:format("Command ~p not found in namespace ~p",
                                           [Command, Namespace])}
             end;
+        not_found when Command =:= do, Namespace =/= default ->
+            do([{default, do} | TargetProviders], State);
         CommandProvider ->
             case Command of
-                Command when Command =:= do, Namespace =:= undefined ->
-                    %% We're definitely in the default namespace. 'do' doesn't
-                    %% properly exist for non-default namespaces outside of
-                    %% dynamic dispatch calls for namespaces.
-                    do(TargetProviders, rebar_state:namespace(State, default));
-                Command when Command =:= as, Namespace =:= undefined ->
-                    %% Because of the possible forms such as:
-                    %% 'rebar3 as profile task`, `rebar3 as profile do task`
-                    %% and `rebar3 as profile namespace task`, we can only know
-                    %% whether we're in the first 'as' or a namespace 'as' by
-                    %% looking at profiles (as makes them non-default).
-                    %% The namespace 'as' is banned. It also makes it impossible
-                    %% to have both $REBAR_PROFILE set and use 'as' in a command
-                    case rebar_state:current_profiles(State) of
-                        [default] ->
-                            do(TargetProviders, State);
-                        _ ->
-                            {error, "Namespace 'as' is forbidden"}
-                    end;
-                Command when Command =:= do ->
+                do ->
                     do(TargetProviders, State);
                 _ ->
                     Profiles = providers:profiles(CommandProvider),
@@ -97,12 +89,7 @@ process_command(State, Command) ->
                     case getopt:parse(Opts, rebar_state:command_args(State1)) of
                         {ok, Args} ->
                             State2 = rebar_state:command_parsed_args(State1, Args),
-                            case Namespace of
-                                undefined -> % we're executing commands, set the default namespace
-                                    do(TargetProviders, rebar_state:namespace(State2, default));
-                                _ ->
-                                    do(TargetProviders, State2)
-                            end;
+                            do(TargetProviders, State2);
                         {error, {invalid_option, Option}} ->
                             {error, io_lib:format("Invalid option ~s on task ~p", [Option, Command])}
                     end

src/rebar_prv_as.erl

@@ -38,7 +38,17 @@ do(State) ->
             {error, "At least one profile must be specified when using `as`"};
         _  ->
             State1 = rebar_state:apply_profiles(State, [list_to_atom(X) || X <- Profiles]),
-            rebar_prv_do:do_tasks(Tasks, State1)
+            {FirstTask, FirstTaskArgs} = hd(Tasks),
+            FirstTaskAtom = list_to_atom(FirstTask),
+            case rebar_core:process_namespace(State1, FirstTaskAtom) of
+                {ok, State2, NewTask} ->
+                    rebar_prv_do:do_tasks(
+                        [{atom_to_list(NewTask),FirstTaskArgs}|tl(Tasks)],
+                        State2
+                    );
+                {error, Reason} ->
+                    {error, Reason}
+            end
     end.
 
 -spec format_error(any()) -> iolist().