as: convert to module-tagged errors, format_error/1, and error:format/1; improve specs

erlang/apps/as/src/as.erl

@@ -36,8 +36,8 @@ main_(Argv) ->
         ok -> halt(0);
         {error, _Reason} = Error -> escript_runtime:fatal("~p\n", [Error])
       end;
-    {error, ErrMsg} ->
-      escript_runtime:errmsg("~s\n", [ErrMsg]),
+    {error, Reason} ->
+      escript_runtime:errmsg("~s\n", [error:format(Reason)]),
       usage()
   end.
 

erlang/apps/as/src/assemble.erl

@@ -21,11 +21,13 @@
 -module(assemble).
 
 -export([ tunit/1
+        , format_error/1
         ]).
 
 -include("tunit.hrl").
 -include_lib("lib/include/pdp10_elf36.hrl").
 
+-spec tunit(#tunit{}) -> {ok, #tunit{}} | {error, {module(), term()}}.
 tunit(Tunit) ->
   sections(maps:values(Tunit#tunit.sections), Tunit).
 
@@ -47,7 +49,7 @@ section(Section, Tunit) ->
             , sh_flags = ?SHF_MERGE bor ?SHF_STRINGS
             } -> comment(Section, Tunit);
     #section{ name = Name } ->
-      {error, io_lib:format("don't know how to assemble section ~s", [Name])}
+      {error, {?MODULE, {cannot_assemble, Name}}}
   end.
 
 %% Assemble .comment -----------------------------------------------------------
@@ -100,3 +102,9 @@ insn_image(Insn) ->
    (Word bsr 18) band 511,
    (Word bsr  9) band 511,
    Word          band 511].
+
+%% Error reporting -------------------------------------------------------------
+
+-spec format_error(term()) -> io_lib:chars().
+format_error({cannot_assemble, Name}) ->
+  io_lib:format("don't know how to assemble section ~s", [Name]).

erlang/apps/as/src/input.erl

@@ -21,11 +21,13 @@
 -module(input).
 
 -export([ files/1
+        , format_error/1
         ]).
 
 -include("tunit.hrl").
 -include_lib("lib/include/pdp10_elf36.hrl").
 
+-spec files([string()]) -> {ok, #tunit{}} | {error, {module(), term()}}.
 files(Files) ->
   NewFiles =
     case Files of
@@ -235,9 +237,11 @@ section_dot_text() -> % ".text"
 
 %% Error reporting -------------------------------------------------------------
 
-%% FIXME: this is duplicated a few times, move it to scan_state.erl
 fmterr(ScanState, Fmt, Args) ->
   {ok, FileName} = scan_state:filename(ScanState),
   {ok, LineNr} = scan_state:linenr(ScanState),
-  {error, lists:flatten(io_lib:format("file ~s line ~p: " ++ Fmt,
-                                      [FileName, LineNr | Args]))}.
+  {error, {?MODULE, {FileName, LineNr, Fmt, Args}}}.
+
+-spec format_error(term()) -> io_lib:chars().
+format_error({FileName, LineNr, Fmt, Args}) ->
+  io_lib:format("file ~s line ~p: " ++ Fmt, [FileName, LineNr | Args]).

erlang/apps/as/src/output.erl

@@ -46,6 +46,7 @@
 -module(output).
 
 -export([ tunit/2
+        , format_error/1
         ]).
 
 -include("tunit.hrl").
@@ -64,6 +65,7 @@
         , strtab   :: #strtab{}
         }).
 
+-spec tunit(#tunit{}, string()) -> ok | {error, {module(), term()}}.
 tunit(Tunit, File) ->
   emit(layout(Tunit), File).
 
@@ -330,7 +332,7 @@ emit(Context, File) ->
         emit(Funs, Context, FP, 0)
       after pdp10_stdio:fclose(FP)
       end;
-    {error, Reason} -> {error, io_lib:format("opening ~s: ~p", [File, Reason])}
+    {error, Reason} -> {error, {?MODULE, {cannot_open, File, Reason}}}
   end.
 
 emit([], _Context, _FP, _Offset) -> ok;
@@ -558,3 +560,9 @@ image_write([H | T], FP) ->
 image_write([], _FP) -> ok;
 image_write(TByte, FP) when is_integer(TByte), 0 =< TByte, TByte =< 511 ->
   pdp10_stdio:fputc(TByte, FP).
+
+%% Error reporting -------------------------------------------------------------
+
+-spec format_error(term()) -> io_lib:chars().
+format_error({cannot_open, File, Reason}) ->
+  io_lib:format("opening ~s: ~s", [File, error:format(Reason)]).

erlang/apps/as/src/parse.erl

@@ -21,12 +21,15 @@
 -module(parse).
 
 -export([ stmt/1
+        , format_error/1
         ]).
 
 -include("token.hrl").
 -include("tunit.hrl").
 -include_lib("lib/include/pdp10_opcodes.hrl").
 
+-spec stmt(scan_state:scan_state())
+      -> {ok, stmt()} | eof | {error, {module(), term()}}.
 stmt(ScanState) ->
   case scan:token(ScanState) of
     {ok, ?T_DOT_FILE} -> dot_file(ScanState);
@@ -303,10 +306,13 @@ dot_type(ScanState) ->
 
 badtok(_ScanState, _ErrMsg, {error, _Reason} = Error) -> Error;
 badtok(ScanState, ErrMsg, {ok, Token}) ->
-  fmterr(ScanState, ErrMsg ++ "; current token is ~s", [token:to_string(Token)]).
+  fmterr(ScanState, ErrMsg ++ "; current token is ~s", [token:format(Token)]).
 
 fmterr(ScanState, Fmt, Args) ->
   {ok, FileName} = scan_state:filename(ScanState),
   {ok, LineNr} = scan_state:linenr(ScanState),
-  {error, lists:flatten(io_lib:format("file ~s line ~p: " ++ Fmt,
-                                      [FileName, LineNr | Args]))}.
+  {error, {?MODULE, {FileName, LineNr, Fmt, Args}}}.
+
+-spec format_error(term()) -> io_lib:chars().
+format_error({FileName, LineNr, Fmt, Args}) ->
+  io_lib:format("file ~s line ~p: " ++ Fmt, [FileName, LineNr | Args]).

erlang/apps/as/src/scan.erl

@@ -21,10 +21,13 @@
 -module(scan).
 
 -export([ token/1
+        , format_error/1
         ]).
 
 -include("token.hrl").
 
+-spec token(scan_state:scan_state())
+      -> {ok, token()} | {error, {module(), term()}}.
 token(ScanState) ->
   case scan_state:fgetc(ScanState) of
     {error, _Reason} = Error -> Error;
@@ -220,11 +223,14 @@ chval(Ch) ->
   end.
 
 badchar(ScanState, Ch, Context) ->
-  ChStr = char_to_string(Ch),
   {ok, FileName} = scan_state:filename(ScanState),
   {ok, LineNr} = scan_state:linenr(ScanState),
-  {error, lists:flatten(io_lib:format("~s line ~p: invalid character '~s' ~s",
-                                      [FileName, LineNr, ChStr, Context]))}.
+  {error, {?MODULE, {FileName, LineNr, Ch, Context}}}.
+
+-spec format_error(term()) -> io_lib:chars().
+format_error({FileName, LineNr, Ch, Context}) ->
+  io_lib:format("~s line ~p: invalid character '~s' ~s",
+                [FileName, LineNr, char_to_string(Ch), Context]).
 
 char_to_string(eof) -> "<EOF>";
 char_to_string(Ch) when $\s =< Ch, Ch =< $~ -> [$', Ch, $'];

erlang/apps/as/src/scan_state.erl

@@ -31,6 +31,7 @@
           % meta-data accessors
         , filename/1
         , linenr/1
+        , format_error/1
         ]).
 
 %% gen_server callbacks
@@ -52,39 +53,54 @@
         , linenr        :: pos_integer()
         }).
 
+-type scan_state() :: pid().
+
+-export_type([scan_state/0]).
+
 %% API -------------------------------------------------------------------------
 
--spec fclose(pid()) -> ok | {error, any()}.
+-spec fclose(scan_state()) -> ok | {error, {module(), term()}}.
 fclose(Pid) ->
   gen_server:call(Pid, fclose, infinity).
 
--spec fgetc(pid()) -> {ok, byte()} | eof | {error, any()}.
+-spec fgetc(scan_state()) -> {ok, byte()} | eof | {error, {module(), term()}}.
 fgetc(Pid) ->
   gen_server:call(Pid, fgetc, infinity).
 
--spec fopen(string()) -> {ok, pid()} | {error, any()}.
+-spec fopen(string()) -> {ok, scan_state()} | {error, {module(), term()}}.
 fopen(File) ->
   do_fopen(File).
 
--spec stdin() -> {ok, pid()}.
+-spec stdin() -> {ok, scan_state()}.
 stdin() ->
   do_fopen(stdin).
 
 do_fopen(File) ->
   gen_server:start(?MODULE, File, []).
 
--spec ungetc(byte(), pid()) -> ok | {error, any()}.
+-spec ungetc(byte(), scan_state()) -> ok | {error, {module(), term()}}.
 ungetc(Ch, Pid) ->
   gen_server:call(Pid, {ungetc, Ch}, infinity).
 
--spec filename(pid()) -> {ok, string()}.
+-spec filename(scan_state()) -> {ok, string()}.
 filename(Pid) ->
   gen_server:call(Pid, filename, infinity).
 
--spec linenr(pid()) -> {ok, pos_integer()}.
+-spec linenr(scan_state()) -> {ok, pos_integer()}.
 linenr(Pid) ->
   gen_server:call(Pid, linenr, infinity).
 
+-spec format_error(term()) -> io_lib:chars().
+format_error(Reason) ->
+  case Reason of
+    {bad_request, Req} ->
+      io_lib:format("internal error: bad request: ~p", [Req]);
+    ungetc ->
+      "internal error: invalid ungetc";
+    _ ->
+      io_lib:format("~p", [Reason])
+  end.
+
 %% gen_server callbacks --------------------------------------------------------
 
 init(stdin) ->
@@ -92,7 +108,7 @@ init(stdin) ->
 init(File) ->
   case file:open(File, [raw, read, read_ahead]) of
     {ok, IoDev} -> do_init(File, IoDev);
-    {error, Reason} -> {stop, Reason}
+    {error, Reason} -> {stop, {file, Reason}}
   end.
 
 do_init(FileName, IoDev) ->
@@ -115,7 +131,7 @@ handle_call(Req, _From, State) ->
     linenr ->
       {reply, {ok, State#state.linenr}, State};
     _ ->
-      {reply, {error, {bad_request, Req}}, State}
+      {reply, {error, {?MODULE, {bad_request, Req}}}, State}
   end.
 
 handle_cast(_Req, State) ->
@@ -155,7 +171,7 @@ handle_fgetc(State) ->
                _ -> State
              end};
           eof -> {eof, State};
-          {error, _Reason} = Error -> {Error, State}
+          {error, Reason} -> {{error, {file, Reason}}, State}
         end,
       {reply, Result, NewState};
     Ch ->
@@ -167,5 +183,5 @@ handle_fgetc(State) ->
 handle_ungetc(State, Ch) ->
   case State#state.ungetc of
     [] -> {reply, ok, State#state{ungetc = Ch}};
-    _ -> {reply, {error, ungetc}, State}
+    _ -> {reply, {error, {?MODULE, ungetc}}, State}
   end.

erlang/apps/as/src/token.erl

@@ -21,7 +21,7 @@
 -module(token).
 
 -export([ from_symbol/1
-        , to_string/1
+        , format/1
         ]).
 
 -include("token.hrl").
@@ -38,8 +38,8 @@ from_symbol(Name) ->
     _                   -> {?T_SYMBOL, Name}
   end.
 
--spec to_string(token()) -> string().
-to_string(Token) ->
+-spec format(token()) -> io_lib:chars().
+format(Token) ->
   case Token of
     ?T_DOT_FILE         -> ".file";
     ?T_DOT_GLOBL        -> ".globl";