aboutsummaryrefslogblamecommitdiffstats
path: root/lib/parsetools/src/yecc.erl
blob: 2f0f70f39bca56e54638080d5d71f4cebcba8f0c (plain) (tree)
1
2
3
4
5
6
7
8
9
10
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624

                   
  
                                                        
  




                                                                      
  



                                                                         
  















                                                                             

                                                              









                              
                          


























































































                                                                           

                                                                         


                                             
                                                              
                                                                              
                                                                    
                                          

















































































                                                                            




                                                                  































                                                                            
                            






















                                                                     

                                                                             
















                                                                 


                                                       





                                               


                                                     























                                                     
                                            







                                                        
                                                             






                                                        
                           















                                                     

                                                               


































                                                                


                                                                          





                                                                            
                                        
                          



                                             
             

                                                            
 



                                                               

                                                   





































                                                                           
                                       


                                                                 
                                              

                                                                        
                                                              










                                                    
                            




                                         
                                                         































                                                                           

                                                         



















                                                                            
                                 




                                                               




                                                           













































































































































































                                                                              
                                                                  


                                 
                                                       
 

                                               






                                   
                                                              
                                                                   
                












































                                                                              
                        
       
                 
                                        





                                                            






                                                  





































                                                                             
                                                      

                                                                  
                                                         






                                                                      

                                                         


                                     

                                                                         

                                                
                                                        

                                                             
                                                
                                                           

                                                            





























                                                                             

                                      



























































































































                                                                             
                




























































































                                                                             
                                                   

                                                   
                                         


































































































































































































































































































































































































































































































                                                                              




                                                         






























































































































































































                                                                              

                                                                              

















                                                                             

                                                 






































                                                                            



                                                                 































                                                                              



                                                                            
 
                             


















                                                                             



                                                                          



















                                                                             


                                                                               


                     
                                                              















































































                                                                             



                                                                           




                                                        
 











































































                                                                              
                                                                           












                                                                              

                                        

                                                                             
                                             















































































































                                                                              

                                                                








































































































































































                                                                       
                                         
                                           


                                                                

        




                                                              




                                    
                                                                           

                          
          














                                                      
                  






                                              

                                               
    
                                    
       
                                       
                         
                                                                              
 

                                       

                                                                  


                                                                     







                                             









                                                                  











































                                                                    
                                                 




































                                                                              
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%% Yacc like LALR-1 parser generator for Erlang.
%% Ref: Aho & Johnson: "LR Parsing", ACM Computing Surveys, vol. 6:2, 1974.
%% Auxiliary files: yeccgramm.yrl, yeccparser.erl, yeccpre.hrl, yeccscan.erl.
%%

-module(yecc).

-export([compile/3, file/1, file/2, format_error/1]).

%% Kept for compatibility with R10B.
-export([yecc/2, yecc/3, yecc/4]).

-import(lists, [append/1, append/2, concat/1, delete/2, filter/2,
                flatmap/2, foldl/3, foldr/3, foreach/2, keydelete/3,
                keysort/2, last/1, map/2, member/2, reverse/1,
                sort/1, usort/1]).

-include("erl_compile.hrl").
-include("ms_transform.hrl").

-record(yecc, {
          infile,
          outfile,
          includefile,
          includefile_version,
          module,
          encoding = none,
          options = [],
          verbose = false,
          file_attrs = true,
          errors = [],
          warnings = [],
          conflicts_done = false,
          shift_reduce = [],
          reduce_reduce = [],
          n_states = 0,
          inport,
          outport,
          line,

          parse_actions,
          symbol_tab,
          inv_symbol_tab,
          state_tab,
          prec_tab,
          goto_tab,

          terminals = [],
          nonterminals = [],
          all_symbols = [],
          prec = [],
          rules_list = [],
          rules, % a tuple of rules_list
          rule_pointer2rule,
          rootsymbol = [],
          endsymbol = [],
          expect_shift_reduce = [],
          expect_n_states = [],
          header = [],
          erlang_code = none
         }).

-record(rule, {
          n,             % rule n in the grammar file
          line,
          symbols,       % the names of symbols
          tokens,
          is_guard,      % the action is a guard (not used)
          is_well_formed % can be parsed (without macro expansion)
         }).

-record(reduce, {
          rule_nmbr,
          head,
          nmbr_of_daughters,
          prec,
          unused % assure that #reduce{} comes before #shift{} when sorting
         }).

-record(shift, {
          state,
          pos,
          prec,
          rule_nmbr
         }).

-record(user_code, {state, terminal, funname, action}).

-record(symbol, {line = none, name}).

%% ACCEPT is neither an atom nor a non-terminal.
-define(ACCEPT, {}).

%% During the phase 'compute_states' terminals in lookahead sets are
%% coded as integers; sets of terminals are integer bit masks. This is
%% for efficiency only. '$empty' is always given the mask 1. The
%% behaviour can be turned off by un-defining SYMBOLS_AS_CODES (useful
%% when debugging).

%% Non-terminals are also given integer codes, starting with -1. The
%% absolut value of the code is used for indexing a tuple of lists of
%% rules.

-define(SYMBOLS_AS_CODES, true).

-ifdef(SYMBOLS_AS_CODES).
-define(EMPTY, 0).
-else.
-define(EMPTY, '$empty').
-endif.

%%%
%%% Exported functions
%%%

%%% Interface to erl_compile.

compile(Input0, Output0, 
        #options{warning = WarnLevel, verbose=Verbose, includes=Includes,
		 specific=Specific}) ->
    Input = shorten_filename(Input0),
    Output = shorten_filename(Output0),
    Includefile = lists:sublist(Includes, 1),
    Werror = proplists:get_bool(warnings_as_errors, Specific),
    Opts = [{parserfile,Output}, {includefile,Includefile}, {verbose,Verbose},
            {report_errors, true}, {report_warnings, WarnLevel > 0},
	    {warnings_as_errors, Werror}],
    case file(Input, Opts) of
        {ok, _OutFile} ->
            ok;
        error ->
            error
    end.

format_error(bad_declaration) ->
    io_lib:fwrite("unknown or bad declaration, ignored", []);
format_error({bad_expect, SymName}) ->
    io_lib:fwrite("argument ~s of Expect is not an integer", 
                  [format_symbol(SymName)]);
format_error({bad_rootsymbol, SymName}) ->
    io_lib:fwrite("rootsymbol ~s is not a nonterminal", 
                  [format_symbol(SymName)]);
format_error({bad_states, SymName}) ->
    io_lib:fwrite("argument ~s of States is not an integer", 
                  [format_symbol(SymName)]);
format_error({conflict, Conflict}) ->
    format_conflict(Conflict);
format_error({conflicts, SR, RR}) ->
    io_lib:fwrite("conflicts: ~w shift/reduce, ~w reduce/reduce", [SR, RR]);
format_error({duplicate_declaration, Tag}) ->
    io_lib:fwrite("duplicate declaration of ~s", [atom_to_list(Tag)]);
format_error({duplicate_nonterminal, Nonterminal}) ->
    io_lib:fwrite("duplicate non-terminals ~s", 
                  [format_symbol(Nonterminal)]);
format_error({duplicate_precedence, Op}) ->
    io_lib:fwrite("duplicate precedence operator ~s", 
                  [format_symbol(Op)]);
format_error({duplicate_terminal, Terminal}) ->
    io_lib:fwrite("duplicate terminal ~s", 
                  [format_symbol(Terminal)]);
format_error({endsymbol_is_nonterminal, Symbol}) ->
    io_lib:fwrite("endsymbol ~s is a nonterminal", 
                  [format_symbol(Symbol)]);
format_error({endsymbol_is_terminal, Symbol}) ->
    io_lib:fwrite("endsymbol ~s is a terminal", 
                  [format_symbol(Symbol)]);
format_error({error, Module, Error}) ->
    Module:format_error(Error);
format_error({file_error, Reason}) ->
    io_lib:fwrite("~s",[file:format_error(Reason)]);
format_error(illegal_empty) ->
    io_lib:fwrite("illegal use of empty symbol", []);
format_error({internal_error, Error}) ->
    io_lib:fwrite("internal yecc error: ~w", [Error]);
format_error({missing_syntax_rule, Nonterminal}) ->
    io_lib:fwrite("no syntax rule for non-terminal symbol ~s",
                  [format_symbol(Nonterminal)]);
format_error({n_states, Exp, N}) ->
    io_lib:fwrite("expected ~w states, but got ~p states", [Exp, N]);
format_error(no_grammar_rules) ->
    io_lib:fwrite("grammar rules are missing", []);
format_error(nonterminals_missing) ->
    io_lib:fwrite("Nonterminals is missing", []);
format_error({precedence_op_is_endsymbol, SymName}) ->
    io_lib:fwrite("precedence operator ~s is endsymbol",
                  [format_symbol(SymName)]);
format_error({precedence_op_is_unknown, SymName}) ->
    io_lib:fwrite("unknown precedence operator ~s",
                  [format_symbol(SymName)]);
format_error({reserved, N}) ->
    io_lib:fwrite("the use of ~w should be avoided", [N]);
format_error({symbol_terminal_and_nonterminal, SymName}) ->
    io_lib:fwrite("symbol ~s is both a terminal and nonterminal",
                  [format_symbol(SymName)]);
format_error(rootsymbol_missing) ->
    io_lib:fwrite("Rootsymbol is missing", []);
format_error(terminals_missing) ->
    io_lib:fwrite("Terminals is missing", []);
format_error({undefined_nonterminal, Symbol}) ->
    io_lib:fwrite("undefined nonterminal: ~s", [format_symbol(Symbol)]);
format_error({undefined_pseudo_variable, Atom}) ->
    io_lib:fwrite("undefined pseudo variable ~w", [Atom]);
format_error({undefined_symbol, SymName}) ->
    io_lib:fwrite("undefined rhs symbol ~s", [format_symbol(SymName)]);
format_error({unused_nonterminal, Nonterminal}) ->
    io_lib:fwrite("non-terminal symbol ~s not used", 
                  [format_symbol(Nonterminal)]);
format_error({unused_terminal, Terminal}) ->
    io_lib:fwrite("terminal symbol ~s not used", 
                  [format_symbol(Terminal)]);
format_error({bad_symbol, String}) ->
    io_lib:fwrite("bad symbol ~ts", [String]);
format_error(cannot_parse) ->
    io_lib:fwrite("cannot parse; possibly encoding mismatch", []).

file(File) ->
    file(File, [report_errors, report_warnings]).

file(File, Options) ->
    case is_filename(File) of
        no -> erlang:error(badarg, [File, Options]);
        _ -> ok
    end,
    case options(Options) of
        badarg ->
            erlang:error(badarg, [File, Options]);
        OptionValues ->
            Self = self(),
            Flag = process_flag(trap_exit, false),
            Pid = spawn_link(fun() -> infile(Self, File, OptionValues) end),
            receive
                {Pid, Rep} -> 
                    receive after 1 -> ok end,
                    process_flag(trap_exit, Flag),
                    Rep
            end
    end.

%% Kept for backward compatibility.
yecc(Infile, Outfile) ->
    yecc(Infile, Outfile, false, []).

yecc(Infile, Outfile, Verbose) ->
    yecc(Infile, Outfile, Verbose, []).

yecc(Infilex, Outfilex, Verbose, Includefilex) ->
    _ = statistics(runtime),
    case file(Infilex, [{parserfile, Outfilex}, 
                        {verbose, Verbose}, 
                        {report, true},
                        {includefile, Includefilex}]) of
        {ok, _File} ->
            statistics(runtime);
        error ->
            exit(error)
    end.

%%%
%%% Local functions
%%%

options(Options0) when is_list(Options0) ->
    try 
        Options = flatmap(fun(return) -> short_option(return, true);
                             (report) -> short_option(report, true);
                             ({return,T}) -> short_option(return, T);
                             ({report,T}) -> short_option(report, T);
                             (T) -> [T]
                          end, Options0),
        options(Options, [file_attributes, includefile, parserfile, 
                          report_errors, report_warnings, warnings_as_errors,
                          return_errors, return_warnings, time, verbose], [])
    catch error: _ -> badarg
    end;
options(Option) ->
    options([Option]).

short_option(return, T) ->
    [{return_errors,T}, {return_warnings,T}];
short_option(report, T) ->
    [{report_errors,T}, {report_warnings,T}].

options(Options0, [Key | Keys], L) when is_list(Options0) ->
    Options = case member(Key, Options0) of
                  true -> 
                      [atom_option(Key) | delete(Key, Options0)];
                  false ->
                      Options0
              end,
    V = case lists:keyfind(Key, 1, Options) of
            {Key, Filename0} when Key =:= includefile;
                                  Key =:= parserfile ->
                case is_filename(Filename0) of
                    no -> 
                        badarg;
                    Filename -> 
                        {ok, [{Key, Filename}]}
                end;
            {Key, Bool} = KB when is_boolean(Bool) ->
                {ok, [KB]};
            {Key, _} ->
                badarg;
            false ->
                {ok, [{Key, default_option(Key)}]}
        end,
    case V of
        badarg ->
            badarg;
        {ok, KeyValueL} ->
            NewOptions = keydelete(Key, 1, Options),
            options(NewOptions, Keys, KeyValueL ++ L)
    end;
options([], [], L) ->
    foldl(fun({_,false}, A) -> A;
             ({Tag,true}, A) -> [Tag | A];
             (F, A) -> [F | A]
          end, [], L);
options(_Options, _, _L) ->
    badarg.

default_option(file_attributes) -> true;
default_option(includefile) -> [];
default_option(parserfile) -> [];
default_option(report_errors) -> true;
default_option(report_warnings) -> true;
default_option(warnings_as_errors) -> false;
default_option(return_errors) -> false;
default_option(return_warnings) -> false;
default_option(time) -> false;
default_option(verbose) -> false.

atom_option(file_attributes) -> {file_attributes, true};
atom_option(report_errors) -> {report_errors, true};
atom_option(report_warnings) -> {report_warnings, true};
atom_option(warnings_as_errors) -> {warnings_as_errors,true};
atom_option(return_errors) -> {return_errors, true};
atom_option(return_warnings) -> {return_warnings, true};
atom_option(time) -> {time, true};
atom_option(verbose) -> {verbose, true};
atom_option(Key) -> Key.

is_filename(T) ->
    try filename:flatten(T)
    catch error: _ -> no
    end.    

shorten_filename(Name0) ->
    {ok,Cwd} = file:get_cwd(),
    case lists:prefix(Cwd, Name0) of
        false -> Name0;
        true ->
            case lists:nthtail(length(Cwd), Name0) of
                "/"++N -> N;
                N -> N
            end
    end.

start(Infilex, Options) ->
    Infile = assure_extension(Infilex, ".yrl"),
    {_, Outfilex0} = lists:keyfind(parserfile, 1, Options),
    {_, Includefilex} = lists:keyfind(includefile, 1, Options),
    Outfilex = case Outfilex0 of
                   [] -> filename:rootname(Infilex, ".yrl");
                   _ -> Outfilex0
               end,
    Includefile = case Includefilex of
                      [] -> [];
                      _ -> assure_extension(Includefilex,".hrl")
                  end,
    IncludefileVersion = includefile_version(Includefile),
    Outfile = assure_extension(Outfilex, ".erl"),
    Module = list_to_atom(filename:basename(Outfile, ".erl")),
    #yecc{infile = Infile, 
          outfile = Outfile,
          includefile = Includefile,
          includefile_version = IncludefileVersion,
          module = Module,
          options = Options,
          verbose = member(verbose, Options),
          file_attrs = member(file_attributes, Options)}.

assure_extension(File, Ext) ->
    concat([strip_extension(File, Ext), Ext]).

%% Assumes File is a filename.
strip_extension(File, Ext) ->
    case filename:extension(File) of
        Ext -> filename:rootname(File);
        _Other -> File
    end.

infile(Parent, Infilex, Options) ->
    St0 = start(Infilex, Options),
    St = case file:open(St0#yecc.infile, [read, read_ahead]) of
             {ok, Inport} ->
                 try 
                     Encoding = epp:set_encoding(Inport),
                     St1 = St0#yecc{inport = Inport, encoding = Encoding},
                     outfile(St1)
                 after
                     ok = file:close(Inport)
                 end;
             {error, Reason} ->
                 add_error(St0#yecc.infile, none, {file_error, Reason}, St0)
         end,
    case {St#yecc.errors, werror(St)} of
        {[], false} -> ok;
        _ -> _ = file:delete(St#yecc.outfile)
    end,
    Parent ! {self(), yecc_ret(St)}.

werror(St) ->
    St#yecc.warnings =/= []
	andalso member(warnings_as_errors, St#yecc.options).

outfile(St0) ->
    case file:open(St0#yecc.outfile, [write, delayed_write]) of
        {ok, Outport} ->
            try 
                %% Set the same encoding as infile:
                set_encoding(St0, Outport),
                generate(St0#yecc{outport = Outport, line = 1})
            catch 
                throw: St1  ->
                    St1;
                exit: Reason ->
                    add_error({internal_error, Reason}, St0)
            after
               ok = file:close(Outport)
            end;
        {error, Reason} ->
            add_error(St0#yecc.outfile, none, {file_error, Reason}, St0)
    end.

os_process_size() ->
    case os:type() of
        {unix, sunos} ->
            Size = os:cmd("ps -o vsz -p " ++ os:getpid() ++ " | tail -1"),
            list_to_integer(lib:nonl(Size));
        _ ->
            0
    end.            

timeit(Name, Fun, St0) ->
    Time = runtime,
    %% Time = wall_clock,
    {Before, _} = statistics(Time),
    St = Fun(St0), 
    {After, _} = statistics(Time),
    Mem0 = erts_debug:flat_size(St)*erlang:system_info(wordsize),
    Mem = lists:flatten(io_lib:format("~.1f kB", [Mem0/1024])),
    Sz = lists:flatten(io_lib:format("~.1f MB", [os_process_size()/1024])),
    io:fwrite(" ~-30w: ~10.2f s ~12s ~10s\n", 
              [Name, (After-Before)/1000, Mem, Sz]),
    St.

-define(PASS(P), {P, fun P/1}).

generate(St0) ->
    St1 = output_encoding_comment(St0),
    Passes = [?PASS(parse_grammar), ?PASS(check_grammar),
              ?PASS(states_and_goto_table), ?PASS(parse_actions),
              ?PASS(action_conflicts), ?PASS(write_file)],
    F = case member(time, St1#yecc.options) of
            true -> 
                io:fwrite(<<"Generating parser from grammar in ~s\n">>, 
                          [format_filename(St1#yecc.infile)]),
                fun timeit/3;
            false ->
                fun(_Name, Fn, St) -> Fn(St) end
        end,
    Fun = fun({Name, Fun}, St) ->
                  St2 = F(Name, Fun, St),
                  if 
                      St2#yecc.errors =:= [] -> St2;
                      true -> throw(St2)
                  end
          end,
    foldl(Fun, St1, Passes).

parse_grammar(St) ->
    parse_grammar(St#yecc.inport, 1, St).

parse_grammar(Inport, Line, St) ->
    {NextLine, Grammar} = read_grammar(Inport, St, Line),
    parse_grammar(Grammar, Inport, NextLine, St).

parse_grammar(eof, _Inport, _NextLine, St) ->
    St;
parse_grammar({#symbol{name = 'Header'}, Ss}, Inport, NextLine, St0) ->
    St1 = St0#yecc{header = [S || {string,_,S} <- Ss]},
    parse_grammar(Inport, NextLine, St1);
parse_grammar({#symbol{name = 'Erlang'}, [#symbol{name = code}]}, _Inport, 
              NextLine, St) ->
    St#yecc{erlang_code = NextLine};
parse_grammar(Grammar, Inport, NextLine, St0) ->
    St = parse_grammar(Grammar, St0),
    parse_grammar(Inport, NextLine, St).

parse_grammar({error,ErrorLine,Error}, St) ->
    add_error(ErrorLine, Error, St);
parse_grammar({rule, Rule, Tokens}, St0) ->
    NmbrOfDaughters = case Rule of
                          [_, #symbol{name = '$empty'}]  -> 0;
                          _ -> length(Rule) - 1
                      end,
    {IsGuard, IsWellFormed} = check_action(Tokens),
    {Tokens1, St} = subst_pseudo_vars(Tokens,
                                      NmbrOfDaughters,
                                      St0),
    RuleDef = #rule{symbols = Rule, 
                    tokens = Tokens1, 
                    is_guard = IsGuard, 
                    is_well_formed = IsWellFormed},
    St#yecc{rules_list = [RuleDef | St#yecc.rules_list]};
parse_grammar({prec, Prec}, St) ->
    St#yecc{prec = Prec ++ St#yecc.prec};
parse_grammar({#symbol{}, [{string,Line,String}]}, St) ->
    add_error(Line, {bad_symbol, String}, St);
parse_grammar({#symbol{line = Line, name = Name}, Symbols}, St) ->
    CF = fun(I) ->
                 case element(I, St) of
                     [] -> 
                         setelement(I, St, Symbols);
                     _ -> 
                         add_error(Line, {duplicate_declaration, Name}, St)
                 end
         end,
    OneSymbol = length(Symbols) =:= 1,
    case Name of
        'Nonterminals' -> CF(#yecc.nonterminals);
        'Terminals' -> CF(#yecc.terminals);
        'Rootsymbol' when OneSymbol -> CF(#yecc.rootsymbol);
        'Endsymbol' when OneSymbol ->  CF(#yecc.endsymbol);
        'Expect' when OneSymbol -> CF(#yecc.expect_shift_reduce);
        'States' when OneSymbol -> CF(#yecc.expect_n_states); % undocumented
        _ -> add_warning(Line, bad_declaration, St)
    end.

read_grammar(Inport, St, Line) ->
    case yeccscan:scan(Inport, '', Line) of
        {eof, NextLine} ->
            {NextLine, eof};
        {error, {ErrorLine, Mod, What}, NextLine} ->
            {NextLine, {error, ErrorLine, {error, Mod, What}}};
        {error, terminated} ->
            throw(St);
        {error, _} ->
            File = St#yecc.infile,
            throw(add_error(File, none, cannot_parse, St));
        {ok, Input, NextLine} ->
            {NextLine, case yeccparser:parse(Input) of
                           {error, {ErrorLine, Mod, Message}} ->
                               {error, ErrorLine, {error, Mod, Message}};
                           {ok, {rule, Rule, {erlang_code, Tokens}}} ->
                               {rule, Rule, Tokens};
                           {ok, {#symbol{name=P}, 
                                 [#symbol{name=I} | OpL]}=Ss} ->
                               A = precedence(P),
                               if
                                   A =/= unknown, 
                                   is_integer(I),
                                   OpL =/= [] ->
                                       Ps = [{Op, I , A} || Op <- OpL],
                                       {prec, Ps};
                                   true -> 
                                       Ss
                               end;
                           {ok, Ss} -> 
                               Ss
                       end}
    end.

precedence('Left') -> left;
precedence('Right') -> right;
precedence('Unary') -> unary;
precedence('Nonassoc') -> nonassoc;
precedence(_) -> unknown.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

check_grammar(St0) ->
    Empty = #symbol{line = none, name = '$empty'},
    AllSymbols = St0#yecc.nonterminals ++ St0#yecc.terminals ++ [Empty],
    St1 = St0#yecc{all_symbols = AllSymbols},
    Cs = [fun check_nonterminals/1, fun check_terminals/1, 
          fun check_rootsymbol/1, fun check_endsymbol/1, 
          fun check_expect/1, fun check_states/1,
          fun check_precedences/1, fun check_rules/1],
    foldl(fun(F, St) -> F(St) end, St1, Cs).

check_nonterminals(St) ->
    case St#yecc.nonterminals of 
        [] ->
            add_error(nonterminals_missing, St);
        Nonterminals ->
            {Unique, Dups} = duplicates(names(Nonterminals)),
            St1 = add_warnings(Dups, duplicate_nonterminal, St),
            St2 = check_reserved(Unique, St1),
            St2#yecc{nonterminals = [?ACCEPT | Unique]}
    end.

check_terminals(St0) ->
    case St0#yecc.terminals of
        [] ->
            add_error(terminals_missing, St0);
        Terminals ->
            {Unique, Dups} = duplicates(names(Terminals)),
            St1 = add_warnings(Dups, duplicate_terminal, St0),
            Common = intersect(St1#yecc.nonterminals, Unique),
            St2 = add_errors(Common, symbol_terminal_and_nonterminal, St1),
            St3 = check_reserved(Unique, St2),
            St3#yecc{terminals = ['$empty' | Unique]}
    end.

check_reserved(Names, St) ->
    add_errors(intersect(Names, ['$empty', '$end', '$undefined']),
               reserved, St).

check_rootsymbol(St) ->
    case St#yecc.rootsymbol of
        [] ->
            add_error(rootsymbol_missing, St);
        [#symbol{line = Line, name = SymName}] ->
            case kind_of_symbol(St, SymName) of
                nonterminal ->
                    St#yecc{rootsymbol = SymName};
                _ ->
                    add_error(Line, {bad_rootsymbol, SymName}, St)
            end
    end.

check_endsymbol(St) ->
    case St#yecc.endsymbol of
        [] ->
            St#yecc{endsymbol = '$end'};
        [#symbol{line = Line, name = SymName}] ->
            case kind_of_symbol(St, SymName) of
                nonterminal ->
                    add_error(Line, {endsymbol_is_nonterminal, SymName}, St);
                terminal ->
                    add_error(Line, {endsymbol_is_terminal, SymName}, St);
                _ ->
                    St#yecc{endsymbol = SymName}
            end
    end.

check_expect(St0) ->
    case St0#yecc.expect_shift_reduce of
        [] ->
            St0#yecc{expect_shift_reduce = 0};
        [#symbol{name = Expect}] when is_integer(Expect) ->
            St0#yecc{expect_shift_reduce = Expect};
        [#symbol{line = Line, name = Name}] ->
            St1 = add_error(Line, {bad_expect, Name}, St0),
            St1#yecc{expect_shift_reduce = 0}
    end.

check_states(St) ->
    case St#yecc.expect_n_states of
        [] ->
            St;
        [#symbol{name = NStates}] when is_integer(NStates) ->
            St#yecc{expect_n_states = NStates};
        [#symbol{line = Line, name = Name}] ->
            add_error(Line, {bad_states, Name}, St)
    end.

check_precedences(St0) ->
    {St1, _} = 
        foldr(fun({#symbol{line = Line, name = Op},_I,_A}, {St,Ps}) ->
                      case member(Op, Ps) of
                          true ->
                              {add_error(Line, {duplicate_precedence,Op}, St),
                               Ps};
                          false ->
                              {St, [Op | Ps]}
                      end
              end, {St0,[]}, St0#yecc.prec),
    foldl(fun({#symbol{line = Line, name = Op},I,A}, St) ->
                  case kind_of_symbol(St, Op) of
                      endsymbol ->
                          add_error(Line,{precedence_op_is_endsymbol,Op}, St);
                      unknown ->
                          add_error(Line, {precedence_op_is_unknown, Op}, St);
                      _ -> 
                          St#yecc{prec = [{Op,I,A} | St#yecc.prec]}
                  end
          end, St1#yecc{prec = []}, St1#yecc.prec).

check_rule(Rule0, {St0,Rules}) ->
    Symbols = Rule0#rule.symbols,
    #symbol{line = HeadLine, name = Head} = hd(Symbols),
    case member(Head, St0#yecc.nonterminals) of
        false -> 
            {add_error(HeadLine, {undefined_nonterminal, Head}, St0), Rules};
        true ->
            St = check_rhs(tl(Symbols), St0),
            Rule = Rule0#rule{line = HeadLine, symbols = names(Symbols)},
            {St, [Rule | Rules]}
    end.

check_rules(St0) ->
    {St,Rules0} = foldl(fun check_rule/2, {St0,[]}, St0#yecc.rules_list),
    case St#yecc.rules_list of
        [] ->
            add_error(no_grammar_rules, St);
        _ ->
            Rule = #rule{line = none, 
                         symbols = [?ACCEPT, St#yecc.rootsymbol],
                         tokens = []},
            Rules1 = [Rule | Rules0],
            Rules = map(fun({R,I}) -> R#rule{n = I} end,  count(0, Rules1)),
            St#yecc{rules_list = Rules, rules = list_to_tuple(Rules)}
    end.

duplicates(List) ->
    Unique = usort(List),
    {Unique, List -- Unique}.

names(Symbols) ->
    map(fun(Symbol) -> Symbol#symbol.name end, Symbols).

symbol_line(Name, St) ->
    #symbol{line = Line} = symbol_find(Name, St#yecc.all_symbols),
    Line.

symbol_member(Symbol, Symbols) ->
    symbol_find(Symbol#symbol.name, Symbols) =/= false.

symbol_find(Name, Symbols) ->
    lists:keyfind(Name, #symbol.name, Symbols).

states_and_goto_table(St0) ->
    St1 = create_symbol_table(St0),
    St = compute_states(St1),
    create_precedence_table(St).

parse_actions(St) ->
    _ = erase(), % the pd is used when decoding lookahead sets
    ParseActions = compute_parse_actions(St#yecc.n_states, St, []),
    _ = erase(),
    St#yecc{parse_actions = ParseActions, state_tab = []}.

action_conflicts(St0) ->
    St = find_action_conflicts(St0),
    St#yecc{conflicts_done = true}.

-record(state_info, {reduce_only, state_repr, comment}).

write_file(St0) ->
    #yecc{parse_actions = ParseActions, goto_tab = GotoTab} = St0,
    Sorted = sort_parse_actions(ParseActions),
    StateReprs = find_identical_shift_states(Sorted),
    StateInfo = collect_some_state_info(Sorted, StateReprs),
    StateJumps = find_partial_shift_states(Sorted, StateReprs),
    UserCodeActions = find_user_code(Sorted, St0),
    #yecc{infile = Infile, outfile = Outfile,
          inport = Inport, outport = Outport,
          nonterminals = Nonterminals} = St0,
    {St10, N_lines, LastErlangCodeLine} = 
        output_prelude(Outport, Inport, St0),
    St20 = St10#yecc{line = St10#yecc.line + N_lines},
    St25 = nl(St20),
    St30 = output_file_directive(St25, Outfile, St25#yecc.line),
    St40 = nl(St30),
    St50 = output_actions(St40, StateJumps, StateInfo),
    Go0 = [{Symbol,{From,To}} || {{From,Symbol},To} <- ets:tab2list(GotoTab)],
    Go = family_with_domain(Go0, Nonterminals),
    St60 = output_goto(St50, Go, StateInfo),
    St70 = output_inlined(St60, UserCodeActions, Infile),
    St = nl(St70),
    case LastErlangCodeLine of
        %% Just in case warnings or errors are emitted after the last
        %% line of the file.
        {last_erlang_code_line, Last_line} ->
            output_file_directive(St, Infile, Last_line);
        no_erlang_code ->
            St
    end.

yecc_ret(St0) ->
    St = check_expected(St0),
    report_errors(St),
    report_warnings(St),
    Es = pack_errors(St#yecc.errors),
    Ws = pack_warnings(St#yecc.warnings),
    Werror = werror(St),
    if 
        Werror ->
            do_error_return(St, Es, Ws);
        Es =:= [] -> 
            case member(return_warnings, St#yecc.options) of
                true -> {ok, St#yecc.outfile, Ws};
                false -> {ok, St#yecc.outfile}
            end;
        true -> 
            do_error_return(St, Es, Ws)
    end.

do_error_return(St, Es, Ws) ->
    case member(return_errors, St#yecc.options) of
        true -> {error, Es, Ws};
        false -> error
    end.

check_expected(St0) ->
    #yecc{shift_reduce = SR, reduce_reduce = RR, expect_shift_reduce = ExpSR,
          n_states = NStates0, expect_n_states = ExpStates,
          conflicts_done = Done} = St0,
    N_RR = length(usort(RR)),
    N_SR = length(usort(SR)),
    St1 = if
              not Done ->
                  St0;
              N_SR =:= ExpSR, N_RR =:= 0 ->
                  St0;
              true ->
                  add_warning(none, {conflicts, N_SR, N_RR}, St0)
          end,
    NStates = NStates0 + 1,
    if
        (not Done) or (ExpStates =:= []) or (NStates =:= ExpStates) ->
            St1;
        true ->
            add_warning(none, {n_states, ExpStates, NStates}, St1)
    end.

pack_errors([{File,_} | _] = Es) ->
    [{File, flatmap(fun({_,E}) -> [E] end, sort(Es))}];
pack_errors([]) ->
    [].
    
pack_warnings([{File,_} | _] = Ws) ->
    [{File, flatmap(fun({_,W}) -> [W] end, sort(Ws))}];
pack_warnings([]) ->
    [].

report_errors(St) ->
    case member(report_errors, St#yecc.options) of
        true ->
            foreach(fun({File,{none,Mod,E}}) -> 
                            io:fwrite(<<"~s: ~ts\n">>,
                                      [File,Mod:format_error(E)]);
                       ({File,{Line,Mod,E}}) -> 
                            io:fwrite(<<"~s:~w: ~ts\n">>,
                                      [File,Line,Mod:format_error(E)])
                    end, sort(St#yecc.errors));
        false -> 
            ok
    end.

report_warnings(St) ->
    Werror = member(warnings_as_errors, St#yecc.options),
    Prefix = case Werror of
		 true -> "";
		 false -> "Warning: "
	     end,
    ReportWerror = Werror andalso member(report_errors, St#yecc.options),
    case member(report_warnings, St#yecc.options) orelse ReportWerror of
        true ->
            foreach(fun({File,{none,Mod,W}}) -> 
                            io:fwrite(<<"~s: ~s~ts\n">>,
                                      [File,Prefix,
				       Mod:format_error(W)]);
                       ({File,{Line,Mod,W}}) -> 
                            io:fwrite(<<"~s:~w: ~s~ts\n">>,
                                      [File,Line,Prefix,
				       Mod:format_error(W)])
                    end, sort(St#yecc.warnings));
        false -> 
            ok
    end.

add_error(E, St) ->
    add_error(none, E, St).

add_error(Line, E, St) ->
    add_error(St#yecc.infile, Line, E, St).

add_error(File, Line, E, St) ->
    St#yecc{errors = [{File,{Line,?MODULE,E}}|St#yecc.errors]}.    

add_errors(SymNames, E0, St0) ->
    foldl(fun(SymName, St) ->
                  add_error(symbol_line(SymName, St), {E0, SymName}, St)
          end, St0, SymNames).

add_warning(Line, W, St) ->
    St#yecc{warnings = [{St#yecc.infile,{Line,?MODULE,W}}|St#yecc.warnings]}.

add_warnings(SymNames, W0, St0) ->
    foldl(fun(SymName, St) ->
                  add_warning(symbol_line(SymName, St), {W0, SymName}, St)
          end, St0, SymNames).

check_rhs([#symbol{name = '$empty'}], St) ->
    St;
check_rhs(Rhs, St0) ->
    case symbol_find('$empty', Rhs) of
        #symbol{line = Line} ->
            add_error(Line, illegal_empty, St0);
        false ->
            foldl(fun(Sym, St) ->
                          case symbol_member(Sym, St#yecc.all_symbols) of
                              true -> 
                                  St;
                              false -> 
                                  E = {undefined_symbol,Sym#symbol.name},
                                  add_error(Sym#symbol.line, E, St)
                          end
                  end, St0, Rhs)
    end.

check_action(Tokens) ->
    case erl_parse:parse_exprs(add_roberts_dot(Tokens, 0)) of
        {error, _Error} ->
            {false, false};
        {ok, [Expr | Exprs]} ->
            IsGuard = Exprs =:= [] andalso erl_lint:is_guard_test(Expr),
            {IsGuard, true}
    end.

add_roberts_dot([], Line) ->
    [{'dot', Line}];
add_roberts_dot([{'dot', Line} | _], _) ->
    [{'dot', Line}];
add_roberts_dot([Token | Tokens], _) ->
    [Token | add_roberts_dot(Tokens, element(2, Token))].

subst_pseudo_vars([], _, St) ->
    {[], St};
subst_pseudo_vars([H0 | T0], NmbrOfDaughters, St0) ->
    {H, St1} = subst_pseudo_vars(H0, NmbrOfDaughters, St0),
    {T, St} = subst_pseudo_vars(T0, NmbrOfDaughters, St1),
    {[H | T], St};
subst_pseudo_vars({atom, Line, Atom}, NmbrOfDaughters, St0) ->
    case atom_to_list(Atom) of
        [$$ | Rest] ->
            try list_to_integer(Rest) of
                N when N > 0, N =< NmbrOfDaughters ->
                    {{var, Line, list_to_atom(append("__", Rest))}, St0};
                _ ->
                    St = add_error(Line, {undefined_pseudo_variable, Atom}, 
                                   St0),
                    {{atom, Line, '$undefined'}, St}
            catch 
                error: _ -> {{atom, Line, Atom}, St0}
            end;
        _ ->
            {{atom, Line, Atom}, St0}
    end;
subst_pseudo_vars(Tuple, NmbrOfDaughters, St0) when is_tuple(Tuple) ->
    {L, St} = subst_pseudo_vars(tuple_to_list(Tuple), NmbrOfDaughters, St0),
    {list_to_tuple(L), St};
subst_pseudo_vars(Something_else, _, St) ->
    {Something_else, St}.

kind_of_symbol(St, SymName) ->
    case member(SymName, St#yecc.nonterminals) of
        false ->
            case member(SymName, St#yecc.terminals) of
                false ->
                    case St#yecc.endsymbol of
                        SymName ->
                            endsymbol;
                        _ ->
                            unknown
                    end;
                true ->
                    terminal
            end;
        true ->
            nonterminal
    end.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Computing parse states and goto table from grammar.
% Start item: {0, [Endsymbol]} <->
% (['ACCEPT' '.', Rootsymbol], {'$'}) in Aho & Johnson
% where '$end' is the default end of input symbol of the
% scanner if no 'Endsymbol' has been declared in the syntax file.

-record(tabs, {
          symbols,      % ETS-set, keypos 1: {SymbolName, SymbolCode}
          inv_symbols,  % ETS-set, keypos 2: {SymbolName, SymbolCode}
          state_id,     % ETS-bag, keypos 1: {StateId, StateNum}
                        % StateId is not unique for a state.
          rp_rhs,       % rule pointer -> the remaining rhs symbols
          rp_info,      % rule pointer -> expanding rules and lookahead
          goto          % ETS-bag, keypos 1: first 
                        % {{FromStateNum, Symbol, ToStateNum}}, then
                        % {{FromStateNum, Symbol}, ToStateNum}
         }).

-record(item, { % what states are made of
          rule_pointer,
          look_ahead,
          rhs
         }).

compute_states(St0) ->
    SymbolTab = St0#yecc.symbol_tab,
    CodedRules = map(fun(#rule{symbols = Syms} = R) ->
                             R#rule{symbols = code_symbols(Syms, SymbolTab)}
                     end, St0#yecc.rules_list),
    CodedNonterminals = code_symbols(St0#yecc.nonterminals, SymbolTab),
    %% Only coded in this phase; StC is thrown away.
    StC = St0#yecc{rules_list = CodedRules, 
                   rules = list_to_tuple(CodedRules),
                   nonterminals = CodedNonterminals},
    {RuleIndex, RulePointer2Rule} = 
        make_rule_index(StC, St0#yecc.rules_list),
    StateTab0 = {},
    StateIdTab = ets:new(yecc_state_id, [set]),
    GotoTab = ets:new(yecc_goto, [bag]),
    RulePointerRhs = make_rhs_index(StC#yecc.rules_list),
    RulePointerInfo = make_rule_pointer_info(StC, RulePointerRhs, RuleIndex),

    Tables = #tabs{symbols = SymbolTab, 
                   state_id = StateIdTab,
                   rp_rhs = RulePointerRhs,
                   rp_info = RulePointerInfo,
                   goto = GotoTab},

    _ = erase(),
    EndsymCode = code_terminal(StC#yecc.endsymbol, StC#yecc.symbol_tab),
    {StateId, State0} = compute_state([{EndsymCode, 1}], Tables),

    StateNum0 = first_state(),
    FirstState = {StateNum0, State0},
    StateTab1 = insert_state(Tables, StateTab0, FirstState, StateId),
    {StateTab, N} = 
        compute_states1([{StateNum0, get_current_symbols(State0)}], 
                        FirstState, StateTab1, Tables),
    true = ets:delete(StateIdTab),
    St = St0#yecc{state_tab = StateTab, goto_tab = GotoTab, n_states = N,
                  rule_pointer2rule = RulePointer2Rule},
    decode_goto(GotoTab, St#yecc.inv_symbol_tab),
    check_usage(St).

first_state() ->
    0.

decode_goto(GotoTab, InvSymTab) ->
    G = ets:tab2list(GotoTab),
    ets:delete_all_objects(GotoTab),
    ets:insert(GotoTab, 
               map(fun({{From, Sym, Next}}) ->
                           {{From, decode_symbol(Sym, InvSymTab)}, Next}
                   end, G)).

check_usage(St0) ->
    SelSyms = ets:fun2ms(fun({{_,Sym},_}) -> Sym end),
    UsedSymbols = ets:select(St0#yecc.goto_tab, SelSyms),
    Syms = ordsets:from_list([?ACCEPT, '$empty' | UsedSymbols]),
    NonTerms = ordsets:from_list(St0#yecc.nonterminals),
    UnusedNonTerms = ordsets:to_list(ordsets:subtract(NonTerms, Syms)),
    St1 = add_warnings(UnusedNonTerms, unused_nonterminal, St0),
    Terms = ordsets:from_list(St0#yecc.terminals),
    St2 = add_warnings(ordsets:to_list(ordsets:subtract(Terms, Syms)),
                       unused_terminal, St1),
    DefinedNonTerminals = map(fun(#rule{symbols = [Name | _]}) -> 
                                            Name
                              end, St2#yecc.rules_list),
    DefNonTerms = ordsets:from_list(DefinedNonTerminals),
    UndefNonTerms = ordsets:subtract(NonTerms, DefNonTerms),
    add_errors(ordsets:to_list(ordsets:subtract(UndefNonTerms, 
                                                UnusedNonTerms)),
               missing_syntax_rule, St2).

%% States are sometimes big, should not be copied to ETS tables.
%% Here an "extendible" tuple is used.
lookup_state(StateTab, N) ->
    element(N+1, StateTab).

insert_state(#tabs{state_id = StateIdTab}, StateTab0, State, StateId) ->
    {N, _Items} = State,
    insert_state_id(StateIdTab, N, StateId),
    StateTab = if 
                   tuple_size(StateTab0) > N ->
                       StateTab0;
                   true ->
                       list_to_tuple(tuple_to_list(StateTab0) ++
                                     lists:duplicate(round(1 + N * 1.5), []))
               end,
    setelement(N+1, StateTab, State).

insert_state_id(StateIdTab, N, StateId) ->
    true = ets:insert(StateIdTab, {StateId, N}).

compute_states1([], {N, _}=_CurrState, StateTab0, _Tables) ->
    {StateTab0, N};
compute_states1([{N, Symbols} | Try], CurrState, StateTab, Tables) ->
    {_N, S} = lookup_state(StateTab, N),
    Seeds = state_seeds(S, Symbols),
    compute_states2(Seeds, N, Try, CurrState, StateTab, Tables).

compute_states2([], _N, Try, CurrState, StateTab, Tables) ->
    compute_states1(Try, CurrState, StateTab, Tables);
compute_states2([{Sym,Seed} | Seeds], N, Try, CurrState, StateTab, Tables) ->
    {StateId, NewState} = compute_state(Seed, Tables),
    case check_states(NewState, StateId, StateTab, Tables) of
        add ->
            {M, _} = CurrState,
            %% io:fwrite(<<"Adding state ~w\n">>, [M + 1]),
            CurrentSymbols = get_current_symbols(NewState),
            Next = M + 1,
            NextState = {Next, NewState},
            NewStateTab = insert_state(Tables, StateTab, NextState, StateId),
            insert_goto(Tables, N, Sym, Next),
            compute_states2(Seeds, N, [{Next, CurrentSymbols} | Try],
                            NextState, NewStateTab, Tables);
        {old, M} ->
            %% io:fwrite(<<"Identical to old state ~w\n">>, [M]),
            insert_goto(Tables, N, Sym, M),
            compute_states2(Seeds, N, Try, CurrState, StateTab, Tables);
        {merge, M, NewCurrent} ->
            %% io:fwrite(<<"Merging with state ~w\n">>, [M]),
            Try1 = case lists:keyfind(M, 1, Try) of
                       false ->
                           [{M, NewCurrent} | Try];
                       {_, OldCurrent} ->
                           case ordsets:is_subset(NewCurrent, OldCurrent) of
                               true ->
                                   Try;
                               false ->
                                   [{M, ordsets:union(NewCurrent, OldCurrent)}
                                    | keydelete(M, 1, Try)]
                           end
                   end,
            NewStateTab = merge_states(NewState, StateTab, Tables, M,StateId),
            insert_goto(Tables, N, Sym, M),
            compute_states2(Seeds, N, Try1, CurrState, NewStateTab, Tables)
    end.

insert_goto(Tables, From, Sym, To) ->
    true = ets:insert(Tables#tabs.goto, {{From, Sym, To}}).

%% Create an ets table for faster lookups.
create_symbol_table(St) ->
    #yecc{terminals = Terminals, endsymbol = Endsymbol} = St,
    SymbolTab = ets:new(yecc_symbols, [{keypos,1}]),
    %% '$empty' is always assigned 0
    Ts = ['$empty', Endsymbol | delete('$empty', Terminals)],
    TsC = count(0, Ts),
    NTsC = map(fun({NT,I}) -> {NT,-I} end, count(1, St#yecc.nonterminals)),
    Cs = TsC++NTsC,
    true = ets:insert(SymbolTab, Cs),

    InvSymTable = ets:new(yecc_inverted_terminals, [{keypos,2}]),
    true = ets:insert(InvSymTable, Cs),

    St#yecc{symbol_tab = SymbolTab, inv_symbol_tab = InvSymTable}.

get_current_symbols(State) ->
    usort(get_current_symbols1(State, [])).

get_current_symbols1([], Syms) ->
    Syms;
get_current_symbols1([#item{rhs = Rhs} | Items], Syms) ->
    case Rhs of
        [] ->
            get_current_symbols1(Items, Syms);
        [Symbol | _] ->
            get_current_symbols1(Items, [Symbol | Syms])
    end.

state_seeds(Items, Symbols) ->
    L = [{S,{LA,RP + 1}} || #item{rule_pointer = RP, look_ahead = LA, 
                                  rhs = [S | _]} <- Items],
    state_seeds1(keysort(1, L), Symbols).

state_seeds1(_L, []) ->
    [];
state_seeds1(L, [Symbol | Symbols]) ->
    state_seeds(L, Symbol, Symbols, []).

state_seeds([{Symbol, Item} | L], Symbol, Symbols, Is) ->
    state_seeds(L, Symbol, Symbols, [Item | Is]);
state_seeds([{S, _Item} | L], Symbol, Symbols, Is) when S < Symbol ->
    state_seeds(L, Symbol, Symbols, Is);
state_seeds(L, Symbol, Symbols, Is) ->
    [{Symbol, Is} | state_seeds1(L, Symbols)].

compute_state(Seed, Tables) ->
    RpInfo = Tables#tabs.rp_info,
    foreach(fun({LA, RulePointer}) -> put(RulePointer, LA) end, Seed),
    foreach(fun({LA, RP}) -> compute_closure(LA, RP, RpInfo) end, Seed),
    Closure = keysort(1, erase()),
    state_items(Closure, [], [], Tables#tabs.rp_rhs).

%% Collects a uniqe id for the state (all rule pointers). 
state_items([{RP, LA} | L], Is, Id, RpRhs) ->
    I = #item{rule_pointer = RP, look_ahead = LA, rhs = element(RP, RpRhs)},
    state_items(L, [I | Is], [RP | Id], RpRhs);
state_items(_, Is, Id, _RpRhs) ->
    {Id, Is}.

-compile({inline,[compute_closure/3]}).
compute_closure(Lookahead, RulePointer, RpInfo) ->
    case element(RulePointer, RpInfo) of
        []=Void -> % no followers, or terminal
            Void;
        {no_union, ExpandingRules, NewLookahead} ->
            compute_closure1(ExpandingRules, NewLookahead, RpInfo);
        {union, ExpandingRules, Lookahead0} ->
            NewLookahead = set_union(Lookahead0, Lookahead),
            compute_closure1(ExpandingRules, NewLookahead, RpInfo);
        ExpandingRules ->
            compute_closure1(ExpandingRules, Lookahead, RpInfo)
    end.
    
compute_closure1([RulePointer | Tail], NewLookahead, RpInfo) ->
    compute_closure1(Tail, NewLookahead, RpInfo),
    case get(RulePointer) of
        undefined -> % New
            put(RulePointer, NewLookahead),
            compute_closure(NewLookahead, RulePointer, RpInfo);
        Lookahead2 ->
            Lookahead = set_union(Lookahead2, NewLookahead),
            if 
                Lookahead =:= Lookahead2 -> % Old
                    Lookahead2; % void()
                true -> % Merge
                    put(RulePointer, Lookahead),
                    compute_closure(NewLookahead, RulePointer, RpInfo)
            end
    end;
compute_closure1(Nil, _, _RpInfo) ->
    Nil.

%% Check if some old state is a superset of our NewState
check_states(NewState, StateId, StateTab, #tabs{state_id = StateIdTab}) ->
    try ets:lookup_element(StateIdTab, StateId, 2) of
        N ->
            {_N, OldState} = lookup_state(StateTab, N),
            check_state1(NewState, OldState, [], N)
    catch error:_ -> add
    end.

check_state1([#item{look_ahead = Lookahead1, rhs = Rhs} | Items1],
             [#item{look_ahead = Lookahead2} | Items2], Symbols, N) ->
    case set_is_subset(Lookahead1, Lookahead2) of
        true ->
            check_state1(Items1, Items2, Symbols, N);
        false ->
            case Rhs of
                [] ->
                    check_state2(Items1, Items2, Symbols, N);
                [Symbol | _] ->
                    check_state2(Items1, Items2, [Symbol | Symbols], N)
            end
    end;
check_state1([], [], _Symbols, N) ->
    {old, N}.

check_state2([#item{look_ahead = Lookahead1, rhs = Rhs} | Items1],
             [#item{look_ahead = Lookahead2} | Items2], Symbols, N) ->
    case set_is_subset(Lookahead1, Lookahead2) of
        true ->
            check_state2(Items1, Items2, Symbols, N);
        false ->
            case Rhs of
                [] ->
                    check_state2(Items1, Items2, Symbols, N);
                [Symbol | _] ->
                    check_state2(Items1, Items2, [Symbol | Symbols], N)
            end
    end;
check_state2([], [], Symbols, N) ->
    {merge, N, usort(Symbols)}.

merge_states(NewState, StateTab, Tables, M, StateId) ->
    {_M, Old_state} = lookup_state(StateTab, M),
    MergedState = merge_states1(NewState, Old_state),
    insert_state(Tables, StateTab, {M, MergedState}, StateId).

merge_states1([Item1 | Items1], [Item2 | Items2]) ->
    LA1 = Item1#item.look_ahead,
    LA2 = Item2#item.look_ahead,
    if
        LA1 =:= LA2 ->
            [Item1 | merge_states1(Items1, Items2)];
        true ->
            [Item1#item{look_ahead = set_union(LA1, LA2)}
             | merge_states1(Items1, Items2)]
    end;
merge_states1(_, _) ->
    [].

%% RulePointer -> Rhs. Every position Rhs in has its unique "rule pointer".
make_rhs_index(RulesList) ->
    Index = flatmap(fun(#rule{symbols = [_Non | Daughters]}) ->
                            suffixes0(Daughters)
                    end, RulesList),
    list_to_tuple(Index).

suffixes0([?EMPTY]) ->
    [[], []];
suffixes0(L) ->
    suffixes(L).

suffixes([]=L) ->
    [L];
suffixes([_ | T]=L) ->
    [L | suffixes(T)].

%% Setup info about lookahead and expanding rules for each point
%% ("rule pointer") in the grammar. 
make_rule_pointer_info(StC, RpRhs, RuleIndex) ->
    SymbolTab = StC#yecc.symbol_tab,
    LcTab = make_left_corner_table(StC),
    LA_index = map(fun(Syms) ->
                           rp_info(Syms, SymbolTab, LcTab, RuleIndex)
                   end, tuple_to_list(RpRhs)),
    list_to_tuple(LA_index).

rp_info([], _SymbolTab, _LcTab, _RuleIndex) ->
    [];
rp_info([Category | Followers], SymbolTab, LcTab, RuleIndex) ->
    case dict:find(Category, RuleIndex) of
        error -> % terminal
            [];
        {ok, ExpandingRules} when Followers =:= [] ->
            ExpandingRules;
        {ok, ExpandingRules} ->
            case make_lookahead(Followers, SymbolTab, LcTab, set_empty()) of
                {empty, LA} ->
                    {union, ExpandingRules, LA};
                LA ->
                    {no_union, ExpandingRules, LA}
            end
    end.

%% Lookahead computation is complicated by the possible existence
%% of null string rewriting rules, such as A -> '$empty'.
make_lookahead([], _, _, LA) ->
    {empty, LA};
make_lookahead([Symbol | Symbols], SymbolTab, LcTab, LA) ->
    case dict:find(Symbol, LcTab) of
        {ok, LeftCorner} -> % nonterminal
            case empty_member(LeftCorner) of
                true ->
                    make_lookahead(Symbols, SymbolTab, LcTab,
                                   set_union(empty_delete(LeftCorner), LA));
                false ->
                    set_union(LeftCorner, LA)
            end;
        error -> % terminal
            set_add(Symbol, LA)
    end.

%% -> dict-of({Nonterminal, [Terminal]}).
%% The algorithm FIRST/1 from the Dragon Book.
%% Left corner table, all terminals (including '$empty') that can
%% begin strings generated by Nonterminal.
make_left_corner_table(#yecc{rules_list = RulesList} = St) ->
    SymbolTab = left_corner_symbol_table(St),
    Rules = map(fun(#rule{symbols = [Lhs | Rhs]}) ->
                        {Lhs,{Lhs, Rhs}}
                end, RulesList),
    LeftHandTab = dict:from_list(family(Rules)),
    X0 = [{S,H} || {H,{H,Rhs}} <- Rules, 
                   S <- Rhs, 
                   not is_terminal(SymbolTab, S)],
    XL = family_with_domain(X0, St#yecc.nonterminals),
    X = dict:from_list(XL),
    Xref = fun(NT) -> dict:fetch(NT, X) end,
    E = set_empty(),
    LC0 = dict:from_list([{H, E} || {H,_} <- XL]),
    %% Handle H -> a S, where a is a terminal ('$empty' inclusive).
    {Q, LC1} =
        foldl(fun({H,{H,[S | _]}}, {Q0, LC}) ->
                      case ets:lookup(SymbolTab, S) of
                          [{_,Num}=SymbolAndNum] when Num >= 0 ->
                              F = set_add_terminal(SymbolAndNum, E),
                              {[Xref(H) | Q0], upd_first(H, F, LC)};
                          _ ->
                              {Q0, LC}
                      end
              end, {[], LC0}, Rules),
    left_corners(Q, LC1, LeftHandTab, SymbolTab, Xref).

left_corners(Q0, LC0, LeftHandTab, SymbolTab, Xref) ->
    case usort(append(Q0)) of
        [] -> 
            LC0;
        Q1 -> 
            Rs = flatmap(fun(NT) -> dict:fetch(NT, LeftHandTab) end, Q1),
            {LC, Q} = left_corners2(Rs, LC0, [], SymbolTab, Xref),
            left_corners(Q, LC, LeftHandTab, SymbolTab, Xref)
    end.
    
left_corners2([], LC, Q, _SymbolTab, _Xref) ->
    {LC, Q};
left_corners2([{Head,Rhs} | Rs], LC, Q0, SymbolTab, Xref) ->
    Ts = left_corner_rhs(Rhs, Head, LC, set_empty(), SymbolTab),
    First0 = dict:fetch(Head, LC),
    case set_is_subset(Ts, First0) of
        true ->
            left_corners2(Rs, LC, Q0, SymbolTab, Xref);
        false ->
            LC1 = upd_first(Head, Ts, LC),
            left_corners2(Rs, LC1, [Xref(Head) | Q0], SymbolTab, Xref)
    end.

upd_first(NT, Ts, LC) ->
    dict:update(NT, fun(First) -> set_union(First, Ts) end, LC).

left_corner_rhs([S | Ss], Head, LC, Ts, SymbolTab) ->
    case ets:lookup(SymbolTab, S) of
        [{_,Num}=SymbolAndNum] when Num >= 0 ->
            set_add_terminal(SymbolAndNum, Ts);
        [_NonTerminalSymbol] ->
            First = dict:fetch(S, LC),
            case empty_member(First) of
                true ->
                    NTs = set_union(empty_delete(First), Ts),
                    left_corner_rhs(Ss, Head, LC, NTs, SymbolTab);
                false ->
                    set_union(First, Ts)
            end
    end;
left_corner_rhs([], _Head, _LC, Ts, _SymbolTab) ->
    set_add(?EMPTY, Ts).

%% For every non-terminal return a list of "rule pointers" for rules
%% expanding the non-terminal.
%% Also assigns a unique number to each point in the grammar, "rule pointer".
make_rule_index(#yecc{nonterminals = Nonterminals, 
                      rules_list = RulesList}, RulesListNoCodes) ->
    {RulesL, _N} = 
        lists:mapfoldl(fun(#rule{symbols = [Nonterminal | Daughters]}, I) ->
                               I1 = I + length(Daughters)+1,
                               {{Nonterminal, I}, I1}
                       end, 1, RulesList),
    IndexedTab = family_with_domain(RulesL, Nonterminals),

    Symbol2Rule = [{Foo,R} || #rule{symbols = Symbols}=R <- RulesListNoCodes,
                              Foo <- Symbols],
    Pointer2Rule = [{I, R} || {{_Foo,R},I} <- count(1, Symbol2Rule)],
    {dict:from_list(IndexedTab), dict:from_list(Pointer2Rule)}.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Computing parse action table from list of states and goto table:

compute_parse_actions(N, St, StateActions) ->
    case N < first_state() of
        true -> 
            StateActions;
        false ->
            {N, StateN} = lookup_state(St#yecc.state_tab, N),
            %% There can be duplicates in Actions.
            Actions = compute_parse_actions1(StateN, N, St),
            compute_parse_actions(N - 1, St, [{N, Actions} | StateActions])
    end.

compute_parse_actions1([], _, _) ->
    [];
compute_parse_actions1([#item{rule_pointer = RulePointer, 
                              look_ahead = Lookahead0, 
                              rhs = Rhs} | Items], N, St) ->
    case Rhs of
        [] ->
            Lookahead = decode_terminals(Lookahead0, St#yecc.inv_symbol_tab),
            case rule(RulePointer, St) of
                {[?ACCEPT | _], _RuleLine, _} ->
                    [{Lookahead, accept}
                     | compute_parse_actions1(Items, N, St)];
                %% Head is placed after the daughters when finding the
                %% precedence. This is how giving precedence to
                %% non-terminals takes effect.
                {[Head | Daughters0], _RuleLine, _} ->
                    Daughters = delete('$empty', Daughters0),
                    [{Lookahead,
                      #reduce{rule_nmbr = RulePointer, head = Head, 
                              nmbr_of_daughters = length(Daughters), 
                              prec = get_prec(Daughters ++ [Head], St)}}
                     | compute_parse_actions1(Items, N, St)]
            end;
        [Symbol | Daughters] ->
            case is_terminal(St#yecc.symbol_tab, Symbol) of
                true ->
                    DecSymbol = decode_symbol(Symbol, St#yecc.inv_symbol_tab),
                    {[Head | _], _RuleLine, _} = rule(RulePointer, St),
                    %% A bogus shift-shift conflict can be introduced
                    %% here if some terminal occurs in different rules
                    %% which have been given precedence "one level up".
                    Prec1 = case Daughters of
                                [] -> get_prec([DecSymbol, Head], St);
                                _ -> get_prec([DecSymbol], St)
                            end,
                    Pos = case Daughters of
                              [] -> z;
                              _ -> a
                          end,
                    [{[DecSymbol],
                      #shift{state = goto(N, DecSymbol, St), 
                             pos = Pos,
                             prec = Prec1,
                             rule_nmbr = RulePointer}}
                     | compute_parse_actions1(Items, N, St)];
                false ->
                    compute_parse_actions1(Items, N, St)
            end
    end.

get_prec(Symbols, St) ->
    get_prec1(Symbols, St#yecc.prec_tab, {0, none}).

get_prec1([], _, P) ->
    P;
get_prec1([Symbol | T], PrecTab, P) ->
    case ets:lookup(PrecTab, Symbol) of
        [] ->
            get_prec1(T, PrecTab, P);
        [{_, N, Ass}] ->
            get_prec1(T, PrecTab, {N, Ass})
    end.

create_precedence_table(St) ->
    PrecTab = ets:new(yecc_precedences, []),
    true = ets:insert(PrecTab, St#yecc.prec),
    St#yecc{prec_tab = PrecTab}.
    
-record(cxt, {terminal, state_n, yecc, res}).

%% Detects shift-reduce and reduce-reduce conflicts.
%% Also removes all but one conflicting action. As a consequence the
%% lookahead sets for a state are always disjoint.
%% Reduce/reduce conflicts are considered errors.
find_action_conflicts(St0) ->
    Cxt0 = #cxt{yecc = St0, res = []},
    {#cxt{yecc = St, res = Res}, NewParseActions0} = 
        foldl(fun({N, Actions0}, {Cxt1, StateActions}) ->
                      L = [{Terminal, Act} || {Lookahead, Act} <- Actions0,
                                              Terminal <- Lookahead],
                      {Cxt, Actions} = 
                          foldl(fun({Terminal, As}, {Cxt2,Acts0}) ->
                                        Cxt3 = Cxt2#cxt{terminal = Terminal, 
                                                        state_n = N},
                                        {Action, Cxt} = 
                                            find_action_conflicts2(As, Cxt3),
                                        {Cxt,[{Action,Terminal} | Acts0]}
                                end, {Cxt1,[]}, family(L)),
                      {Cxt,[{N,inverse(family(Actions))} | StateActions]}
              end, {Cxt0, []}, St0#yecc.parse_actions),
    if 
        length(Res) > 0, St#yecc.verbose -> 
            io:fwrite(<<"\n*** Conflicts resolved by operator "
                        "precedences:\n\n">>),
            foreach(fun({Confl, Name}) ->
                            report_conflict(Confl, St, Name, prec)
                    end, reverse(Res)),
            io:fwrite(<<"*** End of resolved conflicts\n\n">>);
        true -> 
            ok
    end,
    NewParseActions = reverse(NewParseActions0),
    St#yecc{parse_actions = NewParseActions}.

find_action_conflicts2([Action], Cxt) ->
    {Action, Cxt};
find_action_conflicts2([#shift{state = St, pos = Pos, prec = Prec},
                        #shift{state = St}=S | As], 
                       Cxt) when Pos =:= a; Prec =:= {0,none} ->
    %% This is a kludge to remove the bogus shift-shift conflict
    %% introduced in compute_parse_actions1().
    find_action_conflicts2([S | As], Cxt);
find_action_conflicts2([#shift{state = NewState, pos = z}=S1,
                        #shift{state = NewState}=S2 | _], Cxt) ->
    %% This is even worse than last clause. Give up.
    Confl = conflict(S1, S2, Cxt),
    #cxt{yecc = St0} = Cxt,
    St = conflict_error(Confl, St0),
    {S1, Cxt#cxt{yecc = St}}; % return any action
find_action_conflicts2([#shift{prec = {P1, Ass1}}=S | Rs], Cxt0) ->
    {R, Cxt1} = find_reduce_reduce(Rs, Cxt0),
    #cxt{res = Res0, yecc = St0} = Cxt1,
    #reduce{prec = {P2, Ass2}} = R,
    Confl = conflict(R, S, Cxt1),
    if
        P1 > P2 ->
            {S, Cxt1#cxt{res = [{Confl, shift} | Res0]}};
        P2 > P1 ->
            {R, Cxt1#cxt{res = [{Confl, reduce} | Res0]}};
        Ass1 =:= left, Ass2 =:= left ->
            {R, Cxt1#cxt{res = [{Confl, reduce} | Res0]}};
        Ass1 =:= right, Ass2 =:= right ->
            {S, Cxt1#cxt{res = [{Confl, shift} | Res0]}};
        Ass1 =:= nonassoc, Ass2 =:= nonassoc ->
            {nonassoc, Cxt1};
        P1 =:= 0, P2 =:= 0 ->
            report_conflict(Confl, St0, shift, default),
            St = add_conflict(Confl, St0),
            {S, Cxt1#cxt{yecc = St}};
        true ->
            St = conflict_error(Confl, St0),
            {S, Cxt1#cxt{yecc = St}} % return any action
    end;
find_action_conflicts2(Rs, Cxt0) ->
    find_reduce_reduce(Rs, Cxt0).
         
find_reduce_reduce([R], Cxt) ->
    {R, Cxt};
find_reduce_reduce([accept=A, #reduce{}=R | Rs], Cxt0) ->
    Confl = conflict(R, A, Cxt0),
    St = conflict_error(Confl, Cxt0#cxt.yecc), 
    Cxt = Cxt0#cxt{yecc = St},
    find_reduce_reduce([R | Rs], Cxt);
find_reduce_reduce([#reduce{head = Categ1, prec = {P1, _}}=R1, 
                    #reduce{head = Categ2, prec = {P2, _}}=R2 | Rs], Cxt0) ->
    #cxt{res = Res0, yecc = St0} = Cxt0,
    Confl = conflict(R1, R2, Cxt0),
    {R, Res, St} = 
        if
            P1 > P2 ->
                {R1, [{Confl, Categ1} | Res0], St0};
            P2 > P1 ->
                {R2, [{Confl, Categ2} | Res0], St0};
            true ->
                St1 = conflict_error(Confl, St0), 
                {R1, Res0, St1}
        end,
    Cxt = Cxt0#cxt{res = Res, yecc = St},
    find_reduce_reduce([R | Rs], Cxt).

%% Since the lookahead sets are disjoint (assured by
%% find_action_conflicts), the order between actions can be chosen
%% almost arbitrarily. nonassoc has to come last, though (but is later
%% discarded!). And shift has to come before reduce.
sort_parse_actions([]) ->
    [];
sort_parse_actions([{N, La_actions} | Tail]) ->
    [{N, sort_parse_actions1(La_actions)} | sort_parse_actions(Tail)].

sort_parse_actions1(LaActions) ->
    As = filter(fun({_LA, A}) -> A =:= accept end, LaActions),
    Ss = filter(fun({_LA, A}) -> is_record(A, shift) end, LaActions),
    Rs = filter(fun({_LA, A}) -> is_record(A, reduce) end, LaActions),
    Ns = filter(fun({_LA, A}) -> A =:= nonassoc end, LaActions),
    As ++ Ss ++ Rs ++ Ns.

%% -> {State, StateRepr}. StateRepr has the same set of shift actions
%% as State. No code will be output for State if State =/= StateRepr.
find_identical_shift_states(StateActions) ->
    L1 = [{Actions, State} || {State,Actions} <- StateActions],
    {SO, NotSO} = lists:partition(fun({Actions,_States}) ->
                                          shift_actions_only(Actions)
                                  end, family(L1)),
    R = [{State, hd(States)} || {_Actions, States} <- SO, State <- States]
        ++ 
        [{State, State} || {_Actions, States} <- NotSO, State <- States],
    lists:keysort(1, R).

-record(part_data, {name, eq_state, actions, n_actions, states}).

%% Replace {SStates,Actions} with {SStates,{Actions,Jump}} where
%% Jump describes which clauses that have been extracted from shift
%% states so that they can be used from other states. Some space is
%% saved.
find_partial_shift_states(StateActionsL, StateReprs) ->
    L = [{State, Actions} || {{State,Actions}, {State,State}} <-
                                 lists:zip(StateActionsL, StateReprs),
                             shift_actions_only(Actions)],
    StateActions = sofs:family(L, [{state,[action]}]),
    StateAction = sofs:family_to_relation(StateActions),

    %% Two actions are equal if they occur in the same states:
    Parts = sofs:partition(sofs:range(StateActions)),
    PartsL = sofs:to_external(Parts),
    %% Assign temporary names to the parts of the partition (of actions):
    PartNameL = lists:zip(seq1(length(PartsL)), PartsL),
    ActPartL = [{Action,PartName} || 
                   {PartName,Actions} <- PartNameL,
                   Action <- Actions],
    ActionPartName = sofs:relation(ActPartL, [{action,partname}]),
    StatePartName = sofs:relative_product(StateAction, ActionPartName),
    PartInStates = sofs:relation_to_family(sofs:converse(StatePartName)),

    %% Parts that equal all actions of a state:
    PartActions = sofs:family(PartNameL, [{partname,[action]}]),
    PartState = 
        sofs:relative_product(PartActions, sofs:converse(StateActions)),
    PartStates = sofs_family_with_domain(PartState, sofs:domain(PartActions)),

    PartDataL = [#part_data{name = Nm, eq_state = EqS, actions = P, 
                            n_actions = length(P), 
                            states = ordsets:from_list(S)} || 
                    {{Nm,P}, {Nm,S}, {Nm,EqS}} <- 
                        lists:zip3(PartNameL, 
                                   sofs:to_external(PartInStates),
                                   sofs:to_external(PartStates))],
    true = length(PartDataL) =:= length(PartNameL),
    Ps = select_parts(PartDataL),

    J1 = [{State, Actions, {jump_some,hd(States)}} ||
             {_W, #part_data{actions = Actions, eq_state = [], 
                             states = States}} <- Ps,
             State <- States],
    J2 = [{State, Actions, {jump_all,To}} ||
             {_W, #part_data{actions = Actions, eq_state = EqS, 
                             states = States}} <- Ps,
             To <- EqS,
             State <- States,
             State =/= To],
    J = lists:keysort(1, J1 ++ J2),

    JumpStates = ordsets:from_list([S || {S,_,_} <- J]),
    {JS, NJS} = 
        sofs:partition(1, sofs:relation(StateActionsL, [{state, actions}]),
                       sofs:set(JumpStates, [state])),
    R = 
        [{S, {Actions,jump_none}} || {S,Actions} <- sofs:to_external(NJS)]
        ++
        [{S, {Actions--Part, {Tag,ToS,Part}}} || 
            {{S,Actions}, {S,Part,{Tag,ToS}}} <- 
                lists:zip(sofs:to_external(JS), J)],
    true = length(StateActionsL) =:= length(R),
    lists:keysort(1, R).

%% Very greedy. By no means optimal. 
select_parts([]) ->
    [];
select_parts(PartDataL) ->
    T1 = [{score(PD), PD} || PD <- PartDataL],
    [{W, PD} | Ws] = lists:reverse(lists:keysort(1, T1)),
    #part_data{n_actions = NActions, states = S} = PD,
    if
        W < 8 -> % don't bother
            [];
        true ->
            %% Cannot extract more clauses from the chosen part's states:
            NL = [D#part_data{states = NewS} || 
                     {W1, #part_data{states = S0}=D} <- Ws,
                     W1 > 0,
                     (NewS = ordsets:subtract(S0, S)) =/= []],
            if 
                length(S) =:= 1; NActions =:= 1 ->
                    select_parts(NL);
                true -> 
                    [{W,PD} | select_parts(NL)]
            end
    end.

%% Does it pay off to extract clauses into a new function?
%% Assumptions:
%% - a call costs 8 (C = 8);
%% - a clause (per action) costs 20 plus 8 (select) (Cl = 28);
%% - a new function costs 20 (funinfo) plus 16 (select) (F = 36).
%% A is number of actions, S is number of states.
%% Special case (the part equals all actions of some state):
%% C * (S - 1) < (S - 1) * A * Cl
%% Normal case (introduce new function):
%% F + A * Cl + C * S < S * A * Cl
score(#part_data{n_actions = NActions, eq_state = [], states = S}) ->
    (length(S) * NActions * 28) - (36 + NActions * 28 + length(S) * 8);
score(#part_data{n_actions = NActions, states = S}) ->
    ((length(S) - 1) * NActions * 28) - (8 * (length(S) - 1)).

shift_actions_only(Actions) ->
    length([foo || {_Ts,{shift,_,_,_,_}} <- Actions]) =:= length(Actions).

collect_some_state_info(StateActions, StateReprs) ->
    RF = fun({_LA, A}) -> is_record(A, reduce) end,
    L = [{State, 
          begin
              RO = lists:all(RF, LaActions),
              %% C is currently always ""; identical states are all shift.
              C = [io_lib:fwrite(<<" %% ~w\n">>, [State]) || 
                      true <- [RO], Repr =/= State],
              #state_info{reduce_only = RO, state_repr = Repr, comment = C}
          end} ||
            {{State, LaActions}, {State, Repr}} <-
                lists:zip(StateActions, StateReprs)],
    list_to_tuple(L).

conflict_error(Conflict, St0) ->
    St1 = add_conflict(Conflict, St0),
    add_error({conflict, Conflict}, St1).

report_conflict(Conflict, St, ActionName, How) ->
    if
        St#yecc.verbose ->
            io:fwrite(<<"~s\n">>, [format_conflict(Conflict)]),
            Formated = format_symbol(ActionName),
            case How of 
                prec ->
                    io:fwrite(<<"Resolved in favor of ~s.\n\n">>, [Formated]);
                default ->
                    io:fwrite(<<"Conflict resolved in favor of ~s.\n\n">>, 
                              [Formated])
            end;
        true ->
            ok
    end.

add_conflict(Conflict, St) ->
    case Conflict of
        {Symbol, StateN, _, {reduce, _, _, _}} ->
            St#yecc{reduce_reduce = [{StateN,Symbol} |St#yecc.reduce_reduce]};
        {Symbol, StateN, _, {accept, _}} ->
            St#yecc{reduce_reduce = [{StateN,Symbol} |St#yecc.reduce_reduce]};
        {Symbol, StateN, _, {shift, _, _}} ->
            St#yecc{shift_reduce = [{StateN,Symbol} | St#yecc.shift_reduce]};
        {_Symbol, _StateN, {one_level_up, _, _}, _Confl} ->
            St
    end.

conflict(#shift{prec = Prec1, rule_nmbr = RuleNmbr1}, 
         #shift{prec = Prec2, rule_nmbr = RuleNmbr2}, Cxt) ->
    %% Conflict due to precedences "one level up". Kludge.
    #cxt{terminal = Symbol, state_n = N, yecc = St} = Cxt,    
    {_, L1, RuleN1} = rule(RuleNmbr1, St),
    {_, L2, RuleN2} = rule(RuleNmbr2, St),
    Confl = {one_level_up, {L1, RuleN1, Prec1}, {L2, RuleN2, Prec2}},
    {Symbol, N, Confl, Confl};
conflict(#reduce{rule_nmbr = RuleNmbr1}, NewAction, Cxt) ->
    #cxt{terminal = Symbol, state_n = N, yecc = St} = Cxt,
    {R1, RuleLine1, RuleN1} = rule(RuleNmbr1, St),
    Confl = case NewAction of
                accept -> 
                    {accept, St#yecc.rootsymbol};
                #reduce{rule_nmbr = RuleNmbr2} -> 
                    {R2, RuleLine2, RuleN2} = rule(RuleNmbr2, St),
                    {reduce, R2, RuleN2, RuleLine2};
                #shift{state = NewState} ->
                    {shift, NewState, last(R1)}
            end,
    {Symbol, N, {R1, RuleN1, RuleLine1}, Confl}.

format_conflict({Symbol, N, _, {one_level_up, 
                                {L1, RuleN1, {P1, Ass1}}, 
                                {L2, RuleN2, {P2, Ass2}}}}) ->
    S1 = io_lib:fwrite(<<"Conflicting precedences of symbols when "
                         "scanning ~s in state ~w:\n">>, 
                       [format_symbol(Symbol), N]),
    S2 = io_lib:fwrite(<<"   ~s ~w (rule ~w at line ~w)\n"
                          "      vs.\n">>,
                       [format_assoc(Ass1), P1, RuleN1, L1]),
    S3 = io_lib:fwrite(<<"   ~s ~w (rule ~w at line ~w)\n">>, 
                       [format_assoc(Ass2), P2, RuleN2, L2]),
    [S1, S2, S3];
format_conflict({Symbol, N, Reduce, Confl}) ->
    S1 = io_lib:fwrite(<<"Parse action conflict scanning symbol "
                         "~s in state ~w:\n">>, [format_symbol(Symbol), N]),
    S2 = case Reduce of
             {[HR | TR], RuleNmbr, RuleLine} ->
                 io_lib:fwrite(<<"   Reduce to ~s from ~s (rule ~w at "
                                 "line ~w)\n      vs.\n">>,
                               [format_symbol(HR), format_symbols(TR), 
                                RuleNmbr, RuleLine])
         end,
    S3 = case Confl of 
             {reduce, [HR2|TR2], RuleNmbr2, RuleLine2} ->
                 io_lib:fwrite(<<"   reduce to ~s from ~s "
                                 "(rule ~w at line ~w).">>,
                               [format_symbol(HR2), format_symbols(TR2), 
                                RuleNmbr2, RuleLine2]);
             {shift, NewState, Sym} ->
                 io_lib:fwrite(<<"   shift to state ~w, adding right "
                                 "sisters to ~s.">>,
                               [NewState, format_symbol(Sym)]);
             {accept, Rootsymbol} ->
                 io_lib:fwrite(<<"   reduce to rootsymbol ~s.">>,
                               [format_symbol(Rootsymbol)])
         end,
    [S1, S2, S3].

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Code generation:

%% The version up to and including parsetools-1.3 is called "1.0".
%%
%% "1.1", parsetools-1.4:
%% - the prologue file has been updated;
%% - nonassoc is new;
%% - different order of clauses;
%% - never more than one clause matching a given symbol in a given state;
%% - file attributes relate messages to .yrl file;
%% - actions put in inlined functions;
%% - a few other minor fixes.
%%
%% "1.2", parsetools-1.4.2:
%% - the generated code has been changed as follows:
%%   - yeccpars2() calls the functions yeccpars2_State();
%%   - several states can share yeccpars2_State(), which reduces code size;
%%   - yeccgoto() has been split on one function per nonterminal;
%%   - several minor changes have made the loaded code smaller.
%% - the include file yeccpre.hrl has been changed incompatibly.
%%
%% "1.3", parsetools-1.4.4:
%% - the generated code has been changed as follows:
%%   - yeccgoto_T() no longer returns the next state, but calls yeccpars_S();
%%   - yeccpars2() is not called when it is known which yeccpars2_S() to call;
%%   - "__Stack" has been substituted for "Stack";
%%   - several states can share yeccpars2_S_cont(), which reduces code size;
%%   - instead if calling lists:nthtail() matching code is emitted.
%%
%% "1.4", parsetools-2.0.4:
%% - yeccerror() is called when a syntax error is found (as in version 1.1).
%% - the include file yeccpre.hrl has been changed.

-define(CODE_VERSION, "1.4").
-define(YECC_BUG(M, A), 
        iolist_to_binary([" erlang:error({yecc_bug,\"",?CODE_VERSION,"\",",
                          io_lib:fwrite(M, A), "}).\n\n"])).

%% Returns number of newlines in included files.
output_prelude(Outport, Inport, St0) when St0#yecc.includefile =:= [] ->
    St5 = output_header(St0),
    #yecc{infile = Infile, module = Module} = St5,
    St10 = fwrite(St5, <<"-module(~w).\n">>, [Module]),
    St20 = 
        fwrite(St10,
               <<"-export([parse/1, parse_and_scan/1, format_error/1]).\n">>,
               []),
    {St25, N_lines_1, LastErlangCodeLine} = 
        case St20#yecc.erlang_code of 
            none ->
                {St20, 0, no_erlang_code};
            Next_line ->
                St_10 = output_file_directive(St20, Infile, Next_line-1),
                Last_line = include1([], Inport, Outport, Infile,
                                     Next_line, St_10),
                Nmbr_of_lines = Last_line - Next_line,
                {St_10, Nmbr_of_lines, {last_erlang_code_line, Last_line}}
    end,
    St30 = nl(St25),
    IncludeFile = 
        filename:join([code:lib_dir(parsetools), "include","yeccpre.hrl"]),
    %% Maybe one could assume there are no warnings in this file.
    St = output_file_directive(St30, IncludeFile, 0),
    N_lines_2 = include(St, IncludeFile, Outport),
    {St, N_lines_1 + N_lines_2, LastErlangCodeLine};
output_prelude(Outport, Inport, St0) ->
    St5 = output_header(St0),
    #yecc{infile = Infile, module = Module, includefile = Includefile} = St5,
    St10 = fwrite(St5, <<"-module(~w).\n">>, [Module]),
    St20 = output_file_directive(St10, Includefile, 0),
    N_lines_1 = include(St20, Includefile, Outport),
    St30 = nl(St20),
    case St30#yecc.erlang_code of 
        none ->
            {St30, N_lines_1, no_erlang_code};
        Next_line ->
            St = output_file_directive(St30, Infile, Next_line-1),
            Last_line = include1([], Inport, Outport, Infile, Next_line, St),
            Nmbr_of_lines = Last_line - Next_line,
            {St, Nmbr_of_lines + N_lines_1, {last_erlang_code_line, Last_line}}
    end.

output_header(St0) ->
    lists:foldl(fun(Str, St) -> fwrite(St, <<"~ts\n">>, [Str])
                end, St0, St0#yecc.header).

output_goto(St, [{_Nonterminal, []} | Go], StateInfo) ->
    output_goto(St, Go, StateInfo);
output_goto(St0, [{Nonterminal, List} | Go], StateInfo) ->
    F = function_name(yeccgoto, Nonterminal),
    St10 = output_goto1(St0, List, F, StateInfo, true),
    St = output_goto_fini(F, Nonterminal, St10),
    output_goto(St, Go, StateInfo);
output_goto(St, [], _StateInfo) ->
    St.

output_goto1(St0, [{From, To} | Tail], F, StateInfo, IsFirst) ->
    St10 = delim(St0, IsFirst),
    {To, ToInfo} = lookup_state(StateInfo, To),
    #state_info{reduce_only = RO, state_repr = Repr, comment = C} = ToInfo,
    if
        RO -> 
            %% Reduce actions do not use the state, so we just pass
            %% the old (now bogus) on:
            FromS = io_lib:fwrite("~w=_S", [From]),
            ToS = "_S";
        true ->
            FromS = io_lib:fwrite("~w", [From]),
            ToS = io_lib:fwrite("~w", [To])
    end,
    St20 = fwrite(St10, <<"~w(~s, Cat, Ss, Stack, T, Ts, Tzr) ->\n">>, 
                  [F,FromS]),
    St30 = fwrite(St20, <<"~s">>, [C]),
    %% Short-circuit call to yeccpars2:
    St = fwrite(St30, <<" yeccpars2_~w(~s, Cat, Ss, Stack, T, Ts, Tzr)">>, 
                [Repr, ToS]),
    output_goto1(St, Tail, F, StateInfo, false);
output_goto1(St, [], _F, _StateInfo, _IsFirst) ->
    St.

output_goto_fini(F, NT, #yecc{includefile_version = {1,1}}=St0) ->
    %% Backward compatibility.
    St10 = delim(St0, false),
    St = fwrite(St10, <<"~w(State, _Cat, _Ss, _Stack, _T, _Ts, _Tzr) ->\n">>,
                [F]),
    fwrite(St, 
           ?YECC_BUG(<<"{~w, State, missing_in_goto_table}">>, [NT]),
           []);
output_goto_fini(_F, _NT, St) ->
    fwrite(St, <<".\n\n">>, []).

%% Find actions having user code.
find_user_code(ParseActions, St) ->
    [#user_code{state = State, 
                terminal = Terminal, 
                funname = inlined_function_name(State, Terminal), 
                action = Action} || 
        {State, La_actions} <- ParseActions,
        {Action, Terminals, RuleNmbr, NmbrOfDaughters} 
            <- find_user_code2(La_actions),
        case tokens(RuleNmbr, St) of
            [{var, _, '__1'}] -> NmbrOfDaughters =/= 1;
            _ -> true
        end,
        Terminal <- Terminals].

find_user_code2([]) ->
    [];
find_user_code2([{_, #reduce{rule_nmbr = RuleNmbr,
                             nmbr_of_daughters = NmbrOfDaughters}
                  =Action}]) ->
    %% Same optimization as in output_state_actions.
    [{Action, ["Cat"], RuleNmbr, NmbrOfDaughters}];
find_user_code2([{La, #reduce{rule_nmbr = RuleNmbr,
                              nmbr_of_daughters = NmbrOfDaughters}
                  =Action} | T]) ->
    [{Action,La, RuleNmbr, NmbrOfDaughters} | find_user_code2(T)];
find_user_code2([_ | T]) ->
    find_user_code2(T).

output_actions(St0, StateJumps, StateInfo) ->
    %% Not all the clauses of the dispatcher function yeccpars2() can
    %% be reached. Only when shifting, that is, calling yeccpars1(),
    %% will yeccpars2() be called.
    Y2CL = [NewState || {_State,{Actions,J}} <- StateJumps,
                        {_LA, #shift{state = NewState}} <- 
                            (Actions
                             ++ [A || {_Tag,_To,Part} <- [J], A <- Part])],
    Y2CS = ordsets:from_list([0 | Y2CL]),
    Y2S = ordsets:from_list([S || {S,_} <- StateJumps]),
    NY2CS = ordsets:subtract(Y2S, Y2CS),
    Sel = [{S,true} || S <- ordsets:to_list(Y2CS)] ++
          [{S,false} || S <- ordsets:to_list(NY2CS)],

    SelS = [{State,Called} || 
               {{State,_JActions}, {State,Called}} <- 
                   lists:zip(StateJumps, lists:keysort(1, Sel))],
    St10 = foldl(fun({State, Called}, St_0) ->
                         {State, #state_info{state_repr = IState}} = 
                             lookup_state(StateInfo, State),
                         output_state_selection(St_0, State, IState, Called)
            end, St0, SelS),
    St20 = fwrite(St10, <<"yeccpars2(Other, _, _, _, _, _, _) ->\n">>, []),
    St = fwrite(St20,
                ?YECC_BUG(<<"{missing_state_in_action_table, Other}">>, []),
                []),
    foldl(fun({State, JActions}, St_0) ->
                  {State, #state_info{state_repr = IState}} = 
                      lookup_state(StateInfo, State),
                  output_state_actions(St_0, State, IState, 
                                       JActions, StateInfo)
          end, St, StateJumps).

output_state_selection(St0, State, IState, Called) ->
    Comment = [<<"%% ">> || false <- [Called]],
    St = fwrite(St0, <<"~syeccpars2(~w=S, Cat, Ss, Stack, T, Ts, Tzr) ->\n">>,
                [Comment, State]),
    fwrite(St, 
           <<"~s yeccpars2_~w(S, Cat, Ss, Stack, T, Ts, Tzr);\n">>, 
           [Comment, IState]).

output_state_actions(St, State, State, {Actions,jump_none}, SI) ->
    output_state_actions1(St, State, Actions, true, normal, SI);
output_state_actions(St0, State, State, {Actions, Jump}, SI) ->
    {Tag, To, Common} = Jump,
    CS = case Tag of
             jump_some -> list_to_atom(lists:concat([cont_, To]));
             jump_all -> To
         end,
    St = output_state_actions1(St0, State, Actions, true, {to, CS}, SI),
    if 
        To =:= State ->
            output_state_actions1(St, CS, Common, true, normal, SI);
        true ->
            St
    end;
output_state_actions(St, State, JState, _XActions, _SI) ->
    fwrite(St, <<"%% yeccpars2_~w: see yeccpars2_~w\n\n">>, [State, JState]).

output_state_actions1(St, State, [], _IsFirst, normal, _SI) ->
    output_state_actions_fini(State, St);
output_state_actions1(St0, State, [], IsFirst, {to, ToS}, _SI) ->
    St = delim(St0, IsFirst),
    fwrite(St, 
           <<"yeccpars2_~w(S, Cat, Ss, Stack, T, Ts, Tzr) ->\n"
            " yeccpars2_~w(S, Cat, Ss, Stack, T, Ts, Tzr).\n\n">>,
           [State, ToS]);
output_state_actions1(St0, State, [{_, #reduce{}=Action}], 
                      IsFirst, _End, SI) ->
    St = output_reduce(St0, State, "Cat", Action, IsFirst, SI),
    fwrite(St, <<".\n\n">>, []);
output_state_actions1(St0, State, [{Lookahead,Action} | Tail],
                      IsFirst, End, SI) ->
    {_, St} = 
        foldl(fun(Terminal, {IsFst,St_0}) ->
                      {false,
                       output_action(St_0, State, Terminal, Action, IsFst,SI)}
              end, {IsFirst,St0}, Lookahead),
    output_state_actions1(St, State, Tail, false, End, SI).

output_action(St, State, Terminal, #reduce{}=Action, IsFirst, SI) ->
    output_reduce(St, State, Terminal, Action, IsFirst, SI);
output_action(St0, State, Terminal, #shift{state = NewState}, IsFirst, _SI) ->
    St10 = delim(St0, IsFirst),
    St = fwrite(St10, <<"yeccpars2_~w(S, ~s, Ss, Stack, T, Ts, Tzr) ->\n">>,
                [State, quoted_atom(Terminal)]),
    output_call_to_includefile(NewState, St);
output_action(St0, State, Terminal, accept, IsFirst, _SI) ->
    St10 = delim(St0, IsFirst),
    St = fwrite(St10, 
                <<"yeccpars2_~w(_S, ~s, _Ss, Stack, _T, _Ts, _Tzr) ->\n">>,
                [State, quoted_atom(Terminal)]),
    fwrite(St, <<" {ok, hd(Stack)}">>, []);
output_action(St, _State, _Terminal, nonassoc, _IsFirst, _SI) ->
    St.

output_call_to_includefile(NewState, #yecc{includefile_version = {1,1}}=St) ->
    %% Backward compatibility.
    fwrite(St, <<" yeccpars1(Ts, Tzr, ~w, [S | Ss], [T | Stack])">>, 
           [NewState]);
output_call_to_includefile(NewState, St) ->
    fwrite(St, <<" yeccpars1(S, ~w, Ss, Stack, T, Ts, Tzr)">>, 
           [NewState]).

output_state_actions_fini(State, St0) ->
    %% Backward compatible.
    St10 = delim(St0, false),
    St = fwrite(St10, <<"yeccpars2_~w(_, _, _, _, T, _, _) ->\n">>, [State]),
    fwrite(St, <<" yeccerror(T).\n\n">>, []).

output_reduce(St0, State, Terminal0, 
              #reduce{rule_nmbr = RuleNmbr, 
                      head = Head, 
                      nmbr_of_daughters = NmbrOfDaughters},
              IsFirst, StateInfo) ->
    St10 = delim(St0, IsFirst),
    Terminal = if 
                   is_atom(Terminal0) -> quoted_atom(Terminal0);
                   true -> Terminal0
               end,
    St20 = fwrite(St10,
                  <<"yeccpars2_~w(_S, ~s, Ss, Stack, T, Ts, Tzr) ->\n">>,
                  [State, Terminal]),
    St30 = 
        if
            NmbrOfDaughters < 2 ->
                Ns = "Ss",
                St20;
            true ->
                Ns = "Nss",
                Tmp = string:join(lists:duplicate(NmbrOfDaughters - 1, "_"),
                                  ","),
                fwrite(St20, <<" [~s|Nss] = Ss,\n">>, [Tmp])
        end,
    St40 = case tokens(RuleNmbr, St30) of
               [{var, _, '__1'}] when NmbrOfDaughters =:= 1 ->
                   NewStack = "Stack",
                   St30;
               _ ->
                   NewStack = "NewStack",
                   fwrite(St30, <<" NewStack = ~w(Stack),\n">>, 
                          [inlined_function_name(State, Terminal0)])
               end,
    if 
        NmbrOfDaughters =:= 0 ->
            NextState = goto(State, Head, St40),
            {NextState, I} = lookup_state(StateInfo, NextState),
            #state_info{reduce_only = RO, state_repr = Repr, comment = C} = I,
            %% Reduce actions do not use the state, so we just pass
            %% the old (now bogus) on:
            if
                RO -> NextS = "_S";
                true -> NextS = io_lib:fwrite("~w", [NextState])
            end,
            St = fwrite(St40, <<"~s">>, [C]),
            %% Short-circuit call to yeccpars2:
            fwrite(St,
                   <<" yeccpars2_~w(~s, ~s, [~w | Ss], ~s, T, Ts, Tzr)">>,
                   [Repr, NextS, Terminal, State, NewStack]);
        true ->
            fwrite(St40, 
                   <<" ~w(hd(~s), ~s, ~s, ~s, T, Ts, Tzr)">>,
                   [function_name(yeccgoto, Head), Ns,
                    Terminal, Ns, NewStack])
    end.

delim(St, true) ->
    St;
delim(St, false) ->
    fwrite(St, <<";\n">>, []).

quoted_atom(Atom) ->
    io_lib:fwrite(<<"~w">>, [Atom]).
    
output_inlined(St, UserCodeActions, Infile) ->
    foldl(fun(#user_code{funname = InlinedFunctionName, 
                         action = Action}, St_0) ->
                  output_inlined(St_0, InlinedFunctionName, 
                                 Action, Infile)
          end, St, UserCodeActions).

%% Each action with user code is placed in a separate inlined function.
%% The purpose is to be able to pinpoint errors and warnings correctly.
output_inlined(St0, FunctionName, Reduce, Infile) ->
    #reduce{rule_nmbr = RuleNmbr, nmbr_of_daughters = N_daughters} = Reduce,
    #rule{tokens = Tokens, is_well_formed = WF} = get_rule(RuleNmbr, St0),
    Line0 = first_line(Tokens),
    NLines = last_line(Tokens) - Line0,

    St5 = if 
              WF ->
                  St0;
              not WF -> 
                  %% The compiler will generate an error message for
                  %% the inlined function (unless the reason that yecc
                  %% failed to parse the action was some macro). The
                  %% line number of the message will be correct since
                  %% we are keeping track of the current line of the
                  %% output file...
                  #yecc{outfile = Outfile, line = CurLine} = St0,
                  output_file_directive(St0, Outfile, CurLine)
          end,

    CodeStartLine = lists:max([0, Line0 - 4]),
    St10 = fwrite(St5, <<"-compile({inline,~w/1}).\n">>, [FunctionName]),
    St20 = output_file_directive(St10, Infile, CodeStartLine),
    St30 = fwrite(St20, <<"~w(__Stack0) ->\n">>, [FunctionName]),
    %% Currently the (old) inliner emits less code if matching the
    %% stack inside the body rather than in the head...
    St40 = case N_daughters of
               0 -> 
                   Stack = "__Stack0",
                   St30;
               _ -> 
                   Stack = "__Stack",
                   A = concat(flatmap(fun(I) -> [",__",I] end, 
                                      lists:seq(N_daughters, 1, -1))),
                   fwrite(St30, <<" ~s = __Stack0,\n">>, 
                          [append(["[", tl(A), " | __Stack]"])])
           end,
    St = St40#yecc{line = St40#yecc.line + NLines},
    fwrite(St, <<" [begin\n  ~ts\n  end | ~s].\n\n">>,
           [pp_tokens(Tokens, Line0, St#yecc.encoding), Stack]).

inlined_function_name(State, "Cat") ->
    inlined_function_name(State, "");
inlined_function_name(State, Terminal) ->
    list_to_atom(concat([yeccpars2_, State, '_', Terminal])).

-compile({nowarn_unused_function,function_name/2}).
function_name(Name, Suf) ->
    list_to_atom(concat([Name, '_' | quoted_atom(Suf)])).

rule(RulePointer, St) ->
    #rule{n = N, line = Line, symbols = Symbols} = 
        dict:fetch(RulePointer, St#yecc.rule_pointer2rule),
    {Symbols, Line, N}.

get_rule(RuleNmbr, St) ->
    dict:fetch(RuleNmbr, St#yecc.rule_pointer2rule).

tokens(RuleNmbr, St) ->
    Rule = dict:fetch(RuleNmbr, St#yecc.rule_pointer2rule),
    Rule#rule.tokens.

goto(From, Symbol, St) ->
    case ets:lookup(St#yecc.goto_tab, {From, Symbol}) of
        [{_, To}] ->
            To;
        [] ->
            erlang:error({error_in_goto_table, From, Symbol})
    end.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Auxiliaries:

-ifdef(SYMBOLS_AS_CODES).

%%% Bit mask operations.

-compile({inline,[set_empty/0]}).
set_empty() ->
    0.

set_add(I, BM) ->
    (1 bsl I) bor BM.

-compile({inline,[set_member/2]}).
set_member(I, BM) ->
    ((1 bsl I) band BM) =/= 0.

%% Assumes I is a member...
-compile({inline,[set_delete/2]}).
set_delete(I, BM) ->
    (1 bsl I) bxor BM.

-compile({inline,[set_union/2]}).
set_union(BM1, BM2) ->
    BM1 bor BM2.

-compile({inline,[set_is_subset/2]}).
set_is_subset(BM1, BM2) ->
    (BM1 band BM2) =:= BM1.

empty_member(BM) ->
    set_member(0, BM).

empty_delete(BM) ->
    set_delete(0, BM).

code_symbols(Ss, SymbolTable) ->
    map(fun(S) -> ets:lookup_element(SymbolTable, S, 2) end, Ss).

decode_symbol(C, InvSymbolTable) ->
    ets:lookup_element(InvSymbolTable, C, 1).

code_terminal(T, SymbolTab) ->
    set_add(ets:lookup_element(SymbolTab, T, 2), 0).

decode_terminals(BM, InvSymbolTab) ->
    case get(BM) of
        undefined -> 
            Symbols = decode_terminals(BM, 0, InvSymbolTab),
            put(BM, Symbols),
            Symbols;
        Symbols -> 
            Symbols
    end.

decode_terminals(0, _I, _InvSymbolTab) ->
    [];
decode_terminals(BM, I, InvSymbolTab) ->
    case set_member(I, BM) of
        true ->
            [ets:lookup_element(InvSymbolTab, I, 1)
             | decode_terminals(set_delete(I, BM), I+1, InvSymbolTab)];
        false ->
            decode_terminals(BM, I+1, InvSymbolTab)
    end.

set_add_terminal({_Symbol, TerminalNum}, BM) ->
    set_add(TerminalNum, BM).

-compile({inline,[is_terminal/2]}).
is_terminal(_Tab, SymbolCode) ->
    SymbolCode >= 0.

left_corner_symbol_table(St) ->
    St#yecc.inv_symbol_tab.

-else.

set_empty() ->
    [].

set_add(Symbol, L) ->
    ordsets:union([Symbol], L).

set_union(Es1, Es2) ->
    ordsets:union(Es1, Es2).

set_is_subset(Es1, Es2) ->
    ordsets:is_subset(Es1, Es2).

code_symbols(Ss, _SymbolTab) ->
    Ss.

decode_symbol(S, _InvSymbolTab) ->
    S.

code_terminal(T, _SymbolTab) ->
    [T].

decode_terminals(Ts, _InvSymbolTab) ->
    Ts.

empty_member(['$empty' | _]) ->
    true;
empty_member(_) ->
    false.

empty_delete(['$empty' | Terminals]) ->
    Terminals.

set_add_terminal({Symbol, _TerminalNum}, L) ->
    set_add(Symbol, L).

is_terminal(Tab, SymbolName) ->
   ets:lookup_element(Tab, SymbolName, 2) >= 0.

left_corner_symbol_table(St) ->
    St#yecc.symbol_tab.

-endif. % SYMBOLS_AS_CODES

intersect(L1, L2) ->
    ordsets:to_list(ordsets:intersection(ordsets:from_list(L1),
                                         ordsets:from_list(L2))).

format_symbols([Sym | Syms]) ->
    concat([format_symbol(Sym) | format_symbols1(Syms)]).

format_symbols1([]) ->
    [];
format_symbols1([H | T]) ->
    [" ", format_symbol(H) | format_symbols1(T)].

include(St, File, Outport) ->
    case file:open(File, [read]) of
        {error, Reason} ->
            throw(add_error(File, none, {file_error, Reason}, St));
        {ok, Inport} ->
            _ = epp:set_encoding(Inport),
            Line = io:get_line(Inport, ''),
            try include1(Line, Inport, Outport, File, 1, St) - 1
            after ok = file:close(Inport)
            end
    end.

include1(eof, _, _, _File, L, _St) ->
    L;
include1({error, _}=_Error, _Inport, _Outport, File, L, St) ->
    throw(add_error(File, L, cannot_parse, St));
include1(Line, Inport, Outport, File, L, St) ->
    Incr = case member($\n, Line) of
               true -> 1;
               false -> 0
           end,
    io:put_chars(Outport, Line),
    include1(io:get_line(Inport, ''), Inport, Outport, File, L + Incr, St).

includefile_version([]) ->
    {1,4};
includefile_version(Includefile) ->
    case epp:open(Includefile, []) of
        {ok, Epp} ->
            try
                parse_file(Epp)
            after
                epp:close(Epp)
            end;
        {error, _Error} ->
            {1,1}
    end.

parse_file(Epp) ->
    case epp:parse_erl_form(Epp) of
        {ok, {function,_Line,yeccpars1,7,_Clauses}} ->
            {1,4};
        {eof,_Line} ->
            {1,1};
        _Form ->
            parse_file(Epp)
    end.

%% Keeps the line breaks of the original code.
pp_tokens(Tokens, Line0, Enc) ->
    concat(pp_tokens1(Tokens, Line0, Enc, [])).
    
pp_tokens1([], _Line0, _Enc, _T0) ->
    [];
pp_tokens1([T | Ts], Line0, Enc, T0) ->
    Line = element(2, T),
    [pp_sep(Line, Line0, T0), pp_symbol(T, Enc)|pp_tokens1(Ts, Line, Enc, T)].

pp_symbol({var,_,Var}, _Enc) -> Var;
pp_symbol({string,_,String}, latin1) ->
    io_lib:write_string_as_latin1(String);
pp_symbol({string,_,String}, _Enc) -> io_lib:write_string(String);
pp_symbol({_,_,Symbol}, latin1) -> io_lib:fwrite(<<"~p">>, [Symbol]);
pp_symbol({_,_,Symbol}, _Enc) -> io_lib:fwrite(<<"~tp">>, [Symbol]);
pp_symbol({Symbol, _}, _Enc) -> Symbol.

pp_sep(Line, Line0, T0) when Line > Line0 -> 
    ["\n   " | pp_sep(Line - 1, Line0, T0)];
pp_sep(_Line, _Line0, {'.',_}) -> 
    "";
pp_sep(_Line, _Line0, _T0) -> 
    " ".

set_encoding(#yecc{encoding = none}, Port) ->
    ok = io:setopts(Port, [{encoding, epp:default_encoding()}]);
set_encoding(#yecc{encoding = E}, Port) ->
    ok = io:setopts(Port, [{encoding, E}]).

output_encoding_comment(#yecc{encoding = none}=St) ->
    St;
output_encoding_comment(#yecc{encoding = Encoding}=St) ->
    fwrite(St, <<"%% ~s\n">>, [epp:encoding_to_string(Encoding)]).

output_file_directive(St, Filename, Line) when St#yecc.file_attrs ->
    fwrite(St, <<"-file(~s, ~w).\n">>, 
           [format_filename(Filename), Line]);
output_file_directive(St, _Filename, _Line) ->
    St.

first_line(Tokens) ->
    element(2, hd(Tokens)).

last_line(Tokens) ->
    element(2, lists:last(Tokens)).

%% Keep track of the current line in the generated file.
fwrite(#yecc{outport = Outport, line = Line}=St, Format, Args) ->
    NLines = count_nl(Format),
    io:fwrite(Outport, Format, Args),
    St#yecc{line = Line + NLines}.

%% Assumes \n is used, and never ~n.
count_nl(<<$\n,Rest/binary>>) ->
    1 + count_nl(Rest);
count_nl(<<_,Rest/binary>>) ->
    count_nl(Rest);
count_nl(<<>>) ->
    0.

nl(#yecc{outport = Outport, line = Line}=St) ->
    io:nl(Outport),
    St#yecc{line = Line + 1}.

format_filename(Filename) ->
    io_lib:write_string(filename:flatten(Filename)).

format_assoc(left) ->
    "Left";
format_assoc(right) ->
    "Right";
format_assoc(unary) ->
    "Unary";
format_assoc(nonassoc) ->
    "Nonassoc".

format_symbol(Symbol) ->
    String = concat([Symbol]),
    case erl_scan:string(String, 1, [unicode]) of
        {ok, [{atom, _, _}], _} ->
            io_lib:fwrite(<<"~w">>, [Symbol]);
        {ok, [{Word, _}], _} when Word =/= ':', Word =/= '->' ->
            case erl_scan:reserved_word(Word) of
                true ->
                    String;
                false ->
                    io_lib:fwrite(<<"~w">>, [Symbol])
            end;
        {ok, [{var, _, _}], _} ->
            String;
        _ -> 
            io_lib:fwrite(<<"~w">>, [Symbol])
    end.

inverse(L) ->
    sort([{A,B} || {B,A} <- L]).

family(L) ->
    sofs:to_external(sofs:relation_to_family(sofs:relation(L))).

seq1(To) when To < 1 ->
    [];
seq1(To) ->
    lists:seq(1, To).

count(From, L) ->
    lists:zip(L, lists:seq(From, length(L)-1+From)).

family_with_domain(L, DL) ->
    sofs:to_external(sofs_family_with_domain(sofs:relation(L), sofs:set(DL))).

sofs_family_with_domain(R0, D) ->
    R = sofs:restriction(R0, D),
    F = sofs:relation_to_family(R),
    FD = sofs:constant_function(D, sofs:from_term([])),
    sofs:family_union(F, FD).