gcc/ada/par-util.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             P A R . U T I L                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2003, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- GNAT was originally developed  by the GNAT team at  New York University. --
  23 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  24 --                                                                          --
  25 ------------------------------------------------------------------------------
  26
  27 with Csets; use Csets;
  28 with Uintp; use Uintp;
  29
  30 with GNAT.Spelling_Checker; use GNAT.Spelling_Checker;
  31
  32 separate (Par)
  33 package body Util is
  34
  35    ---------------------
  36    -- Bad_Spelling_Of --
  37    ---------------------
  38
  39    function Bad_Spelling_Of (T : Token_Type) return Boolean is
  40       Tname : constant String := Token_Type'Image (T);
  41       --  Characters of token name
  42
  43       S : String (1 .. Tname'Last - 4);
  44       --  Characters of token name folded to lower case, omitting TOK_ at start
  45
  46       M1 : String (1 .. 42) := "incorrect spelling of keyword ************";
  47       M2 : String (1 .. 44) := "illegal abbreviation of keyword ************";
  48       --  Buffers used to construct error message
  49
  50       P1 : constant := 30;
  51       P2 : constant := 32;
  52       --  Starting subscripts in M1, M2 for keyword name
  53
  54       SL : constant Natural := S'Length;
  55       --  Length of expected token name excluding TOK_ at start
  56
  57    begin
  58       if Token /= Tok_Identifier then
  59          return False;
  60       end if;
  61
  62       for J in S'Range loop
  63          S (J) := Fold_Lower (Tname (Integer (J) + 4));
  64       end loop;
  65
  66       Get_Name_String (Token_Name);
  67
  68       --  A special check for case of PROGRAM used for PROCEDURE
  69
  70       if T = Tok_Procedure
  71         and then Name_Len = 7
  72         and then Name_Buffer (1 .. 7) = "program"
  73       then
  74          Error_Msg_SC ("PROCEDURE expected");
  75          Token := T;
  76          return True;
  77
  78       --  A special check for an illegal abbrevation
  79
  80       elsif Name_Len < S'Length
  81         and then Name_Len >= 4
  82         and then Name_Buffer (1 .. Name_Len) = S (1 .. Name_Len)
  83       then
  84          for J in 1 .. S'Last loop
  85             M2 (P2 + J - 1) := Fold_Upper (S (J));
  86          end loop;
  87
  88          Error_Msg_SC (M2 (1 .. P2 - 1 + S'Last));
  89          Token := T;
  90          return True;
  91       end if;
  92
  93       --  Now we go into the full circuit to check for a misspelling
  94
  95       --  Never consider something a misspelling if either the actual or
  96       --  expected string is less than 3 characters (before this check we
  97       --  used to consider i to be a misspelled if in some cases!)
  98
  99       if SL < 3 or else Name_Len < 3 then
 100          return False;
 101
 102       --  Special case: prefix matches, i.e. the leading characters of the
 103       --  token that we have exactly match the required keyword. If there
 104       --  are at least two characters left over, assume that we have a case
 105       --  of two keywords joined together which should not be joined.
 106
 107       elsif Name_Len > SL + 1
 108         and then S = Name_Buffer (1 .. SL)
 109       then
 110          Scan_Ptr := Token_Ptr + S'Length;
 111          Error_Msg_S ("missing space");
 112          Token := T;
 113          return True;
 114       end if;
 115
 116       if Is_Bad_Spelling_Of (Name_Buffer (1 .. Name_Len), S) then
 117
 118          for J in 1 .. S'Last loop
 119             M1 (P1 + J - 1) := Fold_Upper (S (J));
 120          end loop;
 121
 122          Error_Msg_SC (M1 (1 .. P1 - 1 + S'Last));
 123          Token := T;
 124          return True;
 125
 126       else
 127          return False;
 128       end if;
 129
 130    end Bad_Spelling_Of;
 131
 132    ----------------------
 133    -- Check_95_Keyword --
 134    ----------------------
 135
 136    --  On entry, the caller has checked that current token is an identifier
 137    --  whose name matches the name of the 95 keyword New_Tok.
 138
 139    procedure Check_95_Keyword (Token_95, Next : Token_Type) is
 140       Scan_State : Saved_Scan_State;
 141
 142    begin
 143       Save_Scan_State (Scan_State); -- at identifier/keyword
 144       Scan; -- past identifier/keyword
 145
 146       if Token = Next then
 147          Restore_Scan_State (Scan_State); -- to identifier
 148          Error_Msg_Name_1 := Token_Name;
 149          Error_Msg_SC ("(Ada 83) keyword* cannot be used!");
 150          Token := Token_95;
 151       else
 152          Restore_Scan_State (Scan_State); -- to identifier
 153       end if;
 154    end Check_95_Keyword;
 155
 156    ----------------------
 157    -- Check_Bad_Layout --
 158    ----------------------
 159
 160    procedure Check_Bad_Layout is
 161    begin
 162       if Style.RM_Column_Check and then Token_Is_At_Start_Of_Line
 163         and then Start_Column <= Scope.Table (Scope.Last).Ecol
 164       then
 165          Error_Msg_BC ("(style) incorrect layout");
 166       end if;
 167    end Check_Bad_Layout;
 168
 169    --------------------------
 170    -- Check_Misspelling_Of --
 171    --------------------------
 172
 173    procedure Check_Misspelling_Of (T : Token_Type) is
 174    begin
 175       if Bad_Spelling_Of (T) then
 176          null;
 177       end if;
 178    end Check_Misspelling_Of;
 179
 180    -----------------------------
 181    -- Check_Simple_Expression --
 182    -----------------------------
 183
 184    procedure Check_Simple_Expression (E : Node_Id) is
 185    begin
 186       if Expr_Form = EF_Non_Simple then
 187          Error_Msg_N ("this expression must be parenthesized", E);
 188       end if;
 189    end Check_Simple_Expression;
 190
 191    ---------------------------------------
 192    -- Check_Simple_Expression_In_Ada_83 --
 193    ---------------------------------------
 194
 195    procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id) is
 196    begin
 197       if Expr_Form = EF_Non_Simple then
 198          if Ada_83 then
 199             Error_Msg_N ("(Ada 83) this expression must be parenthesized!", E);
 200          end if;
 201       end if;
 202    end Check_Simple_Expression_In_Ada_83;
 203
 204    ------------------------
 205    -- Check_Subtype_Mark --
 206    ------------------------
 207
 208    function Check_Subtype_Mark (Mark : Node_Id) return Node_Id is
 209    begin
 210       if Nkind (Mark) = N_Identifier
 211         or else Nkind (Mark) = N_Selected_Component
 212         or else (Nkind (Mark) = N_Attribute_Reference
 213                   and then Is_Type_Attribute_Name (Attribute_Name (Mark)))
 214         or else Mark = Error
 215       then
 216          return Mark;
 217       else
 218          Error_Msg ("subtype mark expected", Sloc (Mark));
 219          return Error;
 220       end if;
 221    end Check_Subtype_Mark;
 222
 223    -------------------
 224    -- Comma_Present --
 225    -------------------
 226
 227    function Comma_Present return Boolean is
 228       Scan_State  : Saved_Scan_State;
 229       Paren_Count : Nat;
 230
 231    begin
 232       --  First check, if a comma is present, then a comma is present!
 233
 234       if Token = Tok_Comma then
 235          T_Comma;
 236          return True;
 237
 238       --  If we have a right paren, then that is taken as ending the list
 239       --  i.e. no comma is present.
 240
 241       elsif Token = Tok_Right_Paren then
 242          return False;
 243
 244       --  If pragmas, then get rid of them and make a recursive call
 245       --  to process what follows these pragmas.
 246
 247       elsif Token = Tok_Pragma then
 248          P_Pragmas_Misplaced;
 249          return Comma_Present;
 250
 251       --  At this stage we have an error, and the goal is to decide on whether
 252       --  or not we should diagnose an error and report a (non-existent)
 253       --  comma as being present, or simply to report no comma is present
 254
 255       --  If we are a semicolon, then the question is whether we have a missing
 256       --  right paren, or whether the semicolon should have been a comma. To
 257       --  guess the right answer, we scan ahead keeping track of the paren
 258       --  level, looking for a clue that helps us make the right decision.
 259
 260       --  This approach is highly accurate in the single error case, and does
 261       --  not make bad mistakes in the multiple error case (indeed we can't
 262       --  really make a very bad decision at this point in any case).
 263
 264       elsif Token = Tok_Semicolon then
 265          Save_Scan_State (Scan_State);
 266          Scan; -- past semicolon
 267
 268          --  Check for being followed by identifier => which almost certainly
 269          --  means we are still in a parameter list and the comma should have
 270          --  been a semicolon (such a sequence could not follow a semicolon)
 271
 272          if Token = Tok_Identifier then
 273             Scan;
 274
 275             if Token = Tok_Arrow then
 276                goto Assume_Comma;
 277             end if;
 278          end if;
 279
 280          --  If that test didn't work, loop ahead looking for a comma or
 281          --  semicolon at the same parenthesis level. Always remember that
 282          --  we can't go badly wrong in an error situation like this!
 283
 284          Paren_Count := 0;
 285
 286          --  Here is the look ahead loop, Paren_Count tells us whether the
 287          --  token we are looking at is at the same paren level as the
 288          --  suspicious semicolon that we are trying to figure out.
 289
 290          loop
 291
 292             --  If we hit another semicolon or an end of file, and we have
 293             --  not seen a right paren or another comma on the way, then
 294             --  probably the semicolon did end the list. Indeed that is
 295             --  certainly the only single error correction possible here.
 296
 297             if Token = Tok_Semicolon or else Token = Tok_EOF then
 298                Restore_Scan_State (Scan_State);
 299                return False;
 300
 301             --  A comma at the same paren level as the semicolon is a strong
 302             --  indicator that the semicolon should have been a comma, indeed
 303             --  again this is the only possible single error correction.
 304
 305             elsif Token = Tok_Comma then
 306                exit when Paren_Count = 0;
 307
 308             --  A left paren just bumps the paren count
 309
 310             elsif Token = Tok_Left_Paren then
 311                Paren_Count := Paren_Count + 1;
 312
 313             --  A right paren that is at the same paren level as the semicolon
 314             --  also means that the only possible single error correction is
 315             --  to assume that the semicolon should have been a comma. If we
 316             --  are not at the same paren level, then adjust the paren level.
 317
 318             elsif Token = Tok_Right_Paren then
 319                exit when Paren_Count = 0;
 320                Paren_Count := Paren_Count - 1;
 321             end if;
 322
 323             --  Keep going, we haven't made a decision yet
 324
 325             Scan;
 326          end loop;
 327
 328          --  If we fall through the loop, it means that we found a terminating
 329          --  right paren or another comma. In either case it is reasonable to
 330          --  assume that the semicolon was really intended to be a comma. Also
 331          --  come here for the identifier arrow case.
 332
 333          <<Assume_Comma>>
 334             Restore_Scan_State (Scan_State);
 335             Error_Msg_SC (""";"" illegal here, replaced by "",""");
 336             Scan; -- past the semicolon
 337             return True;
 338
 339       --  If we are not at semicolon or a right paren, then we base the
 340       --  decision on whether or not the next token can be part of an
 341       --  expression. If not, then decide that no comma is present (the
 342       --  caller will eventually generate a missing right parent message)
 343
 344       elsif Token in Token_Class_Eterm then
 345          return False;
 346
 347       --  Otherwise we assume a comma is present, even if none is present,
 348       --  since the next token must be part of an expression, so if we were
 349       --  at the end of the list, then there is more than one error present.
 350
 351       else
 352          T_Comma; -- to give error
 353          return True;
 354       end if;
 355    end Comma_Present;
 356
 357    -----------------------
 358    -- Discard_Junk_List --
 359    -----------------------
 360
 361    procedure Discard_Junk_List (L : List_Id) is
 362       pragma Warnings (Off, L);
 363
 364    begin
 365       null;
 366    end Discard_Junk_List;
 367
 368    -----------------------
 369    -- Discard_Junk_Node --
 370    -----------------------
 371
 372    procedure Discard_Junk_Node (N : Node_Id) is
 373       pragma Warnings (Off, N);
 374
 375    begin
 376       null;
 377    end Discard_Junk_Node;
 378
 379    ------------
 380    -- Ignore --
 381    ------------
 382
 383    procedure Ignore (T : Token_Type) is
 384    begin
 385       if Token = T then
 386          if T = Tok_Comma then
 387             Error_Msg_SC ("unexpected "","" ignored");
 388
 389          elsif T = Tok_Left_Paren then
 390             Error_Msg_SC ("unexpected ""("" ignored");
 391
 392          elsif T = Tok_Right_Paren then
 393             Error_Msg_SC ("unexpected "")"" ignored");
 394
 395          elsif T = Tok_Semicolon then
 396             Error_Msg_SC ("unexpected "";"" ignored");
 397
 398          else
 399             declare
 400                Tname : constant String := Token_Type'Image (Token);
 401                Msg   : String := "unexpected keyword ????????????????????????";
 402
 403             begin
 404                --  Loop to copy characters of keyword name (ignoring Tok_)
 405
 406                for J in 5 .. Tname'Last loop
 407                   Msg (J + 14) := Fold_Upper (Tname (J));
 408                end loop;
 409
 410                Msg (Tname'Last + 15 .. Tname'Last + 22) := " ignored";
 411                Error_Msg_SC (Msg (1 .. Tname'Last + 22));
 412             end;
 413          end if;
 414
 415          Scan; -- Scan past ignored token
 416       end if;
 417    end Ignore;
 418
 419    ----------------------------
 420    -- Is_Reserved_Identifier --
 421    ----------------------------
 422
 423    function Is_Reserved_Identifier (C : Id_Check := None) return Boolean is
 424    begin
 425       if not Is_Reserved_Keyword (Token) then
 426          return False;
 427
 428       else
 429          declare
 430             Ident_Casing : constant Casing_Type :=
 431                              Identifier_Casing (Current_Source_File);
 432
 433             Key_Casing   : constant Casing_Type :=
 434                              Keyword_Casing (Current_Source_File);
 435
 436          begin
 437             --  If the casing of identifiers and keywords is different in
 438             --  this source file, and the casing of this token matches the
 439             --  keyword casing, then we return False, since it is pretty
 440             --  clearly intended to be a keyword.
 441
 442             if Ident_Casing = Unknown
 443               or else Key_Casing = Unknown
 444               or else Ident_Casing = Key_Casing
 445               or else Determine_Token_Casing /= Key_Casing
 446             then
 447                return True;
 448
 449             --  Here we have a keyword written clearly with keyword casing.
 450             --  In default mode, we would not be willing to consider this as
 451             --  a reserved identifier, but if C is set, we may still accept it
 452
 453             elsif C /= None then
 454                declare
 455                   Scan_State  : Saved_Scan_State;
 456                   OK_Next_Tok : Boolean;
 457
 458                begin
 459                   Save_Scan_State (Scan_State);
 460                   Scan;
 461
 462                   if Token_Is_At_Start_Of_Line then
 463                      return False;
 464                   end if;
 465
 466                   case C is
 467                      when None =>
 468                         raise Program_Error;
 469
 470                      when C_Comma_Right_Paren =>
 471                         OK_Next_Tok :=
 472                           Token = Tok_Comma or else Token = Tok_Right_Paren;
 473
 474                      when C_Comma_Colon =>
 475                         OK_Next_Tok :=
 476                           Token = Tok_Comma or else Token = Tok_Colon;
 477
 478                      when C_Do =>
 479                         OK_Next_Tok :=
 480                           Token = Tok_Do;
 481
 482                      when C_Dot =>
 483                         OK_Next_Tok :=
 484                           Token = Tok_Dot;
 485
 486                      when C_Greater_Greater =>
 487                         OK_Next_Tok :=
 488                           Token = Tok_Greater_Greater;
 489
 490                      when C_In =>
 491                         OK_Next_Tok :=
 492                           Token = Tok_In;
 493
 494                      when C_Is =>
 495                         OK_Next_Tok :=
 496                           Token = Tok_Is;
 497
 498                      when C_Left_Paren_Semicolon =>
 499                         OK_Next_Tok :=
 500                           Token = Tok_Left_Paren or else Token = Tok_Semicolon;
 501
 502                      when C_Use =>
 503                         OK_Next_Tok :=
 504                           Token = Tok_Use;
 505
 506                      when C_Vertical_Bar_Arrow =>
 507                         OK_Next_Tok :=
 508                           Token = Tok_Vertical_Bar or else Token = Tok_Arrow;
 509                   end case;
 510
 511                   Restore_Scan_State (Scan_State);
 512
 513                   if OK_Next_Tok then
 514                      return True;
 515                   end if;
 516                end;
 517             end if;
 518          end;
 519       end if;
 520
 521       --  If we fall through it is not a reserved identifier
 522
 523       return False;
 524    end Is_Reserved_Identifier;
 525
 526    ----------------------
 527    -- Merge_Identifier --
 528    ----------------------
 529
 530    procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type) is
 531    begin
 532       if Token /= Tok_Identifier then
 533          return;
 534       end if;
 535
 536       declare
 537          S : Saved_Scan_State;
 538          T : Token_Type;
 539
 540       begin
 541          Save_Scan_State (S);
 542          Scan;
 543          T := Token;
 544          Restore_Scan_State (S);
 545
 546          if T /= Nxt then
 547             return;
 548          end if;
 549       end;
 550
 551       --  Check exactly one space between identifiers
 552
 553       if Source (Token_Ptr - 1) /= ' '
 554         or else Int (Token_Ptr) /=
 555                   Int (Prev_Token_Ptr) + Length_Of_Name (Chars (Prev)) + 1
 556       then
 557          return;
 558       end if;
 559
 560       --  Do the merge
 561
 562       Get_Name_String (Chars (Token_Node));
 563
 564       declare
 565          Buf : constant String (1 .. Name_Len) :=
 566                  Name_Buffer (1 .. Name_Len);
 567
 568       begin
 569          Get_Name_String (Chars (Prev));
 570          Add_Char_To_Name_Buffer ('_');
 571          Add_Str_To_Name_Buffer (Buf);
 572          Set_Chars (Prev, Name_Find);
 573       end;
 574
 575       Error_Msg_Node_1 := Prev;
 576       Error_Msg_SC
 577         ("unexpected identifier, possibly & was meant here");
 578       Scan;
 579    end Merge_Identifier;
 580
 581    -------------------
 582    -- No_Constraint --
 583    -------------------
 584
 585    procedure No_Constraint is
 586    begin
 587       if Token in Token_Class_Consk then
 588          Error_Msg_SC ("constraint not allowed here");
 589          Discard_Junk_Node (P_Constraint_Opt);
 590       end if;
 591    end No_Constraint;
 592
 593    --------------------
 594    -- No_Right_Paren --
 595    --------------------
 596
 597    function No_Right_Paren (Expr : Node_Id) return Node_Id is
 598    begin
 599       if Token = Tok_Right_Paren then
 600          Error_Msg_SC ("unexpected right parenthesis");
 601          Resync_Expression;
 602          return Error;
 603       else
 604          return Expr;
 605       end if;
 606    end No_Right_Paren;
 607
 608    ---------------------
 609    -- Pop_Scope_Stack --
 610    ---------------------
 611
 612    procedure Pop_Scope_Stack is
 613    begin
 614       pragma Assert (Scope.Last > 0);
 615       Scope.Decrement_Last;
 616
 617       if Debug_Flag_P then
 618          Error_Msg_Uint_1 := UI_From_Int (Scope.Last);
 619          Error_Msg_SC ("decrement scope stack ptr, new value = ^!");
 620       end if;
 621    end Pop_Scope_Stack;
 622
 623    ----------------------
 624    -- Push_Scope_Stack --
 625    ----------------------
 626
 627    procedure Push_Scope_Stack is
 628    begin
 629       Scope.Increment_Last;
 630       Scope.Table (Scope.Last).Junk := False;
 631       Scope.Table (Scope.Last).Node := Empty;
 632
 633       if Debug_Flag_P then
 634          Error_Msg_Uint_1 := UI_From_Int (Scope.Last);
 635          Error_Msg_SC ("increment scope stack ptr, new value = ^!");
 636       end if;
 637    end Push_Scope_Stack;
 638
 639    ----------------------
 640    -- Separate_Present --
 641    ----------------------
 642
 643    function Separate_Present return Boolean is
 644       Scan_State : Saved_Scan_State;
 645
 646    begin
 647       if Token = Tok_Separate then
 648          return True;
 649
 650       elsif Token /= Tok_Identifier then
 651          return False;
 652
 653       else
 654          Save_Scan_State (Scan_State);
 655          Scan; -- past identifier
 656
 657          if Token = Tok_Semicolon then
 658             Restore_Scan_State (Scan_State);
 659             return Bad_Spelling_Of (Tok_Separate);
 660
 661          else
 662             Restore_Scan_State (Scan_State);
 663             return False;
 664          end if;
 665       end if;
 666    end Separate_Present;
 667
 668    --------------------------
 669    -- Signal_Bad_Attribute --
 670    --------------------------
 671
 672    procedure Signal_Bad_Attribute is
 673    begin
 674       Error_Msg_N ("unrecognized attribute&", Token_Node);
 675
 676       --  Check for possible misspelling
 677
 678       Get_Name_String (Token_Name);
 679
 680       declare
 681          AN : constant String := Name_Buffer (1 .. Name_Len);
 682
 683       begin
 684          Error_Msg_Name_1 := First_Attribute_Name;
 685          while Error_Msg_Name_1 <= Last_Attribute_Name loop
 686             Get_Name_String (Error_Msg_Name_1);
 687
 688             if Is_Bad_Spelling_Of
 689                  (AN, Name_Buffer (1 .. Name_Len))
 690             then
 691                Error_Msg_N
 692                  ("\possible misspelling of %", Token_Node);
 693                exit;
 694             end if;
 695
 696             Error_Msg_Name_1 := Error_Msg_Name_1 + 1;
 697          end loop;
 698       end;
 699    end Signal_Bad_Attribute;
 700
 701    -----------------------------
 702    -- Token_Is_At_End_Of_Line --
 703    -----------------------------
 704
 705    function Token_Is_At_End_Of_Line return Boolean is
 706       S : Source_Ptr;
 707
 708    begin
 709       --  Skip past blanks and horizontal tabs
 710
 711       S := Scan_Ptr;
 712       while Source (S) = ' ' or else Source (S) = ASCII.HT loop
 713          S := S + 1;
 714       end loop;
 715
 716       --  We are at end of line if at a control character (CR/LF/VT/FF/EOF)
 717       --  or if we are at the start of an end of line comment sequence.
 718
 719       return Source (S) < ' '
 720         or else (Source (S) = '-' and then Source (S + 1) = '-');
 721    end Token_Is_At_End_Of_Line;
 722
 723    -------------------------------
 724    -- Token_Is_At_Start_Of_Line --
 725    -------------------------------
 726
 727    function Token_Is_At_Start_Of_Line return Boolean is
 728    begin
 729       return (Token_Ptr = First_Non_Blank_Location or else Token = Tok_EOF);
 730    end Token_Is_At_Start_Of_Line;
 731
 732 end Util;