gcc/ada/scng.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                                 S C N G                                  --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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 3,  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 COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 with Csets;    use Csets;
  27 with Err_Vars; use Err_Vars;
  28 with Hostparm; use Hostparm;
  29 with Namet;    use Namet;
  30 with Opt;      use Opt;
  31 with Scans;    use Scans;
  32 with Sinput;   use Sinput;
  33 with Snames;   use Snames;
  34 with Stringt;  use Stringt;
  35 with Stylesw;  use Stylesw;
  36 with Uintp;    use Uintp;
  37 with Urealp;   use Urealp;
  38 with Widechar; use Widechar;
  39
  40 with System.CRC32;
  41 with System.UTF_32;  use System.UTF_32;
  42 with System.WCh_Con; use System.WCh_Con;
  43
  44 package body Scng is
  45
  46    use ASCII;
  47    --  Make control characters visible
  48
  49    Special_Characters : array (Character) of Boolean := (others => False);
  50    --  For characters that are Special token, the value is True
  51
  52    Comment_Is_Token : Boolean := False;
  53    --  True if comments are tokens
  54
  55    End_Of_Line_Is_Token : Boolean := False;
  56    --  True if End_Of_Line is a token
  57
  58    -----------------------
  59    -- Local Subprograms --
  60    -----------------------
  61
  62    procedure Accumulate_Token_Checksum;
  63    pragma Inline (Accumulate_Token_Checksum);
  64
  65    procedure Accumulate_Checksum (C : Character);
  66    pragma Inline (Accumulate_Checksum);
  67    --  This routine accumulates the checksum given character C. During the
  68    --  scanning of a source file, this routine is called with every character
  69    --  in the source, excluding blanks, and all control characters (except
  70    --  that ESC is included in the checksum). Upper case letters not in string
  71    --  literals are folded by the caller. See Sinput spec for the documentation
  72    --  of the checksum algorithm. Note: checksum values are only used if we
  73    --  generate code, so it is not necessary to worry about making the right
  74    --  sequence of calls in any error situation.
  75
  76    procedure Accumulate_Checksum (C : Char_Code);
  77    pragma Inline (Accumulate_Checksum);
  78    --  This version is identical, except that the argument, C, is a character
  79    --  code value instead of a character. This is used when wide characters
  80    --  are scanned. We use the character code rather than the ASCII characters
  81    --  so that the checksum is independent of wide character encoding method.
  82
  83    procedure Initialize_Checksum;
  84    pragma Inline (Initialize_Checksum);
  85    --  Initialize checksum value
  86
  87    -------------------------
  88    -- Accumulate_Checksum --
  89    -------------------------
  90
  91    procedure Accumulate_Checksum (C : Character) is
  92    begin
  93       System.CRC32.Update (System.CRC32.CRC32 (Checksum), C);
  94    end Accumulate_Checksum;
  95
  96    procedure Accumulate_Checksum (C : Char_Code) is
  97    begin
  98       if C > 16#FFFF# then
  99          Accumulate_Checksum (Character'Val (C / 2 ** 24));
 100          Accumulate_Checksum (Character'Val ((C / 2 ** 16) mod 256));
 101          Accumulate_Checksum (Character'Val ((C / 256) mod 256));
 102       else
 103          Accumulate_Checksum (Character'Val (C / 256));
 104       end if;
 105
 106       Accumulate_Checksum (Character'Val (C mod 256));
 107    end Accumulate_Checksum;
 108
 109    -------------------------------
 110    -- Accumulate_Token_Checksum --
 111    -------------------------------
 112
 113    procedure Accumulate_Token_Checksum is
 114    begin
 115       System.CRC32.Update
 116         (System.CRC32.CRC32 (Checksum),
 117          Character'Val (Token_Type'Pos (Token)));
 118    end Accumulate_Token_Checksum;
 119
 120    ----------------------------
 121    -- Determine_Token_Casing --
 122    ----------------------------
 123
 124    function Determine_Token_Casing return Casing_Type is
 125    begin
 126       return Determine_Casing (Source (Token_Ptr .. Scan_Ptr - 1));
 127    end Determine_Token_Casing;
 128
 129    -------------------------
 130    -- Initialize_Checksum --
 131    -------------------------
 132
 133    procedure Initialize_Checksum is
 134    begin
 135       System.CRC32.Initialize (System.CRC32.CRC32 (Checksum));
 136    end Initialize_Checksum;
 137
 138    ------------------------
 139    -- Initialize_Scanner --
 140    ------------------------
 141
 142    procedure Initialize_Scanner (Index : Source_File_Index) is
 143    begin
 144       --  Establish reserved words
 145
 146       Scans.Initialize_Ada_Keywords;
 147
 148       --  Initialize scan control variables
 149
 150       Current_Source_File       := Index;
 151       Source                    := Source_Text (Current_Source_File);
 152       Scan_Ptr                  := Source_First (Current_Source_File);
 153       Token                     := No_Token;
 154       Token_Ptr                 := Scan_Ptr;
 155       Current_Line_Start        := Scan_Ptr;
 156       Token_Node                := Empty;
 157       Token_Name                := No_Name;
 158       Start_Column              := Set_Start_Column;
 159       First_Non_Blank_Location  := Scan_Ptr;
 160
 161       Initialize_Checksum;
 162       Wide_Char_Byte_Count := 0;
 163
 164       --  Do not call Scan, otherwise the License stuff does not work in Scn
 165
 166    end Initialize_Scanner;
 167
 168    ------------------------------
 169    -- Reset_Special_Characters --
 170    ------------------------------
 171
 172    procedure Reset_Special_Characters is
 173    begin
 174       Special_Characters := (others => False);
 175    end Reset_Special_Characters;
 176
 177    ----------
 178    -- Scan --
 179    ----------
 180
 181    procedure Scan is
 182
 183       Start_Of_Comment : Source_Ptr;
 184       --  Record start of comment position
 185
 186       Underline_Found : Boolean;
 187       --  During scanning of an identifier, set to True if last character
 188       --  scanned was an underline or other punctuation character. This
 189       --  is used to flag the error of two underlines/punctuations in a
 190       --  row or ending an identifier with a underline/punctuation. Here
 191       --  punctuation means any UTF_32 character in the Unicode category
 192       --  Punctuation,Connector.
 193
 194       Wptr : Source_Ptr;
 195       --  Used to remember start of last wide character scanned
 196
 197       procedure Check_End_Of_Line;
 198       --  Called when end of line encountered. Checks that line is not too
 199       --  long, and that other style checks for the end of line are met.
 200
 201       function Double_Char_Token (C : Character) return Boolean;
 202       --  This function is used for double character tokens like := or <>. It
 203       --  checks if the character following Source (Scan_Ptr) is C, and if so
 204       --  bumps Scan_Ptr past the pair of characters and returns True. A space
 205       --  between the two characters is also recognized with an appropriate
 206       --  error message being issued. If C is not present, False is returned.
 207       --  Note that Double_Char_Token can only be used for tokens defined in
 208       --  the Ada syntax (it's use for error cases like && is not appropriate
 209       --  since we do not want a junk message for a case like &-space-&).
 210
 211       procedure Error_Illegal_Character;
 212       --  Give illegal character error, Scan_Ptr points to character. On
 213       --  return, Scan_Ptr is bumped past the illegal character.
 214
 215       procedure Error_Illegal_Wide_Character;
 216       --  Give illegal wide character message. On return, Scan_Ptr is bumped
 217       --  past the illegal character, which may still leave us pointing to
 218       --  junk, not much we can do if the escape sequence is messed up!
 219
 220       procedure Error_Long_Line;
 221       --  Signal error of excessively long line
 222
 223       procedure Error_No_Double_Underline;
 224       --  Signal error of two underline or punctuation characters in a row.
 225       --  Called with Scan_Ptr pointing to second underline/punctuation char.
 226
 227       procedure Nlit;
 228       --  This is the procedure for scanning out numeric literals. On entry,
 229       --  Scan_Ptr points to the digit that starts the numeric literal (the
 230       --  checksum for this character has not been accumulated yet). On return
 231       --  Scan_Ptr points past the last character of the numeric literal, Token
 232       --  and Token_Node are set appropriately, and the checksum is updated.
 233
 234       procedure Slit;
 235       --  This is the procedure for scanning out string literals. On entry,
 236       --  Scan_Ptr points to the opening string quote (the checksum for this
 237       --  character has not been accumulated yet). On return Scan_Ptr points
 238       --  past the closing quote of the string literal, Token and Token_Node
 239       --  are set appropriately, and the checksum is updated.
 240
 241       -----------------------
 242       -- Check_End_Of_Line --
 243       -----------------------
 244
 245       procedure Check_End_Of_Line is
 246          Len : constant Int :=
 247                  Int (Scan_Ptr) -
 248                  Int (Current_Line_Start) -
 249                  Wide_Char_Byte_Count;
 250
 251       begin
 252          if Style_Check then
 253             Style.Check_Line_Terminator (Len);
 254          end if;
 255
 256          --  Deal with checking maximum line length
 257
 258          if Style_Check and Style_Check_Max_Line_Length then
 259             Style.Check_Line_Max_Length (Len);
 260
 261          --  If style checking is inactive, check maximum line length against
 262          --  standard value.
 263
 264          elsif Len > Max_Line_Length then
 265             Error_Long_Line;
 266          end if;
 267
 268          --  Now one more checking circuit. Normally we are only enforcing a
 269          --  limit of physical characters, with tabs counting as one character.
 270          --  But if after tab expansion we would have a total line length that
 271          --  exceeded 32766, that would really cause trouble, because column
 272          --  positions would exceed the maximum we allow for a column count.
 273          --  Note: the limit is 32766 rather than 32767, since we use a value
 274          --  of 32767 for special purposes (see Sinput). Now we really do not
 275          --  want to go messing with tabs in the normal case, so what we do is
 276          --  to check for a line that has more than 4096 physical characters.
 277          --  Any shorter line could not be a problem, even if it was all tabs.
 278
 279          if Len >= 4096 then
 280             declare
 281                Col : Natural;
 282                Ptr : Source_Ptr;
 283
 284             begin
 285                Col := 1;
 286                Ptr := Current_Line_Start;
 287                loop
 288                   exit when Ptr = Scan_Ptr;
 289
 290                   if Source (Ptr) = ASCII.HT then
 291                      Col := (Col - 1 + 8) / 8 * 8 + 1;
 292                   else
 293                      Col := Col + 1;
 294                   end if;
 295
 296                   if Col > 32766 then
 297                      Error_Msg
 298                        ("this line is longer than 32766 characters",
 299                         Current_Line_Start);
 300                      raise Unrecoverable_Error;
 301                   end if;
 302
 303                   Ptr := Ptr + 1;
 304                end loop;
 305             end;
 306          end if;
 307
 308          --  Reset wide character byte count for next line
 309
 310          Wide_Char_Byte_Count := 0;
 311       end Check_End_Of_Line;
 312
 313       -----------------------
 314       -- Double_Char_Token --
 315       -----------------------
 316
 317       function Double_Char_Token (C : Character) return Boolean is
 318       begin
 319          if Source (Scan_Ptr + 1) = C then
 320             Accumulate_Checksum (C);
 321             Scan_Ptr := Scan_Ptr + 2;
 322             return True;
 323
 324          elsif Source (Scan_Ptr + 1) = ' '
 325            and then Source (Scan_Ptr + 2) = C
 326          then
 327             Scan_Ptr := Scan_Ptr + 1;
 328             Error_Msg_S ("no space allowed here");
 329             Scan_Ptr := Scan_Ptr + 2;
 330             return True;
 331
 332          else
 333             return False;
 334          end if;
 335       end Double_Char_Token;
 336
 337       -----------------------------
 338       -- Error_Illegal_Character --
 339       -----------------------------
 340
 341       procedure Error_Illegal_Character is
 342       begin
 343          Error_Msg_S ("illegal character");
 344          Scan_Ptr := Scan_Ptr + 1;
 345       end Error_Illegal_Character;
 346
 347       ----------------------------------
 348       -- Error_Illegal_Wide_Character --
 349       ----------------------------------
 350
 351       procedure Error_Illegal_Wide_Character is
 352       begin
 353          Scan_Ptr := Scan_Ptr + 1;
 354          Error_Msg ("illegal wide character", Wptr);
 355       end Error_Illegal_Wide_Character;
 356
 357       ---------------------
 358       -- Error_Long_Line --
 359       ---------------------
 360
 361       procedure Error_Long_Line is
 362       begin
 363          Error_Msg
 364            ("this line is too long",
 365             Current_Line_Start + Source_Ptr (Max_Line_Length));
 366       end Error_Long_Line;
 367
 368       -------------------------------
 369       -- Error_No_Double_Underline --
 370       -------------------------------
 371
 372       procedure Error_No_Double_Underline is
 373       begin
 374          Underline_Found := False;
 375
 376          --  There are four cases, and we special case the messages
 377
 378          if Source (Scan_Ptr) = '_' then
 379             if Source (Scan_Ptr - 1) = '_' then
 380                Error_Msg_S -- CODEFIX
 381                  ("two consecutive underlines not permitted");
 382             else
 383                Error_Msg_S -- CODEFIX???
 384                  ("underline cannot follow punctuation character");
 385             end if;
 386
 387          else
 388             if Source (Scan_Ptr - 1) = '_' then
 389                Error_Msg_S -- CODEFIX???
 390                  ("punctuation character cannot follow underline");
 391             else
 392                Error_Msg_S -- CODEFIX???
 393                  ("two consecutive punctuation characters not permitted");
 394             end if;
 395          end if;
 396       end Error_No_Double_Underline;
 397
 398       ----------
 399       -- Nlit --
 400       ----------
 401
 402       procedure Nlit is
 403
 404          C : Character;
 405          --  Current source program character
 406
 407          Base_Char : Character;
 408          --  Either # or : (character at start of based number)
 409
 410          Base : Int;
 411          --  Value of base
 412
 413          UI_Base : Uint;
 414          --  Value of base in Uint format
 415
 416          UI_Int_Value : Uint;
 417          --  Value of integer scanned by Scan_Integer in Uint format
 418
 419          UI_Num_Value : Uint;
 420          --  Value of integer in numeric value being scanned
 421
 422          Scale : Int;
 423          --  Scale value for real literal
 424
 425          UI_Scale : Uint;
 426          --  Scale in Uint format
 427
 428          Exponent_Is_Negative : Boolean;
 429          --  Set true for negative exponent
 430
 431          Extended_Digit_Value : Int;
 432          --  Extended digit value
 433
 434          Point_Scanned : Boolean;
 435          --  Flag for decimal point scanned in numeric literal
 436
 437          -----------------------
 438          -- Local Subprograms --
 439          -----------------------
 440
 441          procedure Error_Digit_Expected;
 442          --  Signal error of bad digit, Scan_Ptr points to the location at
 443          --  which the digit was expected on input, and is unchanged on return.
 444
 445          procedure Scan_Integer;
 446          --  Procedure to scan integer literal. On entry, Scan_Ptr points to a
 447          --  digit, on exit Scan_Ptr points past the last character of the
 448          --  integer.
 449          --
 450          --  For each digit encountered, UI_Int_Value is multiplied by 10, and
 451          --  the value of the digit added to the result. In addition, the
 452          --  value in Scale is decremented by one for each actual digit
 453          --  scanned.
 454
 455          --------------------------
 456          -- Error_Digit_Expected --
 457          --------------------------
 458
 459          procedure Error_Digit_Expected is
 460          begin
 461             Error_Msg_S ("digit expected");
 462          end Error_Digit_Expected;
 463
 464          ------------------
 465          -- Scan_Integer --
 466          ------------------
 467
 468          procedure Scan_Integer is
 469             C : Character;
 470             --  Next character scanned
 471
 472          begin
 473             C := Source (Scan_Ptr);
 474
 475             --  Loop through digits (allowing underlines)
 476
 477             loop
 478                Accumulate_Checksum (C);
 479                UI_Int_Value :=
 480                  UI_Int_Value * 10 + (Character'Pos (C) - Character'Pos ('0'));
 481                Scan_Ptr := Scan_Ptr + 1;
 482                Scale := Scale - 1;
 483                C := Source (Scan_Ptr);
 484
 485                --  Case of underline encountered
 486
 487                if C = '_' then
 488
 489                   --  We do not accumulate the '_' in the checksum, so that
 490                   --  1_234 is equivalent to 1234, and does not trigger
 491                   --  compilation for "minimal recompilation" (gnatmake -m).
 492
 493                   loop
 494                      Scan_Ptr := Scan_Ptr + 1;
 495                      C := Source (Scan_Ptr);
 496                      exit when C /= '_';
 497                      Error_No_Double_Underline;
 498                   end loop;
 499
 500                   if C not in '0' .. '9' then
 501                      Error_Digit_Expected;
 502                      exit;
 503                   end if;
 504
 505                else
 506                   exit when C not in '0' .. '9';
 507                end if;
 508             end loop;
 509          end Scan_Integer;
 510
 511       --  Start of Processing for Nlit
 512
 513       begin
 514          Base := 10;
 515          UI_Base := Uint_10;
 516          UI_Int_Value := Uint_0;
 517          Scale := 0;
 518          Scan_Integer;
 519          Point_Scanned := False;
 520          UI_Num_Value := UI_Int_Value;
 521
 522          --  Various possibilities now for continuing the literal are period,
 523          --  E/e (for exponent), or :/# (for based literal).
 524
 525          Scale := 0;
 526          C := Source (Scan_Ptr);
 527
 528          if C = '.' then
 529
 530             --  Scan out point, but do not scan past .. which is a range
 531             --  sequence, and must not be eaten up scanning a numeric literal.
 532
 533             while C = '.' and then Source (Scan_Ptr + 1) /= '.' loop
 534                Accumulate_Checksum ('.');
 535
 536                if Point_Scanned then
 537                   Error_Msg_S ("duplicate point ignored");
 538                end if;
 539
 540                Point_Scanned := True;
 541                Scan_Ptr := Scan_Ptr + 1;
 542                C := Source (Scan_Ptr);
 543
 544                if C not in '0' .. '9' then
 545                   Error_Msg
 546                     ("real literal cannot end with point", Scan_Ptr - 1);
 547                else
 548                   Scan_Integer;
 549                   UI_Num_Value := UI_Int_Value;
 550                end if;
 551             end loop;
 552
 553          --  Based literal case. The base is the value we already scanned.
 554          --  In the case of colon, we insist that the following character
 555          --  is indeed an extended digit or a period. This catches a number
 556          --  of common errors, as well as catching the well known tricky
 557          --  bug otherwise arising from "x : integer range 1 .. 10:= 6;"
 558
 559          elsif C = '#'
 560            or else (C = ':' and then
 561                       (Source (Scan_Ptr + 1) = '.'
 562                          or else
 563                        Source (Scan_Ptr + 1) in '0' .. '9'
 564                          or else
 565                        Source (Scan_Ptr + 1) in 'A' .. 'Z'
 566                          or else
 567                        Source (Scan_Ptr + 1) in 'a' .. 'z'))
 568          then
 569             if C = ':' then
 570                Obsolescent_Check (Scan_Ptr);
 571
 572                if Warn_On_Obsolescent_Feature then
 573                   Error_Msg_S
 574                     ("use of "":"" is an obsolescent feature (RM J.2(3))?");
 575                   Error_Msg_S
 576                     ("\use ""'#"" instead?");
 577                end if;
 578             end if;
 579
 580             Accumulate_Checksum (C);
 581             Base_Char := C;
 582             UI_Base := UI_Int_Value;
 583
 584             if UI_Base < 2 or else UI_Base > 16 then
 585                Error_Msg_SC ("base not 2-16");
 586                UI_Base := Uint_16;
 587             end if;
 588
 589             Base := UI_To_Int (UI_Base);
 590             Scan_Ptr := Scan_Ptr + 1;
 591
 592             --  Scan out extended integer [. integer]
 593
 594             C := Source (Scan_Ptr);
 595             UI_Int_Value := Uint_0;
 596             Scale := 0;
 597
 598             loop
 599                if C in '0' .. '9' then
 600                   Accumulate_Checksum (C);
 601                   Extended_Digit_Value :=
 602                     Int'(Character'Pos (C)) - Int'(Character'Pos ('0'));
 603
 604                elsif C in 'A' .. 'F' then
 605                   Accumulate_Checksum (Character'Val (Character'Pos (C) + 32));
 606                   Extended_Digit_Value :=
 607                     Int'(Character'Pos (C)) - Int'(Character'Pos ('A')) + 10;
 608
 609                elsif C in 'a' .. 'f' then
 610                   Accumulate_Checksum (C);
 611                   Extended_Digit_Value :=
 612                     Int'(Character'Pos (C)) - Int'(Character'Pos ('a')) + 10;
 613
 614                else
 615                   Error_Msg_S ("extended digit expected");
 616                   exit;
 617                end if;
 618
 619                if Extended_Digit_Value >= Base then
 620                   Error_Msg_S ("digit '>= base");
 621                end if;
 622
 623                UI_Int_Value := UI_Int_Value * UI_Base + Extended_Digit_Value;
 624                Scale := Scale - 1;
 625                Scan_Ptr := Scan_Ptr + 1;
 626                C := Source (Scan_Ptr);
 627
 628                if C = '_' then
 629                   loop
 630                      Accumulate_Checksum ('_');
 631                      Scan_Ptr := Scan_Ptr + 1;
 632                      C := Source (Scan_Ptr);
 633                      exit when C /= '_';
 634                      Error_No_Double_Underline;
 635                   end loop;
 636
 637                elsif C = '.' then
 638                   Accumulate_Checksum ('.');
 639
 640                   if Point_Scanned then
 641                      Error_Msg_S ("duplicate point ignored");
 642                   end if;
 643
 644                   Scan_Ptr := Scan_Ptr + 1;
 645                   C := Source (Scan_Ptr);
 646                   Point_Scanned := True;
 647                   Scale := 0;
 648
 649                elsif C = Base_Char then
 650                   Accumulate_Checksum (C);
 651                   Scan_Ptr := Scan_Ptr + 1;
 652                   exit;
 653
 654                elsif C = '#' or else C = ':' then
 655                   Error_Msg_S ("based number delimiters must match");
 656                   Scan_Ptr := Scan_Ptr + 1;
 657                   exit;
 658
 659                elsif not Identifier_Char (C) then
 660                   if Base_Char = '#' then
 661                      Error_Msg_S ("missing '#");
 662                   else
 663                      Error_Msg_S ("missing ':");
 664                   end if;
 665
 666                   exit;
 667                end if;
 668
 669             end loop;
 670
 671             UI_Num_Value := UI_Int_Value;
 672          end if;
 673
 674          --  Scan out exponent
 675
 676          if not Point_Scanned then
 677             Scale := 0;
 678             UI_Scale := Uint_0;
 679          else
 680             UI_Scale := UI_From_Int (Scale);
 681          end if;
 682
 683          if Source (Scan_Ptr) = 'e' or else Source (Scan_Ptr) = 'E' then
 684             Accumulate_Checksum ('e');
 685             Scan_Ptr := Scan_Ptr + 1;
 686             Exponent_Is_Negative := False;
 687
 688             if Source (Scan_Ptr) = '+' then
 689                Accumulate_Checksum ('+');
 690                Scan_Ptr := Scan_Ptr + 1;
 691
 692             elsif Source (Scan_Ptr) = '-' then
 693                Accumulate_Checksum ('-');
 694
 695                if not Point_Scanned then
 696                   Error_Msg_S
 697                     ("negative exponent not allowed for integer literal");
 698                else
 699                   Exponent_Is_Negative := True;
 700                end if;
 701
 702                Scan_Ptr := Scan_Ptr + 1;
 703             end if;
 704
 705             UI_Int_Value := Uint_0;
 706
 707             if Source (Scan_Ptr) in '0' .. '9' then
 708                Scan_Integer;
 709             else
 710                Error_Digit_Expected;
 711             end if;
 712
 713             if Exponent_Is_Negative then
 714                UI_Scale := UI_Scale - UI_Int_Value;
 715             else
 716                UI_Scale := UI_Scale + UI_Int_Value;
 717             end if;
 718          end if;
 719
 720          --  Case of real literal to be returned
 721
 722          if Point_Scanned then
 723             Token := Tok_Real_Literal;
 724             Real_Literal_Value :=
 725               UR_From_Components (
 726                                   Num   => UI_Num_Value,
 727                                   Den   => -UI_Scale,
 728                                   Rbase => Base);
 729
 730          --  Case of integer literal to be returned
 731
 732          else
 733             Token := Tok_Integer_Literal;
 734
 735             if UI_Scale = 0 then
 736                Int_Literal_Value := UI_Num_Value;
 737
 738             --  Avoid doing possibly expensive calculations in cases like
 739             --  parsing 163E800_000# when semantics will not be done anyway.
 740             --  This is especially useful when parsing garbled input.
 741
 742             elsif Operating_Mode /= Check_Syntax
 743               and then (Serious_Errors_Detected = 0 or else Try_Semantics)
 744             then
 745                Int_Literal_Value := UI_Num_Value * UI_Base ** UI_Scale;
 746
 747             else
 748                Int_Literal_Value := No_Uint;
 749             end if;
 750          end if;
 751
 752          Accumulate_Token_Checksum;
 753
 754          return;
 755       end Nlit;
 756
 757       ----------
 758       -- Slit --
 759       ----------
 760
 761       procedure Slit is
 762
 763          Delimiter : Character;
 764          --  Delimiter (first character of string)
 765
 766          C : Character;
 767          --  Current source program character
 768
 769          Code : Char_Code;
 770          --  Current character code value
 771
 772          Err : Boolean;
 773          --  Error flag for Scan_Wide call
 774
 775          procedure Error_Bad_String_Char;
 776          --  Signal bad character in string/character literal. On entry
 777          --  Scan_Ptr points to the improper character encountered during the
 778          --  scan. Scan_Ptr is not modified, so it still points to the bad
 779          --  character on return.
 780
 781          procedure Error_Unterminated_String;
 782          --  Procedure called if a line terminator character is encountered
 783          --  during scanning a string, meaning that the string is not properly
 784          --  terminated.
 785
 786          procedure Set_String;
 787          --  Procedure used to distinguish between string and operator symbol.
 788          --  On entry the string has been scanned out, and its characters
 789          --  start at Token_Ptr and end one character before Scan_Ptr. On exit
 790          --  Token is set to Tok_String_Literal or Tok_Operator_Symbol as
 791          --  appropriate, and Token_Node is appropriately initialized. In
 792          --  addition, in the operator symbol case, Token_Name is
 793          --  appropriately set.
 794
 795          ---------------------------
 796          -- Error_Bad_String_Char --
 797          ---------------------------
 798
 799          procedure Error_Bad_String_Char is
 800             C : constant Character := Source (Scan_Ptr);
 801
 802          begin
 803             if C = HT then
 804                Error_Msg_S ("horizontal tab not allowed in string");
 805
 806             elsif C = VT or else C = FF then
 807                Error_Msg_S ("format effector not allowed in string");
 808
 809             elsif C in Upper_Half_Character then
 810                Error_Msg_S ("(Ada 83) upper half character not allowed");
 811
 812             else
 813                Error_Msg_S ("control character not allowed in string");
 814             end if;
 815          end Error_Bad_String_Char;
 816
 817          -------------------------------
 818          -- Error_Unterminated_String --
 819          -------------------------------
 820
 821          procedure Error_Unterminated_String is
 822          begin
 823             --  An interesting little refinement. Consider the following
 824             --  examples:
 825
 826             --     A := "this is an unterminated string;
 827             --     A := "this is an unterminated string &
 828             --     P(A, "this is a parameter that didn't get terminated);
 829
 830             --  We fiddle a little to do slightly better placement in these
 831             --  cases also if there is white space at the end of the line we
 832             --  place the flag at the start of this white space, not at the
 833             --  end. Note that we only have to test for blanks, since tabs
 834             --  aren't allowed in strings in the first place and would have
 835             --  caused an error message.
 836
 837             --  Two more cases that we treat specially are:
 838
 839             --     A := "this string uses the wrong terminator'
 840             --     A := "this string uses the wrong terminator' &
 841
 842             --  In these cases we give a different error message as well
 843
 844             --  We actually reposition the scan pointer to the point where we
 845             --  place the flag in these cases, since it seems a better bet on
 846             --  the original intention.
 847
 848             while Source (Scan_Ptr - 1) = ' '
 849               or else Source (Scan_Ptr - 1) = '&'
 850             loop
 851                Scan_Ptr := Scan_Ptr - 1;
 852                Unstore_String_Char;
 853             end loop;
 854
 855             --  Check for case of incorrect string terminator, but single quote
 856             --  is not considered incorrect if the opening terminator misused
 857             --  a single quote (error message already given).
 858
 859             if Delimiter /= '''
 860               and then Source (Scan_Ptr - 1) = '''
 861             then
 862                Unstore_String_Char;
 863                Error_Msg
 864                  ("incorrect string terminator character", Scan_Ptr - 1);
 865                return;
 866             end if;
 867
 868             if Source (Scan_Ptr - 1) = ';' then
 869                Scan_Ptr := Scan_Ptr - 1;
 870                Unstore_String_Char;
 871
 872                if Source (Scan_Ptr - 1) = ')' then
 873                   Scan_Ptr := Scan_Ptr - 1;
 874                   Unstore_String_Char;
 875                end if;
 876             end if;
 877
 878             Error_Msg_S ("missing string quote");
 879          end Error_Unterminated_String;
 880
 881          ----------------
 882          -- Set_String --
 883          ----------------
 884
 885          procedure Set_String is
 886             Slen : constant Int := Int (Scan_Ptr - Token_Ptr - 2);
 887             C1   : Character;
 888             C2   : Character;
 889             C3   : Character;
 890
 891          begin
 892             --  Token_Name is currently set to Error_Name. The following
 893             --  section of code resets Token_Name to the proper Name_Op_xx
 894             --  value if the string is a valid operator symbol, otherwise it is
 895             --  left set to Error_Name.
 896
 897             if Slen = 1 then
 898                C1 := Source (Token_Ptr + 1);
 899
 900                case C1 is
 901                   when '=' =>
 902                      Token_Name := Name_Op_Eq;
 903
 904                   when '>' =>
 905                      Token_Name := Name_Op_Gt;
 906
 907                   when '<' =>
 908                      Token_Name := Name_Op_Lt;
 909
 910                   when '+' =>
 911                      Token_Name := Name_Op_Add;
 912
 913                   when '-' =>
 914                      Token_Name := Name_Op_Subtract;
 915
 916                   when '&' =>
 917                      Token_Name := Name_Op_Concat;
 918
 919                   when '*' =>
 920                      Token_Name := Name_Op_Multiply;
 921
 922                   when '/' =>
 923                      Token_Name := Name_Op_Divide;
 924
 925                   when others =>
 926                      null;
 927                end case;
 928
 929             elsif Slen = 2 then
 930                C1 := Source (Token_Ptr + 1);
 931                C2 := Source (Token_Ptr + 2);
 932
 933                if C1 = '*' and then C2 = '*' then
 934                   Token_Name := Name_Op_Expon;
 935
 936                elsif C2 = '=' then
 937
 938                   if C1 = '/' then
 939                      Token_Name := Name_Op_Ne;
 940                   elsif C1 = '<' then
 941                      Token_Name := Name_Op_Le;
 942                   elsif C1 = '>' then
 943                      Token_Name := Name_Op_Ge;
 944                   end if;
 945
 946                elsif (C1 = 'O' or else C1 = 'o') and then    -- OR
 947                  (C2 = 'R' or else C2 = 'r')
 948                then
 949                   Token_Name := Name_Op_Or;
 950                end if;
 951
 952             elsif Slen = 3 then
 953                C1 := Source (Token_Ptr + 1);
 954                C2 := Source (Token_Ptr + 2);
 955                C3 := Source (Token_Ptr + 3);
 956
 957                if (C1 = 'A' or else C1 = 'a') and then       -- AND
 958                  (C2 = 'N' or else C2 = 'n') and then
 959                  (C3 = 'D' or else C3 = 'd')
 960                then
 961                   Token_Name := Name_Op_And;
 962
 963                elsif (C1 = 'A' or else C1 = 'a') and then    -- ABS
 964                  (C2 = 'B' or else C2 = 'b') and then
 965                  (C3 = 'S' or else C3 = 's')
 966                then
 967                   Token_Name := Name_Op_Abs;
 968
 969                elsif (C1 = 'M' or else C1 = 'm') and then    -- MOD
 970                  (C2 = 'O' or else C2 = 'o') and then
 971                  (C3 = 'D' or else C3 = 'd')
 972                then
 973                   Token_Name := Name_Op_Mod;
 974
 975                elsif (C1 = 'N' or else C1 = 'n') and then    -- NOT
 976                  (C2 = 'O' or else C2 = 'o') and then
 977                  (C3 = 'T' or else C3 = 't')
 978                then
 979                   Token_Name := Name_Op_Not;
 980
 981                elsif (C1 = 'R' or else C1 = 'r') and then    -- REM
 982                  (C2 = 'E' or else C2 = 'e') and then
 983                  (C3 = 'M' or else C3 = 'm')
 984                then
 985                   Token_Name := Name_Op_Rem;
 986
 987                elsif (C1 = 'X' or else C1 = 'x') and then    -- XOR
 988                  (C2 = 'O' or else C2 = 'o') and then
 989                  (C3 = 'R' or else C3 = 'r')
 990                then
 991                   Token_Name := Name_Op_Xor;
 992                end if;
 993
 994             end if;
 995
 996             --  If it is an operator symbol, then Token_Name is set. If it is
 997             --  some other string value, then Token_Name still contains
 998             --  Error_Name.
 999
1000             if Token_Name = Error_Name then
1001                Token := Tok_String_Literal;
1002
1003             else
1004                Token := Tok_Operator_Symbol;
1005             end if;
1006          end Set_String;
1007
1008       --  Start of processing for Slit
1009
1010       begin
1011          --  On entry, Scan_Ptr points to the opening character of the string
1012          --  which is either a percent, double quote, or apostrophe (single
1013          --  quote). The latter case is an error detected by the character
1014          --  literal circuit.
1015
1016          Delimiter := Source (Scan_Ptr);
1017          Accumulate_Checksum (Delimiter);
1018          Start_String;
1019          Scan_Ptr := Scan_Ptr + 1;
1020
1021          --  Loop to scan out characters of string literal
1022
1023          loop
1024             C := Source (Scan_Ptr);
1025
1026             if C = Delimiter then
1027                Accumulate_Checksum (C);
1028                Scan_Ptr := Scan_Ptr + 1;
1029                exit when Source (Scan_Ptr) /= Delimiter;
1030                Code := Get_Char_Code (C);
1031                Accumulate_Checksum (C);
1032                Scan_Ptr := Scan_Ptr + 1;
1033
1034             else
1035                if C = '"' and then Delimiter = '%' then
1036                   Error_Msg_S
1037                     ("quote not allowed in percent delimited string");
1038                   Code := Get_Char_Code (C);
1039                   Scan_Ptr := Scan_Ptr + 1;
1040
1041                elsif (C = ESC
1042                         and then Wide_Character_Encoding_Method
1043                                    in WC_ESC_Encoding_Method)
1044                  or else (C in Upper_Half_Character
1045                             and then Upper_Half_Encoding)
1046                  or else (C = '['
1047                             and then Source (Scan_Ptr + 1) = '"'
1048                             and then Identifier_Char (Source (Scan_Ptr + 2)))
1049                then
1050                   Wptr := Scan_Ptr;
1051                   Scan_Wide (Source, Scan_Ptr, Code, Err);
1052
1053                   if Err then
1054                      Error_Illegal_Wide_Character;
1055                      Code := Get_Char_Code (' ');
1056                   end if;
1057
1058                   Accumulate_Checksum (Code);
1059
1060                   --  In Ada 95 mode we allow any wide characters in a string
1061                   --  but in Ada 2005, the set of characters allowed has been
1062                   --  restricted to graphic characters.
1063
1064                   if Ada_Version >= Ada_05
1065                     and then Is_UTF_32_Non_Graphic (UTF_32 (Code))
1066                   then
1067                      Error_Msg
1068                        ("(Ada 2005) non-graphic character not permitted " &
1069                         "in string literal", Wptr);
1070                   end if;
1071
1072                else
1073                   Accumulate_Checksum (C);
1074
1075                   if C not in Graphic_Character then
1076                      if C in Line_Terminator then
1077                         Error_Unterminated_String;
1078                         exit;
1079
1080                      elsif C in Upper_Half_Character then
1081                         if Ada_Version = Ada_83 then
1082                            Error_Bad_String_Char;
1083                         end if;
1084
1085                      else
1086                         Error_Bad_String_Char;
1087                      end if;
1088                   end if;
1089
1090                   Code := Get_Char_Code (C);
1091                   Scan_Ptr := Scan_Ptr + 1;
1092                end if;
1093             end if;
1094
1095             Store_String_Char (Code);
1096
1097             if not In_Character_Range (Code) then
1098                Wide_Character_Found := True;
1099             end if;
1100          end loop;
1101
1102          String_Literal_Id := End_String;
1103          Set_String;
1104          return;
1105       end Slit;
1106
1107    --  Start of processing for Scan
1108
1109    begin
1110       Prev_Token := Token;
1111       Prev_Token_Ptr := Token_Ptr;
1112       Token_Name := Error_Name;
1113
1114       --  The following loop runs more than once only if a format effector
1115       --  (tab, vertical tab, form  feed, line feed, carriage return) is
1116       --  encountered and skipped, or some error situation, such as an
1117       --  illegal character, is encountered.
1118
1119       <<Scan_Next_Character>>
1120
1121       loop
1122          --  Skip past blanks, loop is opened up for speed
1123
1124          while Source (Scan_Ptr) = ' ' loop
1125             if Source (Scan_Ptr + 1) /= ' ' then
1126                Scan_Ptr := Scan_Ptr + 1;
1127                exit;
1128             end if;
1129
1130             if Source (Scan_Ptr + 2) /= ' ' then
1131                Scan_Ptr := Scan_Ptr + 2;
1132                exit;
1133             end if;
1134
1135             if Source (Scan_Ptr + 3) /= ' ' then
1136                Scan_Ptr := Scan_Ptr + 3;
1137                exit;
1138             end if;
1139
1140             if Source (Scan_Ptr + 4) /= ' ' then
1141                Scan_Ptr := Scan_Ptr + 4;
1142                exit;
1143             end if;
1144
1145             if Source (Scan_Ptr + 5) /= ' ' then
1146                Scan_Ptr := Scan_Ptr + 5;
1147                exit;
1148             end if;
1149
1150             if Source (Scan_Ptr + 6) /= ' ' then
1151                Scan_Ptr := Scan_Ptr + 6;
1152                exit;
1153             end if;
1154
1155             if Source (Scan_Ptr + 7) /= ' ' then
1156                Scan_Ptr := Scan_Ptr + 7;
1157                exit;
1158             end if;
1159
1160             Scan_Ptr := Scan_Ptr + 8;
1161          end loop;
1162
1163          --  We are now at a non-blank character, which is the first character
1164          --  of the token we will scan, and hence the value of Token_Ptr.
1165
1166          Token_Ptr := Scan_Ptr;
1167
1168          --  Here begins the main case statement which transfers control on the
1169          --  basis of the non-blank character we have encountered.
1170
1171          case Source (Scan_Ptr) is
1172
1173          --  Line terminator characters
1174
1175          when CR | LF | FF | VT =>
1176             goto Scan_Line_Terminator;
1177
1178          --  Horizontal tab, just skip past it
1179
1180          when HT =>
1181             if Style_Check then
1182                Style.Check_HT;
1183             end if;
1184
1185             Scan_Ptr := Scan_Ptr + 1;
1186
1187          --  End of file character, treated as an end of file only if it is
1188          --  the last character in the buffer, otherwise it is ignored.
1189
1190          when EOF =>
1191             if Scan_Ptr = Source_Last (Current_Source_File) then
1192                Check_End_Of_Line;
1193
1194                if Style_Check then
1195                   Style.Check_EOF;
1196                end if;
1197
1198                Token := Tok_EOF;
1199                return;
1200             else
1201                Scan_Ptr := Scan_Ptr + 1;
1202             end if;
1203
1204          --  Ampersand
1205
1206          when '&' =>
1207             Accumulate_Checksum ('&');
1208
1209             if Source (Scan_Ptr + 1) = '&' then
1210                Error_Msg_S ("'&'& should be `AND THEN`");
1211                Scan_Ptr := Scan_Ptr + 2;
1212                Token := Tok_And;
1213                return;
1214
1215             else
1216                Scan_Ptr := Scan_Ptr + 1;
1217                Token := Tok_Ampersand;
1218                return;
1219             end if;
1220
1221          --  Asterisk (can be multiplication operator or double asterisk which
1222          --  is the exponentiation compound delimiter).
1223
1224          when '*' =>
1225             Accumulate_Checksum ('*');
1226
1227             if Source (Scan_Ptr + 1) = '*' then
1228                Accumulate_Checksum ('*');
1229                Scan_Ptr := Scan_Ptr + 2;
1230                Token := Tok_Double_Asterisk;
1231                return;
1232
1233             else
1234                Scan_Ptr := Scan_Ptr + 1;
1235                Token := Tok_Asterisk;
1236                return;
1237             end if;
1238
1239          --  Colon, which can either be an isolated colon, or part of an
1240          --  assignment compound delimiter.
1241
1242          when ':' =>
1243             Accumulate_Checksum (':');
1244
1245             if Double_Char_Token ('=') then
1246                Token := Tok_Colon_Equal;
1247
1248                if Style_Check then
1249                   Style.Check_Colon_Equal;
1250                end if;
1251
1252                return;
1253
1254             elsif Source (Scan_Ptr + 1) = '-'
1255               and then Source (Scan_Ptr + 2) /= '-'
1256             then
1257                Token := Tok_Colon_Equal;
1258                Error_Msg (":- should be :=", Scan_Ptr);
1259                Scan_Ptr := Scan_Ptr + 2;
1260                return;
1261
1262             else
1263                Scan_Ptr := Scan_Ptr + 1;
1264                Token := Tok_Colon;
1265
1266                if Style_Check then
1267                   Style.Check_Colon;
1268                end if;
1269
1270                return;
1271             end if;
1272
1273          --  Left parenthesis
1274
1275          when '(' =>
1276             Accumulate_Checksum ('(');
1277             Scan_Ptr := Scan_Ptr + 1;
1278             Token := Tok_Left_Paren;
1279
1280             if Style_Check then
1281                Style.Check_Left_Paren;
1282             end if;
1283
1284             return;
1285
1286          --  Left bracket
1287
1288          when '[' =>
1289             if Source (Scan_Ptr + 1) = '"' then
1290                goto Scan_Wide_Character;
1291
1292             else
1293                Error_Msg_S ("illegal character, replaced by ""(""");
1294                Scan_Ptr := Scan_Ptr + 1;
1295                Token := Tok_Left_Paren;
1296                return;
1297             end if;
1298
1299          --  Left brace
1300
1301          when '{' =>
1302             Error_Msg_S ("illegal character, replaced by ""(""");
1303             Scan_Ptr := Scan_Ptr + 1;
1304             Token := Tok_Left_Paren;
1305             return;
1306
1307          --  Comma
1308
1309          when ',' =>
1310             Accumulate_Checksum (',');
1311             Scan_Ptr := Scan_Ptr + 1;
1312             Token := Tok_Comma;
1313
1314             if Style_Check then
1315                Style.Check_Comma;
1316             end if;
1317
1318             return;
1319
1320          --  Dot, which is either an isolated period, or part of a double dot
1321          --  compound delimiter sequence. We also check for the case of a
1322          --  digit following the period, to give a better error message.
1323
1324          when '.' =>
1325             Accumulate_Checksum ('.');
1326
1327             if Double_Char_Token ('.') then
1328                Token := Tok_Dot_Dot;
1329
1330                if Style_Check then
1331                   Style.Check_Dot_Dot;
1332                end if;
1333
1334                return;
1335
1336             elsif Source (Scan_Ptr + 1) in '0' .. '9' then
1337                Error_Msg_S ("numeric literal cannot start with point");
1338                Scan_Ptr := Scan_Ptr + 1;
1339
1340             else
1341                Scan_Ptr := Scan_Ptr + 1;
1342                Token := Tok_Dot;
1343                return;
1344             end if;
1345
1346          --  Equal, which can either be an equality operator, or part of the
1347          --  arrow (=>) compound delimiter.
1348
1349          when '=' =>
1350             Accumulate_Checksum ('=');
1351
1352             if Double_Char_Token ('>') then
1353                Token := Tok_Arrow;
1354
1355                if Style_Check then
1356                   Style.Check_Arrow;
1357                end if;
1358
1359                return;
1360
1361             elsif Source (Scan_Ptr + 1) = '=' then
1362                Error_Msg_S ("== should be =");
1363                Scan_Ptr := Scan_Ptr + 1;
1364             end if;
1365
1366             Scan_Ptr := Scan_Ptr + 1;
1367             Token := Tok_Equal;
1368             return;
1369
1370          --  Greater than, which can be a greater than operator, greater than
1371          --  or equal operator, or first character of a right label bracket.
1372
1373          when '>' =>
1374             Accumulate_Checksum ('>');
1375
1376             if Double_Char_Token ('=') then
1377                Token := Tok_Greater_Equal;
1378                return;
1379
1380             elsif Double_Char_Token ('>') then
1381                Token := Tok_Greater_Greater;
1382                return;
1383
1384             else
1385                Scan_Ptr := Scan_Ptr + 1;
1386                Token := Tok_Greater;
1387                return;
1388             end if;
1389
1390          --  Less than, which can be a less than operator, less than or equal
1391          --  operator, or the first character of a left label bracket, or the
1392          --  first character of a box (<>) compound delimiter.
1393
1394          when '<' =>
1395             Accumulate_Checksum ('<');
1396
1397             if Double_Char_Token ('=') then
1398                Token := Tok_Less_Equal;
1399                return;
1400
1401             elsif Double_Char_Token ('>') then
1402                Token := Tok_Box;
1403
1404                if Style_Check then
1405                   Style.Check_Box;
1406                end if;
1407
1408                return;
1409
1410             elsif Double_Char_Token ('<') then
1411                Token := Tok_Less_Less;
1412                return;
1413
1414             else
1415                Scan_Ptr := Scan_Ptr + 1;
1416                Token := Tok_Less;
1417                return;
1418             end if;
1419
1420          --  Minus, which is either a subtraction operator, or the first
1421          --  character of double minus starting a comment
1422
1423          when '-' => Minus_Case : begin
1424             if Source (Scan_Ptr + 1) = '>' then
1425                Error_Msg_S ("invalid token");
1426                Scan_Ptr := Scan_Ptr + 2;
1427                Token := Tok_Arrow;
1428                return;
1429
1430             elsif Source (Scan_Ptr + 1) /= '-' then
1431                Accumulate_Checksum ('-');
1432                Scan_Ptr := Scan_Ptr + 1;
1433                Token := Tok_Minus;
1434                return;
1435
1436             --  Comment
1437
1438             else -- Source (Scan_Ptr + 1) = '-' then
1439                if Style_Check then
1440                   Style.Check_Comment;
1441                end if;
1442
1443                Scan_Ptr := Scan_Ptr + 2;
1444
1445                --  If we are in preprocessor mode with Replace_In_Comments set,
1446                --  then we return the "--" as a token on its own.
1447
1448                if Replace_In_Comments then
1449                   Token := Tok_Comment;
1450                   return;
1451                end if;
1452
1453                --  Otherwise scan out the comment
1454
1455                Start_Of_Comment := Scan_Ptr;
1456
1457                --  Loop to scan comment (this loop runs more than once only if
1458                --  a horizontal tab or other non-graphic character is scanned)
1459
1460                loop
1461                   --  Scan to non graphic character (opened up for speed)
1462
1463                   --  Note that we just eat left brackets, which means that
1464                   --  bracket notation cannot be used for end of line
1465                   --  characters in comments. This seems a reasonable choice,
1466                   --  since no one would ever use brackets notation in a real
1467                   --  program in this situation, and if we allow brackets
1468                   --  notation, we forbid some valid comments which contain a
1469                   --  brackets sequence that happens to match an end of line
1470                   --  character.
1471
1472                   loop
1473                      exit when Source (Scan_Ptr) not in Graphic_Character;
1474                      Scan_Ptr := Scan_Ptr + 1;
1475                      exit when Source (Scan_Ptr) not in Graphic_Character;
1476                      Scan_Ptr := Scan_Ptr + 1;
1477                      exit when Source (Scan_Ptr) not in Graphic_Character;
1478                      Scan_Ptr := Scan_Ptr + 1;
1479                      exit when Source (Scan_Ptr) not in Graphic_Character;
1480                      Scan_Ptr := Scan_Ptr + 1;
1481                      exit when Source (Scan_Ptr) not in Graphic_Character;
1482                      Scan_Ptr := Scan_Ptr + 1;
1483                   end loop;
1484
1485                   --  Keep going if horizontal tab
1486
1487                   if Source (Scan_Ptr) = HT then
1488                      if Style_Check then
1489                         Style.Check_HT;
1490                      end if;
1491
1492                      Scan_Ptr := Scan_Ptr + 1;
1493
1494                   --  Terminate scan of comment if line terminator
1495
1496                   elsif Source (Scan_Ptr) in Line_Terminator then
1497                      exit;
1498
1499                   --  Terminate scan of comment if end of file encountered
1500                   --  (embedded EOF character or real last character in file)
1501
1502                   elsif Source (Scan_Ptr) = EOF then
1503                      exit;
1504
1505                   --  If we have a wide character, we have to scan it out,
1506                   --  because it might be a legitimate line terminator
1507
1508                   elsif (Source (Scan_Ptr) = ESC
1509                            and then Identifier_Char (ESC))
1510                     or else
1511                          (Source (Scan_Ptr) in Upper_Half_Character
1512                             and then Upper_Half_Encoding)
1513                   then
1514                      declare
1515                         Wptr : constant Source_Ptr := Scan_Ptr;
1516                         Code : Char_Code;
1517                         Err  : Boolean;
1518
1519                      begin
1520                         Scan_Wide (Source, Scan_Ptr, Code, Err);
1521
1522                         --  If not well formed wide character, then just skip
1523                         --  past it and ignore it.
1524
1525                         if Err then
1526                            Scan_Ptr := Wptr + 1;
1527
1528                         --  If UTF_32 terminator, terminate comment scan
1529
1530                         elsif Is_UTF_32_Line_Terminator (UTF_32 (Code)) then
1531                            Scan_Ptr := Wptr;
1532                            exit;
1533                         end if;
1534                      end;
1535
1536                   --  Keep going if character in 80-FF range, or is ESC. These
1537                   --  characters are allowed in comments by RM-2.1(1), 2.7(2).
1538                   --  They are allowed even in Ada 83 mode according to the
1539                   --  approved AI. ESC was added to the AI in June 93.
1540
1541                   elsif Source (Scan_Ptr) in Upper_Half_Character
1542                      or else Source (Scan_Ptr) = ESC
1543                   then
1544                      Scan_Ptr := Scan_Ptr + 1;
1545
1546                   --  Otherwise we have an illegal comment character
1547
1548                   else
1549                      Error_Illegal_Character;
1550                   end if;
1551                end loop;
1552
1553                --  Note that, except when comments are tokens, we do NOT
1554                --  execute a return here, instead we fall through to reexecute
1555                --  the scan loop to look for a token.
1556
1557                if Comment_Is_Token then
1558                   Name_Len := Integer (Scan_Ptr - Start_Of_Comment);
1559                   Name_Buffer (1 .. Name_Len) :=
1560                     String (Source (Start_Of_Comment .. Scan_Ptr - 1));
1561                   Comment_Id := Name_Find;
1562                   Token := Tok_Comment;
1563                   return;
1564                end if;
1565             end if;
1566          end Minus_Case;
1567
1568          --  Double quote starting a string literal
1569
1570          when '"' =>
1571             Slit;
1572             Post_Scan;
1573             return;
1574
1575          --  Percent starting a string literal
1576
1577          when '%' =>
1578             Obsolescent_Check (Token_Ptr);
1579
1580             if Warn_On_Obsolescent_Feature then
1581                Error_Msg_S
1582                  ("use of ""'%"" is an obsolescent feature (RM J.2(4))?");
1583                Error_Msg_S
1584                  ("\use """""" instead?");
1585             end if;
1586
1587             Slit;
1588             Post_Scan;
1589             return;
1590
1591          --  Apostrophe. This can either be the start of a character literal,
1592          --  or an isolated apostrophe used in a qualified expression or an
1593          --  attribute. We treat it as a character literal if it does not
1594          --  follow a right parenthesis, identifier, the keyword ALL or
1595          --  a literal. This means that we correctly treat constructs like:
1596
1597          --    A := CHARACTER'('A');
1598
1599          --  Note that RM-2.2(7) does not require a separator between
1600          --  "CHARACTER" and "'" in the above.
1601
1602          when ''' => Char_Literal_Case : declare
1603             Code : Char_Code;
1604             Err  : Boolean;
1605
1606          begin
1607             Accumulate_Checksum (''');
1608             Scan_Ptr := Scan_Ptr + 1;
1609
1610             --  Here is where we make the test to distinguish the cases. Treat
1611             --  as apostrophe if previous token is an identifier, right paren
1612             --  or the reserved word "all" (latter case as in A.all'Address)
1613             --  (or the reserved word "project" in project files). Also treat
1614             --  it as apostrophe after a literal (this catches some legitimate
1615             --  cases, like A."abs"'Address, and also gives better error
1616             --  behavior for impossible cases like 123'xxx).
1617
1618             if Prev_Token = Tok_Identifier
1619                or else Prev_Token = Tok_Right_Paren
1620                or else Prev_Token = Tok_All
1621                or else Prev_Token = Tok_Project
1622                or else Prev_Token in Token_Class_Literal
1623             then
1624                Token := Tok_Apostrophe;
1625
1626                if Style_Check then
1627                   Style.Check_Apostrophe;
1628                end if;
1629
1630                return;
1631
1632             --  Otherwise the apostrophe starts a character literal
1633
1634             else
1635                --  Case of wide character literal
1636
1637                if (Source (Scan_Ptr) = ESC
1638                      and then
1639                     Wide_Character_Encoding_Method in WC_ESC_Encoding_Method)
1640                  or else
1641                    (Source (Scan_Ptr) in Upper_Half_Character
1642                      and then
1643                     Upper_Half_Encoding)
1644                  or else
1645                    (Source (Scan_Ptr) = '['
1646                      and then
1647                     Source (Scan_Ptr + 1) = '"')
1648                then
1649                   Wptr := Scan_Ptr;
1650                   Scan_Wide (Source, Scan_Ptr, Code, Err);
1651                   Accumulate_Checksum (Code);
1652
1653                   if Err then
1654                      Error_Illegal_Wide_Character;
1655                      Code := Character'Pos (' ');
1656
1657                   --  In Ada 95 mode we allow any wide character in a character
1658                   --  literal, but in Ada 2005, the set of characters allowed
1659                   --  is restricted to graphic characters.
1660
1661                   elsif Ada_Version >= Ada_05
1662                     and then Is_UTF_32_Non_Graphic (UTF_32 (Code))
1663                   then
1664                      Error_Msg
1665                        ("(Ada 2005) non-graphic character not permitted " &
1666                         "in character literal", Wptr);
1667                   end if;
1668
1669                   if Source (Scan_Ptr) /= ''' then
1670                      Error_Msg_S ("missing apostrophe");
1671                   else
1672                      Scan_Ptr := Scan_Ptr + 1;
1673                   end if;
1674
1675                --  If we do not find a closing quote in the expected place then
1676                --  assume that we have a misguided attempt at a string literal.
1677
1678                --  However, if previous token is RANGE, then we return an
1679                --  apostrophe instead since this gives better error recovery
1680
1681                elsif Source (Scan_Ptr + 1) /= ''' then
1682                   if Prev_Token = Tok_Range then
1683                      Token := Tok_Apostrophe;
1684                      return;
1685
1686                   else
1687                      Scan_Ptr := Scan_Ptr - 1;
1688                      Error_Msg_S
1689                        ("strings are delimited by double quote character");
1690                      Slit;
1691                      Post_Scan;
1692                      return;
1693                   end if;
1694
1695                --  Otherwise we have a (non-wide) character literal
1696
1697                else
1698                   Accumulate_Checksum (Source (Scan_Ptr));
1699
1700                   if Source (Scan_Ptr) not in Graphic_Character then
1701                      if Source (Scan_Ptr) in Upper_Half_Character then
1702                         if Ada_Version = Ada_83 then
1703                            Error_Illegal_Character;
1704                         end if;
1705
1706                      else
1707                         Error_Illegal_Character;
1708                      end if;
1709                   end if;
1710
1711                   Code := Get_Char_Code (Source (Scan_Ptr));
1712                   Scan_Ptr := Scan_Ptr + 2;
1713                end if;
1714
1715                --  Fall through here with Scan_Ptr updated past the closing
1716                --  quote, and Code set to the Char_Code value for the literal
1717
1718                Accumulate_Checksum (''');
1719                Token := Tok_Char_Literal;
1720                Set_Character_Literal_Name (Code);
1721                Token_Name := Name_Find;
1722                Character_Code := Code;
1723                Post_Scan;
1724                return;
1725             end if;
1726          end Char_Literal_Case;
1727
1728          --  Right parenthesis
1729
1730          when ')' =>
1731             Accumulate_Checksum (')');
1732             Scan_Ptr := Scan_Ptr + 1;
1733             Token := Tok_Right_Paren;
1734
1735             if Style_Check then
1736                Style.Check_Right_Paren;
1737             end if;
1738
1739             return;
1740
1741          --  Right bracket or right brace, treated as right paren
1742
1743          when ']' | '}' =>
1744             Error_Msg_S ("illegal character, replaced by "")""");
1745             Scan_Ptr := Scan_Ptr + 1;
1746             Token := Tok_Right_Paren;
1747             return;
1748
1749          --  Slash (can be division operator or first character of not equal)
1750
1751          when '/' =>
1752             Accumulate_Checksum ('/');
1753
1754             if Double_Char_Token ('=') then
1755                Token := Tok_Not_Equal;
1756                return;
1757             else
1758                Scan_Ptr := Scan_Ptr + 1;
1759                Token := Tok_Slash;
1760                return;
1761             end if;
1762
1763          --  Semicolon
1764
1765          when ';' =>
1766             Accumulate_Checksum (';');
1767             Scan_Ptr := Scan_Ptr + 1;
1768             Token := Tok_Semicolon;
1769
1770             if Style_Check then
1771                Style.Check_Semicolon;
1772             end if;
1773
1774             return;
1775
1776          --  Vertical bar
1777
1778          when '|' => Vertical_Bar_Case : begin
1779             Accumulate_Checksum ('|');
1780
1781             --  Special check for || to give nice message
1782
1783             if Source (Scan_Ptr + 1) = '|' then
1784                Error_Msg_S ("""'|'|"" should be `OR ELSE`");
1785                Scan_Ptr := Scan_Ptr + 2;
1786                Token := Tok_Or;
1787                return;
1788
1789             else
1790                Scan_Ptr := Scan_Ptr + 1;
1791                Token := Tok_Vertical_Bar;
1792
1793                if Style_Check then
1794                   Style.Check_Vertical_Bar;
1795                end if;
1796
1797                return;
1798             end if;
1799          end Vertical_Bar_Case;
1800
1801          --  Exclamation, replacement character for vertical bar
1802
1803          when '!' => Exclamation_Case : begin
1804             Accumulate_Checksum ('!');
1805             Obsolescent_Check (Token_Ptr);
1806
1807             if Warn_On_Obsolescent_Feature then
1808                Error_Msg_S
1809                  ("use of ""'!"" is an obsolescent feature (RM J.2(2))?");
1810                Error_Msg_S
1811                  ("\use ""'|"" instead?");
1812             end if;
1813
1814             if Source (Scan_Ptr + 1) = '=' then
1815                Error_Msg_S ("'!= should be /=");
1816                Scan_Ptr := Scan_Ptr + 2;
1817                Token := Tok_Not_Equal;
1818                return;
1819
1820             else
1821                Scan_Ptr := Scan_Ptr + 1;
1822                Token := Tok_Vertical_Bar;
1823                return;
1824             end if;
1825          end Exclamation_Case;
1826
1827          --  Plus
1828
1829          when '+' => Plus_Case : begin
1830             Accumulate_Checksum ('+');
1831             Scan_Ptr := Scan_Ptr + 1;
1832             Token := Tok_Plus;
1833             return;
1834          end Plus_Case;
1835
1836          --  Digits starting a numeric literal
1837
1838          when '0' .. '9' =>
1839
1840             --  First a bit of a scan ahead to see if we have a case of an
1841             --  identifier starting with a digit (remembering exponent case).
1842
1843             declare
1844                C : constant Character := Source (Scan_Ptr + 1);
1845
1846             begin
1847                --  OK literal if digit followed by digit or underscore
1848
1849                if C in '0' .. '9' or else C = '_' then
1850                   null;
1851
1852                --  OK literal if digit not followed by identifier char
1853
1854                elsif not Identifier_Char (C) then
1855                   null;
1856
1857                --  OK literal if digit followed by e/E followed by digit/sign.
1858                --  We also allow underscore after the E, which is an error, but
1859                --  better handled by Nlit than deciding this is an identifier.
1860
1861                elsif (C = 'e' or else C = 'E')
1862                  and then (Source (Scan_Ptr + 2) in '0' .. '9'
1863                              or else Source (Scan_Ptr + 2) = '+'
1864                              or else Source (Scan_Ptr + 2) = '-'
1865                              or else Source (Scan_Ptr + 2) = '_')
1866                then
1867                   null;
1868
1869                --  Here we have what really looks like an identifier that
1870                --  starts with a digit, so give error msg.
1871
1872                else
1873                   Error_Msg_S ("identifier may not start with digit");
1874                   Name_Len := 1;
1875                   Underline_Found := False;
1876                   Name_Buffer (1) := Source (Scan_Ptr);
1877                   Accumulate_Checksum (Name_Buffer (1));
1878                   Scan_Ptr := Scan_Ptr + 1;
1879                   goto Scan_Identifier;
1880                end if;
1881             end;
1882
1883             --  Here we have an OK integer literal
1884
1885             Nlit;
1886
1887             if Identifier_Char (Source (Scan_Ptr)) then
1888                Error_Msg_S
1889                  ("delimiter required between literal and identifier");
1890             end if;
1891
1892             Post_Scan;
1893             return;
1894
1895          --  Lower case letters
1896
1897          when 'a' .. 'z' =>
1898             Name_Len := 1;
1899             Underline_Found := False;
1900             Name_Buffer (1) := Source (Scan_Ptr);
1901             Accumulate_Checksum (Name_Buffer (1));
1902             Scan_Ptr := Scan_Ptr + 1;
1903             goto Scan_Identifier;
1904
1905          --  Upper case letters
1906
1907          when 'A' .. 'Z' =>
1908             Name_Len := 1;
1909             Underline_Found := False;
1910             Name_Buffer (1) :=
1911               Character'Val (Character'Pos (Source (Scan_Ptr)) + 32);
1912             Accumulate_Checksum (Name_Buffer (1));
1913             Scan_Ptr := Scan_Ptr + 1;
1914             goto Scan_Identifier;
1915
1916          --  Underline character
1917
1918          when '_' =>
1919             if Special_Characters ('_') then
1920                Token_Ptr := Scan_Ptr;
1921                Scan_Ptr := Scan_Ptr + 1;
1922                Token := Tok_Special;
1923                Special_Character := '_';
1924                return;
1925             end if;
1926
1927             Error_Msg_S ("identifier cannot start with underline");
1928             Name_Len := 1;
1929             Name_Buffer (1) := '_';
1930             Scan_Ptr := Scan_Ptr + 1;
1931             Underline_Found := False;
1932             goto Scan_Identifier;
1933
1934          --  Space (not possible, because we scanned past blanks)
1935
1936          when ' ' =>
1937             raise Program_Error;
1938
1939          --  Characters in top half of ASCII 8-bit chart
1940
1941          when Upper_Half_Character =>
1942
1943             --  Wide character case
1944
1945             if Upper_Half_Encoding then
1946                goto Scan_Wide_Character;
1947
1948             --  Otherwise we have OK Latin-1 character
1949
1950             else
1951                --  Upper half characters may possibly be identifier letters
1952                --  but can never be digits, so Identifier_Char can be used to
1953                --  test for a valid start of identifier character.
1954
1955                if Identifier_Char (Source (Scan_Ptr)) then
1956                   Name_Len := 0;
1957                   Underline_Found := False;
1958                   goto Scan_Identifier;
1959                else
1960                   Error_Illegal_Character;
1961                end if;
1962             end if;
1963
1964          when ESC =>
1965
1966             --  ESC character, possible start of identifier if wide characters
1967             --  using ESC encoding are allowed in identifiers, which we can
1968             --  tell by looking at the Identifier_Char flag for ESC, which is
1969             --  only true if these conditions are met. In Ada 2005 mode, may
1970             --  also be valid UTF_32 space or line terminator character.
1971
1972             if Identifier_Char (ESC) then
1973                Name_Len := 0;
1974                goto Scan_Wide_Character;
1975             else
1976                Error_Illegal_Character;
1977             end if;
1978
1979          --  Invalid control characters
1980
1981          when NUL | SOH | STX | ETX | EOT | ENQ | ACK | BEL | BS  | ASCII.SO |
1982               SI  | DLE | DC1 | DC2 | DC3 | DC4 | NAK | SYN | ETB | CAN |
1983               EM  | FS  | GS  | RS  | US  | DEL
1984          =>
1985             Error_Illegal_Character;
1986
1987          --  Invalid graphic characters
1988
1989          when '#' | '$' | '?' | '@' | '`' | '\' | '^' | '~' =>
1990
1991             --  If Set_Special_Character has been called for this character,
1992             --  set Scans.Special_Character and return a Special token.
1993
1994             if Special_Characters (Source (Scan_Ptr)) then
1995                Token_Ptr := Scan_Ptr;
1996                Token := Tok_Special;
1997                Special_Character := Source (Scan_Ptr);
1998                Scan_Ptr := Scan_Ptr + 1;
1999                return;
2000
2001             --  Otherwise, this is an illegal character
2002
2003             else
2004                Error_Illegal_Character;
2005             end if;
2006
2007          --  End switch on non-blank character
2008
2009          end case;
2010
2011       --  End loop past format effectors. The exit from this loop is by
2012       --  executing a return statement following completion of token scan
2013       --  (control never falls out of this loop to the code which follows)
2014
2015       end loop;
2016
2017       --  Wide_Character scanning routine. On entry we have encountered the
2018       --  initial character of a wide character sequence.
2019
2020       <<Scan_Wide_Character>>
2021
2022          declare
2023             Code : Char_Code;
2024             Cat  : Category;
2025             Err  : Boolean;
2026
2027          begin
2028             Wptr := Scan_Ptr;
2029             Scan_Wide (Source, Scan_Ptr, Code, Err);
2030
2031             --  If bad wide character, signal error and continue scan
2032
2033             if Err then
2034                Error_Illegal_Wide_Character;
2035                goto Scan_Next_Character;
2036             end if;
2037
2038             Cat := Get_Category (UTF_32 (Code));
2039
2040             --  If OK letter, reset scan ptr and go scan identifier
2041
2042             if Is_UTF_32_Letter (Cat) then
2043                Scan_Ptr := Wptr;
2044                Name_Len := 0;
2045                Underline_Found := False;
2046                goto Scan_Identifier;
2047
2048             --  If OK wide space, ignore and keep scanning (we do not include
2049             --  any ignored spaces in checksum)
2050
2051             elsif Is_UTF_32_Space (Cat) then
2052                goto Scan_Next_Character;
2053
2054             --  If OK wide line terminator, terminate current line
2055
2056             elsif Is_UTF_32_Line_Terminator (UTF_32 (Code)) then
2057                Scan_Ptr := Wptr;
2058                goto Scan_Line_Terminator;
2059
2060             --  Punctuation is an error (at start of identifier)
2061
2062             elsif Is_UTF_32_Punctuation (Cat) then
2063                Error_Msg
2064                  ("identifier cannot start with punctuation", Wptr);
2065                Scan_Ptr := Wptr;
2066                Name_Len := 0;
2067                Underline_Found := False;
2068                goto Scan_Identifier;
2069
2070             --  Mark character is an error (at start of identifier)
2071
2072             elsif Is_UTF_32_Mark (Cat) then
2073                Error_Msg
2074                  ("identifier cannot start with mark character", Wptr);
2075                Scan_Ptr := Wptr;
2076                Name_Len := 0;
2077                Underline_Found := False;
2078                goto Scan_Identifier;
2079
2080             --  Other format character is an error (at start of identifier)
2081
2082             elsif Is_UTF_32_Other (Cat) then
2083                Error_Msg
2084                  ("identifier cannot start with other format character", Wptr);
2085                Scan_Ptr := Wptr;
2086                Name_Len := 0;
2087                Underline_Found := False;
2088                goto Scan_Identifier;
2089
2090             --  Extended digit character is an error. Could be bad start of
2091             --  identifier or bad literal. Not worth doing too much to try to
2092             --  distinguish these cases, but we will do a little bit.
2093
2094             elsif Is_UTF_32_Digit (Cat) then
2095                Error_Msg
2096                  ("identifier cannot start with digit character", Wptr);
2097                Scan_Ptr := Wptr;
2098                Name_Len := 0;
2099                Underline_Found := False;
2100                goto Scan_Identifier;
2101
2102             --  All other wide characters are illegal here
2103
2104             else
2105                Error_Illegal_Wide_Character;
2106                goto Scan_Next_Character;
2107             end if;
2108          end;
2109
2110       --  Routine to scan line terminator. On entry Scan_Ptr points to a
2111       --  character which is one of FF,LR,CR,VT, or one of the wide characters
2112       --  that is treated as a line terminator.
2113
2114       <<Scan_Line_Terminator>>
2115
2116          --  Check line too long
2117
2118          Check_End_Of_Line;
2119
2120          --  Set Token_Ptr, if End_Of_Line is a token, for the case when it is
2121          --  a physical line.
2122
2123          if End_Of_Line_Is_Token then
2124             Token_Ptr := Scan_Ptr;
2125          end if;
2126
2127          declare
2128             Physical : Boolean;
2129
2130          begin
2131             Skip_Line_Terminators (Scan_Ptr, Physical);
2132
2133             --  If we are at start of physical line, update scan pointers to
2134             --  reflect the start of the new line.
2135
2136             if Physical then
2137                Current_Line_Start       := Scan_Ptr;
2138                Start_Column             := Set_Start_Column;
2139                First_Non_Blank_Location := Scan_Ptr;
2140
2141                --  If End_Of_Line is a token, we return it as it is a
2142                --  physical line.
2143
2144                if End_Of_Line_Is_Token then
2145                   Token := Tok_End_Of_Line;
2146                   return;
2147                end if;
2148             end if;
2149          end;
2150
2151          goto Scan_Next_Character;
2152
2153       --  Identifier scanning routine. On entry, some initial characters of
2154       --  the identifier may have already been stored in Name_Buffer. If so,
2155       --  Name_Len has the number of characters stored, otherwise Name_Len is
2156       --  set to zero on entry. Underline_Found is also set False on entry.
2157
2158       <<Scan_Identifier>>
2159
2160          --  This loop scans as fast as possible past lower half letters and
2161          --  digits, which we expect to be the most common characters.
2162
2163          loop
2164             if Source (Scan_Ptr) in 'a' .. 'z'
2165               or else Source (Scan_Ptr) in '0' .. '9'
2166             then
2167                Name_Buffer (Name_Len + 1) := Source (Scan_Ptr);
2168                Accumulate_Checksum (Source (Scan_Ptr));
2169
2170             elsif Source (Scan_Ptr) in 'A' .. 'Z' then
2171                Name_Buffer (Name_Len + 1) :=
2172                  Character'Val (Character'Pos (Source (Scan_Ptr)) + 32);
2173                Accumulate_Checksum (Name_Buffer (Name_Len + 1));
2174
2175             else
2176                exit;
2177             end if;
2178
2179             Underline_Found := False;
2180             Scan_Ptr := Scan_Ptr + 1;
2181             Name_Len := Name_Len + 1;
2182          end loop;
2183
2184          --  If we fall through, then we have encountered either an underline
2185          --  character, or an extended identifier character (i.e. one from the
2186          --  upper half), or a wide character, or an identifier terminator. The
2187          --  initial test speeds us up in the most common case where we have
2188          --  an identifier terminator. Note that ESC is an identifier character
2189          --  only if a wide character encoding method that uses ESC encoding
2190          --  is active, so if we find an ESC character we know that we have a
2191          --  wide character.
2192
2193          if Identifier_Char (Source (Scan_Ptr))
2194            or else (Source (Scan_Ptr) in Upper_Half_Character
2195                      and then Upper_Half_Encoding)
2196          then
2197             --  Case of underline
2198
2199             if Source (Scan_Ptr) = '_' then
2200                Accumulate_Checksum ('_');
2201
2202                if Underline_Found then
2203                   Error_No_Double_Underline;
2204                else
2205                   Underline_Found := True;
2206                   Name_Len := Name_Len + 1;
2207                   Name_Buffer (Name_Len) := '_';
2208                end if;
2209
2210                Scan_Ptr := Scan_Ptr + 1;
2211                goto Scan_Identifier;
2212
2213             --  Upper half character
2214
2215             elsif Source (Scan_Ptr) in Upper_Half_Character
2216               and then not Upper_Half_Encoding
2217             then
2218                Accumulate_Checksum (Source (Scan_Ptr));
2219                Store_Encoded_Character
2220                  (Get_Char_Code (Fold_Lower (Source (Scan_Ptr))));
2221                Scan_Ptr := Scan_Ptr + 1;
2222                Underline_Found := False;
2223                goto Scan_Identifier;
2224
2225             --  Left bracket not followed by a quote terminates an identifier.
2226             --  This is an error, but we don't want to give a junk error msg
2227             --  about wide characters in this case!
2228
2229             elsif Source (Scan_Ptr) = '['
2230               and then Source (Scan_Ptr + 1) /= '"'
2231             then
2232                null;
2233
2234             --  We know we have a wide character encoding here (the current
2235             --  character is either ESC, left bracket, or an upper half
2236             --  character depending on the encoding method).
2237
2238             else
2239                --  Scan out the wide character and insert the appropriate
2240                --  encoding into the name table entry for the identifier.
2241
2242                declare
2243                   Code : Char_Code;
2244                   Err  : Boolean;
2245                   Chr  : Character;
2246                   Cat  : Category;
2247
2248                begin
2249                   Wptr := Scan_Ptr;
2250                   Scan_Wide (Source, Scan_Ptr, Code, Err);
2251
2252                   --  If error, signal error
2253
2254                   if Err then
2255                      Error_Illegal_Wide_Character;
2256
2257                   --  If the character scanned is a normal identifier
2258                   --  character, then we treat it that way.
2259
2260                   elsif In_Character_Range (Code)
2261                     and then Identifier_Char (Get_Character (Code))
2262                   then
2263                      Chr := Get_Character (Code);
2264                      Accumulate_Checksum (Chr);
2265                      Store_Encoded_Character
2266                        (Get_Char_Code (Fold_Lower (Chr)));
2267                      Underline_Found := False;
2268
2269                   --  Here if not a normal identifier character
2270
2271                   else
2272                      --  Make sure we are allowing wide characters in
2273                      --  identifiers. Note that we allow wide character
2274                      --  notation for an OK identifier character. This in
2275                      --  particular allows bracket or other notation to be
2276                      --  used for upper half letters.
2277
2278                      --  Wide characters are always allowed in Ada 2005
2279
2280                      if Identifier_Character_Set /= 'w'
2281                        and then Ada_Version < Ada_05
2282                      then
2283                         Error_Msg
2284                        ("wide character not allowed in identifier", Wptr);
2285                      end if;
2286
2287                      Cat := Get_Category (UTF_32 (Code));
2288
2289                      --  If OK letter, store it folding to upper case. Note
2290                      --  that we include the folded letter in the checksum.
2291
2292                      if Is_UTF_32_Letter (Cat) then
2293                         Code :=
2294                           Char_Code (UTF_32_To_Upper_Case (UTF_32 (Code)));
2295                         Accumulate_Checksum (Code);
2296                         Store_Encoded_Character (Code);
2297                         Underline_Found := False;
2298
2299                      --  If OK extended digit or mark, then store it
2300
2301                      elsif Is_UTF_32_Digit (Cat)
2302                        or else Is_UTF_32_Mark (Cat)
2303                      then
2304                         Accumulate_Checksum (Code);
2305                         Store_Encoded_Character (Code);
2306                         Underline_Found := False;
2307
2308                      --  Wide punctuation is also stored, but counts as an
2309                      --  underline character for error checking purposes.
2310
2311                      elsif Is_UTF_32_Punctuation (Cat) then
2312                         Accumulate_Checksum (Code);
2313
2314                         if Underline_Found then
2315                            declare
2316                               Cend : constant Source_Ptr := Scan_Ptr;
2317                            begin
2318                               Scan_Ptr := Wptr;
2319                               Error_No_Double_Underline;
2320                               Scan_Ptr := Cend;
2321                            end;
2322
2323                         else
2324                            Store_Encoded_Character (Code);
2325                            Underline_Found := True;
2326                         end if;
2327
2328                      --  Wide character in Unicode category "Other, Format"
2329                      --  is accepted in an identifier, but is ignored and not
2330                      --  stored. It seems reasonable to exclude it from the
2331                      --  checksum.
2332
2333                      --  Note that it is correct (see AI-395) to simply strip
2334                      --  other format characters, before testing for double
2335                      --  underlines, or for reserved words).
2336
2337                      elsif Is_UTF_32_Other (Cat) then
2338                         null;
2339
2340                      --  Wide character in category Separator,Space terminates
2341
2342                      elsif Is_UTF_32_Space (Cat) then
2343                         goto Scan_Identifier_Complete;
2344
2345                      --  Any other wide character is not acceptable
2346
2347                      else
2348                         Error_Msg
2349                           ("invalid wide character in identifier", Wptr);
2350                      end if;
2351                   end if;
2352
2353                   goto Scan_Identifier;
2354                end;
2355             end if;
2356          end if;
2357
2358       --  Scan of identifier is complete. The identifier is stored in
2359       --  Name_Buffer, and Scan_Ptr points past the last character.
2360
2361       <<Scan_Identifier_Complete>>
2362          Token_Name := Name_Find;
2363
2364          --  Check for identifier ending with underline or punctuation char
2365
2366          if Underline_Found then
2367             Underline_Found := False;
2368
2369             if Source (Scan_Ptr - 1) = '_' then
2370                Error_Msg
2371                  ("identifier cannot end with underline", Scan_Ptr - 1);
2372             else
2373                Error_Msg
2374                  ("identifier cannot end with punctuation character", Wptr);
2375             end if;
2376          end if;
2377
2378          --  Here is where we check if it was a keyword
2379
2380          if Is_Keyword_Name (Token_Name) then
2381             Token := Token_Type'Val (Get_Name_Table_Byte (Token_Name));
2382
2383             --  Keyword style checks
2384
2385             if Style_Check then
2386
2387                --  Deal with possible style check for non-lower case keyword,
2388                --  but we don't treat ACCESS, DELTA, DIGITS, RANGE as keywords
2389                --  for this purpose if they appear as attribute designators.
2390                --  Actually we only check the first character for speed.
2391
2392                --  Ada 2005 (AI-284): Do not apply the style check in case of
2393                --  "pragma Interface"
2394
2395                --  Ada 2005 (AI-340): Do not apply the style check in case of
2396                --  MOD attribute.
2397
2398                if Source (Token_Ptr) <= 'Z'
2399                  and then (Prev_Token /= Tok_Apostrophe
2400                            or else
2401                              (Token /= Tok_Access and then
2402                               Token /= Tok_Delta  and then
2403                               Token /= Tok_Digits and then
2404                               Token /= Tok_Mod    and then
2405                               Token /= Tok_Range))
2406                        and then (Token /= Tok_Interface
2407                                   or else
2408                                     (Token = Tok_Interface
2409                                       and then Prev_Token /= Tok_Pragma))
2410                then
2411                   Style.Non_Lower_Case_Keyword;
2412                end if;
2413
2414                if (Token = Tok_Then and then Prev_Token /= Tok_And)
2415                     or else
2416                   (Token = Tok_Else and then Prev_Token /= Tok_Or)
2417                then
2418                   Style.Check_Separate_Stmt_Lines;
2419                end if;
2420             end if;
2421
2422             --  We must reset Token_Name since this is not an identifier and
2423             --  if we leave Token_Name set, the parser gets confused because
2424             --  it thinks it is dealing with an identifier instead of the
2425             --  corresponding keyword.
2426
2427             Token_Name := No_Name;
2428             Accumulate_Token_Checksum;
2429             return;
2430
2431          --  It is an identifier after all
2432
2433          else
2434             Token := Tok_Identifier;
2435             Accumulate_Token_Checksum;
2436             Post_Scan;
2437             return;
2438          end if;
2439    end Scan;
2440
2441    --------------------------
2442    -- Set_Comment_As_Token --
2443    --------------------------
2444
2445    procedure Set_Comment_As_Token (Value : Boolean) is
2446    begin
2447       Comment_Is_Token := Value;
2448    end Set_Comment_As_Token;
2449
2450    ------------------------------
2451    -- Set_End_Of_Line_As_Token --
2452    ------------------------------
2453
2454    procedure Set_End_Of_Line_As_Token (Value : Boolean) is
2455    begin
2456       End_Of_Line_Is_Token := Value;
2457    end Set_End_Of_Line_As_Token;
2458
2459    ---------------------------
2460    -- Set_Special_Character --
2461    ---------------------------
2462
2463    procedure Set_Special_Character (C : Character) is
2464    begin
2465       case C is
2466          when '#' | '$' | '_' | '?' | '@' | '`' | '\' | '^' | '~' =>
2467             Special_Characters (C) := True;
2468
2469          when others =>
2470             null;
2471       end case;
2472    end Set_Special_Character;
2473
2474    ----------------------
2475    -- Set_Start_Column --
2476    ----------------------
2477
2478    --  Note: it seems at first glance a little expensive to compute this value
2479    --  for every source line (since it is certainly not used for all source
2480    --  lines). On the other hand, it doesn't take much more work to skip past
2481    --  the initial white space on the line counting the columns than it would
2482    --  to scan past the white space using the standard scanning circuits.
2483
2484    function Set_Start_Column return Column_Number is
2485       Start_Column : Column_Number := 0;
2486
2487    begin
2488       --  Outer loop scans past horizontal tab characters
2489
2490       Tabs_Loop : loop
2491
2492          --  Inner loop scans past blanks as fast as possible, bumping Scan_Ptr
2493          --  past the blanks and adjusting Start_Column to account for them.
2494
2495          Blanks_Loop : loop
2496             if Source (Scan_Ptr) = ' ' then
2497                if Source (Scan_Ptr + 1) = ' ' then
2498                   if Source (Scan_Ptr + 2) = ' ' then
2499                      if Source (Scan_Ptr + 3) = ' ' then
2500                         if Source (Scan_Ptr + 4) = ' ' then
2501                            if Source (Scan_Ptr + 5) = ' ' then
2502                               if Source (Scan_Ptr + 6) = ' ' then
2503                                  Scan_Ptr := Scan_Ptr + 7;
2504                                  Start_Column := Start_Column + 7;
2505                               else
2506                                  Scan_Ptr := Scan_Ptr + 6;
2507                                  Start_Column := Start_Column + 6;
2508                                  exit Blanks_Loop;
2509                               end if;
2510                            else
2511                               Scan_Ptr := Scan_Ptr + 5;
2512                               Start_Column := Start_Column + 5;
2513                               exit Blanks_Loop;
2514                            end if;
2515                         else
2516                            Scan_Ptr := Scan_Ptr + 4;
2517                            Start_Column := Start_Column + 4;
2518                            exit Blanks_Loop;
2519                         end if;
2520                      else
2521                         Scan_Ptr := Scan_Ptr + 3;
2522                         Start_Column := Start_Column + 3;
2523                         exit Blanks_Loop;
2524                      end if;
2525                   else
2526                      Scan_Ptr := Scan_Ptr + 2;
2527                      Start_Column := Start_Column + 2;
2528                      exit Blanks_Loop;
2529                   end if;
2530                else
2531                   Scan_Ptr := Scan_Ptr + 1;
2532                   Start_Column := Start_Column + 1;
2533                   exit Blanks_Loop;
2534                end if;
2535             else
2536                exit Blanks_Loop;
2537             end if;
2538          end loop Blanks_Loop;
2539
2540          --  Outer loop keeps going only if a horizontal tab follows
2541
2542          if Source (Scan_Ptr) = HT then
2543             if Style_Check then
2544                Style.Check_HT;
2545             end if;
2546
2547             Scan_Ptr := Scan_Ptr + 1;
2548             Start_Column := (Start_Column / 8) * 8 + 8;
2549          else
2550             exit Tabs_Loop;
2551          end if;
2552
2553       end loop Tabs_Loop;
2554
2555       return Start_Column;
2556
2557    --  A constraint error can happen only if we have a compiler with checks on
2558    --  and a line with a ludicrous number of tabs or spaces at the start. In
2559    --  such a case, we really don't care if Start_Column is right or not.
2560
2561    exception
2562       when Constraint_Error =>
2563          return Start_Column;
2564    end Set_Start_Column;
2565
2566 end Scng;