gcc/ada/scn.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                                  S C N                                   --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2013, 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 Atree;    use Atree;
  27 with Csets;    use Csets;
  28 with Namet;    use Namet;
  29 with Opt;      use Opt;
  30 with Restrict; use Restrict;
  31 with Rident;   use Rident;
  32 with Scans;    use Scans;
  33 with Sinfo;    use Sinfo;
  34 with Sinput;   use Sinput;
  35 with Uintp;    use Uintp;
  36
  37 package body Scn is
  38
  39    use ASCII;
  40
  41    Used_As_Identifier : array (Token_Type) of Boolean;
  42    --  Flags set True if a given keyword is used as an identifier (used to
  43    --  make sure that we only post an error message for incorrect use of a
  44    --  keyword as an identifier once for a given keyword).
  45
  46    function Determine_License return License_Type;
  47    --  Scan header of file and check that it has an appropriate GNAT-style
  48    --  header with a proper license statement. Returns GPL, Unrestricted,
  49    --  or Modified_GPL depending on header. If none of these, returns Unknown.
  50
  51    -----------------------
  52    -- Determine_License --
  53    -----------------------
  54
  55    function Determine_License return License_Type is
  56       GPL_Found : Boolean := False;
  57       Result    : License_Type;
  58
  59       function Contains (S : String) return Boolean;
  60       --  See if current comment contains successive non-blank characters
  61       --  matching the contents of S. If so leave Scan_Ptr unchanged and
  62       --  return True, otherwise leave Scan_Ptr unchanged and return False.
  63
  64       procedure Skip_EOL;
  65       --  Skip to line terminator character
  66
  67       --------------
  68       -- Contains --
  69       --------------
  70
  71       function Contains (S : String) return Boolean is
  72          CP : Natural;
  73          SP : Source_Ptr;
  74          SS : Source_Ptr;
  75
  76       begin
  77          --  Loop to check characters. This loop is terminated by end of
  78          --  line, and also we need to check for the EOF case, to take
  79          --  care of files containing only comments.
  80
  81          SP := Scan_Ptr;
  82          while Source (SP) /= CR and then
  83                Source (SP) /= LF and then
  84                Source (SP) /= EOF
  85          loop
  86             if Source (SP) = S (S'First) then
  87                SS := SP;
  88                CP := S'First;
  89
  90                loop
  91                   SS := SS + 1;
  92                   CP := CP + 1;
  93
  94                   if CP > S'Last then
  95                      return True;
  96                   end if;
  97
  98                   while Source (SS) = ' ' loop
  99                      SS := SS + 1;
 100                   end loop;
 101
 102                   exit when Source (SS) /= S (CP);
 103                end loop;
 104             end if;
 105
 106             SP := SP + 1;
 107          end loop;
 108
 109          return False;
 110       end Contains;
 111
 112       --------------
 113       -- Skip_EOL --
 114       --------------
 115
 116       procedure Skip_EOL is
 117       begin
 118          while Source (Scan_Ptr) /= CR
 119            and then Source (Scan_Ptr) /= LF
 120            and then Source (Scan_Ptr) /= EOF
 121          loop
 122             Scan_Ptr := Scan_Ptr + 1;
 123          end loop;
 124       end Skip_EOL;
 125
 126    --  Start of processing for Determine_License
 127
 128    begin
 129       loop
 130          if Source (Scan_Ptr) /= '-'
 131            or else Source (Scan_Ptr + 1) /= '-'
 132          then
 133             if GPL_Found then
 134                Result := GPL;
 135                exit;
 136             else
 137                Result := Unknown;
 138                exit;
 139             end if;
 140
 141          elsif Contains ("Asaspecialexception") then
 142             if GPL_Found then
 143                Result := Modified_GPL;
 144                exit;
 145             end if;
 146
 147          elsif Contains ("GNUGeneralPublicLicense") then
 148             GPL_Found := True;
 149
 150          elsif
 151              Contains
 152                ("ThisspecificationisadaptedfromtheAdaSemanticInterface")
 153            or else
 154              Contains
 155               ("ThisspecificationisderivedfromtheAdaReferenceManual")
 156          then
 157             Result := Unrestricted;
 158             exit;
 159          end if;
 160
 161          Skip_EOL;
 162
 163          Scanner.Check_End_Of_Line;
 164
 165          if Source (Scan_Ptr) /= EOF then
 166
 167             --  We have to take into account a degenerate case when the source
 168             --  file contains only comments and no Ada code.
 169
 170             declare
 171                Physical : Boolean;
 172
 173             begin
 174                Skip_Line_Terminators (Scan_Ptr, Physical);
 175
 176                --  If we are at start of physical line, update scan pointers
 177                --  to reflect the start of the new line.
 178
 179                if Physical then
 180                   Current_Line_Start       := Scan_Ptr;
 181                   Start_Column             := Scanner.Set_Start_Column;
 182                   First_Non_Blank_Location := Scan_Ptr;
 183                end if;
 184             end;
 185          end if;
 186       end loop;
 187
 188       return Result;
 189    end Determine_License;
 190
 191    ----------------------------
 192    -- Determine_Token_Casing --
 193    ----------------------------
 194
 195    function Determine_Token_Casing return Casing_Type is
 196    begin
 197       return Scanner.Determine_Token_Casing;
 198    end Determine_Token_Casing;
 199
 200    ------------------------
 201    -- Initialize_Scanner --
 202    ------------------------
 203
 204    procedure Initialize_Scanner
 205      (Unit  : Unit_Number_Type;
 206       Index : Source_File_Index)
 207    is
 208       GNAT_Hedr : constant Text_Buffer (1 .. 78) := (others => '-');
 209
 210    begin
 211       Scanner.Initialize_Scanner (Index);
 212
 213       if Index /= Internal_Source_File then
 214          Set_Unit (Index, Unit);
 215       end if;
 216
 217       Current_Source_Unit := Unit;
 218
 219       --  Set default for Comes_From_Source (except if we are going to process
 220       --  an artificial string internally created within the compiler and
 221       --  placed into internal source duffer). All nodes built now until we
 222       --  reenter the analyzer will have Comes_From_Source set to True
 223
 224       if Index /= Internal_Source_File then
 225          Set_Comes_From_Source_Default (True);
 226       end if;
 227
 228       --  Check license if GNAT type header possibly present
 229
 230       if Source_Last (Index) - Scan_Ptr > 80
 231         and then Source (Scan_Ptr .. Scan_Ptr + 77) = GNAT_Hedr
 232       then
 233          Set_License (Current_Source_File, Determine_License);
 234       end if;
 235
 236       Check_For_BOM;
 237
 238       --  Because of the License stuff above, Scng.Initialize_Scanner cannot
 239       --  call Scan. Scan initial token (note this initializes Prev_Token,
 240       --  Prev_Token_Ptr).
 241
 242       --  There are two reasons not to do the Scan step in case if we
 243       --  initialize the scanner for the internal source buffer:
 244
 245       --  - The artificial string may not be created by the compiler in this
 246       --    buffer when we call Initialize_Scanner
 247
 248       --  - For these artificial strings a special way of scanning is used, so
 249       --    the standard step of the scanner may just break the algorithm of
 250       --    processing these strings.
 251
 252       if Index /= Internal_Source_File then
 253          Scan;
 254       end if;
 255
 256       --  Clear flags for reserved words used as identifiers
 257
 258       for J in Token_Type loop
 259          Used_As_Identifier (J) := False;
 260       end loop;
 261    end Initialize_Scanner;
 262
 263    ---------------
 264    -- Post_Scan --
 265    ---------------
 266
 267    procedure Post_Scan is
 268       procedure Check_Obsolescent_Features_Restriction (S : Source_Ptr);
 269       --  This checks for Obsolescent_Features restriction being active, and
 270       --  if so, flags the restriction as occurring at the given scan location.
 271
 272       procedure Check_Obsolete_Base_Char;
 273       --  Check for numeric literal using ':' instead of '#' for based case
 274
 275       --------------------------------------------
 276       -- Check_Obsolescent_Features_Restriction --
 277       --------------------------------------------
 278
 279       procedure Check_Obsolescent_Features_Restriction (S : Source_Ptr) is
 280       begin
 281          --  Normally we have a node handy for posting restrictions. We don't
 282          --  have such a node here, so construct a dummy one with the right
 283          --  scan pointer. This is only used to get the Sloc value anyway.
 284
 285          Check_Restriction (No_Obsolescent_Features, New_Node (N_Empty, S));
 286       end Check_Obsolescent_Features_Restriction;
 287
 288       ------------------------------
 289       -- Check_Obsolete_Base_Char --
 290       ------------------------------
 291
 292       procedure Check_Obsolete_Base_Char is
 293          S : Source_Ptr;
 294
 295       begin
 296          if Based_Literal_Uses_Colon then
 297
 298             --  Find the : for the restriction or warning message
 299
 300             S := Token_Ptr;
 301             while Source (S) /= ':' loop
 302                S := S + 1;
 303             end loop;
 304
 305             Check_Obsolescent_Features_Restriction (S);
 306
 307             if Warn_On_Obsolescent_Feature then
 308                Error_Msg
 309                  ("?j?use of "":"" is an obsolescent feature (RM J.2(3))", S);
 310                Error_Msg
 311                  ("\?j?use ""'#"" instead", S);
 312             end if;
 313          end if;
 314       end Check_Obsolete_Base_Char;
 315
 316    --  Start of processing for Post_Scan
 317
 318    begin
 319       case Token is
 320          when Tok_Char_Literal =>
 321             Token_Node := New_Node (N_Character_Literal, Token_Ptr);
 322             Set_Char_Literal_Value (Token_Node, UI_From_CC (Character_Code));
 323             Set_Chars (Token_Node, Token_Name);
 324
 325          when Tok_Identifier =>
 326             Token_Node := New_Node (N_Identifier, Token_Ptr);
 327             Set_Chars (Token_Node, Token_Name);
 328
 329          when Tok_Real_Literal =>
 330             Token_Node := New_Node (N_Real_Literal, Token_Ptr);
 331             Set_Realval (Token_Node, Real_Literal_Value);
 332             Check_Obsolete_Base_Char;
 333
 334          when Tok_Integer_Literal =>
 335             Token_Node := New_Node (N_Integer_Literal, Token_Ptr);
 336             Set_Intval (Token_Node, Int_Literal_Value);
 337             Check_Obsolete_Base_Char;
 338
 339          when Tok_String_Literal =>
 340             Token_Node := New_Node (N_String_Literal, Token_Ptr);
 341             Set_Has_Wide_Character
 342               (Token_Node, Wide_Character_Found);
 343             Set_Has_Wide_Wide_Character
 344               (Token_Node, Wide_Wide_Character_Found);
 345             Set_Strval (Token_Node, String_Literal_Id);
 346
 347             if Source (Token_Ptr) = '%' then
 348                Check_Obsolescent_Features_Restriction (Token_Ptr);
 349
 350                if Warn_On_Obsolescent_Feature then
 351                   Error_Msg_SC
 352                     ("?j?use of ""'%"" is an obsolescent feature (RM J.2(4))");
 353                   Error_Msg_SC ("\?j?use """""" instead");
 354                end if;
 355             end if;
 356
 357          when Tok_Operator_Symbol =>
 358             Token_Node := New_Node (N_Operator_Symbol, Token_Ptr);
 359             Set_Chars (Token_Node, Token_Name);
 360             Set_Strval (Token_Node, String_Literal_Id);
 361
 362          when Tok_Vertical_Bar =>
 363             if Source (Token_Ptr) = '!' then
 364                Check_Obsolescent_Features_Restriction (Token_Ptr);
 365
 366                if Warn_On_Obsolescent_Feature then
 367                   Error_Msg_SC
 368                     ("?j?use of ""'!"" is an obsolescent feature (RM J.2(2))");
 369                   Error_Msg_SC ("\?j?use ""'|"" instead");
 370                end if;
 371             end if;
 372
 373          when others =>
 374             null;
 375       end case;
 376    end Post_Scan;
 377
 378    ------------------------------
 379    -- Scan_Reserved_Identifier --
 380    ------------------------------
 381
 382    procedure Scan_Reserved_Identifier (Force_Msg : Boolean) is
 383       Token_Chars : constant String := Token_Type'Image (Token);
 384
 385    begin
 386       --  We have in Token_Chars the image of the Token name, i.e. Tok_xxx.
 387       --  This code extracts the xxx and makes an identifier out of it.
 388
 389       Name_Len := 0;
 390
 391       for J in 5 .. Token_Chars'Length loop
 392          Name_Len := Name_Len + 1;
 393          Name_Buffer (Name_Len) := Fold_Lower (Token_Chars (J));
 394       end loop;
 395
 396       Token_Name := Name_Find;
 397
 398       if not Used_As_Identifier (Token) or else Force_Msg then
 399          Error_Msg_Name_1 := Token_Name;
 400          Error_Msg_SC ("reserved word* cannot be used as identifier!");
 401          Used_As_Identifier (Token) := True;
 402       end if;
 403
 404       Token := Tok_Identifier;
 405       Token_Node := New_Node (N_Identifier, Token_Ptr);
 406       Set_Chars (Token_Node, Token_Name);
 407    end Scan_Reserved_Identifier;
 408
 409 end Scn;