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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                                  S C N                                   --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with Atree;    use Atree;

with Csets;    use Csets;

with Hostparm; use Hostparm;

with Namet;    use Namet;

with Opt;      use Opt;

with Output;   use Output;

with Restrict; use Restrict;

with Rident;   use Rident;

with Scans;    use Scans;

with Sinfo;    use Sinfo;

with Sinput;   use Sinput;

with Uintp;    use Uintp;

with GNAT.Byte_Order_Mark; use GNAT.Byte_Order_Mark;

with System.WCh_Con; use System.WCh_Con;

package body Scn is

   use ASCII;

   Obsolescent_Check_Flag : Boolean := True;

   --  Obsolescent check activation. Set to False during integrated

   --  preprocessing.

   Used_As_Identifier : array (Token_Type) of Boolean;

   --  Flags set True if a given keyword is used as an identifier (used to

   --  make sure that we only post an error message for incorrect use of a

   --  keyword as an identifier once for a given keyword).

   procedure Check_End_Of_Line;

   --  Called when end of line encountered. Checks that line is not too long,

   --  and that other style checks for the end of line are met.

   function Determine_License return License_Type;

   --  Scan header of file and check that it has an appropriate GNAT-style

   --  header with a proper license statement. Returns GPL, Unrestricted,

   --  or Modified_GPL depending on header. If none of these, returns Unknown.

   procedure Error_Long_Line;

   --  Signal error of excessively long line

   -----------------------

   -- Check_End_Of_Line --

   -----------------------

   procedure Check_End_Of_Line is

      Len : constant Int := Int (Scan_Ptr) - Int (Current_Line_Start);

   begin

      if Style_Check then

         Style.Check_Line_Terminator (Len);

      elsif Len > Max_Line_Length then

         Error_Long_Line;

      end if;

   end Check_End_Of_Line;

   -----------------------

   -- Determine_License --

   -----------------------

   function Determine_License return License_Type is

      GPL_Found : Boolean := False;

      Result    : License_Type;

      function Contains (S : String) return Boolean;

      --  See if current comment contains successive non-blank characters

      --  matching the contents of S. If so leave Scan_Ptr unchanged and

      --  return True, otherwise leave Scan_Ptr unchanged and return False.

      procedure Skip_EOL;

      --  Skip to line terminator character

      --------------

      -- Contains --

      --------------

      function Contains (S : String) return Boolean is

         CP : Natural;

         SP : Source_Ptr;

         SS : Source_Ptr;

      begin

         --  Loop to check characters. This loop is terminated by end of

         --  line, and also we need to check for the EOF case, to take

         --  care of files containing only comments.

         SP := Scan_Ptr;

         while Source (SP) /= CR and then

               Source (SP) /= LF and then

               Source (SP) /= EOF

         loop

            if Source (SP) = S (S'First) then

               SS := SP;

               CP := S'First;

               loop

                  SS := SS + 1;

                  CP := CP + 1;

                  if CP > S'Last then

                     return True;

                  end if;

                  while Source (SS) = ' ' loop

                     SS := SS + 1;

                  end loop;

                  exit when Source (SS) /= S (CP);

               end loop;

            end if;

            SP := SP + 1;

         end loop;

         return False;

      end Contains;

      --------------

      -- Skip_EOL --

      --------------

      procedure Skip_EOL is

      begin

         while Source (Scan_Ptr) /= CR

           and then Source (Scan_Ptr) /= LF

           and then Source (Scan_Ptr) /= EOF

         loop

            Scan_Ptr := Scan_Ptr + 1;

         end loop;

      end Skip_EOL;

   --  Start of processing for Determine_License

   begin

      loop

         if Source (Scan_Ptr) /= '-'

           or else Source (Scan_Ptr + 1) /= '-'

         then

            if GPL_Found then

               Result := GPL;

               exit;

            else

               Result := Unknown;

               exit;

            end if;

         elsif Contains ("Asaspecialexception") then

            if GPL_Found then

               Result := Modified_GPL;

               exit;

            end if;

         elsif Contains ("GNUGeneralPublicLicense") then

            GPL_Found := True;

         elsif

             Contains

               ("ThisspecificationisadaptedfromtheAdaSemanticInterface")

           or else

             Contains

              ("ThisspecificationisderivedfromtheAdaReferenceManual")

         then

            Result := Unrestricted;

            exit;

         end if;

         Skip_EOL;

         Check_End_Of_Line;

         if Source (Scan_Ptr) /= EOF then

            --  We have to take into account a degenerate case when the source

            --  file contains only comments and no Ada code.

            declare

               Physical : Boolean;

            begin

               Skip_Line_Terminators (Scan_Ptr, Physical);

               --  If we are at start of physical line, update scan pointers

               --  to reflect the start of the new line.

               if Physical then

                  Current_Line_Start       := Scan_Ptr;

                  Start_Column             := Scanner.Set_Start_Column;

                  First_Non_Blank_Location := Scan_Ptr;

               end if;

            end;

         end if;

      end loop;

      return Result;

   end Determine_License;

   ----------------------------

   -- Determine_Token_Casing --

   ----------------------------

   function Determine_Token_Casing return Casing_Type is

   begin

      return Scanner.Determine_Token_Casing;

   end Determine_Token_Casing;

   ---------------------

   -- Error_Long_Line --

   ---------------------

   procedure Error_Long_Line is

   begin

      Error_Msg

        ("this line is too long",

         Current_Line_Start + Source_Ptr (Max_Line_Length));

   end Error_Long_Line;

   ------------------------

   -- Initialize_Scanner --

   ------------------------

   procedure Initialize_Scanner

     (Unit  : Unit_Number_Type;

      Index : Source_File_Index)

   is

      GNAT_Hedr : constant Text_Buffer (1 .. 78) := (others => '-');

   begin

      Scanner.Initialize_Scanner (Index);

      if Index /= Internal_Source_File then

         Set_Unit (Index, Unit);

      end if;

      Current_Source_Unit := Unit;

      --  Set default for Comes_From_Source (except if we are going to process

      --  an artificial string internally created within the compiler and

      --  placed into internal source duffer). All nodes built now until we

      --  reenter the analyzer will have Comes_From_Source set to True

      if Index /= Internal_Source_File then

         Set_Comes_From_Source_Default (True);

      end if;

      --  Check license if GNAT type header possibly present

      if Source_Last (Index) - Scan_Ptr > 80

        and then Source (Scan_Ptr .. Scan_Ptr + 77) = GNAT_Hedr

      then

         Set_License (Current_Source_File, Determine_License);

      end if;

      --  Check for BOM

      declare

         BOM : BOM_Kind;

         Len : Natural;

         Tst : String (1 .. 5);

      begin

         for J in 1 .. 5 loop

            Tst (J) := Source (Scan_Ptr + Source_Ptr (J) - 1);

         end loop;

         Read_BOM (Tst, Len, BOM, False);

         case BOM is

            when UTF8_All =>

               Scan_Ptr := Scan_Ptr + Source_Ptr (Len);

               Wide_Character_Encoding_Method := WCEM_UTF8;

               Upper_Half_Encoding := True;

            when UTF16_LE | UTF16_BE =>

               Set_Standard_Error;

               Write_Line ("UTF-16 encoding format not recognized");

               Set_Standard_Output;

               raise Unrecoverable_Error;

            when UTF32_LE | UTF32_BE =>

               Set_Standard_Error;

               Write_Line ("UTF-32 encoding format not recognized");

               Set_Standard_Output;

               raise Unrecoverable_Error;

            when Unknown =>

               null;

            when others =>

               raise Program_Error;

         end case;

      end;

      --  Because of the License stuff above, Scng.Initialize_Scanner cannot

      --  call Scan. Scan initial token (note this initializes Prev_Token,

      --  Prev_Token_Ptr).

      --  There are two reasons not to do the Scan step in case if we

      --  initialize the scanner for the internal source buffer:

      --  - The artificial string may not be created by the compiler in this

      --    buffer when we call Initialize_Scanner

      --  - For these artificial strings a special way of scanning is used, so

      --    the standard step of the scanner may just break the algorithm of

      --    processing these strings.

      if Index /= Internal_Source_File then

         Scan;

      end if;

      --  Clear flags for reserved words used as identifiers

      for J in Token_Type loop

         Used_As_Identifier (J) := False;

      end loop;

   end Initialize_Scanner;

   -----------------------

   -- Obsolescent_Check --

   -----------------------

   procedure Obsolescent_Check (S : Source_Ptr) is

   begin

      if Obsolescent_Check_Flag then

         --  This is a pain in the neck case, since we normally need a node to

         --  call Check_Restrictions, and all we have is a source pointer. The

         --  easiest thing is to construct a dummy node. A bit kludgy, but this

         --  is a marginal case. It's not worth trying to do things more

         --  cleanly.

         Check_Restriction (No_Obsolescent_Features, New_Node (N_Empty, S));

      end if;

   end Obsolescent_Check;

   ---------------

   -- Post_Scan --

   ---------------

   procedure Post_Scan is

   begin

      case Token is

         when Tok_Char_Literal =>

            Token_Node := New_Node (N_Character_Literal, Token_Ptr);

            Set_Char_Literal_Value (Token_Node, UI_From_CC (Character_Code));

            Set_Chars (Token_Node, Token_Name);

         when Tok_Identifier =>

            Token_Node := New_Node (N_Identifier, Token_Ptr);

            Set_Chars (Token_Node, Token_Name);

         when Tok_Real_Literal =>

            Token_Node := New_Node (N_Real_Literal, Token_Ptr);

            Set_Realval (Token_Node, Real_Literal_Value);

         when Tok_Integer_Literal =>

            Token_Node := New_Node (N_Integer_Literal, Token_Ptr);

            Set_Intval (Token_Node, Int_Literal_Value);

         when Tok_String_Literal =>

            Token_Node := New_Node (N_String_Literal, Token_Ptr);

            Set_Has_Wide_Character

              (Token_Node, Wide_Character_Found);

            Set_Has_Wide_Wide_Character

              (Token_Node, Wide_Wide_Character_Found);

            Set_Strval (Token_Node, String_Literal_Id);

         when Tok_Operator_Symbol =>

            Token_Node := New_Node (N_Operator_Symbol, Token_Ptr);

            Set_Chars (Token_Node, Token_Name);

            Set_Strval (Token_Node, String_Literal_Id);

         when others =>

            null;

      end case;

   end Post_Scan;

   ------------------------------

   -- Scan_Reserved_Identifier --

   ------------------------------

   procedure Scan_Reserved_Identifier (Force_Msg : Boolean) is

      Token_Chars : constant String := Token_Type'Image (Token);

   begin

      --  We have in Token_Chars the image of the Token name, i.e. Tok_xxx.

      --  This code extracts the xxx and makes an identifier out of it.

      Name_Len := 0;

      for J in 5 .. Token_Chars'Length loop

         Name_Len := Name_Len + 1;

         Name_Buffer (Name_Len) := Fold_Lower (Token_Chars (J));

      end loop;

      Token_Name := Name_Find;

      if not Used_As_Identifier (Token) or else Force_Msg then

         Error_Msg_Name_1 := Token_Name;

         Error_Msg_SC ("reserved word* cannot be used as identifier!");

         Used_As_Identifier (Token) := True;

      end if;

      Token := Tok_Identifier;

      Token_Node := New_Node (N_Identifier, Token_Ptr);

      Set_Chars (Token_Node, Token_Name);

   end Scan_Reserved_Identifier;

   ---------------------------

   -- Set_Obsolescent_Check --

   ---------------------------

   procedure Set_Obsolescent_Check (Value : Boolean) is

   begin

      Obsolescent_Check_Flag := Value;

   end Set_Obsolescent_Check;

end Scn;