old-autovect-branch/gcc/ada/par-ch2.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                              P A R . C H 2                               --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2005, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- GNAT was originally developed  by the GNAT team at  New York University. --
  23 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  24 --                                                                          --
  25 ------------------------------------------------------------------------------
  26
  27 pragma Style_Checks (All_Checks);
  28 --  Turn off subprogram body ordering check. Subprograms are in order
  29 --  by RM section rather than alphabetical
  30
  31 separate (Par)
  32 package body Ch2 is
  33
  34    --  Local functions, used only in this chapter
  35
  36    procedure Scan_Pragma_Argument_Association
  37      (Identifier_Seen : in out Boolean;
  38       Association     : out Node_Id);
  39    --  Scans out a pragma argument association. Identifier_Seen is true on
  40    --  entry if a previous association had an identifier, and gets set True if
  41    --  the scanned association has an identifier (this is used to check the
  42    --  rule that no associations without identifiers can follow an association
  43    --  which has an identifier). The result is returned in Association.
  44
  45    ---------------------
  46    -- 2.3  Identifier --
  47    ---------------------
  48
  49    --  IDENTIFIER ::= LETTER {[UNDERLINE] LETTER_OR_DIGIT}
  50
  51    --  LETTER_OR_DIGIT ::= IDENTIFIER_LETTER | DIGIT
  52
  53    --  An IDENTIFIER shall not be a reserved word
  54
  55    --  Error recovery: can raise Error_Resync (cannot return Error)
  56
  57    function P_Identifier (C : Id_Check := None) return Node_Id is
  58       Ident_Node : Node_Id;
  59
  60    begin
  61       --  All set if we do indeed have an identifier
  62
  63       if Token = Tok_Identifier then
  64
  65          --  Ada 2005 (AI-284): Compiling in Ada95 mode we warn that INTERFACE,
  66          --  OVERRIDING, and SYNCHRONIZED are new reserved words.
  67
  68          if Ada_Version = Ada_95
  69            and then Warn_On_Ada_2005_Compatibility
  70          then
  71             if Token_Name = Name_Overriding
  72               or else Token_Name = Name_Synchronized
  73               or else (Token_Name = Name_Interface
  74                         and then Prev_Token /= Tok_Pragma)
  75             then
  76                Error_Msg_N ("& is a reserved word in Ada 2005?", Token_Node);
  77             end if;
  78          end if;
  79
  80          Ident_Node := Token_Node;
  81          Scan; -- past Identifier
  82          return Ident_Node;
  83
  84       --  If we have a reserved identifier, manufacture an identifier with
  85       --  a corresponding name after posting an appropriate error message
  86
  87       elsif Is_Reserved_Identifier (C) then
  88          Scan_Reserved_Identifier (Force_Msg => False);
  89          Ident_Node := Token_Node;
  90          Scan; -- past the node
  91          return Ident_Node;
  92
  93       --  Otherwise we have junk that cannot be interpreted as an identifier
  94
  95       else
  96          T_Identifier; -- to give message
  97          raise Error_Resync;
  98       end if;
  99    end P_Identifier;
 100
 101    --------------------------
 102    -- 2.3  Letter Or Digit --
 103    --------------------------
 104
 105    --  Parsed by P_Identifier (2.3)
 106
 107    --------------------------
 108    -- 2.4  Numeric Literal --
 109    --------------------------
 110
 111    --  NUMERIC_LITERAL ::= DECIMAL_LITERAL | BASED_LITERAL
 112
 113    --  Numeric literal is returned by the scanner as either
 114    --  Tok_Integer_Literal or Tok_Real_Literal
 115
 116    ----------------------------
 117    -- 2.4.1  Decimal Literal --
 118    ----------------------------
 119
 120    --  DECIMAL_LITERAL ::= NUMERAL [.NUMERAL] [EXPONENT]
 121
 122    --  Handled by scanner as part of numeric lIteral handing (see 2.4)
 123
 124    --------------------
 125    -- 2.4.1  Numeral --
 126    --------------------
 127
 128    --  NUMERAL ::= DIGIT {[UNDERLINE] DIGIT}
 129
 130    --  Handled by scanner as part of numeric literal handling (see 2.4)
 131
 132    ---------------------
 133    -- 2.4.1  Exponent --
 134    ---------------------
 135
 136    --  EXPONENT ::= E [+] NUMERAL | E - NUMERAL
 137
 138    --  Handled by scanner as part of numeric literal handling (see 2.4)
 139
 140    --------------------------
 141    -- 2.4.2  Based Literal --
 142    --------------------------
 143
 144    --  BASED_LITERAL ::=
 145    --   BASE # BASED_NUMERAL [.BASED_NUMERAL] # [EXPONENT]
 146
 147    --  Handled by scanner as part of numeric literal handling (see 2.4)
 148
 149    -----------------
 150    -- 2.4.2  Base --
 151    -----------------
 152
 153    --  BASE ::= NUMERAL
 154
 155    --  Handled by scanner as part of numeric literal handling (see 2.4)
 156
 157    --------------------------
 158    -- 2.4.2  Based Numeral --
 159    --------------------------
 160
 161    --  BASED_NUMERAL ::=
 162    --    EXTENDED_DIGIT {[UNDERLINE] EXTENDED_DIGIT}
 163
 164    --  Handled by scanner as part of numeric literal handling (see 2.4)
 165
 166    ---------------------------
 167    -- 2.4.2  Extended Digit --
 168    ---------------------------
 169
 170    --  EXTENDED_DIGIT ::= DIGIT | A | B | C | D | E | F
 171
 172    --  Handled by scanner as part of numeric literal handling (see 2.4)
 173
 174    ----------------------------
 175    -- 2.5  Character Literal --
 176    ----------------------------
 177
 178    --  CHARACTER_LITERAL ::= ' GRAPHIC_CHARACTER '
 179
 180    --  Handled by the scanner and returned as Tok_Character_Literal
 181
 182    -------------------------
 183    -- 2.6  String Literal --
 184    -------------------------
 185
 186    --  STRING LITERAL ::= "{STRING_ELEMENT}"
 187
 188    --  Handled by the scanner and returned as Tok_Character_Literal
 189    --  or if the string looks like an operator as Tok_Operator_Symbol.
 190
 191    -------------------------
 192    -- 2.6  String Element --
 193    -------------------------
 194
 195    --  STRING_ELEMENT ::= "" | non-quotation_mark_GRAPHIC_CHARACTER
 196
 197    --  A STRING_ELEMENT is either a pair of quotation marks ("),
 198    --  or a single GRAPHIC_CHARACTER other than a quotation mark.
 199
 200    --  Handled by scanner as part of string literal handling (see 2.4)
 201
 202    ------------------
 203    -- 2.7  Comment --
 204    ------------------
 205
 206    --  A COMMENT starts with two adjacent hyphens and extends up to the
 207    --  end of the line. A COMMENT may appear on any line of a program.
 208
 209    --  Handled by the scanner which simply skips past encountered comments
 210
 211    -----------------
 212    -- 2.8  Pragma --
 213    -----------------
 214
 215    --  PRAGMA ::= pragma IDENTIFIER
 216    --    [(PRAGMA_ARGUMENT_ASSOCIATION {, PRAGMA_ARGUMENT_ASSOCIATION})];
 217
 218    --  The caller has checked that the initial token is PRAGMA
 219
 220    --  Error recovery: cannot raise Error_Resync
 221
 222    --  One special piece of processing is needed in this routine. As described
 223    --  in the section on "Handling semicolon used in place of IS" in module
 224    --  Parse, the parser detects the case of missing subprogram bodies to
 225    --  allow recovery from this syntactic error. Pragma INTERFACE (and, for
 226    --  Ada 95, pragma IMPORT) can appear in place of the body. The parser must
 227    --  recognize the use of these two pragmas in this context, otherwise it
 228    --  will think there are missing bodies, and try to change ; to IS, when
 229    --  in fact the bodies ARE present, supplied by these pragmas.
 230
 231    function P_Pragma return Node_Id is
 232
 233       Interface_Check_Required : Boolean := False;
 234       --  Set True if check of pragma INTERFACE is required
 235
 236       Import_Check_Required : Boolean := False;
 237       --  Set True if check of pragma IMPORT is required
 238
 239       Arg_Count : Int := 0;
 240       --  Number of argument associations processed
 241
 242       Identifier_Seen : Boolean := False;
 243       --  Set True if an identifier is encountered for a pragma argument. Used
 244       --  to check that there are no more arguments without identifiers.
 245
 246       Pragma_Node   : Node_Id;
 247       Pragma_Name   : Name_Id;
 248       Semicolon_Loc : Source_Ptr;
 249       Ident_Node    : Node_Id;
 250       Assoc_Node    : Node_Id;
 251       Result        : Node_Id;
 252
 253       procedure Skip_Pragma_Semicolon;
 254       --  Skip past semicolon at end of pragma
 255
 256       ---------------------------
 257       -- Skip_Pragma_Semicolon --
 258       ---------------------------
 259
 260       procedure Skip_Pragma_Semicolon is
 261       begin
 262          if Token /= Tok_Semicolon then
 263             T_Semicolon;
 264             Resync_Past_Semicolon;
 265          else
 266             Scan; -- past semicolon
 267          end if;
 268       end Skip_Pragma_Semicolon;
 269
 270    --  Start of processing for P_Pragma
 271
 272    begin
 273       Pragma_Node := New_Node (N_Pragma, Token_Ptr);
 274       Scan; -- past PRAGMA
 275       Pragma_Name := Token_Name;
 276
 277       if Style_Check then
 278          Style.Check_Pragma_Name;
 279       end if;
 280
 281       --  Ada 2005 (AI-284): INTERFACE is a new reserved word but it is
 282       --  allowed as a pragma name.
 283
 284       if Ada_Version >= Ada_05
 285         and then Token = Tok_Interface
 286       then
 287          Pragma_Name := Name_Interface;
 288          Ident_Node  := Token_Node;
 289          Scan; -- past INTERFACE
 290       else
 291          Ident_Node := P_Identifier;
 292          Delete_Node (Ident_Node);
 293       end if;
 294
 295       Set_Chars (Pragma_Node, Pragma_Name);
 296
 297       --  See if special INTERFACE/IMPORT check is required
 298
 299       if SIS_Entry_Active then
 300          Interface_Check_Required := (Pragma_Name = Name_Interface);
 301          Import_Check_Required    := (Pragma_Name = Name_Import);
 302       else
 303          Interface_Check_Required := False;
 304          Import_Check_Required    := False;
 305       end if;
 306
 307       --  Scan arguments. We assume that arguments are present if there is
 308       --  a left paren, or if a semicolon is missing and there is another
 309       --  token on the same line as the pragma name.
 310
 311       if Token = Tok_Left_Paren
 312         or else (Token /= Tok_Semicolon
 313                    and then not Token_Is_At_Start_Of_Line)
 314       then
 315          Set_Pragma_Argument_Associations (Pragma_Node, New_List);
 316          T_Left_Paren;
 317
 318          loop
 319             Arg_Count := Arg_Count + 1;
 320             Scan_Pragma_Argument_Association (Identifier_Seen, Assoc_Node);
 321
 322             if Arg_Count = 2
 323               and then (Interface_Check_Required or else Import_Check_Required)
 324             then
 325                --  Here is where we cancel the SIS active status if this pragma
 326                --  supplies a body for the currently active subprogram spec.
 327
 328                if Nkind (Expression (Assoc_Node)) in N_Direct_Name
 329                  and then Chars (Expression (Assoc_Node)) = Chars (SIS_Labl)
 330                then
 331                   SIS_Entry_Active := False;
 332                end if;
 333             end if;
 334
 335             Append (Assoc_Node, Pragma_Argument_Associations (Pragma_Node));
 336             exit when Token /= Tok_Comma;
 337             Scan; -- past comma
 338          end loop;
 339
 340          --  If we have := for pragma Debug, it is worth special casing
 341          --  the error message (it is easy to think of pragma Debug as
 342          --  taking a statement, and an assignment statement is the most
 343          --  likely candidate for this error)
 344
 345          if Token = Tok_Colon_Equal and then Pragma_Name = Name_Debug then
 346             Error_Msg_SC ("argument for pragma Debug must be procedure call");
 347             Resync_To_Semicolon;
 348
 349          --  Normal case, we expect a right paren here
 350
 351          else
 352             T_Right_Paren;
 353          end if;
 354       end if;
 355
 356       Semicolon_Loc := Token_Ptr;
 357
 358       --  Now we have two tasks left, we need to scan out the semicolon
 359       --  following the pragma, and we have to call Par.Prag to process
 360       --  the pragma. Normally we do them in this order, however, there
 361       --  is one exception namely pragma Style_Checks where we like to
 362       --  skip the semicolon after processing the pragma, since that way
 363       --  the style checks for the scanning of the semicolon follow the
 364       --  settings of the pragma.
 365
 366       --  You might think we could just unconditionally do things in
 367       --  the opposite order, but there are other pragmas, notably the
 368       --  case of pragma Source_File_Name, which assume the semicolon
 369       --  is already scanned out.
 370
 371       if Chars (Pragma_Node) = Name_Style_Checks then
 372          Result := Par.Prag (Pragma_Node, Semicolon_Loc);
 373          Skip_Pragma_Semicolon;
 374          return Result;
 375       else
 376          Skip_Pragma_Semicolon;
 377          return Par.Prag (Pragma_Node, Semicolon_Loc);
 378       end if;
 379
 380    exception
 381       when Error_Resync =>
 382          Resync_Past_Semicolon;
 383          return Error;
 384
 385    end P_Pragma;
 386
 387    --  This routine is called if a pragma is encountered in an inappropriate
 388    --  position, the pragma is scanned out and control returns to continue.
 389
 390    --  The caller has checked that the initial token is pragma
 391
 392    --  Error recovery: cannot raise Error_Resync
 393
 394    procedure P_Pragmas_Misplaced is
 395    begin
 396       while Token = Tok_Pragma loop
 397          Error_Msg_SC ("pragma not allowed here");
 398          Discard_Junk_Node (P_Pragma);
 399       end loop;
 400    end P_Pragmas_Misplaced;
 401
 402    --  This function is called to scan out an optional sequence of pragmas.
 403    --  If no pragmas are found, then No_List is returned.
 404
 405    --  Error recovery: Cannot raise Error_Resync
 406
 407    function P_Pragmas_Opt return List_Id is
 408       L : List_Id;
 409
 410    begin
 411       if Token = Tok_Pragma then
 412          L := New_List;
 413          P_Pragmas_Opt (L);
 414          return L;
 415
 416       else
 417          return No_List;
 418       end if;
 419    end P_Pragmas_Opt;
 420
 421    --  This procedure is called to scan out an optional sequence of pragmas.
 422    --  Any pragmas found are appended to the list provided as an argument.
 423
 424    --  Error recovery: Cannot raise Error_Resync
 425
 426    procedure P_Pragmas_Opt (List : List_Id) is
 427       P : Node_Id;
 428
 429    begin
 430       while Token = Tok_Pragma loop
 431          P := P_Pragma;
 432
 433          if Chars (P) = Name_Assert or else Chars (P) = Name_Debug then
 434             Error_Msg_Name_1 := Chars (P);
 435             Error_Msg_N
 436               ("pragma% must be in declaration/statement context", P);
 437          else
 438             Append (P, List);
 439          end if;
 440       end loop;
 441    end P_Pragmas_Opt;
 442
 443    --------------------------------------
 444    -- 2.8  Pragma_Argument Association --
 445    --------------------------------------
 446
 447    --  PRAGMA_ARGUMENT_ASSOCIATION ::=
 448    --    [pragma_argument_IDENTIFIER =>] NAME
 449    --  | [pragma_argument_IDENTIFIER =>] EXPRESSION
 450
 451    --  Error recovery: cannot raise Error_Resync
 452
 453    procedure Scan_Pragma_Argument_Association
 454      (Identifier_Seen : in out Boolean;
 455       Association     : out Node_Id)
 456    is
 457       Scan_State      : Saved_Scan_State;
 458       Identifier_Node : Node_Id;
 459
 460    begin
 461       Association := New_Node (N_Pragma_Argument_Association, Token_Ptr);
 462       Set_Chars (Association, No_Name);
 463
 464       if Token = Tok_Identifier then
 465          Identifier_Node := Token_Node;
 466          Save_Scan_State (Scan_State); -- at Identifier
 467          Scan; -- past Identifier
 468
 469          if Token = Tok_Arrow then
 470             Identifier_Seen := True;
 471             Scan; -- past arrow
 472             Set_Chars (Association, Chars (Identifier_Node));
 473             Delete_Node (Identifier_Node);
 474
 475             --  Case of argument with no identifier
 476
 477          else
 478             Restore_Scan_State (Scan_State); -- to Identifier
 479
 480             if Identifier_Seen then
 481                Error_Msg_SC
 482                  ("|pragma argument identifier required here ('R'M' 2.8(4))");
 483             end if;
 484          end if;
 485       end if;
 486
 487       Set_Expression (Association, P_Expression);
 488    end Scan_Pragma_Argument_Association;
 489
 490 end Ch2;