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) 1992-2011, 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 pragma Style_Checks (All_Checks);
  27 --  Turn off subprogram body ordering check. Subprograms are in order
  28 --  by RM section rather than alphabetical
  29
  30 separate (Par)
  31 package body Ch2 is
  32
  33    --  Local functions, used only in this chapter
  34
  35    procedure Scan_Pragma_Argument_Association
  36      (Identifier_Seen : in out Boolean;
  37       Association     : out Node_Id);
  38    --  Scans out a pragma argument association. Identifier_Seen is true on
  39    --  entry if a previous association had an identifier, and gets set True if
  40    --  the scanned association has an identifier (this is used to check the
  41    --  rule that no associations without identifiers can follow an association
  42    --  which has an identifier). The result is returned in Association.
  43
  44    ---------------------
  45    -- 2.3  Identifier --
  46    ---------------------
  47
  48    --  IDENTIFIER ::= LETTER {[UNDERLINE] LETTER_OR_DIGIT}
  49
  50    --  LETTER_OR_DIGIT ::= IDENTIFIER_LETTER | DIGIT
  51
  52    --  An IDENTIFIER shall not be a reserved word
  53
  54    --  Error recovery: can raise Error_Resync (cannot return Error)
  55
  56    function P_Identifier (C : Id_Check := None) return Node_Id is
  57       Ident_Node : Node_Id;
  58
  59    begin
  60       --  All set if we do indeed have an identifier
  61
  62       --  Code duplication, see Par_Ch3.P_Defining_Identifier???
  63
  64       if Token = Tok_Identifier then
  65          Check_Future_Keyword;
  66          Ident_Node := Token_Node;
  67          Scan; -- past Identifier
  68          return Ident_Node;
  69
  70       --  If we have a reserved identifier, manufacture an identifier with
  71       --  a corresponding name after posting an appropriate error message
  72
  73       elsif Is_Reserved_Identifier (C) then
  74          Scan_Reserved_Identifier (Force_Msg => False);
  75          Ident_Node := Token_Node;
  76          Scan; -- past the node
  77          return Ident_Node;
  78
  79       --  Otherwise we have junk that cannot be interpreted as an identifier
  80
  81       else
  82          T_Identifier; -- to give message
  83          raise Error_Resync;
  84       end if;
  85    end P_Identifier;
  86
  87    --------------------------
  88    -- 2.3  Letter Or Digit --
  89    --------------------------
  90
  91    --  Parsed by P_Identifier (2.3)
  92
  93    --------------------------
  94    -- 2.4  Numeric Literal --
  95    --------------------------
  96
  97    --  NUMERIC_LITERAL ::= DECIMAL_LITERAL | BASED_LITERAL
  98
  99    --  Numeric literal is returned by the scanner as either
 100    --  Tok_Integer_Literal or Tok_Real_Literal
 101
 102    ----------------------------
 103    -- 2.4.1  Decimal Literal --
 104    ----------------------------
 105
 106    --  DECIMAL_LITERAL ::= NUMERAL [.NUMERAL] [EXPONENT]
 107
 108    --  Handled by scanner as part of numeric literal handing (see 2.4)
 109
 110    --------------------
 111    -- 2.4.1  Numeral --
 112    --------------------
 113
 114    --  NUMERAL ::= DIGIT {[UNDERLINE] DIGIT}
 115
 116    --  Handled by scanner as part of numeric literal handling (see 2.4)
 117
 118    ---------------------
 119    -- 2.4.1  Exponent --
 120    ---------------------
 121
 122    --  EXPONENT ::= E [+] NUMERAL | E - NUMERAL
 123
 124    --  Handled by scanner as part of numeric literal handling (see 2.4)
 125
 126    --------------------------
 127    -- 2.4.2  Based Literal --
 128    --------------------------
 129
 130    --  BASED_LITERAL ::=
 131    --   BASE # BASED_NUMERAL [.BASED_NUMERAL] # [EXPONENT]
 132
 133    --  Handled by scanner as part of numeric literal handling (see 2.4)
 134
 135    -----------------
 136    -- 2.4.2  Base --
 137    -----------------
 138
 139    --  BASE ::= NUMERAL
 140
 141    --  Handled by scanner as part of numeric literal handling (see 2.4)
 142
 143    --------------------------
 144    -- 2.4.2  Based Numeral --
 145    --------------------------
 146
 147    --  BASED_NUMERAL ::=
 148    --    EXTENDED_DIGIT {[UNDERLINE] EXTENDED_DIGIT}
 149
 150    --  Handled by scanner as part of numeric literal handling (see 2.4)
 151
 152    ---------------------------
 153    -- 2.4.2  Extended Digit --
 154    ---------------------------
 155
 156    --  EXTENDED_DIGIT ::= DIGIT | A | B | C | D | E | F
 157
 158    --  Handled by scanner as part of numeric literal handling (see 2.4)
 159
 160    ----------------------------
 161    -- 2.5  Character Literal --
 162    ----------------------------
 163
 164    --  CHARACTER_LITERAL ::= ' GRAPHIC_CHARACTER '
 165
 166    --  Handled by the scanner and returned as Tok_Char_Literal
 167
 168    -------------------------
 169    -- 2.6  String Literal --
 170    -------------------------
 171
 172    --  STRING LITERAL ::= "{STRING_ELEMENT}"
 173
 174    --  Handled by the scanner and returned as Tok_String_Literal
 175    --  or if the string looks like an operator as Tok_Operator_Symbol.
 176
 177    -------------------------
 178    -- 2.6  String Element --
 179    -------------------------
 180
 181    --  STRING_ELEMENT ::= "" | non-quotation_mark_GRAPHIC_CHARACTER
 182
 183    --  A STRING_ELEMENT is either a pair of quotation marks ("),
 184    --  or a single GRAPHIC_CHARACTER other than a quotation mark.
 185
 186    --  Handled by scanner as part of string literal handling (see 2.4)
 187
 188    ------------------
 189    -- 2.7  Comment --
 190    ------------------
 191
 192    --  A COMMENT starts with two adjacent hyphens and extends up to the
 193    --  end of the line. A COMMENT may appear on any line of a program.
 194
 195    --  Handled by the scanner which simply skips past encountered comments
 196
 197    -----------------
 198    -- 2.8  Pragma --
 199    -----------------
 200
 201    --  PRAGMA ::= pragma IDENTIFIER
 202    --    [(PRAGMA_ARGUMENT_ASSOCIATION {, PRAGMA_ARGUMENT_ASSOCIATION})];
 203
 204    --  The caller has checked that the initial token is PRAGMA
 205
 206    --  Error recovery: cannot raise Error_Resync
 207
 208    --  One special piece of processing is needed in this routine. As described
 209    --  in the section on "Handling semicolon used in place of IS" in module
 210    --  Parse, the parser detects the case of missing subprogram bodies to
 211    --  allow recovery from this syntactic error. Pragma INTERFACE (and, for
 212    --  Ada 95, pragma IMPORT) can appear in place of the body. The parser must
 213    --  recognize the use of these two pragmas in this context, otherwise it
 214    --  will think there are missing bodies, and try to change ; to IS, when
 215    --  in fact the bodies ARE present, supplied by these pragmas.
 216
 217    function P_Pragma (Skipping : Boolean := False) return Node_Id is
 218       Interface_Check_Required : Boolean := False;
 219       --  Set True if check of pragma INTERFACE is required
 220
 221       Import_Check_Required : Boolean := False;
 222       --  Set True if check of pragma IMPORT is required
 223
 224       Arg_Count : Int := 0;
 225       --  Number of argument associations processed
 226
 227       Identifier_Seen : Boolean := False;
 228       --  Set True if an identifier is encountered for a pragma argument. Used
 229       --  to check that there are no more arguments without identifiers.
 230
 231       Prag_Node     : Node_Id;
 232       Prag_Name     : Name_Id;
 233       Semicolon_Loc : Source_Ptr;
 234       Ident_Node    : Node_Id;
 235       Assoc_Node    : Node_Id;
 236       Result        : Node_Id;
 237
 238       procedure Skip_Pragma_Semicolon;
 239       --  Skip past semicolon at end of pragma
 240
 241       ---------------------------
 242       -- Skip_Pragma_Semicolon --
 243       ---------------------------
 244
 245       procedure Skip_Pragma_Semicolon is
 246       begin
 247          if Token /= Tok_Semicolon then
 248
 249             --  If skipping the pragma, ignore a missing semicolon
 250
 251             if Skipping then
 252                null;
 253
 254             --  Otherwise demand a semicolon
 255
 256             else
 257                T_Semicolon;
 258             end if;
 259
 260          --  Scan past semicolon if present
 261
 262          else
 263             Scan;
 264          end if;
 265       end Skip_Pragma_Semicolon;
 266
 267    --  Start of processing for P_Pragma
 268
 269    begin
 270       Prag_Node := New_Node (N_Pragma, Token_Ptr);
 271       Scan; -- past PRAGMA
 272       Prag_Name := Token_Name;
 273
 274       if Style_Check then
 275          Style.Check_Pragma_Name;
 276       end if;
 277
 278       --  Ada 2005 (AI-284): INTERFACE is a new reserved word but it is
 279       --  allowed as a pragma name.
 280
 281       if Ada_Version >= Ada_2005
 282         and then Token = Tok_Interface
 283       then
 284          Prag_Name := Name_Interface;
 285          Ident_Node  := Make_Identifier (Token_Ptr, Name_Interface);
 286          Scan; -- past INTERFACE
 287       else
 288          Ident_Node := P_Identifier;
 289       end if;
 290
 291       Set_Pragma_Identifier (Prag_Node, Ident_Node);
 292
 293       --  See if special INTERFACE/IMPORT check is required
 294
 295       if SIS_Entry_Active then
 296          Interface_Check_Required := (Prag_Name = Name_Interface);
 297          Import_Check_Required    := (Prag_Name = Name_Import);
 298       else
 299          Interface_Check_Required := False;
 300          Import_Check_Required    := False;
 301       end if;
 302
 303       --  Scan arguments. We assume that arguments are present if there is
 304       --  a left paren, or if a semicolon is missing and there is another
 305       --  token on the same line as the pragma name.
 306
 307       if Token = Tok_Left_Paren
 308         or else (Token /= Tok_Semicolon
 309                    and then not Token_Is_At_Start_Of_Line)
 310       then
 311          Set_Pragma_Argument_Associations (Prag_Node, New_List);
 312          T_Left_Paren;
 313
 314          loop
 315             Arg_Count := Arg_Count + 1;
 316             Scan_Pragma_Argument_Association (Identifier_Seen, Assoc_Node);
 317
 318             if Arg_Count = 2
 319               and then (Interface_Check_Required or else Import_Check_Required)
 320             then
 321                --  Here is where we cancel the SIS active status if this pragma
 322                --  supplies a body for the currently active subprogram spec.
 323
 324                if Nkind (Expression (Assoc_Node)) in N_Direct_Name
 325                  and then Chars (Expression (Assoc_Node)) = Chars (SIS_Labl)
 326                then
 327                   SIS_Entry_Active := False;
 328                end if;
 329             end if;
 330
 331             Append (Assoc_Node, Pragma_Argument_Associations (Prag_Node));
 332             exit when Token /= Tok_Comma;
 333             Scan; -- past comma
 334          end loop;
 335
 336          --  If we have := for pragma Debug, it is worth special casing the
 337          --  error message (it is easy to think of pragma Debug as taking a
 338          --  statement, and an assignment statement is the most likely
 339          --  candidate for this error)
 340
 341          if Token = Tok_Colon_Equal and then Prag_Name = Name_Debug then
 342             Error_Msg_SC ("argument for pragma Debug must be procedure call");
 343             Resync_To_Semicolon;
 344
 345          --  Normal case, we expect a right paren here
 346
 347          else
 348             T_Right_Paren;
 349          end if;
 350       end if;
 351
 352       Semicolon_Loc := Token_Ptr;
 353
 354       --  Now we have two tasks left, we need to scan out the semicolon
 355       --  following the pragma, and we have to call Par.Prag to process
 356       --  the pragma. Normally we do them in this order, however, there
 357       --  is one exception namely pragma Style_Checks where we like to
 358       --  skip the semicolon after processing the pragma, since that way
 359       --  the style checks for the scanning of the semicolon follow the
 360       --  settings of the pragma.
 361
 362       --  You might think we could just unconditionally do things in
 363       --  the opposite order, but there are other pragmas, notably the
 364       --  case of pragma Source_File_Name, which assume the semicolon
 365       --  is already scanned out.
 366
 367       if Prag_Name = Name_Style_Checks then
 368          Result := Par.Prag (Prag_Node, Semicolon_Loc);
 369          Skip_Pragma_Semicolon;
 370          return Result;
 371       else
 372          Skip_Pragma_Semicolon;
 373          return Par.Prag (Prag_Node, Semicolon_Loc);
 374       end if;
 375
 376    exception
 377       when Error_Resync =>
 378          Resync_Past_Semicolon;
 379          return Error;
 380
 381    end P_Pragma;
 382
 383    --  This routine is called if a pragma is encountered in an inappropriate
 384    --  position, the pragma is scanned out and control returns to continue.
 385
 386    --  The caller has checked that the initial token is pragma
 387
 388    --  Error recovery: cannot raise Error_Resync
 389
 390    procedure P_Pragmas_Misplaced is
 391    begin
 392       while Token = Tok_Pragma loop
 393          Error_Msg_SC ("pragma not allowed here");
 394          Discard_Junk_Node (P_Pragma (Skipping => True));
 395       end loop;
 396    end P_Pragmas_Misplaced;
 397
 398    --  This function is called to scan out an optional sequence of pragmas.
 399    --  If no pragmas are found, then No_List is returned.
 400
 401    --  Error recovery: Cannot raise Error_Resync
 402
 403    function P_Pragmas_Opt return List_Id is
 404       L : List_Id;
 405
 406    begin
 407       if Token = Tok_Pragma then
 408          L := New_List;
 409          P_Pragmas_Opt (L);
 410          return L;
 411
 412       else
 413          return No_List;
 414       end if;
 415    end P_Pragmas_Opt;
 416
 417    --  This procedure is called to scan out an optional sequence of pragmas.
 418    --  Any pragmas found are appended to the list provided as an argument.
 419
 420    --  Error recovery: Cannot raise Error_Resync
 421
 422    procedure P_Pragmas_Opt (List : List_Id) is
 423       P     : Node_Id;
 424
 425    begin
 426       while Token = Tok_Pragma loop
 427          P := P_Pragma;
 428
 429          if Nkind (P) /= N_Error
 430           and then (Pragma_Name (P) = Name_Assert
 431                       or else
 432                     Pragma_Name (P) = Name_Debug)
 433          then
 434             Error_Msg_Name_1 := Pragma_Name (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       Id_Present      : Boolean;
 460
 461    begin
 462       Association := New_Node (N_Pragma_Argument_Association, Token_Ptr);
 463       Set_Chars (Association, No_Name);
 464
 465       --  Argument starts with identifier
 466
 467       if Token = Tok_Identifier then
 468          Identifier_Node := Token_Node;
 469          Save_Scan_State (Scan_State); -- at Identifier
 470          Scan; -- past Identifier
 471
 472          if Token = Tok_Arrow then
 473             Identifier_Seen := True;
 474             Scan; -- past arrow
 475             Set_Chars (Association, Chars (Identifier_Node));
 476             Id_Present := True;
 477
 478          --  Case of argument with no identifier
 479
 480          else
 481             Restore_Scan_State (Scan_State); -- to Identifier
 482             Id_Present := False;
 483          end if;
 484
 485       --  Argument does not start with identifier
 486
 487       else
 488          Id_Present := False;
 489       end if;
 490
 491       --  Diagnose error of "positional" argument for pragma appearing after
 492       --  a "named" argument (quotes here are because that's not quite accurate
 493       --  Ada RM terminology).
 494
 495       --  Since older GNAT versions did not generate this error, disable this
 496       --  message in codepeer mode to help legacy code using codepeer.
 497
 498       if Identifier_Seen and not Id_Present and not CodePeer_Mode then
 499          Error_Msg_SC ("|pragma argument identifier required here");
 500          Error_Msg_SC ("\since previous argument had identifier (RM 2.8(4))");
 501       end if;
 502
 503       if Id_Present then
 504          Set_Expression (Association, P_Expression);
 505       else
 506          Set_Expression (Association, P_Expression_If_OK);
 507       end if;
 508    end Scan_Pragma_Argument_Association;
 509
 510 end Ch2;