gcc/ada/par-ch11.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             P A R . C H 1 1                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2002 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,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, 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 with Sinfo.CN; use Sinfo.CN;
  32
  33 separate (Par)
  34 package body Ch11 is
  35
  36    --  Local functions, used only in this chapter
  37
  38    function P_Exception_Handler  return Node_Id;
  39    function P_Exception_Choice   return Node_Id;
  40
  41    ---------------------------------
  42    -- 11.1  Exception Declaration --
  43    ---------------------------------
  44
  45    --  Parsed by P_Identifier_Declaration (3.3.1)
  46
  47    ------------------------------------------
  48    -- 11.2  Handled Sequence Of Statements --
  49    ------------------------------------------
  50
  51    --  HANDLED_SEQUENCE_OF_STATEMENTS ::=
  52    --      SEQUENCE_OF_STATEMENTS
  53    --    [exception
  54    --      EXCEPTION_HANDLER
  55    --      {EXCEPTION_HANDLER}]
  56
  57    --  Error_Recovery : Cannot raise Error_Resync
  58
  59    function P_Handled_Sequence_Of_Statements return Node_Id is
  60       Handled_Stmt_Seq_Node : Node_Id;
  61
  62    begin
  63       Handled_Stmt_Seq_Node :=
  64         New_Node (N_Handled_Sequence_Of_Statements, Token_Ptr);
  65       Set_Statements
  66         (Handled_Stmt_Seq_Node, P_Sequence_Of_Statements (SS_Extm_Sreq));
  67
  68       if Token = Tok_Exception then
  69          Scan; -- past EXCEPTION
  70          Set_Exception_Handlers
  71            (Handled_Stmt_Seq_Node, Parse_Exception_Handlers);
  72       end if;
  73
  74       return Handled_Stmt_Seq_Node;
  75    end P_Handled_Sequence_Of_Statements;
  76
  77    -----------------------------
  78    -- 11.2  Exception Handler --
  79    -----------------------------
  80
  81    --  EXCEPTION_HANDLER ::=
  82    --    when [CHOICE_PARAMETER_SPECIFICATION :]
  83    --      EXCEPTION_CHOICE {| EXCEPTION_CHOICE} =>
  84    --        SEQUENCE_OF_STATEMENTS
  85
  86    --  CHOICE_PARAMETER_SPECIFICATION ::= DEFINING_IDENTIFIER
  87
  88    --  Error recovery: cannot raise Error_Resync
  89
  90    function P_Exception_Handler return Node_Id is
  91       Scan_State        : Saved_Scan_State;
  92       Handler_Node      : Node_Id;
  93       Choice_Param_Node : Node_Id;
  94
  95    begin
  96       Handler_Node := New_Node (N_Exception_Handler, Token_Ptr);
  97       T_When;
  98
  99       --  Test for possible choice parameter present
 100
 101       if Token = Tok_Identifier then
 102          Choice_Param_Node := Token_Node;
 103          Save_Scan_State (Scan_State); -- at identifier
 104          Scan; -- past identifier
 105
 106          if Token = Tok_Colon then
 107             if Ada_83 then
 108                Error_Msg_SP ("(Ada 83) choice parameter not allowed!");
 109             end if;
 110
 111             Scan; -- past :
 112             Change_Identifier_To_Defining_Identifier (Choice_Param_Node);
 113             Set_Choice_Parameter (Handler_Node, Choice_Param_Node);
 114
 115          elsif Token = Tok_Others then
 116             Error_Msg_AP ("missing "":""");
 117             Change_Identifier_To_Defining_Identifier (Choice_Param_Node);
 118             Set_Choice_Parameter (Handler_Node, Choice_Param_Node);
 119
 120          else
 121             Restore_Scan_State (Scan_State); -- to identifier
 122          end if;
 123       end if;
 124
 125       --  Loop through exception choices
 126
 127       Set_Exception_Choices (Handler_Node, New_List);
 128
 129       loop
 130          Append (P_Exception_Choice, Exception_Choices (Handler_Node));
 131          exit when Token /= Tok_Vertical_Bar;
 132          Scan; -- past vertical bar
 133       end loop;
 134
 135       TF_Arrow;
 136       Set_Statements (Handler_Node, P_Sequence_Of_Statements (SS_Sreq_Whtm));
 137       return Handler_Node;
 138    end P_Exception_Handler;
 139
 140    ------------------------------------------
 141    -- 11.2  Choice Parameter Specification --
 142    ------------------------------------------
 143
 144    --  Parsed by P_Exception_Handler (11.2)
 145
 146    ----------------------------
 147    -- 11.2  Exception Choice --
 148    ----------------------------
 149
 150    --  EXCEPTION_CHOICE ::= exception_NAME | others
 151
 152    --  Error recovery: cannot raise Error_Resync. If an error occurs, then the
 153    --  scan pointer is advanced to the next arrow or vertical bar or semicolon.
 154
 155    function P_Exception_Choice return Node_Id is
 156    begin
 157
 158       if Token = Tok_Others then
 159          Scan; -- past OTHERS
 160          return New_Node (N_Others_Choice, Prev_Token_Ptr);
 161
 162       else
 163          return P_Name; -- exception name
 164       end if;
 165
 166    exception
 167       when Error_Resync =>
 168          Resync_Choice;
 169          return Error;
 170    end P_Exception_Choice;
 171
 172    ---------------------------
 173    -- 11.3  Raise Statement --
 174    ---------------------------
 175
 176    --  RAISE_STATEMENT ::= raise [exception_NAME];
 177
 178    --  The caller has verified that the initial token is RAISE
 179
 180    --  Error recovery: can raise Error_Resync
 181
 182    function P_Raise_Statement return Node_Id is
 183       Raise_Node : Node_Id;
 184
 185    begin
 186       Raise_Node := New_Node (N_Raise_Statement, Token_Ptr);
 187       Scan; -- past RAISE
 188
 189       if Token /= Tok_Semicolon then
 190          Set_Name (Raise_Node, P_Name);
 191       end if;
 192
 193       TF_Semicolon;
 194       return Raise_Node;
 195    end P_Raise_Statement;
 196
 197    ------------------------------
 198    -- Parse_Exception_Handlers --
 199    ------------------------------
 200
 201    --  This routine scans out a list of exception handlers appearing in a
 202    --  construct as:
 203
 204    --    exception
 205    --      EXCEPTION_HANDLER {EXCEPTION_HANDLER}
 206
 207    --  The caller has scanned out the EXCEPTION keyword
 208
 209    --  Control returns after scanning the last exception handler, presumably
 210    --  at the keyword END, but this is not checked in this routine.
 211
 212    --  Error recovery: cannot raise Error_Resync
 213
 214    function Parse_Exception_Handlers return List_Id is
 215       Handler       : Node_Id;
 216       Handlers_List : List_Id;
 217
 218    begin
 219       Handlers_List := New_List;
 220       P_Pragmas_Opt (Handlers_List);
 221
 222       if Token = Tok_End then
 223          Error_Msg_SC ("must have at least one exception handler!");
 224
 225       else
 226          loop
 227             Handler := P_Exception_Handler;
 228             Append (Handler, Handlers_List);
 229
 230             --  Note: no need to check for pragmas here. Although the
 231             --  syntax officially allows them in this position, they
 232             --  will have been swallowed up as part of the statement
 233             --  sequence of the handler we just scanned out.
 234
 235             exit when Token /= Tok_When;
 236          end loop;
 237       end if;
 238
 239       return Handlers_List;
 240    end Parse_Exception_Handlers;
 241
 242 end Ch11;