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) 1992-2008, 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 with Sinfo.CN; use Sinfo.CN;
  31
  32 separate (Par)
  33 package body Ch11 is
  34
  35    --  Local functions, used only in this chapter
  36
  37    function P_Exception_Handler  return Node_Id;
  38    function P_Exception_Choice   return Node_Id;
  39
  40    ---------------------------------
  41    -- 11.1  Exception Declaration --
  42    ---------------------------------
  43
  44    --  Parsed by P_Identifier_Declaration (3.3.1)
  45
  46    ------------------------------------------
  47    -- 11.2  Handled Sequence Of Statements --
  48    ------------------------------------------
  49
  50    --  HANDLED_SEQUENCE_OF_STATEMENTS ::=
  51    --      SEQUENCE_OF_STATEMENTS
  52    --    [exception
  53    --      EXCEPTION_HANDLER
  54    --      {EXCEPTION_HANDLER}]
  55
  56    --  Error_Recovery : Cannot raise Error_Resync
  57
  58    function P_Handled_Sequence_Of_Statements return Node_Id is
  59       Handled_Stmt_Seq_Node : Node_Id;
  60
  61    begin
  62       Handled_Stmt_Seq_Node :=
  63         New_Node (N_Handled_Sequence_Of_Statements, Token_Ptr);
  64       Set_Statements
  65         (Handled_Stmt_Seq_Node, P_Sequence_Of_Statements (SS_Extm_Sreq));
  66
  67       if Token = Tok_Exception then
  68          Scan; -- past EXCEPTION
  69          Set_Exception_Handlers
  70            (Handled_Stmt_Seq_Node, Parse_Exception_Handlers);
  71       end if;
  72
  73       return Handled_Stmt_Seq_Node;
  74    end P_Handled_Sequence_Of_Statements;
  75
  76    -----------------------------
  77    -- 11.2  Exception Handler --
  78    -----------------------------
  79
  80    --  EXCEPTION_HANDLER ::=
  81    --    when [CHOICE_PARAMETER_SPECIFICATION :]
  82    --      EXCEPTION_CHOICE {| EXCEPTION_CHOICE} =>
  83    --        SEQUENCE_OF_STATEMENTS
  84
  85    --  CHOICE_PARAMETER_SPECIFICATION ::= DEFINING_IDENTIFIER
  86
  87    --  Error recovery: cannot raise Error_Resync
  88
  89    function P_Exception_Handler return Node_Id is
  90       Scan_State        : Saved_Scan_State;
  91       Handler_Node      : Node_Id;
  92       Choice_Param_Node : Node_Id;
  93
  94    begin
  95       Handler_Node := New_Node (N_Exception_Handler, Token_Ptr);
  96       Set_Local_Raise_Statements (Handler_Node, No_Elist);
  97
  98       if Style_Check then
  99          Style.Check_Indentation;
 100       end if;
 101
 102       T_When;
 103
 104       --  Test for possible choice parameter present
 105
 106       if Token = Tok_Identifier then
 107          Choice_Param_Node := Token_Node;
 108          Save_Scan_State (Scan_State); -- at identifier
 109          Scan; -- past identifier
 110
 111          if Token = Tok_Colon then
 112             if Ada_Version = Ada_83 then
 113                Error_Msg_SP ("(Ada 83) choice parameter not allowed!");
 114             end if;
 115
 116             Scan; -- past :
 117             Change_Identifier_To_Defining_Identifier (Choice_Param_Node);
 118             Set_Choice_Parameter (Handler_Node, Choice_Param_Node);
 119
 120          elsif Token = Tok_Others then
 121             Error_Msg_AP ("missing "":""");
 122             Change_Identifier_To_Defining_Identifier (Choice_Param_Node);
 123             Set_Choice_Parameter (Handler_Node, Choice_Param_Node);
 124
 125          else
 126             Restore_Scan_State (Scan_State); -- to identifier
 127          end if;
 128       end if;
 129
 130       --  Loop through exception choices
 131
 132       Set_Exception_Choices (Handler_Node, New_List);
 133
 134       loop
 135          Append (P_Exception_Choice, Exception_Choices (Handler_Node));
 136          exit when Token /= Tok_Vertical_Bar;
 137          Scan; -- past vertical bar
 138       end loop;
 139
 140       TF_Arrow;
 141       Set_Statements (Handler_Node, P_Sequence_Of_Statements (SS_Sreq_Whtm));
 142       return Handler_Node;
 143    end P_Exception_Handler;
 144
 145    ------------------------------------------
 146    -- 11.2  Choice Parameter Specification --
 147    ------------------------------------------
 148
 149    --  Parsed by P_Exception_Handler (11.2)
 150
 151    ----------------------------
 152    -- 11.2  Exception Choice --
 153    ----------------------------
 154
 155    --  EXCEPTION_CHOICE ::= exception_NAME | others
 156
 157    --  Error recovery: cannot raise Error_Resync. If an error occurs, then the
 158    --  scan pointer is advanced to the next arrow or vertical bar or semicolon.
 159
 160    function P_Exception_Choice return Node_Id is
 161    begin
 162
 163       if Token = Tok_Others then
 164          Scan; -- past OTHERS
 165          return New_Node (N_Others_Choice, Prev_Token_Ptr);
 166
 167       else
 168          return P_Name; -- exception name
 169       end if;
 170
 171    exception
 172       when Error_Resync =>
 173          Resync_Choice;
 174          return Error;
 175    end P_Exception_Choice;
 176
 177    ---------------------------
 178    -- 11.3  Raise Statement --
 179    ---------------------------
 180
 181    --  RAISE_STATEMENT ::= raise [exception_NAME];
 182
 183    --  The caller has verified that the initial token is RAISE
 184
 185    --  Error recovery: can raise Error_Resync
 186
 187    function P_Raise_Statement return Node_Id is
 188       Raise_Node : Node_Id;
 189
 190    begin
 191       Raise_Node := New_Node (N_Raise_Statement, Token_Ptr);
 192       Scan; -- past RAISE
 193
 194       if Token /= Tok_Semicolon then
 195          Set_Name (Raise_Node, P_Name);
 196       end if;
 197
 198       if Token = Tok_With then
 199          if Ada_Version < Ada_05 then
 200             Error_Msg_SC ("string expression in raise is Ada 2005 extension");
 201             Error_Msg_SC ("\unit must be compiled with -gnat05 switch");
 202          end if;
 203
 204          Scan; -- past WITH
 205          Set_Expression (Raise_Node, P_Expression);
 206       end if;
 207
 208       TF_Semicolon;
 209       return Raise_Node;
 210    end P_Raise_Statement;
 211
 212    ------------------------------
 213    -- Parse_Exception_Handlers --
 214    ------------------------------
 215
 216    --  This routine scans out a list of exception handlers appearing in a
 217    --  construct as:
 218
 219    --    exception
 220    --      EXCEPTION_HANDLER {EXCEPTION_HANDLER}
 221
 222    --  The caller has scanned out the EXCEPTION keyword
 223
 224    --  Control returns after scanning the last exception handler, presumably
 225    --  at the keyword END, but this is not checked in this routine.
 226
 227    --  Error recovery: cannot raise Error_Resync
 228
 229    function Parse_Exception_Handlers return List_Id is
 230       Handler       : Node_Id;
 231       Handlers_List : List_Id;
 232
 233    begin
 234       Handlers_List := New_List;
 235       P_Pragmas_Opt (Handlers_List);
 236
 237       if Token = Tok_End then
 238          Error_Msg_SC ("must have at least one exception handler!");
 239
 240       else
 241          loop
 242             Handler := P_Exception_Handler;
 243             Append (Handler, Handlers_List);
 244
 245             --  Note: no need to check for pragmas here. Although the
 246             --  syntax officially allows them in this position, they
 247             --  will have been swallowed up as part of the statement
 248             --  sequence of the handler we just scanned out.
 249
 250             exit when Token /= Tok_When;
 251          end loop;
 252       end if;
 253
 254       return Handlers_List;
 255    end Parse_Exception_Handlers;
 256
 257 end Ch11;