1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2001, Free Software Foundation, Inc. --
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. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 pragma Style_Checks (All_Checks);
28 -- Turn off subprogram body ordering check. Subprograms are in order
29 -- by RM section rather than alphabetical
34 -- Local functions, used only in this chapter
36 function P_Case_Statement return Node_Id;
37 function P_Case_Statement_Alternative return Node_Id;
38 function P_Condition return Node_Id;
39 function P_Exit_Statement return Node_Id;
40 function P_Goto_Statement return Node_Id;
41 function P_If_Statement return Node_Id;
42 function P_Label return Node_Id;
43 function P_Loop_Parameter_Specification return Node_Id;
44 function P_Null_Statement return Node_Id;
46 function P_Assignment_Statement (LHS : Node_Id) return Node_Id;
47 -- Parse assignment statement. On entry, the caller has scanned the left
48 -- hand side (passed in as Lhs), and the colon-equal (or some symbol
49 -- taken to be an error equivalent such as equal).
51 function P_Begin_Statement (Block_Name : Node_Id := Empty) return Node_Id;
52 -- Parse begin-end statement. If Block_Name is non-Empty on entry, it is
53 -- the N_Identifier node for the label on the block. If Block_Name is
54 -- Empty on entry (the default), then the block statement is unlabeled.
56 function P_Declare_Statement (Block_Name : Node_Id := Empty) return Node_Id;
57 -- Parse declare block. If Block_Name is non-Empty on entry, it is
58 -- the N_Identifier node for the label on the block. If Block_Name is
59 -- Empty on entry (the default), then the block statement is unlabeled.
61 function P_For_Statement (Loop_Name : Node_Id := Empty) return Node_Id;
62 -- Parse for statement. If Loop_Name is non-Empty on entry, it is
63 -- the N_Identifier node for the label on the loop. If Loop_Name is
64 -- Empty on entry (the default), then the for statement is unlabeled.
66 function P_Loop_Statement (Loop_Name : Node_Id := Empty) return Node_Id;
67 -- Parse loop statement. If Loop_Name is non-Empty on entry, it is
68 -- the N_Identifier node for the label on the loop. If Loop_Name is
69 -- Empty on entry (the default), then the loop statement is unlabeled.
71 function P_While_Statement (Loop_Name : Node_Id := Empty) return Node_Id;
72 -- Parse while statement. If Loop_Name is non-Empty on entry, it is
73 -- the N_Identifier node for the label on the loop. If Loop_Name is
74 -- Empty on entry (the default), then the while statement is unlabeled.
76 function Set_Loop_Block_Name (L : Character) return Name_Id;
77 -- Given a letter 'L' for a loop or 'B' for a block, returns a name
78 -- of the form L_nn or B_nn where nn is a serial number obtained by
79 -- incrementing the variable Loop_Block_Count.
82 -- Scan past THEN token, testing for illegal junk after it
84 ---------------------------------
85 -- 5.1 Sequence of Statements --
86 ---------------------------------
88 -- SEQUENCE_OF_STATEMENTS ::= STATEMENT {STATEMENT}
91 -- {LABEL} SIMPLE_STATEMENT | {LABEL} COMPOUND_STATEMENT
93 -- SIMPLE_STATEMENT ::= NULL_STATEMENT
94 -- | ASSIGNMENT_STATEMENT | EXIT_STATEMENT
95 -- | GOTO_STATEMENT | PROCEDURE_CALL_STATEMENT
96 -- | RETURN_STATEMENT | ENTRY_CALL_STATEMENT
97 -- | REQUEUE_STATEMENT | DELAY_STATEMENT
98 -- | ABORT_STATEMENT | RAISE_STATEMENT
101 -- COMPOUND_STATEMENT ::=
102 -- IF_STATEMENT | CASE_STATEMENT
103 -- | LOOP_STATEMENT | BLOCK_STATEMENT
104 -- | ACCEPT_STATEMENT | SELECT_STATEMENT
106 -- This procedure scans a sequence of statements. The caller sets SS_Flags
107 -- to indicate acceptable termination conditions for the sequence:
109 -- SS_Flags.Eftm Terminate on ELSIF
110 -- SS_Flags.Eltm Terminate on ELSE
111 -- SS_Flags.Extm Terminate on EXCEPTION
112 -- SS_Flags.Ortm Terminate on OR
113 -- SS_Flags.Tatm Terminate on THEN ABORT (Token = ABORT on return)
114 -- SS_Flags.Whtm Terminate on WHEN
115 -- SS_Flags.Unco Unconditional terminate after scanning one statement
117 -- In addition, the scan is always terminated by encountering END or the
118 -- end of file (EOF) condition. If one of the six above terminators is
119 -- encountered with the corresponding SS_Flags flag not set, then the
120 -- action taken is as follows:
122 -- If the keyword occurs to the left of the expected column of the end
123 -- for the current sequence (as recorded in the current end context),
124 -- then it is assumed to belong to an outer context, and is considered
125 -- to terminate the sequence of statements.
127 -- If the keyword occurs to the right of, or in the expected column of
128 -- the end for the current sequence, then an error message is output,
129 -- the keyword together with its associated context is skipped, and
130 -- the statement scan continues until another terminator is found.
132 -- Note that the first action means that control can return to the caller
133 -- with Token set to a terminator other than one of those specified by the
134 -- SS parameter. The caller should treat such a case as equivalent to END.
136 -- In addition, the flag SS_Flags.Sreq is set to True to indicate that at
137 -- least one real statement (other than a pragma) is required in the
138 -- statement sequence. During the processing of the sequence, this
139 -- flag is manipulated to indicate the current status of the requirement
140 -- for a statement. For example, it is turned off by the occurrence of a
141 -- statement, and back on by a label (which requires a following statement)
143 -- Error recovery: cannot raise Error_Resync. If an error occurs during
144 -- parsing a statement, then the scan pointer is advanced past the next
145 -- semicolon and the parse continues.
147 function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id is
149 Statement_Required : Boolean;
150 -- This flag indicates if a subsequent statement (other than a pragma)
151 -- is required. It is initialized from the Sreq flag, and modified as
152 -- statements are scanned (a statement turns it off, and a label turns
153 -- it back on again since a statement must follow a label).
155 Declaration_Found : Boolean := False;
156 -- This flag is set True if a declaration is encountered, so that the
157 -- error message about declarations in the statement part is only
158 -- given once for a given sequence of statements.
160 Scan_State_Label : Saved_Scan_State;
161 Scan_State : Saved_Scan_State;
163 Statement_List : List_Id;
164 Block_Label : Name_Id;
168 procedure Junk_Declaration;
169 -- Procedure called to handle error of declaration encountered in
170 -- statement sequence.
172 procedure Test_Statement_Required;
173 -- Flag error if Statement_Required flag set
175 procedure Junk_Declaration is
177 if (not Declaration_Found) or All_Errors_Mode then
178 Error_Msg_SC ("declarations must come before BEGIN");
179 Declaration_Found := True;
182 Skip_Declaration (Statement_List);
183 end Junk_Declaration;
185 procedure Test_Statement_Required is
187 if Statement_Required then
188 Error_Msg_BC ("statement expected");
190 end Test_Statement_Required;
192 -- Start of processing for P_Sequence_Of_Statements
195 Statement_List := New_List;
196 Statement_Required := SS_Flags.Sreq;
199 while Token = Tok_Semicolon loop
200 Error_Msg_SC ("unexpected semicolon ignored");
201 Scan; -- past junk semicolon
205 if Style_Check then Style.Check_Indentation; end if;
207 -- Deal with reserved identifier (in assignment or call)
209 if Is_Reserved_Identifier then
210 Save_Scan_State (Scan_State); -- at possible bad identifier
211 Scan; -- and scan past it
213 -- We have an reserved word which is spelled in identifier
214 -- style, so the question is whether it really is intended
215 -- to be an identifier.
218 -- If followed by a semicolon, then it is an identifier,
219 -- with the exception of the cases tested for below.
221 (Token = Tok_Semicolon
222 and then Prev_Token /= Tok_Return
223 and then Prev_Token /= Tok_Null
224 and then Prev_Token /= Tok_Raise
225 and then Prev_Token /= Tok_End
226 and then Prev_Token /= Tok_Exit)
228 -- If followed by colon, colon-equal, or dot, then we
229 -- definitely have an identifier (could not be reserved)
231 or else Token = Tok_Colon
232 or else Token = Tok_Colon_Equal
233 or else Token = Tok_Dot
235 -- Left paren means we have an identifier except for those
236 -- reserved words that can legitimately be followed by a
240 (Token = Tok_Left_Paren
241 and then Prev_Token /= Tok_Case
242 and then Prev_Token /= Tok_Delay
243 and then Prev_Token /= Tok_If
244 and then Prev_Token /= Tok_Elsif
245 and then Prev_Token /= Tok_Return
246 and then Prev_Token /= Tok_When
247 and then Prev_Token /= Tok_While
248 and then Prev_Token /= Tok_Separate)
250 -- Here we have an apparent reserved identifier and the
251 -- token past it is appropriate to this usage (and would
252 -- be a definite error if this is not an identifier). What
253 -- we do is to use P_Identifier to fix up the identifier,
254 -- and then fall into the normal processing.
256 Restore_Scan_State (Scan_State); -- back to the ID
257 Scan_Reserved_Identifier (Force_Msg => False);
259 -- Not a reserved identifier after all (or at least we can't
260 -- be sure that it is), so reset the scan and continue.
263 Restore_Scan_State (Scan_State); -- back to the reserved word
267 -- Now look to see what kind of statement we have
271 -- Case of end or EOF
273 when Tok_End | Tok_EOF =>
275 -- These tokens always terminate the statement sequence
277 Test_Statement_Required;
284 -- Terminate if Eftm set or if the ELSIF is to the left
285 -- of the expected column of the end for this sequence
288 or else Start_Column < Scope.Table (Scope.Last).Ecol
290 Test_Statement_Required;
293 -- Otherwise complain and skip past ELSIF Condition then
296 Error_Msg_SC ("ELSIF not allowed here");
298 Discard_Junk_Node (P_Expression_No_Right_Paren);
300 Statement_Required := False;
307 -- Terminate if Eltm set or if the else is to the left
308 -- of the expected column of the end for this sequence
311 or else Start_Column < Scope.Table (Scope.Last).Ecol
313 Test_Statement_Required;
316 -- Otherwise complain and skip past else
319 Error_Msg_SC ("ELSE not allowed here");
321 Statement_Required := False;
326 when Tok_Exception =>
327 Test_Statement_Required;
329 -- If Extm not set and the exception is not to the left
330 -- of the expected column of the end for this sequence, then
331 -- we assume it belongs to the current sequence, even though
332 -- it is not permitted.
334 if not SS_Flags.Extm and then
335 Start_Column >= Scope.Table (Scope.Last).Ecol
338 Error_Msg_SC ("exception handler not permitted here");
339 Scan; -- past EXCEPTION
340 Discard_Junk_List (Parse_Exception_Handlers);
343 -- Always return, in the case where we scanned out handlers
344 -- that we did not expect, Parse_Exception_Handlers returned
345 -- with Token being either end or EOF, so we are OK
353 -- Terminate if Ortm set or if the or is to the left
354 -- of the expected column of the end for this sequence
357 or else Start_Column < Scope.Table (Scope.Last).Ecol
359 Test_Statement_Required;
362 -- Otherwise complain and skip past or
365 Error_Msg_SC ("OR not allowed here");
367 Statement_Required := False;
370 -- Case of THEN (deal also with THEN ABORT)
373 Save_Scan_State (Scan_State); -- at THEN
376 -- Terminate if THEN ABORT allowed (ATC case)
378 exit when SS_Flags.Tatm and then Token = Tok_Abort;
380 -- Otherwise we treat THEN as some kind of mess where we
381 -- did not see the associated IF, but we pick up assuming
382 -- it had been there!
384 Restore_Scan_State (Scan_State); -- to THEN
385 Append_To (Statement_List, P_If_Statement);
386 Statement_Required := False;
388 -- Case of WHEN (error because we are not in a case)
390 when Tok_When | Tok_Others =>
392 -- Terminate if Whtm set or if the WHEN is to the left
393 -- of the expected column of the end for this sequence
396 or else Start_Column < Scope.Table (Scope.Last).Ecol
398 Test_Statement_Required;
401 -- Otherwise complain and skip when Choice {| Choice} =>
404 Error_Msg_SC ("WHEN not allowed here");
406 Discard_Junk_List (P_Discrete_Choice_List);
408 Statement_Required := False;
411 -- Cases of statements starting with an identifier
413 when Tok_Identifier =>
416 -- Save scan pointers and line number in case block label
418 Id_Node := Token_Node;
419 Block_Label := Token_Name;
420 Save_Scan_State (Scan_State_Label); -- at possible label
423 -- Check for common case of assignment, since it occurs
424 -- frequently, and we want to process it efficiently.
426 if Token = Tok_Colon_Equal then
427 Scan; -- past the colon-equal
428 Append_To (Statement_List,
429 P_Assignment_Statement (Id_Node));
430 Statement_Required := False;
432 -- Check common case of procedure call, another case that
433 -- we want to speed up as much as possible.
435 elsif Token = Tok_Semicolon then
436 Append_To (Statement_List,
437 P_Statement_Name (Id_Node));
438 Scan; -- past semicolon
439 Statement_Required := False;
441 -- Check for case of "go to" in place of "goto"
443 elsif Token = Tok_Identifier
444 and then Block_Label = Name_Go
445 and then Token_Name = Name_To
447 Error_Msg_SP ("goto is one word");
448 Append_To (Statement_List, P_Goto_Statement);
449 Statement_Required := False;
451 -- Check common case of = used instead of :=, just so we
452 -- give a better error message for this special misuse.
454 elsif Token = Tok_Equal then
455 T_Colon_Equal; -- give := expected message
456 Append_To (Statement_List,
457 P_Assignment_Statement (Id_Node));
458 Statement_Required := False;
460 -- Check case of loop label or block label
462 elsif Token = Tok_Colon
463 or else (Token in Token_Class_Labeled_Stmt
464 and then not Token_Is_At_Start_Of_Line)
466 T_Colon; -- past colon (if there, or msg for missing one)
468 -- Test for more than one label
471 exit when Token /= Tok_Identifier;
472 Save_Scan_State (Scan_State); -- at second Id
475 if Token = Tok_Colon then
477 ("only one label allowed on block or loop");
478 Scan; -- past colon on extra label
480 -- Use the second label as the "real" label
482 Scan_State_Label := Scan_State;
484 -- We will set Error_name as the Block_Label since
485 -- we really don't know which of the labels might
486 -- be used at the end of the loop or block!
488 Block_Label := Error_Name;
490 -- If Id with no colon, then backup to point to the
491 -- Id and we will issue the message below when we try
492 -- to scan out the statement as some other form.
495 Restore_Scan_State (Scan_State); -- to second Id
500 -- Loop_Statement (labeled Loop_Statement)
502 if Token = Tok_Loop then
503 Append_To (Statement_List,
504 P_Loop_Statement (Id_Node));
506 -- While statement (labeled loop statement with WHILE)
508 elsif Token = Tok_While then
509 Append_To (Statement_List,
510 P_While_Statement (Id_Node));
512 -- Declare statement (labeled block statement with
515 elsif Token = Tok_Declare then
516 Append_To (Statement_List,
517 P_Declare_Statement (Id_Node));
519 -- Begin statement (labeled block statement with no
522 elsif Token = Tok_Begin then
523 Append_To (Statement_List,
524 P_Begin_Statement (Id_Node));
526 -- For statement (labeled loop statement with FOR)
528 elsif Token = Tok_For then
529 Append_To (Statement_List,
530 P_For_Statement (Id_Node));
532 -- Improper statement follows label. If we have an
533 -- expression token, then assume the colon was part
534 -- of a misplaced declaration.
536 elsif Token not in Token_Class_Eterm then
537 Restore_Scan_State (Scan_State_Label);
540 -- Otherwise complain we have inappropriate statement
544 ("loop or block statement must follow label");
547 Statement_Required := False;
549 -- Here we have an identifier followed by something
550 -- other than a colon, semicolon or assignment symbol.
551 -- The only valid possibility is a name extension symbol
553 elsif Token in Token_Class_Namext then
554 Restore_Scan_State (Scan_State_Label); -- to Id
557 -- Skip junk right parens in this context
559 while Token = Tok_Right_Paren loop
560 Error_Msg_SC ("extra right paren");
564 -- Check context following call
566 if Token = Tok_Colon_Equal then
567 Scan; -- past colon equal
568 Append_To (Statement_List,
569 P_Assignment_Statement (Name_Node));
570 Statement_Required := False;
572 -- Check common case of = used instead of :=
574 elsif Token = Tok_Equal then
575 T_Colon_Equal; -- give := expected message
576 Append_To (Statement_List,
577 P_Assignment_Statement (Name_Node));
578 Statement_Required := False;
580 -- Check apostrophe cases
582 elsif Token = Tok_Apostrophe then
583 Append_To (Statement_List,
584 P_Code_Statement (Name_Node));
585 Statement_Required := False;
587 -- The only other valid item after a name is ; which
588 -- means that the item we just scanned was a call.
590 elsif Token = Tok_Semicolon then
591 Append_To (Statement_List,
592 P_Statement_Name (Name_Node));
593 Scan; -- past semicolon
594 Statement_Required := False;
596 -- A slash following an identifier or a selected
597 -- component in this situation is most likely a
598 -- period (have a look at the keyboard :-)
600 elsif Token = Tok_Slash
601 and then (Nkind (Name_Node) = N_Identifier
603 Nkind (Name_Node) = N_Selected_Component)
605 Error_Msg_SC ("""/"" should be "".""");
606 Statement_Required := False;
609 -- Else we have a missing semicolon
613 Statement_Required := False;
616 -- If junk after identifier, check if identifier is an
617 -- instance of an incorrectly spelled keyword. If so, we
618 -- do nothing. The Bad_Spelling_Of will have reset Token
619 -- to the appropriate keyword, so the next time round the
620 -- loop we will process the modified token. Note that we
621 -- check for ELSIF before ELSE here. That's not accidental.
622 -- We don't want to identify a misspelling of ELSE as
623 -- ELSIF, and in particular we do not want to treat ELSEIF
627 Restore_Scan_State (Scan_State_Label); -- to identifier
629 if Bad_Spelling_Of (Tok_Abort)
630 or else Bad_Spelling_Of (Tok_Accept)
631 or else Bad_Spelling_Of (Tok_Case)
632 or else Bad_Spelling_Of (Tok_Declare)
633 or else Bad_Spelling_Of (Tok_Delay)
634 or else Bad_Spelling_Of (Tok_Elsif)
635 or else Bad_Spelling_Of (Tok_Else)
636 or else Bad_Spelling_Of (Tok_End)
637 or else Bad_Spelling_Of (Tok_Exception)
638 or else Bad_Spelling_Of (Tok_Exit)
639 or else Bad_Spelling_Of (Tok_For)
640 or else Bad_Spelling_Of (Tok_Goto)
641 or else Bad_Spelling_Of (Tok_If)
642 or else Bad_Spelling_Of (Tok_Loop)
643 or else Bad_Spelling_Of (Tok_Or)
644 or else Bad_Spelling_Of (Tok_Pragma)
645 or else Bad_Spelling_Of (Tok_Raise)
646 or else Bad_Spelling_Of (Tok_Requeue)
647 or else Bad_Spelling_Of (Tok_Return)
648 or else Bad_Spelling_Of (Tok_Select)
649 or else Bad_Spelling_Of (Tok_When)
650 or else Bad_Spelling_Of (Tok_While)
654 -- If not a bad spelling, then we really have junk
657 Scan; -- past identifier again
659 -- If next token is first token on line, then we
660 -- consider that we were missing a semicolon after
661 -- the identifier, and process it as a procedure
662 -- call with no parameters.
664 if Token_Is_At_Start_Of_Line then
665 Append_To (Statement_List,
666 P_Statement_Name (Id_Node));
667 T_Semicolon; -- to give error message
668 Statement_Required := False;
670 -- Otherwise we give a missing := message and
671 -- simply abandon the junk that is there now.
674 T_Colon_Equal; -- give := expected message
681 -- Statement starting with operator symbol. This could be
682 -- a call, a name starting an assignment, or a qualified
685 when Tok_Operator_Symbol =>
689 -- An attempt at a range attribute or a qualified expression
690 -- must be illegal here (a code statement cannot possibly
691 -- allow qualification by a function name).
693 if Token = Tok_Apostrophe then
694 Error_Msg_SC ("apostrophe illegal here");
698 -- Scan possible assignment if we have a name
700 if Expr_Form = EF_Name
701 and then Token = Tok_Colon_Equal
703 Scan; -- past colon equal
704 Append_To (Statement_List,
705 P_Assignment_Statement (Name_Node));
707 Append_To (Statement_List,
708 P_Statement_Name (Name_Node));
712 Statement_Required := False;
714 -- Label starting with << which must precede real statement
716 when Tok_Less_Less =>
717 Append_To (Statement_List, P_Label);
718 Statement_Required := True;
720 -- Pragma appearing as a statement in a statement sequence
724 Append_To (Statement_List, P_Pragma);
730 Append_To (Statement_List, P_Abort_Statement);
731 Statement_Required := False;
737 Append_To (Statement_List, P_Accept_Statement);
738 Statement_Required := False;
740 -- Begin_Statement (Block_Statement with no declare, no label)
744 Append_To (Statement_List, P_Begin_Statement);
745 Statement_Required := False;
751 Append_To (Statement_List, P_Case_Statement);
752 Statement_Required := False;
754 -- Block_Statement with DECLARE and no label
758 Append_To (Statement_List, P_Declare_Statement);
759 Statement_Required := False;
765 Append_To (Statement_List, P_Delay_Statement);
766 Statement_Required := False;
772 Append_To (Statement_List, P_Exit_Statement);
773 Statement_Required := False;
775 -- Loop_Statement with FOR and no label
779 Append_To (Statement_List, P_For_Statement);
780 Statement_Required := False;
786 Append_To (Statement_List, P_Goto_Statement);
787 Statement_Required := False;
793 Append_To (Statement_List, P_If_Statement);
794 Statement_Required := False;
800 Append_To (Statement_List, P_Loop_Statement);
801 Statement_Required := False;
807 Append_To (Statement_List, P_Null_Statement);
808 Statement_Required := False;
814 Append_To (Statement_List, P_Raise_Statement);
815 Statement_Required := False;
821 Append_To (Statement_List, P_Requeue_Statement);
822 Statement_Required := False;
828 Append_To (Statement_List, P_Return_Statement);
829 Statement_Required := False;
835 Append_To (Statement_List, P_Select_Statement);
836 Statement_Required := False;
838 -- While_Statement (Block_Statement with while and no loop)
842 Append_To (Statement_List, P_While_Statement);
843 Statement_Required := False;
845 -- Anything else is some kind of junk, signal an error message
846 -- and then raise Error_Resync, to merge with the normal
847 -- handling of a bad statement.
851 if Token in Token_Class_Declk then
855 Error_Msg_BC ("statement expected");
860 -- On error resynchronization, skip past next semicolon, and, since
861 -- we are still in the statement loop, look for next statement. We
862 -- set Statement_Required False to avoid an unnecessary error message
863 -- complaining that no statement was found (i.e. we consider the
864 -- junk to satisfy the requirement for a statement being present).
868 Resync_Past_Semicolon_Or_To_Loop_Or_Then;
869 Statement_Required := False;
872 exit when SS_Flags.Unco;
876 return Statement_List;
878 end P_Sequence_Of_Statements;
884 -- Parsed by P_Sequence_Of_Statements (5.1), except for the case
885 -- of a statement of the form of a name, which is handled here. The
886 -- argument passed in is the tree for the name which has been scanned
887 -- The returned value is the corresponding statement form.
889 -- This routine is also used by Par.Prag for processing the procedure
890 -- call that appears as the second argument of a pragma Assert.
892 -- Error recovery: cannot raise Error_Resync
894 function P_Statement_Name (Name_Node : Node_Id) return Node_Id is
898 -- Case of Indexed component, which is a procedure call with arguments
900 if Nkind (Name_Node) = N_Indexed_Component then
902 Prefix_Node : Node_Id := Prefix (Name_Node);
903 Exprs_Node : List_Id := Expressions (Name_Node);
905 Change_Node (Name_Node, N_Procedure_Call_Statement);
906 Set_Name (Name_Node, Prefix_Node);
907 Set_Parameter_Associations (Name_Node, Exprs_Node);
911 -- Case of function call node, which is a really a procedure call
913 elsif Nkind (Name_Node) = N_Function_Call then
915 Fname_Node : Node_Id := Name (Name_Node);
916 Params_List : List_Id := Parameter_Associations (Name_Node);
919 Change_Node (Name_Node, N_Procedure_Call_Statement);
920 Set_Name (Name_Node, Fname_Node);
921 Set_Parameter_Associations (Name_Node, Params_List);
925 -- Case of call to attribute that denotes a procedure. Here we
926 -- just leave the attribute reference unchanged.
928 elsif Nkind (Name_Node) = N_Attribute_Reference
929 and then Is_Procedure_Attribute_Name (Attribute_Name (Name_Node))
933 -- All other cases of names are parameterless procedure calls
937 New_Node (N_Procedure_Call_Statement, Sloc (Name_Node));
938 Set_Name (Stmt_Node, Name_Node);
942 end P_Statement_Name;
944 ---------------------------
945 -- 5.1 Simple Statement --
946 ---------------------------
948 -- Parsed by P_Sequence_Of_Statements (5.1)
950 -----------------------------
951 -- 5.1 Compound Statement --
952 -----------------------------
954 -- Parsed by P_Sequence_Of_Statements (5.1)
956 -------------------------
957 -- 5.1 Null Statement --
958 -------------------------
960 -- NULL_STATEMENT ::= null;
962 -- The caller has already checked that the current token is null
964 -- Error recovery: cannot raise Error_Resync
966 function P_Null_Statement return Node_Id is
967 Null_Stmt_Node : Node_Id;
970 Null_Stmt_Node := New_Node (N_Null_Statement, Token_Ptr);
973 return Null_Stmt_Node;
974 end P_Null_Statement;
980 -- LABEL ::= <<label_STATEMENT_IDENTIFIER>>
982 -- STATEMENT_IDENTIFIER ::= DIRECT_NAME
984 -- The IDENTIFIER of a STATEMENT_IDENTIFIER shall be an identifier
985 -- (not an OPERATOR_SYMBOL)
987 -- The caller has already checked that the current token is <<
989 -- Error recovery: can raise Error_Resync
991 function P_Label return Node_Id is
992 Label_Node : Node_Id;
995 Label_Node := New_Node (N_Label, Token_Ptr);
997 Set_Identifier (Label_Node, P_Identifier);
999 Append_Elmt (Label_Node, Label_List);
1003 -------------------------------
1004 -- 5.1 Statement Identifier --
1005 -------------------------------
1007 -- Statement label is parsed by P_Label (5.1)
1009 -- Loop label is parsed by P_Loop_Statement (5.5), P_For_Statement (5.5)
1010 -- or P_While_Statement (5.5)
1012 -- Block label is parsed by P_Begin_Statement (5.6) or
1013 -- P_Declare_Statement (5.6)
1015 -------------------------------
1016 -- 5.2 Assignment Statement --
1017 -------------------------------
1019 -- ASSIGNMENT_STATEMENT ::=
1020 -- variable_NAME := EXPRESSION;
1022 -- Error recovery: can raise Error_Resync
1024 function P_Assignment_Statement (LHS : Node_Id) return Node_Id is
1025 Assign_Node : Node_Id;
1028 Assign_Node := New_Node (N_Assignment_Statement, Prev_Token_Ptr);
1029 Set_Name (Assign_Node, LHS);
1030 Set_Expression (Assign_Node, P_Expression_No_Right_Paren);
1033 end P_Assignment_Statement;
1035 -----------------------
1036 -- 5.3 If Statement --
1037 -----------------------
1040 -- if CONDITION then
1041 -- SEQUENCE_OF_STATEMENTS
1042 -- {elsif CONDITION then
1043 -- SEQUENCE_OF_STATEMENTS}
1045 -- SEQUENCE_OF_STATEMENTS]
1048 -- The caller has checked that the initial token is IF (or in the error
1049 -- case of a mysterious THEN, the initial token may simply be THEN, in
1050 -- which case, no condition (or IF) was scanned).
1052 -- Error recovery: can raise Error_Resync
1054 function P_If_Statement return Node_Id is
1056 Elsif_Node : Node_Id;
1059 procedure Add_Elsif_Part;
1060 -- An internal procedure used to scan out a single ELSIF part. On entry
1061 -- the ELSIF (or an ELSE which has been determined should be ELSIF) is
1062 -- scanned out and is in Prev_Token.
1064 procedure Check_If_Column;
1065 -- An internal procedure used to check that THEN, ELSE ELSE, or ELSIF
1066 -- appear in the right place if column checking is enabled (i.e. if
1067 -- they are the first token on the line, then they must appear in
1068 -- the same column as the opening IF).
1070 procedure Check_Then_Column;
1071 -- This procedure carries out the style checks for a THEN token
1072 -- Note that the caller has set Loc to the Source_Ptr value for
1073 -- the previous IF or ELSIF token. These checks apply only to a
1074 -- THEN at the start of a line.
1076 function Else_Should_Be_Elsif return Boolean;
1077 -- An internal routine used to do a special error recovery check when
1078 -- an ELSE is encountered. It determines if the ELSE should be treated
1079 -- as an ELSIF. A positive decision (TRUE returned, is made if the ELSE
1080 -- is followed by a sequence of tokens, starting on the same line as
1081 -- the ELSE, which are not expression terminators, followed by a THEN.
1082 -- On entry, the ELSE has been scanned out.
1084 procedure Add_Elsif_Part is
1086 if No (Elsif_Parts (If_Node)) then
1087 Set_Elsif_Parts (If_Node, New_List);
1090 Elsif_Node := New_Node (N_Elsif_Part, Prev_Token_Ptr);
1091 Loc := Prev_Token_Ptr;
1092 Set_Condition (Elsif_Node, P_Condition);
1096 (Elsif_Node, P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq));
1097 Append (Elsif_Node, Elsif_Parts (If_Node));
1100 procedure Check_If_Column is
1102 if Style.RM_Column_Check and then Token_Is_At_Start_Of_Line
1103 and then Start_Column /= Scope.Table (Scope.Last).Ecol
1105 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
1106 Error_Msg_SC ("(style) this token should be@");
1108 end Check_If_Column;
1110 procedure Check_Then_Column is
1112 if Token_Is_At_Start_Of_Line and then Token = Tok_Then then
1114 if Style_Check then Style.Check_Then (Loc); end if;
1116 end Check_Then_Column;
1118 function Else_Should_Be_Elsif return Boolean is
1119 Scan_State : Saved_Scan_State;
1122 if Token_Is_At_Start_Of_Line then
1126 Save_Scan_State (Scan_State);
1129 if Token in Token_Class_Eterm then
1130 Restore_Scan_State (Scan_State);
1133 Scan; -- past non-expression terminating token
1135 if Token = Tok_Then then
1136 Restore_Scan_State (Scan_State);
1142 end Else_Should_Be_Elsif;
1144 -- Start of processing for P_If_Statement
1147 If_Node := New_Node (N_If_Statement, Token_Ptr);
1150 Scope.Table (Scope.Last).Etyp := E_If;
1151 Scope.Table (Scope.Last).Ecol := Start_Column;
1152 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1153 Scope.Table (Scope.Last).Labl := Error;
1154 Scope.Table (Scope.Last).Node := If_Node;
1156 if Token = Tok_If then
1159 Set_Condition (If_Node, P_Condition);
1161 -- Deal with misuse of IF expression => used instead
1162 -- of WHEN expression =>
1164 if Token = Tok_Arrow then
1165 Error_Msg_SC ("THEN expected");
1166 Scan; -- past the arrow
1167 Pop_Scope_Stack; -- remove unneeded entry
1174 Error_Msg_SC ("no IF for this THEN");
1175 Set_Condition (If_Node, Error);
1181 (If_Node, P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq));
1183 -- This loop scans out else and elsif parts
1186 if Token = Tok_Elsif then
1189 if Present (Else_Statements (If_Node)) then
1190 Error_Msg_SP ("ELSIF cannot appear after ELSE");
1196 elsif Token = Tok_Else then
1200 if Else_Should_Be_Elsif then
1201 Error_Msg_SP ("ELSE should be ELSIF");
1205 -- Here we have an else that really is an else
1207 if Present (Else_Statements (If_Node)) then
1208 Error_Msg_SP ("Only one ELSE part allowed");
1210 (P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq),
1211 Else_Statements (If_Node));
1214 (If_Node, P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq));
1218 -- If anything other than ELSE or ELSIF, exit the loop. The token
1219 -- had better be END (and in fact it had better be END IF), but
1220 -- we will let End_Statements take care of checking that.
1232 --------------------
1234 --------------------
1236 -- CONDITION ::= boolean_EXPRESSION
1238 function P_Condition return Node_Id is
1242 Cond := P_Expression_No_Right_Paren;
1244 -- It is never possible for := to follow a condition, so if we get
1245 -- a := we assume it is a mistyped equality. Note that we do not try
1246 -- to reconstruct the tree correctly in this case, but we do at least
1247 -- give an accurate error message.
1249 while Token = Tok_Colon_Equal loop
1250 Error_Msg_SC (""":="" should be ""=""");
1251 Scan; -- past junk :=
1252 Discard_Junk_Node (P_Expression_No_Right_Paren);
1258 -------------------------
1259 -- 5.4 Case Statement --
1260 -------------------------
1262 -- CASE_STATEMENT ::=
1263 -- case EXPRESSION is
1264 -- CASE_STATEMENT_ALTERNATIVE
1265 -- {CASE_STATEMENT_ALTERNATIVE}
1268 -- The caller has checked that the first token is CASE
1270 -- Can raise Error_Resync
1272 function P_Case_Statement return Node_Id is
1273 Case_Node : Node_Id;
1274 Alternatives_List : List_Id;
1275 First_When_Loc : Source_Ptr;
1278 Case_Node := New_Node (N_Case_Statement, Token_Ptr);
1281 Scope.Table (Scope.Last).Etyp := E_Case;
1282 Scope.Table (Scope.Last).Ecol := Start_Column;
1283 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1284 Scope.Table (Scope.Last).Labl := Error;
1285 Scope.Table (Scope.Last).Node := Case_Node;
1288 Set_Expression (Case_Node, P_Expression_No_Right_Paren);
1291 -- Prepare to parse case statement alternatives
1293 Alternatives_List := New_List;
1294 P_Pragmas_Opt (Alternatives_List);
1295 First_When_Loc := Token_Ptr;
1297 -- Loop through case statement alternatives
1300 -- If we have a WHEN or OTHERS, then that's fine keep going. Note
1301 -- that it is a semantic check to ensure the proper use of OTHERS
1303 if Token = Tok_When or else Token = Tok_Others then
1304 Append (P_Case_Statement_Alternative, Alternatives_List);
1306 -- If we have an END, then probably we are at the end of the case
1307 -- but we only exit if Check_End thinks the END was reasonable.
1309 elsif Token = Tok_End then
1310 exit when Check_End;
1312 -- Here if token is other than WHEN, OTHERS or END. We definitely
1313 -- have an error, but the question is whether or not to get out of
1314 -- the case statement. We don't want to get out early, or we will
1315 -- get a slew of junk error messages for subsequent when tokens.
1317 -- If the token is not at the start of the line, or if it is indented
1318 -- with respect to the current case statement, then the best guess is
1319 -- that we are still supposed to be inside the case statement. We
1320 -- complain about the missing WHEN, and discard the junk statements.
1322 elsif not Token_Is_At_Start_Of_Line
1323 or else Start_Column > Scope.Table (Scope.Last).Ecol
1325 Error_Msg_BC ("WHEN (case statement alternative) expected");
1327 -- Here is a possibility for infinite looping if we don't make
1328 -- progress. So try to process statements, otherwise exit
1331 Error_Ptr : constant Source_Ptr := Scan_Ptr;
1333 Discard_Junk_List (P_Sequence_Of_Statements (SS_Whtm));
1334 exit when Scan_Ptr = Error_Ptr and then Check_End;
1337 -- Here we have a junk token at the start of the line and it is
1338 -- not indented. If Check_End thinks there is a missing END, then
1339 -- we will get out of the case, otherwise we keep going.
1342 exit when Check_End;
1346 -- Make sure we have at least one alternative
1348 if No (First_Non_Pragma (Alternatives_List)) then
1350 ("WHEN expected, must have at least one alternative in case",
1355 Set_Alternatives (Case_Node, Alternatives_List);
1358 end P_Case_Statement;
1360 -------------------------------------
1361 -- 5.4 Case Statement Alternative --
1362 -------------------------------------
1364 -- CASE_STATEMENT_ALTERNATIVE ::=
1365 -- when DISCRETE_CHOICE_LIST =>
1366 -- SEQUENCE_OF_STATEMENTS
1368 -- The caller has checked that the initial token is WHEN or OTHERS
1369 -- Error recovery: can raise Error_Resync
1371 function P_Case_Statement_Alternative return Node_Id is
1372 Case_Alt_Node : Node_Id;
1375 if Style_Check then Style.Check_Indentation; end if;
1376 Case_Alt_Node := New_Node (N_Case_Statement_Alternative, Token_Ptr);
1377 T_When; -- past WHEN (or give error in OTHERS case)
1378 Set_Discrete_Choices (Case_Alt_Node, P_Discrete_Choice_List);
1380 Set_Statements (Case_Alt_Node, P_Sequence_Of_Statements (SS_Sreq_Whtm));
1381 return Case_Alt_Node;
1382 end P_Case_Statement_Alternative;
1384 -------------------------
1385 -- 5.5 Loop Statement --
1386 -------------------------
1388 -- LOOP_STATEMENT ::=
1389 -- [LOOP_STATEMENT_IDENTIFIER:]
1390 -- [ITERATION_SCHEME] loop
1391 -- SEQUENCE_OF_STATEMENTS
1392 -- end loop [loop_IDENTIFIER];
1394 -- ITERATION_SCHEME ::=
1396 -- | for LOOP_PARAMETER_SPECIFICATION
1398 -- The parsing of loop statements is handled by one of three functions
1399 -- P_Loop_Statement, P_For_Statement or P_While_Statement depending
1400 -- on the initial keyword in the construct (excluding the identifier)
1404 -- This function parses the case where no iteration scheme is present
1406 -- The caller has checked that the initial token is LOOP. The parameter
1407 -- is the node identifiers for the loop label if any (or is set to Empty
1408 -- if there is no loop label).
1410 -- Error recovery : cannot raise Error_Resync
1412 function P_Loop_Statement (Loop_Name : Node_Id := Empty) return Node_Id is
1413 Loop_Node : Node_Id;
1417 Scope.Table (Scope.Last).Labl := Loop_Name;
1418 Scope.Table (Scope.Last).Ecol := Start_Column;
1419 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1420 Scope.Table (Scope.Last).Etyp := E_Loop;
1422 Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
1425 if No (Loop_Name) then
1426 Set_Has_Created_Identifier (Loop_Node, True);
1427 Set_Identifier (Loop_Node,
1428 Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L')));
1430 Set_Identifier (Loop_Node, Loop_Name);
1433 Append_Elmt (Loop_Node, Label_List);
1435 Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
1436 End_Statements (Loop_Node);
1438 end P_Loop_Statement;
1442 -- This function parses a loop statement with a FOR iteration scheme
1444 -- The caller has checked that the initial token is FOR. The parameter
1445 -- is the node identifier for the block label if any (or is set to Empty
1446 -- if there is no block label).
1448 -- Note: the caller fills in the Identifier field if a label was present
1450 -- Error recovery: can raise Error_Resync
1452 function P_For_Statement (Loop_Name : Node_Id := Empty) return Node_Id is
1453 Loop_Node : Node_Id;
1454 Iter_Scheme_Node : Node_Id;
1455 Loop_For_Flag : Boolean;
1459 Scope.Table (Scope.Last).Labl := Loop_Name;
1460 Scope.Table (Scope.Last).Ecol := Start_Column;
1461 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1462 Scope.Table (Scope.Last).Etyp := E_Loop;
1464 Loop_For_Flag := (Prev_Token = Tok_Loop);
1466 Iter_Scheme_Node := New_Node (N_Iteration_Scheme, Token_Ptr);
1467 Set_Loop_Parameter_Specification
1468 (Iter_Scheme_Node, P_Loop_Parameter_Specification);
1470 -- The following is a special test so that a miswritten for loop such
1471 -- as "loop for I in 1..10;" is handled nicely, without making an extra
1472 -- entry in the scope stack. We don't bother to actually fix up the
1473 -- tree in this case since it's not worth the effort. Instead we just
1474 -- eat up the loop junk, leaving the entry for what now looks like an
1475 -- unmodified loop intact.
1477 if Loop_For_Flag and then Token = Tok_Semicolon then
1478 Error_Msg_SC ("LOOP belongs here, not before FOR");
1485 Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
1487 Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
1488 End_Statements (Loop_Node);
1489 Set_Iteration_Scheme (Loop_Node, Iter_Scheme_Node);
1491 if No (Loop_Name) then
1492 Set_Has_Created_Identifier (Loop_Node, True);
1493 Set_Identifier (Loop_Node,
1494 Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L')));
1496 Set_Identifier (Loop_Node, Loop_Name);
1499 Append_Elmt (Loop_Node, Label_List);
1504 end P_For_Statement;
1506 -- P_While_Statement
1508 -- This procedure scans a loop statement with a WHILE iteration scheme
1510 -- The caller has checked that the initial token is WHILE. The parameter
1511 -- is the node identifier for the block label if any (or is set to Empty
1512 -- if there is no block label).
1514 -- Error recovery: cannot raise Error_Resync
1516 function P_While_Statement (Loop_Name : Node_Id := Empty) return Node_Id is
1517 Loop_Node : Node_Id;
1518 Iter_Scheme_Node : Node_Id;
1519 Loop_While_Flag : Boolean;
1523 Scope.Table (Scope.Last).Labl := Loop_Name;
1524 Scope.Table (Scope.Last).Ecol := Start_Column;
1525 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1526 Scope.Table (Scope.Last).Etyp := E_Loop;
1528 Loop_While_Flag := (Prev_Token = Tok_Loop);
1529 Iter_Scheme_Node := New_Node (N_Iteration_Scheme, Token_Ptr);
1531 Set_Condition (Iter_Scheme_Node, P_Condition);
1533 -- The following is a special test so that a miswritten for loop such
1534 -- as "loop while I > 10;" is handled nicely, without making an extra
1535 -- entry in the scope stack. We don't bother to actually fix up the
1536 -- tree in this case since it's not worth the effort. Instead we just
1537 -- eat up the loop junk, leaving the entry for what now looks like an
1538 -- unmodified loop intact.
1540 if Loop_While_Flag and then Token = Tok_Semicolon then
1541 Error_Msg_SC ("LOOP belongs here, not before WHILE");
1548 Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
1550 Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
1551 End_Statements (Loop_Node);
1552 Set_Iteration_Scheme (Loop_Node, Iter_Scheme_Node);
1554 if No (Loop_Name) then
1555 Set_Has_Created_Identifier (Loop_Node, True);
1556 Set_Identifier (Loop_Node,
1557 Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L')));
1559 Set_Identifier (Loop_Node, Loop_Name);
1562 Append_Elmt (Loop_Node, Label_List);
1567 end P_While_Statement;
1569 ---------------------------------------
1570 -- 5.5 Loop Parameter Specification --
1571 ---------------------------------------
1573 -- LOOP_PARAMETER_SPECIFICATION ::=
1574 -- DEFINING_IDENTIFIER in [reverse] DISCRETE_SUBTYPE_DEFINITION
1576 -- Error recovery: cannot raise Error_Resync
1578 function P_Loop_Parameter_Specification return Node_Id is
1579 Loop_Param_Specification_Node : Node_Id;
1582 Scan_State : Saved_Scan_State;
1585 Loop_Param_Specification_Node :=
1586 New_Node (N_Loop_Parameter_Specification, Token_Ptr);
1588 Save_Scan_State (Scan_State);
1589 ID_Node := P_Defining_Identifier;
1590 Set_Defining_Identifier (Loop_Param_Specification_Node, ID_Node);
1592 if Token = Tok_Left_Paren then
1593 Error_Msg_SC ("subscripted loop parameter not allowed");
1594 Restore_Scan_State (Scan_State);
1595 Discard_Junk_Node (P_Name);
1597 elsif Token = Tok_Dot then
1598 Error_Msg_SC ("selected loop parameter not allowed");
1599 Restore_Scan_State (Scan_State);
1600 Discard_Junk_Node (P_Name);
1605 if Token = Tok_Reverse then
1606 Scan; -- past REVERSE
1607 Set_Reverse_Present (Loop_Param_Specification_Node, True);
1610 Set_Discrete_Subtype_Definition
1611 (Loop_Param_Specification_Node, P_Discrete_Subtype_Definition);
1612 return Loop_Param_Specification_Node;
1615 when Error_Resync =>
1617 end P_Loop_Parameter_Specification;
1619 --------------------------
1620 -- 5.6 Block Statement --
1621 --------------------------
1623 -- BLOCK_STATEMENT ::=
1624 -- [block_STATEMENT_IDENTIFIER:]
1626 -- DECLARATIVE_PART]
1628 -- HANDLED_SEQUENCE_OF_STATEMENTS
1629 -- end [block_IDENTIFIER];
1631 -- The parsing of block statements is handled by one of the two functions
1632 -- P_Declare_Statement or P_Begin_Statement depending on whether or not
1633 -- a declare section is present
1635 -- P_Declare_Statement
1637 -- This function parses a block statement with DECLARE present
1639 -- The caller has checked that the initial token is DECLARE.
1641 -- Error recovery: cannot raise Error_Resync
1643 function P_Declare_Statement
1644 (Block_Name : Node_Id := Empty)
1647 Block_Node : Node_Id;
1650 Block_Node := New_Node (N_Block_Statement, Token_Ptr);
1653 Scope.Table (Scope.Last).Etyp := E_Name;
1654 Scope.Table (Scope.Last).Lreq := Present (Block_Name);
1655 Scope.Table (Scope.Last).Ecol := Start_Column;
1656 Scope.Table (Scope.Last).Labl := Block_Name;
1657 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1659 Scan; -- past DECLARE
1661 if No (Block_Name) then
1662 Set_Has_Created_Identifier (Block_Node, True);
1663 Set_Identifier (Block_Node,
1664 Make_Identifier (Sloc (Block_Node), Set_Loop_Block_Name ('B')));
1666 Set_Identifier (Block_Node, Block_Name);
1669 Append_Elmt (Block_Node, Label_List);
1670 Parse_Decls_Begin_End (Block_Node);
1672 end P_Declare_Statement;
1674 -- P_Begin_Statement
1676 -- This function parses a block statement with no DECLARE present
1678 -- The caller has checked that the initial token is BEGIN
1680 -- Error recovery: cannot raise Error_Resync
1682 function P_Begin_Statement
1683 (Block_Name : Node_Id := Empty)
1686 Block_Node : Node_Id;
1689 Block_Node := New_Node (N_Block_Statement, Token_Ptr);
1692 Scope.Table (Scope.Last).Etyp := E_Name;
1693 Scope.Table (Scope.Last).Lreq := Present (Block_Name);
1694 Scope.Table (Scope.Last).Ecol := Start_Column;
1695 Scope.Table (Scope.Last).Labl := Block_Name;
1696 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1698 if No (Block_Name) then
1699 Set_Has_Created_Identifier (Block_Node, True);
1700 Set_Identifier (Block_Node,
1701 Make_Identifier (Sloc (Block_Node), Set_Loop_Block_Name ('B')));
1703 Set_Identifier (Block_Node, Block_Name);
1706 Append_Elmt (Block_Node, Label_List);
1708 Scope.Table (Scope.Last).Ecol := Start_Column;
1709 Scope.Table (Scope.Last).Sloc := Token_Ptr;
1711 Set_Handled_Statement_Sequence
1712 (Block_Node, P_Handled_Sequence_Of_Statements);
1713 End_Statements (Handled_Statement_Sequence (Block_Node));
1715 end P_Begin_Statement;
1717 -------------------------
1718 -- 5.7 Exit Statement --
1719 -------------------------
1721 -- EXIT_STATEMENT ::=
1722 -- exit [loop_NAME] [when CONDITION];
1724 -- The caller has checked that the initial token is EXIT
1726 -- Error recovery: can raise Error_Resync
1728 function P_Exit_Statement return Node_Id is
1729 Exit_Node : Node_Id;
1731 function Missing_Semicolon_On_Exit return Boolean;
1732 -- This function deals with the following specialized situation
1735 -- exit [identifier]
1738 -- This looks like a messed up EXIT WHEN, when in fact the problem
1739 -- is a missing semicolon. It is called with Token pointing to the
1740 -- WHEN token, and returns True if a semicolon is missing before
1741 -- the WHEN as in the above example.
1743 function Missing_Semicolon_On_Exit return Boolean is
1744 State : Saved_Scan_State;
1747 if not Token_Is_At_Start_Of_Line then
1750 elsif Scope.Table (Scope.Last).Etyp /= E_Case then
1754 Save_Scan_State (State);
1756 Scan; -- past token after WHEN
1758 if Token = Tok_Arrow then
1759 Restore_Scan_State (State);
1762 Restore_Scan_State (State);
1766 end Missing_Semicolon_On_Exit;
1768 -- Start of processing for P_Exit_Statement
1771 Exit_Node := New_Node (N_Exit_Statement, Token_Ptr);
1774 if Token = Tok_Identifier then
1775 Set_Name (Exit_Node, P_Qualified_Simple_Name);
1777 elsif Style_Check then
1778 -- This EXIT has no name, so check that
1779 -- the innermost loop is unnamed too.
1781 Check_No_Exit_Name :
1782 for J in reverse 1 .. Scope.Last loop
1783 if Scope.Table (J).Etyp = E_Loop then
1784 if Present (Scope.Table (J).Labl) then
1786 -- Innermost loop in fact had a name, style check fails
1788 Style.No_Exit_Name (Scope.Table (J).Labl);
1791 exit Check_No_Exit_Name;
1793 end loop Check_No_Exit_Name;
1796 if Token = Tok_When and then not Missing_Semicolon_On_Exit then
1798 Set_Condition (Exit_Node, P_Condition);
1800 -- Allow IF instead of WHEN, giving error message
1802 elsif Token = Tok_If then
1804 Scan; -- past IF used in place of WHEN
1805 Set_Condition (Exit_Node, P_Expression_No_Right_Paren);
1810 end P_Exit_Statement;
1812 -------------------------
1813 -- 5.8 Goto Statement --
1814 -------------------------
1816 -- GOTO_STATEMENT ::= goto label_NAME;
1818 -- The caller has checked that the initial token is GOTO (or TO in the
1819 -- error case where GO and TO were incorrectly separated).
1821 -- Error recovery: can raise Error_Resync
1823 function P_Goto_Statement return Node_Id is
1824 Goto_Node : Node_Id;
1827 Goto_Node := New_Node (N_Goto_Statement, Token_Ptr);
1828 Scan; -- past GOTO (or TO)
1829 Set_Name (Goto_Node, P_Qualified_Simple_Name_Resync);
1833 end P_Goto_Statement;
1835 ---------------------------
1836 -- Parse_Decls_Begin_End --
1837 ---------------------------
1839 -- This function parses the construct:
1843 -- HANDLED_SEQUENCE_OF_STATEMENTS
1846 -- The caller has built the scope stack entry, and created the node to
1847 -- whose Declarations and Handled_Statement_Sequence fields are to be
1848 -- set. On return these fields are filled in (except in the case of a
1849 -- task body, where the handled statement sequence is optional, and may
1850 -- thus be Empty), and the scan is positioned past the End sequence.
1852 -- If the BEGIN is missing, then the parent node is used to help construct
1853 -- an appropriate missing BEGIN message. Possibilities for the parent are:
1855 -- N_Block_Statement declare block
1856 -- N_Entry_Body entry body
1857 -- N_Package_Body package body (begin part optional)
1858 -- N_Subprogram_Body procedure or function body
1859 -- N_Task_Body task body
1861 -- Note: in the case of a block statement, there is definitely a DECLARE
1862 -- present (because a Begin statement without a DECLARE is handled by the
1863 -- P_Begin_Statement procedure, which does not call Parse_Decls_Begin_End.
1865 -- Error recovery: cannot raise Error_Resync
1867 procedure Parse_Decls_Begin_End (Parent : Node_Id) is
1868 Body_Decl : Node_Id;
1869 Body_Sloc : Source_Ptr;
1872 Parent_Nkind : Node_Kind;
1873 Spec_Node : Node_Id;
1876 procedure Missing_Begin (Msg : String);
1877 -- Called to post a missing begin message. In the normal case this is
1878 -- posted at the start of the current token. A special case arises when
1879 -- P_Declarative_Items has previously found a missing begin, in which
1880 -- case we replace the original error message.
1882 procedure Set_Null_HSS (Parent : Node_Id);
1883 -- Construct an empty handled statement sequence and install in Parent
1884 -- Leaves HSS set to reference the newly constructed statement sequence.
1890 procedure Missing_Begin (Msg : String) is
1892 if Missing_Begin_Msg = No_Error_Msg then
1895 Change_Error_Text (Missing_Begin_Msg, Msg);
1897 -- Purge any messages issued after than, since a missing begin
1898 -- can cause a lot of havoc, and it is better not to dump these
1899 -- cascaded messages on the user.
1901 Purge_Messages (Get_Location (Missing_Begin_Msg), Prev_Token_Ptr);
1909 procedure Set_Null_HSS (Parent : Node_Id) is
1914 Make_Null_Statement (Token_Ptr);
1915 Set_Comes_From_Source (Null_Stm, False);
1918 Make_Handled_Sequence_Of_Statements (Token_Ptr,
1919 Statements => New_List (Null_Stm));
1920 Set_Comes_From_Source (HSS, False);
1922 Set_Handled_Statement_Sequence (Parent, HSS);
1925 -- Start of processing for Parse_Decls_Begin_End
1928 Decls := P_Declarative_Part;
1930 -- Check for misplacement of later vs basic declarations in Ada 83
1933 Decl := First (Decls);
1935 -- Loop through sequence of basic declarative items
1937 Outer : while Present (Decl) loop
1938 if Nkind (Decl) /= N_Subprogram_Body
1939 and then Nkind (Decl) /= N_Package_Body
1940 and then Nkind (Decl) /= N_Task_Body
1941 and then Nkind (Decl) not in N_Body_Stub
1945 -- Once a body is encountered, we only allow later declarative
1946 -- items. The inner loop checks the rest of the list.
1949 Body_Sloc := Sloc (Decl);
1951 Inner : while Present (Decl) loop
1952 if Nkind (Decl) not in N_Later_Decl_Item
1953 and then Nkind (Decl) /= N_Pragma
1956 Error_Msg_Sloc := Body_Sloc;
1958 ("(Ada 83) decl cannot appear after body#", Decl);
1968 -- Here is where we deal with the case of IS used instead of semicolon.
1969 -- Specifically, if the last declaration in the declarative part is a
1970 -- subprogram body still marked as having a bad IS, then this is where
1971 -- we decide that the IS should really have been a semicolon and that
1972 -- the body should have been a declaration. Note that if the bad IS
1973 -- had turned out to be OK (i.e. a decent begin/end was found for it),
1974 -- then the Bad_Is_Detected flag would have been reset by now.
1976 Body_Decl := Last (Decls);
1978 if Present (Body_Decl)
1979 and then Nkind (Body_Decl) = N_Subprogram_Body
1980 and then Bad_Is_Detected (Body_Decl)
1982 -- OK, we have the case of a bad IS, so we need to fix up the tree.
1983 -- What we have now is a subprogram body with attached declarations
1984 -- and a possible statement sequence.
1986 -- First step is to take the declarations that were part of the bogus
1987 -- subprogram body and append them to the outer declaration chain.
1988 -- In other words we append them past the body (which we will later
1989 -- convert into a declaration).
1991 Append_List (Declarations (Body_Decl), Decls);
1993 -- Now take the handled statement sequence of the bogus body and
1994 -- set it as the statement sequence for the outer construct. Note
1995 -- that it may be empty (we specially allowed a missing BEGIN for
1996 -- a subprogram body marked as having a bad IS -- see below).
1998 Set_Handled_Statement_Sequence (Parent,
1999 Handled_Statement_Sequence (Body_Decl));
2001 -- Next step is to convert the old body node to a declaration node
2003 Spec_Node := Specification (Body_Decl);
2004 Change_Node (Body_Decl, N_Subprogram_Declaration);
2005 Set_Specification (Body_Decl, Spec_Node);
2007 -- Final step is to put the declarations for the parent where
2008 -- they belong, and then fall through the IF to scan out the
2011 Set_Declarations (Parent, Decls);
2013 -- This is the normal case (i.e. any case except the bad IS case)
2014 -- If we have a BEGIN, then scan out the sequence of statements, and
2015 -- also reset the expected column for the END to match the BEGIN.
2018 Set_Declarations (Parent, Decls);
2020 if Token = Tok_Begin then
2021 if Style_Check then Style.Check_Indentation; end if;
2023 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
2025 if Style.RM_Column_Check
2026 and then Token_Is_At_Start_Of_Line
2027 and then Start_Column /= Error_Msg_Col
2029 Error_Msg_SC ("(style) BEGIN in wrong column, should be@");
2032 Scope.Table (Scope.Last).Ecol := Start_Column;
2035 Scope.Table (Scope.Last).Sloc := Token_Ptr;
2037 Set_Handled_Statement_Sequence (Parent,
2038 P_Handled_Sequence_Of_Statements);
2043 Parent_Nkind := Nkind (Parent);
2045 -- A special check for the missing IS case. If we have a
2046 -- subprogram body that was marked as having a suspicious
2047 -- IS, and the current token is END, then we simply confirm
2048 -- the suspicion, and do not require a BEGIN to be present
2050 if Parent_Nkind = N_Subprogram_Body
2051 and then Token = Tok_End
2052 and then Scope.Table (Scope.Last).Etyp = E_Suspicious_Is
2054 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
2056 -- Otherwise BEGIN is not required for a package body, so we
2057 -- don't mind if it is missing, but we do construct a dummy
2058 -- one (so that we have somewhere to set End_Label).
2060 -- However if we have something other than a BEGIN which
2061 -- looks like it might be statements, then we signal a missing
2062 -- BEGIN for these cases as well. We define "something which
2063 -- looks like it might be statements" as a token other than
2064 -- END, EOF, or a token which starts declarations.
2066 elsif Parent_Nkind = N_Package_Body
2067 and then (Token = Tok_End
2068 or else Token = Tok_EOF
2069 or else Token in Token_Class_Declk)
2071 Set_Null_HSS (Parent);
2073 -- These are cases in which a BEGIN is required and not present
2076 Set_Null_HSS (Parent);
2078 -- Prepare to issue error message
2080 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
2081 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
2083 -- Now issue appropriate message
2085 if Parent_Nkind = N_Block_Statement then
2086 Missing_Begin ("missing BEGIN for DECLARE#!");
2088 elsif Parent_Nkind = N_Entry_Body then
2089 Missing_Begin ("missing BEGIN for ENTRY#!");
2091 elsif Parent_Nkind = N_Subprogram_Body then
2092 if Nkind (Specification (Parent))
2093 = N_Function_Specification
2095 Missing_Begin ("missing BEGIN for function&#!");
2097 Missing_Begin ("missing BEGIN for procedure&#!");
2100 -- The case for package body arises only when
2101 -- we have possible statement junk present.
2103 elsif Parent_Nkind = N_Package_Body then
2104 Missing_Begin ("missing BEGIN for package body&#!");
2107 pragma Assert (Parent_Nkind = N_Task_Body);
2108 Missing_Begin ("missing BEGIN for task body&#!");
2111 -- Here we pick up the statements after the BEGIN that
2112 -- should have been present but was not. We don't insist
2113 -- on statements being present if P_Declarative_Part had
2114 -- already found a missing BEGIN, since it might have
2115 -- swallowed a lone statement into the declarative part.
2117 if Missing_Begin_Msg /= No_Error_Msg
2118 and then Token = Tok_End
2122 Set_Handled_Statement_Sequence (Parent,
2123 P_Handled_Sequence_Of_Statements);
2129 -- Here with declarations and handled statement sequence scanned
2131 if Present (Handled_Statement_Sequence (Parent)) then
2132 End_Statements (Handled_Statement_Sequence (Parent));
2137 -- We know that End_Statements removed an entry from the scope stack
2138 -- (because it is required to do so under all circumstances). We can
2139 -- therefore reference the entry it removed one past the stack top.
2140 -- What we are interested in is whether it was a case of a bad IS.
2142 if Scope.Table (Scope.Last + 1).Etyp = E_Bad_Is then
2143 Error_Msg ("IS should be "";""", Scope.Table (Scope.Last + 1).S_Is);
2144 Set_Bad_Is_Detected (Parent, True);
2147 end Parse_Decls_Begin_End;
2149 -------------------------
2150 -- Set_Loop_Block_Name --
2151 -------------------------
2153 function Set_Loop_Block_Name (L : Character) return Name_Id is
2155 Name_Buffer (1) := L;
2156 Name_Buffer (2) := '_';
2158 Loop_Block_Count := Loop_Block_Count + 1;
2159 Add_Nat_To_Name_Buffer (Loop_Block_Count);
2161 end Set_Loop_Block_Name;
2167 procedure Then_Scan is
2171 while Token = Tok_Then loop
2172 Error_Msg_SC ("redundant THEN");
2176 if Token = Tok_And or else Token = Tok_Or then
2177 Error_Msg_SC ("unexpected logical operator");
2180 if (Prev_Token = Tok_And and then Token = Tok_Then)
2182 (Prev_Token = Tok_Or and then Token = Tok_Else)
2187 Discard_Junk_Node (P_Expression);
2190 if Token = Tok_Then then