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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- P A R . C H 5 --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2022, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
pragma Style_Checks (All_Checks);
-- Turn off subprogram body ordering check. Subprograms are in order by RM
-- section rather than alphabetical.
with Sinfo.CN; use Sinfo.CN;
separate (Par)
package body Ch5 is
-- Local functions, used only in this chapter
function P_Case_Statement return Node_Id;
function P_Case_Statement_Alternative return Node_Id;
function P_Exit_Statement return Node_Id;
function P_Goto_Statement return Node_Id;
function P_If_Statement return Node_Id;
function P_Label return Node_Id;
function P_Null_Statement return Node_Id;
function P_Assignment_Statement (LHS : Node_Id) return Node_Id;
-- Parse assignment statement. On entry, the caller has scanned the left
-- hand side (passed in as Lhs), and the colon-equal (or some symbol
-- taken to be an error equivalent such as equal).
function P_Begin_Statement (Block_Name : Node_Id := Empty) return Node_Id;
-- Parse begin-end statement. If Block_Name is non-Empty on entry, it is
-- the N_Identifier node for the label on the block. If Block_Name is
-- Empty on entry (the default), then the block statement is unlabeled.
function P_Declare_Statement (Block_Name : Node_Id := Empty) return Node_Id;
-- Parse declare block. If Block_Name is non-Empty on entry, it is
-- the N_Identifier node for the label on the block. If Block_Name is
-- Empty on entry (the default), then the block statement is unlabeled.
function P_For_Statement (Loop_Name : Node_Id := Empty) return Node_Id;
-- Parse for statement. If Loop_Name is non-Empty on entry, it is
-- the N_Identifier node for the label on the loop. If Loop_Name is
-- Empty on entry (the default), then the for statement is unlabeled.
function P_Loop_Statement (Loop_Name : Node_Id := Empty) return Node_Id;
-- Parse loop statement. If Loop_Name is non-Empty on entry, it is
-- the N_Identifier node for the label on the loop. If Loop_Name is
-- Empty on entry (the default), then the loop statement is unlabeled.
function P_While_Statement (Loop_Name : Node_Id := Empty) return Node_Id;
-- Parse while statement. If Loop_Name is non-Empty on entry, it is
-- the N_Identifier node for the label on the loop. If Loop_Name is
-- Empty on entry (the default), then the while statement is unlabeled.
function Set_Loop_Block_Name (L : Character) return Name_Id;
-- Given a letter 'L' for a loop or 'B' for a block, returns a name
-- of the form L_nn or B_nn where nn is a serial number obtained by
-- incrementing the variable Loop_Block_Count.
procedure Then_Scan;
-- Scan past THEN token, testing for illegal junk after it
---------------------------------
-- 5.1 Sequence of Statements --
---------------------------------
-- SEQUENCE_OF_STATEMENTS ::= STATEMENT {STATEMENT} {LABEL}
-- Note: the final label is an Ada 2012 addition.
-- STATEMENT ::=
-- {LABEL} SIMPLE_STATEMENT | {LABEL} COMPOUND_STATEMENT
-- SIMPLE_STATEMENT ::= NULL_STATEMENT
-- | ASSIGNMENT_STATEMENT | EXIT_STATEMENT
-- | GOTO_STATEMENT | PROCEDURE_CALL_STATEMENT
-- | RETURN_STATEMENT | ENTRY_CALL_STATEMENT
-- | REQUEUE_STATEMENT | DELAY_STATEMENT
-- | ABORT_STATEMENT | RAISE_STATEMENT
-- | CODE_STATEMENT
-- COMPOUND_STATEMENT ::=
-- IF_STATEMENT | CASE_STATEMENT
-- | LOOP_STATEMENT | BLOCK_STATEMENT
-- | ACCEPT_STATEMENT | SELECT_STATEMENT
-- This procedure scans a sequence of statements. SS_Flags indicates
-- termination conditions for the sequence. In addition, the sequence is
-- always terminated by encountering END or end of file. If one of the six
-- above terminators is encountered with the corresponding SS_Flags flag
-- not set, then the action taken is as follows:
-- If the keyword occurs to the left of the expected column of the end
-- for the current sequence (as recorded in the current end context),
-- then it is assumed to belong to an outer context, and is considered
-- to terminate the sequence of statements.
-- If the keyword occurs to the right of, or in the expected column of
-- the end for the current sequence, then an error message is output,
-- the keyword together with its associated context is skipped, and
-- the statement scan continues until another terminator is found.
-- Note that the first action means that control can return to the caller
-- with Token set to a terminator other than one of those specified by the
-- SS_Flags parameter. The caller should treat such a case as equivalent to
-- END.
-- In addition, the flag SS_Flags.Sreq is set to True to indicate that at
-- least one real statement (other than a pragma) is required in the
-- statement sequence. During the processing of the sequence, this
-- flag is manipulated to indicate the current status of the requirement
-- for a statement. For example, it is turned off by the occurrence of a
-- statement, and back on by a label (which requires a following statement)
-- Error recovery: cannot raise Error_Resync. If an error occurs during
-- parsing a statement, then the scan pointer is advanced past the next
-- semicolon and the parse continues.
function P_Sequence_Of_Statements
(SS_Flags : SS_Rec; Handled : Boolean := False) return List_Id
is
Statement_Required : Boolean := SS_Flags.Sreq;
-- This flag indicates if a subsequent statement (other than a pragma)
-- is required. It is initialized from the Sreq flag, and modified as
-- statements are scanned (a statement turns it off, and a label turns
-- it back on again since a statement must follow a label).
-- Note : this final requirement is lifted in Ada 2012.
Statement_Seen : Boolean := False;
-- In Ada 2012, a label can end a sequence of statements, but the
-- sequence cannot contain only labels. This flag is set whenever a
-- label is encountered, to enforce this rule at the end of a sequence.
Scan_State_Label : Saved_Scan_State;
Scan_State : Saved_Scan_State;
Statement_List : constant List_Id := New_List;
Block_Label : Name_Id;
Id_Node : Node_Id;
Name_Node : Node_Id;
Decl_Loc, Label_Loc : Source_Ptr := No_Location;
-- Sloc of the first declaration/label encountered, if any.
procedure Test_Statement_Required;
-- Flag error if Statement_Required flag set
-----------------------------
-- Test_Statement_Required --
-----------------------------
procedure Test_Statement_Required is
function All_Pragmas return Boolean;
-- Return True if statement list is all pragmas
-----------------
-- All_Pragmas --
-----------------
function All_Pragmas return Boolean is
S : Node_Id;
begin
S := First (Statement_List);
while Present (S) loop
if Nkind (S) /= N_Pragma then
return False;
else
Next (S);
end if;
end loop;
return True;
end All_Pragmas;
-- Start of processing for Test_Statement_Required
begin
if Statement_Required then
-- Check no statement required after label in Ada 2012, and that
-- it is OK to have nothing but pragmas in a statement sequence.
if Ada_Version >= Ada_2012
and then not Is_Empty_List (Statement_List)
and then
((Nkind (Last (Statement_List)) = N_Label
and then Statement_Seen)
or else All_Pragmas)
then
null;
-- If not Ada 2012, or not special case above, and no declaration
-- seen (as allowed in Ada 2020), give error message.
elsif No (Decl_Loc) then
Error_Msg_BC -- CODEFIX
("statement expected");
end if;
end if;
end Test_Statement_Required;
-- Start of processing for P_Sequence_Of_Statements
begin
-- In Ada 2022, we allow declarative items to be mixed with
-- statements. The loop below alternates between calling
-- P_Declarative_Items to parse zero or more declarative items,
-- and parsing a statement.
loop
Ignore (Tok_Semicolon);
declare
Num_Statements : constant Nat := List_Length (Statement_List);
begin
P_Declarative_Items
(Statement_List, Declare_Expression => False,
In_Spec => False, In_Statements => True);
-- Use the length of the list to determine whether we parsed
-- any declarative items. If so, it's an error unless language
-- extensions are enabled.
if List_Length (Statement_List) > Num_Statements then
if All_Errors_Mode or else No (Decl_Loc) then
Decl_Loc := Sloc (Pick (Statement_List, Num_Statements + 1));
Error_Msg_GNAT_Extension
("declarations mixed with statements",
Sloc (Pick (Statement_List, Num_Statements + 1)));
end if;
end if;
end;
begin -- handle Error_Resync
if Style_Check then
Style.Check_Indentation;
end if;
-- Deal with reserved identifier (in assignment or call)
if Is_Reserved_Identifier then
Save_Scan_State (Scan_State); -- at possible bad identifier
Scan; -- and scan past it
-- We have an reserved word which is spelled in identifier
-- style, so the question is whether it really is intended
-- to be an identifier.
if
-- If followed by a semicolon, then it is an identifier,
-- with the exception of the cases tested for below.
(Token = Tok_Semicolon
and then Prev_Token not in
Tok_Return | Tok_Null | Tok_Raise | Tok_End | Tok_Exit)
-- If followed by colon, colon-equal, or dot, then we
-- definitely have an identifier (could not be reserved)
or else Token in Tok_Colon | Tok_Colon_Equal | Tok_Dot
-- Left paren means we have an identifier except for those
-- reserved words that can legitimately be followed by a
-- left paren.
or else
(Token = Tok_Left_Paren
and then Prev_Token not in
Tok_Case | Tok_Delay | Tok_If | Tok_Elsif | Tok_Return |
Tok_When | Tok_While | Tok_Separate)
then
-- Here we have an apparent reserved identifier and the
-- token past it is appropriate to this usage (and would
-- be a definite error if this is not an identifier). What
-- we do is to use P_Identifier to fix up the identifier,
-- and then fall into the normal processing.
Restore_Scan_State (Scan_State); -- back to the ID
Scan_Reserved_Identifier (Force_Msg => False);
-- Not a reserved identifier after all (or at least we can't
-- be sure that it is), so reset the scan and continue.
else
Restore_Scan_State (Scan_State); -- back to the reserved word
end if;
end if;
-- Now look to see what kind of statement we have
case Token is
-- Case of end or EOF
when Tok_End
| Tok_EOF
=>
-- These tokens always terminate the statement sequence
Test_Statement_Required;
exit;
-- Case of ELSIF
when Tok_Elsif =>
-- Terminate if Eftm set or if the ELSIF is to the left
-- of the expected column of the end for this sequence
if SS_Flags.Eftm
or else Start_Column < Scopes (Scope.Last).Ecol
then
Test_Statement_Required;
exit;
-- Otherwise complain and skip past ELSIF Condition then
else
Error_Msg_SC ("ELSIF not allowed here");
Scan; -- past ELSIF
Discard_Junk_Node (P_Expression_No_Right_Paren);
Then_Scan;
Statement_Required := False;
end if;
-- Case of ELSE
when Tok_Else =>
-- Terminate if Eltm set or if the else is to the left
-- of the expected column of the end for this sequence
if SS_Flags.Eltm
or else Start_Column < Scopes (Scope.Last).Ecol
then
Test_Statement_Required;
exit;
-- Otherwise complain and skip past else
else
Error_Msg_SC ("ELSE not allowed here");
Scan; -- past ELSE
Statement_Required := False;
end if;
-- Case of exception
when Tok_Exception =>
Test_Statement_Required;
-- If Extm not set and the exception is not to the left of
-- the expected column of the end for this sequence, then we
-- assume it belongs to the current sequence, even though it
-- is not permitted.
if not SS_Flags.Extm and then
Start_Column >= Scopes (Scope.Last).Ecol
then
Error_Msg_SC ("exception handler not permitted here");
Scan; -- past EXCEPTION
Discard_Junk_List (Parse_Exception_Handlers);
end if;
-- Always return, in the case where we scanned out handlers
-- that we did not expect, Parse_Exception_Handlers returned
-- with Token being either end or EOF, so we are OK.
exit;
-- Case of OR
when Tok_Or =>
-- Terminate if Ortm set or if the or is to the left of the
-- expected column of the end for this sequence.
if SS_Flags.Ortm
or else Start_Column < Scopes (Scope.Last).Ecol
then
Test_Statement_Required;
exit;
-- Otherwise complain and skip past or
else
Error_Msg_SC ("OR not allowed here");
Scan; -- past or
Statement_Required := False;
end if;
-- Case of THEN (deal also with THEN ABORT)
when Tok_Then =>
Save_Scan_State (Scan_State); -- at THEN
Scan; -- past THEN
-- Terminate if THEN ABORT allowed (ATC case)
exit when SS_Flags.Tatm and then Token = Tok_Abort;
-- Otherwise we treat THEN as some kind of mess where we did
-- not see the associated IF, but we pick up assuming it had
-- been there.
Restore_Scan_State (Scan_State); -- to THEN
Append_To (Statement_List, P_If_Statement);
Statement_Required := False;
-- Case of WHEN (error because we are not in a case)
when Tok_Others
| Tok_When
=>
-- Terminate if Whtm set or if the WHEN is to the left of
-- the expected column of the end for this sequence.
if SS_Flags.Whtm
or else Start_Column < Scopes (Scope.Last).Ecol
then
Test_Statement_Required;
exit;
-- Otherwise complain and skip when Choice {| Choice} =>
else
Error_Msg_SC ("WHEN not allowed here");
Scan; -- past when
Discard_Junk_List (P_Discrete_Choice_List);
TF_Arrow;
Statement_Required := False;
end if;
-- Cases of statements starting with an identifier
when Tok_Identifier =>
Check_Bad_Layout;
-- Save scan pointers and line number in case block label
Id_Node := Token_Node;
Block_Label := Token_Name;
Save_Scan_State (Scan_State_Label); -- at possible label
Scan; -- past Id
-- Check for common case of assignment, since it occurs
-- frequently, and we want to process it efficiently.
if Token = Tok_Colon_Equal then
Scan; -- past the colon-equal
Append_To (Statement_List,
P_Assignment_Statement (Id_Node));
Statement_Required := False;
-- Check common case of procedure call, another case that
-- we want to speed up as much as possible.
elsif Token = Tok_Semicolon then
Change_Name_To_Procedure_Call_Statement (Id_Node);
Append_To (Statement_List, Id_Node);
Scan; -- past semicolon
Statement_Required := False;
-- Here is the special test for a suspicious label, more
-- accurately a suspicious name, which we think perhaps
-- should have been a label. If next token is one of
-- LOOP, FOR, WHILE, DECLARE, BEGIN, then make an entry
-- in the suspicious label table.
if Token = Tok_Loop or else
Token = Tok_For or else
Token = Tok_While or else
Token = Tok_Declare or else
Token = Tok_Begin
then
Suspicious_Labels.Append
((Proc_Call => Id_Node,
Semicolon_Loc => Prev_Token_Ptr,
Start_Token => Token_Ptr));
end if;
-- Check for case of "go to" in place of "goto"
elsif Token = Tok_Identifier
and then Block_Label = Name_Go
and then Token_Name = Name_To
then
Error_Msg_SP -- CODEFIX
("goto is one word");
Append_To (Statement_List, P_Goto_Statement);
Statement_Required := False;
-- Check common case of = used instead of :=, just so we
-- give a better error message for this special misuse.
elsif Token = Tok_Equal then
T_Colon_Equal; -- give := expected message
Append_To (Statement_List,
P_Assignment_Statement (Id_Node));
Statement_Required := False;
-- Check case of loop label or block label
elsif Token = Tok_Colon
or else (Token in Token_Class_Labeled_Stmt
and then not Token_Is_At_Start_Of_Line)
then
T_Colon; -- past colon (if there, or msg for missing one)
-- Test for more than one label
loop
exit when Token /= Tok_Identifier;
Save_Scan_State (Scan_State); -- at second Id
Scan; -- past Id
if Token = Tok_Colon then
Error_Msg_SP
("only one label allowed on block or loop");
Scan; -- past colon on extra label
-- Use the second label as the "real" label
Scan_State_Label := Scan_State;
-- We will set Error_name as the Block_Label since
-- we really don't know which of the labels might
-- be used at the end of the loop or block.
Block_Label := Error_Name;
-- If Id with no colon, then backup to point to the
-- Id and we will issue the message below when we try
-- to scan out the statement as some other form.
else
Restore_Scan_State (Scan_State); -- to second Id
exit;
end if;
end loop;
-- Loop_Statement (labeled Loop_Statement)
if Token = Tok_Loop then
Append_To (Statement_List,
P_Loop_Statement (Id_Node));
-- While statement (labeled loop statement with WHILE)
elsif Token = Tok_While then
Append_To (Statement_List,
P_While_Statement (Id_Node));
-- Declare statement (labeled block statement with
-- DECLARE part)
elsif Token = Tok_Declare then
Append_To (Statement_List,
P_Declare_Statement (Id_Node));
-- Begin statement (labeled block statement with no
-- DECLARE part)
elsif Token = Tok_Begin then
Append_To (Statement_List,
P_Begin_Statement (Id_Node));
-- For statement (labeled loop statement with FOR)
elsif Token = Tok_For then
Append_To (Statement_List,
P_For_Statement (Id_Node));
-- Otherwise complain we have inappropriate statement
else
Error_Msg_AP
("loop or block statement must follow label");
end if;
Statement_Required := False;
-- Here we have an identifier followed by something
-- other than a colon, semicolon or assignment symbol.
-- The only valid possibility is a name extension symbol
elsif Token in Token_Class_Namext then
Restore_Scan_State (Scan_State_Label); -- to Id
Name_Node := P_Name;
-- Skip junk right parens in this context
Ignore (Tok_Right_Paren);
-- Check context following call
if Token = Tok_Colon_Equal then
Scan; -- past colon equal
Append_To (Statement_List,
P_Assignment_Statement (Name_Node));
Statement_Required := False;
-- Check common case of = used instead of :=
elsif Token = Tok_Equal then
T_Colon_Equal; -- give := expected message
Append_To (Statement_List,
P_Assignment_Statement (Name_Node));
Statement_Required := False;
-- Check apostrophe cases
elsif Token = Tok_Apostrophe then
Append_To (Statement_List,
P_Code_Statement (Name_Node));
Statement_Required := False;
-- The only other valid item after a name is ; which
-- means that the item we just scanned was a call.
elsif Token = Tok_Semicolon then
Change_Name_To_Procedure_Call_Statement (Name_Node);
Append_To (Statement_List, Name_Node);
Scan; -- past semicolon
Statement_Required := False;
-- A slash following an identifier or a selected
-- component in this situation is most likely a period
-- (see location of keys on keyboard).
elsif Token = Tok_Slash
and then (Nkind (Name_Node) = N_Identifier
or else
Nkind (Name_Node) = N_Selected_Component)
then
Error_Msg_SC -- CODEFIX
("""/"" should be "".""");
Statement_Required := False;
raise Error_Resync;
-- Else we have a missing semicolon
else
TF_Semicolon;
-- Normal processing as though semicolon were present
Change_Name_To_Procedure_Call_Statement (Name_Node);
Append_To (Statement_List, Name_Node);
Statement_Required := False;
end if;
-- If junk after identifier, check if identifier is an
-- instance of an incorrectly spelled keyword. If so, we
-- do nothing. The Bad_Spelling_Of will have reset Token
-- to the appropriate keyword, so the next time round the
-- loop we will process the modified token.
--
-- Note that we check for ELSIF before ELSE here, because
-- we don't want to identify a misspelling of ELSE as ELSIF,
-- and in particular we do not want to treat ELSEIF as
-- ELSE IF.
else
Restore_Scan_State (Scan_State_Label); -- to identifier
if Bad_Spelling_Of (Tok_Abort)
or else Bad_Spelling_Of (Tok_Accept)
or else Bad_Spelling_Of (Tok_Case)
or else Bad_Spelling_Of (Tok_Declare)
or else Bad_Spelling_Of (Tok_Delay)
or else Bad_Spelling_Of (Tok_Elsif)
or else Bad_Spelling_Of (Tok_Else)
or else Bad_Spelling_Of (Tok_End)
or else Bad_Spelling_Of (Tok_Exception)
or else Bad_Spelling_Of (Tok_Exit)
or else Bad_Spelling_Of (Tok_For)
or else Bad_Spelling_Of (Tok_Goto)
or else Bad_Spelling_Of (Tok_If)
or else Bad_Spelling_Of (Tok_Loop)
or else Bad_Spelling_Of (Tok_Or)
or else Bad_Spelling_Of (Tok_Pragma)
or else Bad_Spelling_Of (Tok_Raise)
or else Bad_Spelling_Of (Tok_Requeue)
or else Bad_Spelling_Of (Tok_Return)
or else Bad_Spelling_Of (Tok_Select)
or else Bad_Spelling_Of (Tok_When)
or else Bad_Spelling_Of (Tok_While)
then
null;
-- If not a bad spelling, then we really have junk
else
Scan; -- past identifier again
-- If next token is first token on line, then we
-- consider that we were missing a semicolon after
-- the identifier, and process it as a procedure
-- call with no parameters.
if Token_Is_At_Start_Of_Line then
Change_Name_To_Procedure_Call_Statement (Id_Node);
Append_To (Statement_List, Id_Node);
T_Semicolon; -- to give error message
Statement_Required := False;
-- Otherwise we give a missing := message and
-- simply abandon the junk that is there now.
else
T_Colon_Equal; -- give := expected message
raise Error_Resync;
end if;
end if;
end if;
-- Statement starting with operator symbol. This could be
-- a call, a name starting an assignment, or a qualified
-- expression.
when Tok_Operator_Symbol =>
Check_Bad_Layout;
Name_Node := P_Name;
-- An attempt at a range attribute or a qualified expression
-- must be illegal here (a code statement cannot possibly
-- allow qualification by a function name).
if Token = Tok_Apostrophe then
Error_Msg_SC ("apostrophe illegal here");
raise Error_Resync;
end if;
-- Scan possible assignment if we have a name
if Expr_Form = EF_Name
and then Token = Tok_Colon_Equal
then
Scan; -- past colon equal
Append_To (Statement_List,
P_Assignment_Statement (Name_Node));
else
Change_Name_To_Procedure_Call_Statement (Name_Node);
Append_To (Statement_List, Name_Node);
end if;
TF_Semicolon;
Statement_Required := False;
-- Label starting with << which must precede real statement
-- Note: in Ada 2012, the label may end the sequence.
when Tok_Less_Less =>
if Present (Last (Statement_List))
and then Nkind (Last (Statement_List)) /= N_Label
then
Statement_Seen := True;
end if;
Append_To (Statement_List, P_Label);
Statement_Required := True;
if No (Label_Loc) then
Label_Loc := Sloc (Last (Statement_List));
end if;
-- Pragma appearing as a statement in a statement sequence
when Tok_Pragma =>
Check_Bad_Layout;
Append_To (Statement_List, P_Pragma);
-- Abort_Statement
when Tok_Abort =>
Check_Bad_Layout;
Append_To (Statement_List, P_Abort_Statement);
Statement_Required := False;
-- Accept_Statement
when Tok_Accept =>
Check_Bad_Layout;
Append_To (Statement_List, P_Accept_Statement);
Statement_Required := False;
-- Begin_Statement (Block_Statement with no declare, no label)
when Tok_Begin =>
Check_Bad_Layout;
Append_To (Statement_List, P_Begin_Statement);
Statement_Required := False;
-- Case_Statement
when Tok_Case =>
Check_Bad_Layout;
Append_To (Statement_List, P_Case_Statement);
Statement_Required := False;
-- Block_Statement with DECLARE and no label
when Tok_Declare =>
Check_Bad_Layout;
Append_To (Statement_List, P_Declare_Statement);
Statement_Required := False;
-- Delay_Statement
when Tok_Delay =>
Check_Bad_Layout;
Append_To (Statement_List, P_Delay_Statement);
Statement_Required := False;
-- Exit_Statement
when Tok_Exit =>
Check_Bad_Layout;
Append_To (Statement_List, P_Exit_Statement);
Statement_Required := False;
-- Loop_Statement with FOR and no label
when Tok_For =>
Check_Bad_Layout;
Append_To (Statement_List, P_For_Statement);
Statement_Required := False;
-- Goto_Statement
when Tok_Goto =>
Check_Bad_Layout;
Append_To (Statement_List, P_Goto_Statement);
Statement_Required := False;
-- If_Statement
when Tok_If =>
Check_Bad_Layout;
Append_To (Statement_List, P_If_Statement);
Statement_Required := False;
-- Loop_Statement
when Tok_Loop =>
Check_Bad_Layout;
Append_To (Statement_List, P_Loop_Statement);
Statement_Required := False;
-- Null_Statement
when Tok_Null =>
Check_Bad_Layout;
Append_To (Statement_List, P_Null_Statement);
Statement_Required := False;
-- Raise_Statement
when Tok_Raise =>
Check_Bad_Layout;
Append_To (Statement_List, P_Raise_Statement);
Statement_Required := False;
-- Requeue_Statement
when Tok_Requeue =>
Check_Bad_Layout;
Append_To (Statement_List, P_Requeue_Statement);
Statement_Required := False;
-- Return_Statement
when Tok_Return =>
Check_Bad_Layout;
Append_To (Statement_List, P_Return_Statement);
Statement_Required := False;
-- Select_Statement
when Tok_Select =>
Check_Bad_Layout;
Append_To (Statement_List, P_Select_Statement);
Statement_Required := False;
-- While_Statement (Block_Statement with while and no loop)
when Tok_While =>
Check_Bad_Layout;
Append_To (Statement_List, P_While_Statement);
Statement_Required := False;
-- Anything else is some kind of junk, signal an error message
-- and then raise Error_Resync, to merge with the normal
-- handling of a bad statement.
when others =>
Error_Msg_BC -- CODEFIX
("statement expected");
raise Error_Resync;
end case;
-- On error resynchronization, skip past next semicolon, and, since
-- we are still in the statement loop, look for next statement. We
-- set Statement_Required False to avoid an unnecessary error message
-- complaining that no statement was found (i.e. we consider the
-- junk to satisfy the requirement for a statement being present).
exception
when Error_Resync =>
Resync_Past_Semicolon_Or_To_Loop_Or_Then;
Statement_Required := False;
end;
exit when SS_Flags.Unco;
end loop;
-- If there are no declarative items in the list, or if the list is part
-- of a handled sequence of statements, we just return the list.
-- Otherwise, we wrap the list in a block statement, so the declarations
-- will have a proper scope. In the Handled case, it would be wrong to
-- wrap, because we want the code before and after "begin" to be in the
-- same scope. Example:
--
-- if ... then
-- use Some_Package;
-- Do_Something (...);
-- end if;
--
-- is tranformed into:
--
-- if ... then
-- begin
-- use Some_Package;
-- Do_Something (...);
-- end;
-- end if;
--
-- But we don't wrap this:
--
-- declare
-- X : Integer;
-- begin
-- X : Integer;
--
-- Otherwise, we would fail to detect the error (conflicting X's).
-- Similarly, if a representation clause appears in the statement
-- part, we don't want it to appear more nested than the declarative
-- part -- that would cause an unwanted error.
if Present (Decl_Loc) then
-- Forbid labels and declarative items from coexisting. Otherwise,
-- one could jump past a declaration, leading to chaos. Jumping
-- backward past a declaration is also questionable -- does the
-- declaration get elaborated again? Is secondary stack storage
-- reclaimed? (A more liberal rule was proposed, but this is what
-- we're doing for now.)
if Present (Label_Loc) then
Error_Msg ("declarative item in same list as label", Decl_Loc);
Error_Msg ("label in same list as declarative item", Label_Loc);
end if;
-- Forbid exception handlers and declarative items from
-- coexisting. Example:
--
-- X : Integer := 123;
-- procedure P is
-- begin
-- X : Integer := 456;
-- exception
-- when Cain =>
-- Put(X);
-- end P;
--
-- It was proposed that in the handler, X should refer to the outer
-- X, but that's just confusing.
if Token = Tok_Exception then
Error_Msg
("declarative item in statements conflicts with " &
"exception handler below",
Decl_Loc);
Error_Msg
("exception handler conflicts with " &
"declarative item in statements above",
Token_Ptr);
end if;
if Handled then
return Statement_List;
else
declare
Loc : constant Source_Ptr := Sloc (First (Statement_List));
Block : constant Node_Id :=
Make_Block_Statement
(Loc,
Handled_Statement_Sequence =>
Make_Handled_Sequence_Of_Statements
(Loc, Statements => Statement_List));
begin
return New_List (Block);
end;
end if;
else
return Statement_List;
end if;
end P_Sequence_Of_Statements;
--------------------
-- 5.1 Statement --
--------------------
---------------------------
-- 5.1 Simple Statement --
---------------------------
-- Parsed by P_Sequence_Of_Statements (5.1)
-----------------------------
-- 5.1 Compound Statement --
-----------------------------
-- Parsed by P_Sequence_Of_Statements (5.1)
-------------------------
-- 5.1 Null Statement --
-------------------------
-- NULL_STATEMENT ::= null;
-- The caller has already checked that the current token is null
-- Error recovery: cannot raise Error_Resync
function P_Null_Statement return Node_Id is
Null_Stmt_Node : Node_Id;
begin
Null_Stmt_Node := New_Node (N_Null_Statement, Token_Ptr);
Scan; -- past NULL
TF_Semicolon;
return Null_Stmt_Node;
end P_Null_Statement;
----------------
-- 5.1 Label --
----------------
-- LABEL ::= <<label_STATEMENT_IDENTIFIER>>
-- STATEMENT_IDENTIFIER ::= DIRECT_NAME
-- The IDENTIFIER of a STATEMENT_IDENTIFIER shall be an identifier
-- (not an OPERATOR_SYMBOL)
-- The caller has already checked that the current token is <<
-- Error recovery: can raise Error_Resync
function P_Label return Node_Id is
Label_Node : Node_Id;
begin
Label_Node := New_Node (N_Label, Token_Ptr);
Scan; -- past <<
Set_Identifier (Label_Node, P_Identifier (C_Greater_Greater));
T_Greater_Greater;
Append_Elmt (Label_Node, Label_List);
return Label_Node;
end P_Label;
-------------------------------
-- 5.1 Statement Identifier --
-------------------------------
-- Statement label is parsed by P_Label (5.1)
-- Loop label is parsed by P_Loop_Statement (5.5), P_For_Statement (5.5)
-- or P_While_Statement (5.5)
-- Block label is parsed by P_Begin_Statement (5.6) or
-- P_Declare_Statement (5.6)
-------------------------------
-- 5.2 Assignment Statement --
-------------------------------
-- ASSIGNMENT_STATEMENT ::=
-- variable_NAME := EXPRESSION;
-- Error recovery: can raise Error_Resync
function P_Assignment_Statement (LHS : Node_Id) return Node_Id is
Assign_Node : Node_Id;
begin
Assign_Node := New_Node (N_Assignment_Statement, Prev_Token_Ptr);
Current_Assign_Node := Assign_Node;
Set_Name (Assign_Node, LHS);
Set_Expression (Assign_Node, P_Expression_No_Right_Paren);
TF_Semicolon;
Current_Assign_Node := Empty;
return Assign_Node;
end P_Assignment_Statement;
-----------------------
-- 5.3 If Statement --
-----------------------
-- IF_STATEMENT ::=
-- if CONDITION then
-- SEQUENCE_OF_STATEMENTS
-- {elsif CONDITION then
-- SEQUENCE_OF_STATEMENTS}
-- [else
-- SEQUENCE_OF_STATEMENTS]
-- end if;
-- The caller has checked that the initial token is IF (or in the error
-- case of a mysterious THEN, the initial token may simply be THEN, in
-- which case, no condition (or IF) was scanned).
-- Error recovery: can raise Error_Resync
function P_If_Statement return Node_Id is
If_Node : Node_Id;
Elsif_Node : Node_Id;
Loc : Source_Ptr;
procedure Add_Elsif_Part;
-- An internal procedure used to scan out a single ELSIF part. On entry
-- the ELSIF (or an ELSE which has been determined should be ELSIF) is
-- scanned out and is in Prev_Token.
procedure Check_If_Column;
-- An internal procedure used to check that THEN, ELSE, or ELSIF
-- appear in the right place if column checking is enabled (i.e. if
-- they are the first token on the line, then they must appear in
-- the same column as the opening IF).
procedure Check_Then_Column;
-- This procedure carries out the style checks for a THEN token
-- Note that the caller has set Loc to the Source_Ptr value for
-- the previous IF or ELSIF token.
function Else_Should_Be_Elsif return Boolean;
-- An internal routine used to do a special error recovery check when
-- an ELSE is encountered. It determines if the ELSE should be treated
-- as an ELSIF. A positive decision (TRUE returned, is made if the ELSE
-- is followed by a sequence of tokens, starting on the same line as
-- the ELSE, which are not expression terminators, followed by a THEN.
-- On entry, the ELSE has been scanned out.
procedure Add_Elsif_Part is
begin
if No (Elsif_Parts (If_Node)) then
Set_Elsif_Parts (If_Node, New_List);
end if;
Elsif_Node := New_Node (N_Elsif_Part, Prev_Token_Ptr);
Loc := Prev_Token_Ptr;
Set_Condition (Elsif_Node, P_Condition);
Check_Then_Column;
Then_Scan;
Set_Then_Statements
(Elsif_Node, P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq));
Append (Elsif_Node, Elsif_Parts (If_Node));
end Add_Elsif_Part;
procedure Check_If_Column is
begin
if RM_Column_Check and then Token_Is_At_Start_Of_Line
and then Start_Column /= Scopes (Scope.Last).Ecol
then
Error_Msg_Col := Scopes (Scope.Last).Ecol;
Error_Msg_SC ("(style) this token should be@");
end if;
end Check_If_Column;
procedure Check_Then_Column is
begin
if Token = Tok_Then then
Check_If_Column;
if Style_Check then
Style.Check_Then (Loc);
end if;
end if;
end Check_Then_Column;
function Else_Should_Be_Elsif return Boolean is
Scan_State : Saved_Scan_State;
begin
if Token_Is_At_Start_Of_Line then
return False;
else
Save_Scan_State (Scan_State);
loop
if Token in Token_Class_Eterm then
Restore_Scan_State (Scan_State);
return False;
else
Scan; -- past non-expression terminating token
if Token = Tok_Then then
Restore_Scan_State (Scan_State);
return True;
end if;
end if;
end loop;
end if;
end Else_Should_Be_Elsif;
-- Start of processing for P_If_Statement
begin
If_Node := New_Node (N_If_Statement, Token_Ptr);
Push_Scope_Stack;
Scopes (Scope.Last).Etyp := E_If;
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scopes (Scope.Last).Labl := Error;
Scopes (Scope.Last).Node := If_Node;
if Token = Tok_If then
Loc := Token_Ptr;
Scan; -- past IF
Set_Condition (If_Node, P_Condition);
-- Deal with misuse of IF expression => used instead
-- of WHEN expression =>
if Token = Tok_Arrow then
Error_Msg_SC -- CODEFIX
("THEN expected");
Scan; -- past the arrow
Pop_Scope_Stack; -- remove unneeded entry
raise Error_Resync;
end if;
Check_Then_Column;
else
Error_Msg_SC ("no IF for this THEN");
Set_Condition (If_Node, Error);
end if;
Then_Scan;
Set_Then_Statements
(If_Node, P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq));
-- This loop scans out else and elsif parts
loop
if Token = Tok_Elsif then
Check_If_Column;
if Present (Else_Statements (If_Node)) then
Error_Msg_SP ("ELSIF cannot appear after ELSE");
end if;
Scan; -- past ELSIF
Add_Elsif_Part;
elsif Token = Tok_Else then
Check_If_Column;
Scan; -- past ELSE
if Else_Should_Be_Elsif then
Error_Msg_SP -- CODEFIX
("ELSE should be ELSIF");
Add_Elsif_Part;
else
-- Here we have an else that really is an else
if Present (Else_Statements (If_Node)) then
Error_Msg_SP ("only one ELSE part allowed");
Append_List
(P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq),
Else_Statements (If_Node));
else
Set_Else_Statements
(If_Node, P_Sequence_Of_Statements (SS_Eftm_Eltm_Sreq));
end if;
end if;
-- If anything other than ELSE or ELSIF, exit the loop. The token
-- had better be END (and in fact it had better be END IF), but
-- we will let End_Statements take care of checking that.
else
exit;
end if;
end loop;
End_Statements;
return If_Node;
end P_If_Statement;
--------------------
-- 5.3 Condition --
--------------------
-- CONDITION ::= boolean_EXPRESSION
function P_Condition return Node_Id is
begin
return P_Condition (P_Expression_No_Right_Paren);
end P_Condition;
function P_Condition (Cond : Node_Id) return Node_Id is
begin
-- It is never possible for := to follow a condition, so if we get
-- a := we assume it is a mistyped equality. Note that we do not try
-- to reconstruct the tree correctly in this case, but we do at least
-- give an accurate error message.
if Token = Tok_Colon_Equal then
while Token = Tok_Colon_Equal loop
Error_Msg_SC -- CODEFIX
(""":="" should be ""=""");
Scan; -- past junk :=
Discard_Junk_Node (P_Expression_No_Right_Paren);
end loop;
return Cond;
-- Otherwise check for redundant parentheses but do not emit messages
-- about expressions that require parentheses (e.g. conditional,
-- quantified or declaration expressions).
else
if Style_Check
and then
Paren_Count (Cond) >
(if Nkind (Cond) in N_Case_Expression
| N_Expression_With_Actions
| N_If_Expression
| N_Quantified_Expression
then 1
else 0)
then
Style.Check_Xtra_Parens (First_Sloc (Cond));
end if;
-- And return the result
return Cond;
end if;
end P_Condition;
-------------------------
-- 5.4 Case Statement --
-------------------------
-- CASE_STATEMENT ::=
-- case EXPRESSION is
-- CASE_STATEMENT_ALTERNATIVE
-- {CASE_STATEMENT_ALTERNATIVE}
-- end case;
-- The caller has checked that the first token is CASE
-- Can raise Error_Resync
function P_Case_Statement return Node_Id is
Case_Node : Node_Id;
Alternatives_List : List_Id;
First_When_Loc : Source_Ptr;
begin
Case_Node := New_Node (N_Case_Statement, Token_Ptr);
Push_Scope_Stack;
Scopes (Scope.Last).Etyp := E_Case;
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scopes (Scope.Last).Labl := Error;
Scopes (Scope.Last).Node := Case_Node;
Scan; -- past CASE
Set_Expression (Case_Node, P_Expression_No_Right_Paren);
TF_Is;
-- Prepare to parse case statement alternatives
Alternatives_List := New_List;
P_Pragmas_Opt (Alternatives_List);
First_When_Loc := Token_Ptr;
-- Loop through case statement alternatives
loop
-- If we have a WHEN or OTHERS, then that's fine keep going. Note
-- that it is a semantic check to ensure the proper use of OTHERS
if Token in Tok_When | Tok_Others then
Append (P_Case_Statement_Alternative, Alternatives_List);
-- If we have an END, then probably we are at the end of the case
-- but we only exit if Check_End thinks the END was reasonable.
elsif Token = Tok_End then
exit when Check_End;
-- Here if token is other than WHEN, OTHERS or END. We definitely
-- have an error, but the question is whether or not to get out of
-- the case statement. We don't want to get out early, or we will
-- get a slew of junk error messages for subsequent when tokens.
-- If the token is not at the start of the line, or if it is indented
-- with respect to the current case statement, then the best guess is
-- that we are still supposed to be inside the case statement. We
-- complain about the missing WHEN, and discard the junk statements.
elsif not Token_Is_At_Start_Of_Line
or else Start_Column > Scopes (Scope.Last).Ecol
then
Error_Msg_BC ("WHEN (case statement alternative) expected");
-- Here is a possibility for infinite looping if we don't make
-- progress. So try to process statements, otherwise exit
declare
Error_Ptr : constant Source_Ptr := Scan_Ptr;
begin
Discard_Junk_List (P_Sequence_Of_Statements (SS_Whtm));
exit when Scan_Ptr = Error_Ptr and then Check_End;
end;
-- Here we have a junk token at the start of the line and it is
-- not indented. If Check_End thinks there is a missing END, then
-- we will get out of the case, otherwise we keep going.
else
exit when Check_End;
end if;
end loop;
-- Make sure we have at least one alternative
if No (First_Non_Pragma (Alternatives_List)) then
Error_Msg
("WHEN expected, must have at least one alternative in case",
First_When_Loc);
return Error;
else
Set_Alternatives (Case_Node, Alternatives_List);
return Case_Node;
end if;
end P_Case_Statement;
-------------------------------------
-- 5.4 Case Statement Alternative --
-------------------------------------
-- CASE_STATEMENT_ALTERNATIVE ::=
-- when DISCRETE_CHOICE_LIST =>
-- SEQUENCE_OF_STATEMENTS
-- The caller has checked that the initial token is WHEN or OTHERS
-- Error recovery: can raise Error_Resync
function P_Case_Statement_Alternative return Node_Id is
Case_Alt_Node : Node_Id;
begin
if Style_Check then
Style.Check_Indentation;
end if;
Case_Alt_Node := New_Node (N_Case_Statement_Alternative, Token_Ptr);
T_When; -- past WHEN (or give error in OTHERS case)
Set_Discrete_Choices (Case_Alt_Node, P_Discrete_Choice_List);
TF_Arrow;
Set_Statements (Case_Alt_Node, P_Sequence_Of_Statements (SS_Sreq_Whtm));
return Case_Alt_Node;
end P_Case_Statement_Alternative;
-------------------------
-- 5.5 Loop Statement --
-------------------------
-- LOOP_STATEMENT ::=
-- [LOOP_STATEMENT_IDENTIFIER:]
-- [ITERATION_SCHEME] loop
-- SEQUENCE_OF_STATEMENTS
-- end loop [loop_IDENTIFIER];
-- ITERATION_SCHEME ::=
-- while CONDITION
-- | for LOOP_PARAMETER_SPECIFICATION
-- The parsing of loop statements is handled by one of three functions
-- P_Loop_Statement, P_For_Statement or P_While_Statement depending
-- on the initial keyword in the construct (excluding the identifier)
-- P_Loop_Statement
-- This function parses the case where no iteration scheme is present
-- The caller has checked that the initial token is LOOP. The parameter
-- is the node identifiers for the loop label if any (or is set to Empty
-- if there is no loop label).
-- Error recovery : cannot raise Error_Resync
function P_Loop_Statement (Loop_Name : Node_Id := Empty) return Node_Id is
Loop_Node : Node_Id;
Created_Name : Node_Id;
begin
Push_Scope_Stack;
Scopes (Scope.Last).Labl := Loop_Name;
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scopes (Scope.Last).Etyp := E_Loop;
Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
TF_Loop;
if No (Loop_Name) then
Created_Name :=
Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L'));
Set_Comes_From_Source (Created_Name, False);
Set_Has_Created_Identifier (Loop_Node, True);
Set_Identifier (Loop_Node, Created_Name);
Scopes (Scope.Last).Labl := Created_Name;
else
Set_Identifier (Loop_Node, Loop_Name);
end if;
Append_Elmt (Loop_Node, Label_List);
Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
End_Statements (Loop_Node);
return Loop_Node;
end P_Loop_Statement;
-- P_For_Statement
-- This function parses a loop statement with a FOR iteration scheme
-- The caller has checked that the initial token is FOR. The parameter
-- is the node identifier for the block label if any (or is set to Empty
-- if there is no block label).
-- Note: the caller fills in the Identifier field if a label was present
-- Error recovery: can raise Error_Resync
function P_For_Statement (Loop_Name : Node_Id := Empty) return Node_Id is
Loop_Node : Node_Id;
Iter_Scheme_Node : Node_Id;
Loop_For_Flag : Boolean;
Created_Name : Node_Id;
Spec : Node_Id;
begin
Push_Scope_Stack;
Scopes (Scope.Last).Labl := Loop_Name;
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scopes (Scope.Last).Etyp := E_Loop;
Loop_For_Flag := (Prev_Token = Tok_Loop);
Scan; -- past FOR
Iter_Scheme_Node := New_Node (N_Iteration_Scheme, Token_Ptr);
Spec := P_Loop_Parameter_Specification;
if Nkind (Spec) = N_Loop_Parameter_Specification then
Set_Loop_Parameter_Specification (Iter_Scheme_Node, Spec);
else
Set_Iterator_Specification (Iter_Scheme_Node, Spec);
end if;
-- The following is a special test so that a miswritten for loop such
-- as "loop for I in 1..10;" is handled nicely, without making an extra
-- entry in the scope stack. We don't bother to actually fix up the
-- tree in this case since it's not worth the effort. Instead we just
-- eat up the loop junk, leaving the entry for what now looks like an
-- unmodified loop intact.
if Loop_For_Flag and then Token = Tok_Semicolon then
Error_Msg_SC ("LOOP belongs here, not before FOR");
Pop_Scope_Stack;
return Error;
-- Normal case
else
Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
if No (Loop_Name) then
Created_Name :=
Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L'));
Set_Comes_From_Source (Created_Name, False);
Set_Has_Created_Identifier (Loop_Node, True);
Set_Identifier (Loop_Node, Created_Name);
Scopes (Scope.Last).Labl := Created_Name;
else
Set_Identifier (Loop_Node, Loop_Name);
end if;
TF_Loop;
Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
End_Statements (Loop_Node);
Set_Iteration_Scheme (Loop_Node, Iter_Scheme_Node);
Append_Elmt (Loop_Node, Label_List);
return Loop_Node;
end if;
end P_For_Statement;
-- P_While_Statement
-- This procedure scans a loop statement with a WHILE iteration scheme
-- The caller has checked that the initial token is WHILE. The parameter
-- is the node identifier for the block label if any (or is set to Empty
-- if there is no block label).
-- Error recovery: cannot raise Error_Resync
function P_While_Statement (Loop_Name : Node_Id := Empty) return Node_Id is
Loop_Node : Node_Id;
Iter_Scheme_Node : Node_Id;
Loop_While_Flag : Boolean;
Created_Name : Node_Id;
begin
Push_Scope_Stack;
Scopes (Scope.Last).Labl := Loop_Name;
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scopes (Scope.Last).Etyp := E_Loop;
Loop_While_Flag := (Prev_Token = Tok_Loop);
Iter_Scheme_Node := New_Node (N_Iteration_Scheme, Token_Ptr);
Scan; -- past WHILE
Set_Condition (Iter_Scheme_Node, P_Condition);
-- The following is a special test so that a miswritten for loop such
-- as "loop while I > 10;" is handled nicely, without making an extra
-- entry in the scope stack. We don't bother to actually fix up the
-- tree in this case since it's not worth the effort. Instead we just
-- eat up the loop junk, leaving the entry for what now looks like an
-- unmodified loop intact.
if Loop_While_Flag and then Token = Tok_Semicolon then
Error_Msg_SC ("LOOP belongs here, not before WHILE");
Pop_Scope_Stack;
return Error;
-- Normal case
else
Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
TF_Loop;
if No (Loop_Name) then
Created_Name :=
Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L'));
Set_Comes_From_Source (Created_Name, False);
Set_Has_Created_Identifier (Loop_Node, True);
Set_Identifier (Loop_Node, Created_Name);
Scopes (Scope.Last).Labl := Created_Name;
else
Set_Identifier (Loop_Node, Loop_Name);
end if;
Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
End_Statements (Loop_Node);
Set_Iteration_Scheme (Loop_Node, Iter_Scheme_Node);
Append_Elmt (Loop_Node, Label_List);
return Loop_Node;
end if;
end P_While_Statement;
---------------------------------------
-- 5.5 Loop Parameter Specification --
---------------------------------------
-- LOOP_PARAMETER_SPECIFICATION ::=
-- DEFINING_IDENTIFIER in [reverse] DISCRETE_SUBTYPE_DEFINITION
-- [Iterator_Filter]
-- Error recovery: cannot raise Error_Resync
function P_Loop_Parameter_Specification return Node_Id is
Loop_Param_Specification_Node : Node_Id;
ID_Node : Node_Id;
Scan_State : Saved_Scan_State;
begin
Save_Scan_State (Scan_State);
ID_Node := P_Defining_Identifier (C_In);
-- If the next token is OF, it indicates an Ada 2012 iterator. If the
-- next token is a colon, this is also an Ada 2012 iterator, including
-- a subtype indication for the loop parameter. Otherwise we parse the
-- construct as a loop parameter specification. Note that the form
-- "for A in B" is ambiguous, and must be resolved semantically: if B
-- is a discrete subtype this is a loop specification, but if it is an
-- expression it is an iterator specification. Ambiguity is resolved
-- during analysis of the loop parameter specification.
if Token in Tok_Of | Tok_Colon then
Error_Msg_Ada_2012_Feature ("iterator", Token_Ptr);
return P_Iterator_Specification (ID_Node);
end if;
-- The span of the Loop_Parameter_Specification starts at the
-- defining identifier.
Loop_Param_Specification_Node :=
New_Node (N_Loop_Parameter_Specification, Sloc (ID_Node));
Set_Defining_Identifier (Loop_Param_Specification_Node, ID_Node);
if Token = Tok_Left_Paren then
Error_Msg_SC ("subscripted loop parameter not allowed");
Restore_Scan_State (Scan_State);
Discard_Junk_Node (P_Name);
elsif Token = Tok_Dot then
Error_Msg_SC ("selected loop parameter not allowed");
Restore_Scan_State (Scan_State);
Discard_Junk_Node (P_Name);
end if;
T_In;
if Token = Tok_Reverse then
Scan; -- past REVERSE
Set_Reverse_Present (Loop_Param_Specification_Node, True);
end if;
Set_Discrete_Subtype_Definition
(Loop_Param_Specification_Node, P_Discrete_Subtype_Definition);
if Token = Tok_When then
Error_Msg_Ada_2022_Feature ("iterator filter", Token_Ptr);
Scan; -- past WHEN
Set_Iterator_Filter
(Loop_Param_Specification_Node, P_Condition);
end if;
return Loop_Param_Specification_Node;
exception
when Error_Resync =>
return Error;
end P_Loop_Parameter_Specification;
----------------------------------
-- 5.5.1 Iterator_Specification --
----------------------------------
function P_Iterator_Specification (Def_Id : Node_Id) return Node_Id is
Node1 : Node_Id;
begin
Node1 := New_Node (N_Iterator_Specification, Sloc (Def_Id));
Set_Defining_Identifier (Node1, Def_Id);
if Token = Tok_Colon then
Scan; -- past :
if Token = Tok_Access then
Error_Msg_Ada_2022_Feature
("access definition in loop parameter", Token_Ptr);
Set_Subtype_Indication (Node1, P_Access_Definition (False));
else
Set_Subtype_Indication (Node1, P_Subtype_Indication);
end if;
end if;
if Token = Tok_Of then
Set_Of_Present (Node1);
Scan; -- past OF
elsif Token = Tok_In then
Scan; -- past IN
elsif Prev_Token = Tok_In
and then Present (Subtype_Indication (Node1))
then
-- Simplest recovery is to transform it into an element iterator.
-- Error message on 'in" has already been emitted when parsing the
-- optional constraint.
Set_Of_Present (Node1);
Error_Msg_N
("subtype indication is only legal on an element iterator",
Subtype_Indication (Node1));
else
return Error;
end if;
if Token = Tok_Reverse then
Scan; -- past REVERSE
Set_Reverse_Present (Node1, True);
end if;
Set_Name (Node1, P_Name);
if Token = Tok_When then
Error_Msg_Ada_2022_Feature ("iterator filter", Token_Ptr);
Scan; -- past WHEN
Set_Iterator_Filter
(Node1, P_Condition);
end if;
return Node1;
end P_Iterator_Specification;
--------------------------
-- 5.6 Block Statement --
--------------------------
-- BLOCK_STATEMENT ::=
-- [block_STATEMENT_IDENTIFIER:]
-- [declare
-- DECLARATIVE_PART]
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [block_IDENTIFIER];
-- The parsing of block statements is handled by one of the two functions
-- P_Declare_Statement or P_Begin_Statement depending on whether or not
-- a declare section is present
-- P_Declare_Statement
-- This function parses a block statement with DECLARE present
-- The caller has checked that the initial token is DECLARE
-- Error recovery: cannot raise Error_Resync
function P_Declare_Statement
(Block_Name : Node_Id := Empty)
return Node_Id
is
Block_Node : Node_Id;
Created_Name : Node_Id;
begin
Block_Node := New_Node (N_Block_Statement, Token_Ptr);
Push_Scope_Stack;
Scopes (Scope.Last).Etyp := E_Name;
Scopes (Scope.Last).Lreq := Present (Block_Name);
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Labl := Block_Name;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scan; -- past DECLARE
if No (Block_Name) then
Created_Name :=
Make_Identifier (Sloc (Block_Node), Set_Loop_Block_Name ('B'));
Set_Comes_From_Source (Created_Name, False);
Set_Has_Created_Identifier (Block_Node, True);
Set_Identifier (Block_Node, Created_Name);
Scopes (Scope.Last).Labl := Created_Name;
else
Set_Identifier (Block_Node, Block_Name);
end if;
Append_Elmt (Block_Node, Label_List);
Parse_Decls_Begin_End (Block_Node);
return Block_Node;
end P_Declare_Statement;
-- P_Begin_Statement
-- This function parses a block statement with no DECLARE present
-- The caller has checked that the initial token is BEGIN
-- Error recovery: cannot raise Error_Resync
function P_Begin_Statement
(Block_Name : Node_Id := Empty)
return Node_Id
is
Block_Node : Node_Id;
Created_Name : Node_Id;
begin
Block_Node := New_Node (N_Block_Statement, Token_Ptr);
Push_Scope_Stack;
Scopes (Scope.Last).Etyp := E_Name;
Scopes (Scope.Last).Lreq := Present (Block_Name);
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Labl := Block_Name;
Scopes (Scope.Last).Sloc := Token_Ptr;
if No (Block_Name) then
Created_Name :=
Make_Identifier (Sloc (Block_Node), Set_Loop_Block_Name ('B'));
Set_Comes_From_Source (Created_Name, False);
Set_Has_Created_Identifier (Block_Node, True);
Set_Identifier (Block_Node, Created_Name);
Scopes (Scope.Last).Labl := Created_Name;
else
Set_Identifier (Block_Node, Block_Name);
end if;
Append_Elmt (Block_Node, Label_List);
Scopes (Scope.Last).Ecol := Start_Column;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scan; -- past BEGIN
Set_Handled_Statement_Sequence
(Block_Node, P_Handled_Sequence_Of_Statements);
End_Statements (Handled_Statement_Sequence (Block_Node));
return Block_Node;
end P_Begin_Statement;
-------------------------
-- 5.7 Exit Statement --
-------------------------
-- EXIT_STATEMENT ::=
-- exit [loop_NAME] [when CONDITION];
-- The caller has checked that the initial token is EXIT
-- Error recovery: can raise Error_Resync
function P_Exit_Statement return Node_Id is
Exit_Node : Node_Id;
-- Start of processing for P_Exit_Statement
begin
Exit_Node := New_Node (N_Exit_Statement, Token_Ptr);
Scan; -- past EXIT
if Token = Tok_Identifier then
Set_Name (Exit_Node, P_Qualified_Simple_Name);
elsif Style_Check then
-- This EXIT has no name, so check that
-- the innermost loop is unnamed too.
Check_No_Exit_Name :
for J in reverse 1 .. Scope.Last loop
if Scopes (J).Etyp = E_Loop then
if Present (Scopes (J).Labl)
and then Comes_From_Source (Scopes (J).Labl)
then
-- Innermost loop in fact had a name, style check fails
Style.No_Exit_Name (Scopes (J).Labl);
end if;
exit Check_No_Exit_Name;
end if;
end loop Check_No_Exit_Name;
end if;
if Token = Tok_When and then not Missing_Semicolon_On_When then
Scan; -- past WHEN
Set_Condition (Exit_Node, P_Condition);
-- Allow IF instead of WHEN, giving error message
elsif Token = Tok_If then
T_When;
Scan; -- past IF used in place of WHEN
Set_Condition (Exit_Node, P_Expression_No_Right_Paren);
end if;
TF_Semicolon;
return Exit_Node;
end P_Exit_Statement;
-------------------------
-- 5.8 Goto Statement --
-------------------------
-- GOTO_STATEMENT ::= goto label_NAME;
-- The caller has checked that the initial token is GOTO (or TO in the
-- error case where GO and TO were incorrectly separated).
-- Error recovery: can raise Error_Resync
function P_Goto_Statement return Node_Id is
Goto_Node : Node_Id;
begin
Goto_Node := New_Node (N_Goto_Statement, Token_Ptr);
Scan; -- past GOTO (or TO)
Set_Name (Goto_Node, P_Qualified_Simple_Name_Resync);
Append_Elmt (Goto_Node, Goto_List);
if Token = Tok_When then
Error_Msg_GNAT_Extension ("goto when statement", Token_Ptr);
Scan; -- past WHEN
Mutate_Nkind (Goto_Node, N_Goto_When_Statement);
Set_Condition (Goto_Node, P_Expression_No_Right_Paren);
end if;
TF_Semicolon;
return Goto_Node;
end P_Goto_Statement;
---------------------------
-- Parse_Decls_Begin_End --
---------------------------
-- This function parses the construct:
-- DECLARATIVE_PART
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [NAME];
-- The caller has built the scope stack entry, and created the node to
-- whose Declarations and Handled_Statement_Sequence fields are to be
-- set. On return these fields are filled in (except in the case of a
-- task body, where the handled statement sequence is optional, and may
-- thus be Empty), and the scan is positioned past the End sequence.
-- If the BEGIN is missing, then the parent node is used to help construct
-- an appropriate missing BEGIN message. Possibilities for the parent are:
-- N_Block_Statement declare block
-- N_Entry_Body entry body
-- N_Package_Body package body (begin part optional)
-- N_Subprogram_Body procedure or function body
-- N_Task_Body task body
-- Note: in the case of a block statement, there is definitely a DECLARE
-- present (because a Begin statement without a DECLARE is handled by the
-- P_Begin_Statement procedure, which does not call Parse_Decls_Begin_End.
-- Error recovery: cannot raise Error_Resync
procedure Parse_Decls_Begin_End (Parent : Node_Id) is
Body_Decl : Node_Id;
Decls : List_Id;
Parent_Nkind : Node_Kind;
Spec_Node : Node_Id;
HSS : Node_Id;
procedure Missing_Begin (Msg : String);
-- Called to post a missing begin message. In the normal case this is
-- posted at the start of the current token. A special case arises when
-- P_Declarative_Items has previously found a missing begin, in which
-- case we replace the original error message.
procedure Set_Null_HSS (Parent : Node_Id);
-- Construct an empty handled statement sequence and install in Parent
-- Leaves HSS set to reference the newly constructed statement sequence.
-------------------
-- Missing_Begin --
-------------------
procedure Missing_Begin (Msg : String) is
begin
if Missing_Begin_Msg = No_Error_Msg then
Error_Msg_BC (Msg);
else
Change_Error_Text (Missing_Begin_Msg, Msg);
-- Purge any messages issued after than, since a missing begin
-- can cause a lot of havoc, and it is better not to dump these
-- cascaded messages on the user.
Purge_Messages (Get_Location (Missing_Begin_Msg), Prev_Token_Ptr);
end if;
end Missing_Begin;
------------------
-- Set_Null_HSS --
------------------
procedure Set_Null_HSS (Parent : Node_Id) is
Null_Stm : Node_Id;
begin
Null_Stm :=
Make_Null_Statement (Token_Ptr);
Set_Comes_From_Source (Null_Stm, False);
HSS :=
Make_Handled_Sequence_Of_Statements (Token_Ptr,
Statements => New_List (Null_Stm));
Set_Comes_From_Source (HSS, False);
Set_Handled_Statement_Sequence (Parent, HSS);
end Set_Null_HSS;
-- Start of processing for Parse_Decls_Begin_End
begin
Decls := P_Declarative_Part;
if Ada_Version = Ada_83 then
Check_Later_Vs_Basic_Declarations (Decls, During_Parsing => True);
end if;
-- Here is where we deal with the case of IS used instead of semicolon.
-- Specifically, if the last declaration in the declarative part is a
-- subprogram body still marked as having a bad IS, then this is where
-- we decide that the IS should really have been a semicolon and that
-- the body should have been a declaration. Note that if the bad IS
-- had turned out to be OK (i.e. a decent begin/end was found for it),
-- then the Bad_Is_Detected flag would have been reset by now.
Body_Decl := Last (Decls);
if Present (Body_Decl)
and then Nkind (Body_Decl) = N_Subprogram_Body
and then Bad_Is_Detected (Body_Decl)
then
-- OK, we have the case of a bad IS, so we need to fix up the tree.
-- What we have now is a subprogram body with attached declarations
-- and a possible statement sequence.
-- First step is to take the declarations that were part of the bogus
-- subprogram body and append them to the outer declaration chain.
-- In other words we append them past the body (which we will later
-- convert into a declaration).
Append_List (Declarations (Body_Decl), Decls);
-- Now take the handled statement sequence of the bogus body and
-- set it as the statement sequence for the outer construct. Note
-- that it may be empty (we specially allowed a missing BEGIN for
-- a subprogram body marked as having a bad IS -- see below).
Set_Handled_Statement_Sequence (Parent,
Handled_Statement_Sequence (Body_Decl));
-- Next step is to convert the old body node to a declaration node
Spec_Node := Specification (Body_Decl);
Change_Node (Body_Decl, N_Subprogram_Declaration);
Set_Specification (Body_Decl, Spec_Node);
-- Final step is to put the declarations for the parent where
-- they belong, and then fall through the IF to scan out the
-- END statements.
Set_Declarations (Parent, Decls);
-- This is the normal case (i.e. any case except the bad IS case)
-- If we have a BEGIN, then scan out the sequence of statements, and
-- also reset the expected column for the END to match the BEGIN.
else
Set_Declarations (Parent, Decls);
if Token = Tok_Begin then
if Style_Check then
Style.Check_Indentation;
end if;
Error_Msg_Col := Scopes (Scope.Last).Ecol;
if RM_Column_Check
and then Token_Is_At_Start_Of_Line
and then Start_Column /= Error_Msg_Col
then
Error_Msg_SC ("(style) BEGIN in wrong column, should be@");
else
Scopes (Scope.Last).Ecol := Start_Column;
end if;
Scopes (Scope.Last).Sloc := Token_Ptr;
Scan; -- past BEGIN
Set_Handled_Statement_Sequence (Parent,
P_Handled_Sequence_Of_Statements);
-- No BEGIN present
else
Parent_Nkind := Nkind (Parent);
-- A special check for the missing IS case. If we have a
-- subprogram body that was marked as having a suspicious
-- IS, and the current token is END, then we simply confirm
-- the suspicion, and do not require a BEGIN to be present
if Parent_Nkind = N_Subprogram_Body
and then Token = Tok_End
and then Scopes (Scope.Last).Etyp = E_Suspicious_Is
then
Scopes (Scope.Last).Etyp := E_Bad_Is;
-- Otherwise BEGIN is not required for a package body, so we
-- don't mind if it is missing, but we do construct a dummy
-- one (so that we have somewhere to set End_Label).
-- However if we have something other than a BEGIN which
-- looks like it might be statements, then we signal a missing
-- BEGIN for these cases as well. We define "something which
-- looks like it might be statements" as a token other than
-- END, EOF, or a token which starts declarations.
elsif Parent_Nkind = N_Package_Body
and then (Token in Tok_End | Tok_EOF | Token_Class_Declk)
then
Set_Null_HSS (Parent);
-- These are cases in which a BEGIN is required and not present
else
Set_Null_HSS (Parent);
-- Prepare to issue error message
Error_Msg_Sloc := Scopes (Scope.Last).Sloc;
Error_Msg_Node_1 := Scopes (Scope.Last).Labl;
-- Now issue appropriate message
if Parent_Nkind = N_Block_Statement then
Missing_Begin ("missing BEGIN for DECLARE#!");
elsif Parent_Nkind = N_Entry_Body then
Missing_Begin ("missing BEGIN for ENTRY#!");
elsif Parent_Nkind = N_Subprogram_Body then
if Nkind (Specification (Parent))
= N_Function_Specification
then
Missing_Begin ("missing BEGIN for function&#!");
else
Missing_Begin ("missing BEGIN for procedure&#!");
end if;
-- The case for package body arises only when
-- we have possible statement junk present.
elsif Parent_Nkind = N_Package_Body then
Missing_Begin ("missing BEGIN for package body&#!");
else
pragma Assert (Parent_Nkind = N_Task_Body);
Missing_Begin ("missing BEGIN for task body&#!");
end if;
-- Here we pick up the statements after the BEGIN that
-- should have been present but was not. We don't insist
-- on statements being present if P_Declarative_Part had
-- already found a missing BEGIN, since it might have
-- swallowed a lone statement into the declarative part.
if Missing_Begin_Msg /= No_Error_Msg
and then Token = Tok_End
then
null;
else
Set_Handled_Statement_Sequence (Parent,
P_Handled_Sequence_Of_Statements);
end if;
end if;
end if;
end if;
-- Here with declarations and handled statement sequence scanned
if Present (Handled_Statement_Sequence (Parent)) then
End_Statements (Handled_Statement_Sequence (Parent));
else
End_Statements;
end if;
-- We know that End_Statements removed an entry from the scope stack
-- (because it is required to do so under all circumstances). We can
-- therefore reference the entry it removed one past the stack top.
-- What we are interested in is whether it was a case of a bad IS.
-- We can't call Scopes here.
if Scope.Table (Scope.Last + 1).Etyp = E_Bad_Is then
Error_Msg -- CODEFIX
("|IS should be "";""", Scope.Table (Scope.Last + 1).S_Is);
Set_Bad_Is_Detected (Parent, True);
end if;
end Parse_Decls_Begin_End;
-------------------------
-- Set_Loop_Block_Name --
-------------------------
function Set_Loop_Block_Name (L : Character) return Name_Id is
begin
Name_Buffer (1) := L;
Name_Buffer (2) := '_';
Name_Len := 2;
Loop_Block_Count := Loop_Block_Count + 1;
Add_Nat_To_Name_Buffer (Loop_Block_Count);
return Name_Find;
end Set_Loop_Block_Name;
---------------
-- Then_Scan --
---------------
procedure Then_Scan is
begin
TF_Then;
while Token = Tok_Then loop
Error_Msg_SC -- CODEFIX
("redundant THEN");
TF_Then;
end loop;
if Token in Tok_And | Tok_Or then
Error_Msg_SC ("unexpected logical operator");
Scan; -- past logical operator
if (Prev_Token = Tok_And and then Token = Tok_Then)
or else
(Prev_Token = Tok_Or and then Token = Tok_Else)
then
Scan;
end if;
Discard_Junk_Node (P_Expression);
end if;
if Token = Tok_Then then
Scan;
end if;
end Then_Scan;
end Ch5;