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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- P A R . C H 5 --
-- --
-- B o d y --
-- --
-- $Revision: 1.1 $
-- --
-- Copyright (C) 1992-2001, 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 2, 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 COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
pragma Style_Checks (All_Checks);
-- Turn off subprogram body ordering check. Subprograms are in order
-- by RM section rather than alphabetical
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_Condition 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_Loop_Parameter_Specification 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}
-- 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. The caller sets SS_Flags
-- to indicate acceptable termination conditions for the sequence:
-- SS_Flags.Eftm Terminate on ELSIF
-- SS_Flags.Eltm Terminate on ELSE
-- SS_Flags.Extm Terminate on EXCEPTION
-- SS_Flags.Ortm Terminate on OR
-- SS_Flags.Tatm Terminate on THEN ABORT (Token = ABORT on return)
-- SS_Flags.Whtm Terminate on WHEN
-- SS_Flags.Unco Unconditional terminate after scanning one statement
-- In addition, the scan is always terminated by encountering END or the
-- end of file (EOF) condition. 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 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) return List_Id is
Statement_Required : Boolean;
-- 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).
Declaration_Found : Boolean := False;
-- This flag is set True if a declaration is encountered, so that the
-- error message about declarations in the statement part is only
-- given once for a given sequence of statements.
Scan_State_Label : Saved_Scan_State;
Scan_State : Saved_Scan_State;
Statement_List : List_Id;
Block_Label : Name_Id;
Id_Node : Node_Id;
Name_Node : Node_Id;
procedure Junk_Declaration;
-- Procedure called to handle error of declaration encountered in
-- statement sequence.
procedure Test_Statement_Required;
-- Flag error if Statement_Required flag set
procedure Junk_Declaration is
begin
if (not Declaration_Found) or All_Errors_Mode then
Error_Msg_SC ("declarations must come before BEGIN");
Declaration_Found := True;
end if;
Skip_Declaration (Statement_List);
end Junk_Declaration;
procedure Test_Statement_Required is
begin
if Statement_Required then
Error_Msg_BC ("statement expected");
end if;
end Test_Statement_Required;
-- Start of processing for P_Sequence_Of_Statements
begin
Statement_List := New_List;
Statement_Required := SS_Flags.Sreq;
loop
while Token = Tok_Semicolon loop
Error_Msg_SC ("unexpected semicolon ignored");
Scan; -- past junk semicolon
end loop;
begin
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 /= Tok_Return
and then Prev_Token /= Tok_Null
and then Prev_Token /= Tok_Raise
and then Prev_Token /= Tok_End
and then Prev_Token /= Tok_Exit)
-- If followed by colon, colon-equal, or dot, then we
-- definitely have an identifier (could not be reserved)
or else Token = Tok_Colon
or else Token = Tok_Colon_Equal
or else Token = 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 /= Tok_Case
and then Prev_Token /= Tok_Delay
and then Prev_Token /= Tok_If
and then Prev_Token /= Tok_Elsif
and then Prev_Token /= Tok_Return
and then Prev_Token /= Tok_When
and then Prev_Token /= Tok_While
and then Prev_Token /= 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 < Scope.Table (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 < Scope.Table (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 >= Scope.Table (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 < Scope.Table (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_When | Tok_Others =>
-- 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 < Scope.Table (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
Append_To (Statement_List,
P_Statement_Name (Id_Node));
Scan; -- past semicolon
Statement_Required := False;
-- 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 ("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));
-- Improper statement follows label. If we have an
-- expression token, then assume the colon was part
-- of a misplaced declaration.
elsif Token not in Token_Class_Eterm then
Restore_Scan_State (Scan_State_Label);
Junk_Declaration;
-- 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
while Token = Tok_Right_Paren loop
Error_Msg_SC ("extra right paren");
Scan; -- past )
end loop;
-- 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
Append_To (Statement_List,
P_Statement_Name (Name_Node));
Scan; -- past semicolon
Statement_Required := False;
-- Else we have a missing semicolon
else
TF_Semicolon;
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. That's not accidental.
-- 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
Append_To (Statement_List,
P_Statement_Name (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
Append_To (Statement_List,
P_Statement_Name (Name_Node));
end if;
TF_Semicolon;
Statement_Required := False;
-- Label starting with << which must precede real statement
when Tok_Less_Less =>
Append_To (Statement_List, P_Label);
Statement_Required := True;
-- 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 =>
if Token in Token_Class_Declk then
Junk_Declaration;
else
Error_Msg_BC ("statement expected");
raise Error_Resync;
end if;
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;
return Statement_List;
end P_Sequence_Of_Statements;
--------------------
-- 5.1 Statement --
--------------------
-- Parsed by P_Sequence_Of_Statements (5.1), except for the case
-- of a statement of the form of a name, which is handled here. The
-- argument passed in is the tree for the name which has been scanned
-- The returned value is the corresponding statement form.
-- This routine is also used by Par.Prag for processing the procedure
-- call that appears as the second argument of a pragma Assert.
-- Error recovery: cannot raise Error_Resync
function P_Statement_Name (Name_Node : Node_Id) return Node_Id is
Stmt_Node : Node_Id;
begin
-- Case of Indexed component, which is a procedure call with arguments
if Nkind (Name_Node) = N_Indexed_Component then
declare
Prefix_Node : Node_Id := Prefix (Name_Node);
Exprs_Node : List_Id := Expressions (Name_Node);
begin
Change_Node (Name_Node, N_Procedure_Call_Statement);
Set_Name (Name_Node, Prefix_Node);
Set_Parameter_Associations (Name_Node, Exprs_Node);
return Name_Node;
end;
-- Case of function call node, which is a really a procedure call
elsif Nkind (Name_Node) = N_Function_Call then
declare
Fname_Node : Node_Id := Name (Name_Node);
Params_List : List_Id := Parameter_Associations (Name_Node);
begin
Change_Node (Name_Node, N_Procedure_Call_Statement);
Set_Name (Name_Node, Fname_Node);
Set_Parameter_Associations (Name_Node, Params_List);
return Name_Node;
end;
-- Case of call to attribute that denotes a procedure. Here we
-- just leave the attribute reference unchanged.
elsif Nkind (Name_Node) = N_Attribute_Reference
and then Is_Procedure_Attribute_Name (Attribute_Name (Name_Node))
then
return Name_Node;
-- All other cases of names are parameterless procedure calls
else
Stmt_Node :=
New_Node (N_Procedure_Call_Statement, Sloc (Name_Node));
Set_Name (Stmt_Node, Name_Node);
return Stmt_Node;
end if;
end P_Statement_Name;
---------------------------
-- 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);
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);
Set_Name (Assign_Node, LHS);
Set_Expression (Assign_Node, P_Expression_No_Right_Paren);
TF_Semicolon;
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 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. These checks apply only to a
-- THEN at the start of a line.
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 Style.RM_Column_Check and then Token_Is_At_Start_Of_Line
and then Start_Column /= Scope.Table (Scope.Last).Ecol
then
Error_Msg_Col := Scope.Table (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_Is_At_Start_Of_Line and then 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;
Scope.Table (Scope.Last).Etyp := E_If;
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
Scope.Table (Scope.Last).Labl := Error;
Scope.Table (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 ("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 ("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
Cond : Node_Id;
begin
Cond := P_Expression_No_Right_Paren;
-- 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.
while Token = Tok_Colon_Equal loop
Error_Msg_SC (""":="" should be ""=""");
Scan; -- past junk :=
Discard_Junk_Node (P_Expression_No_Right_Paren);
end loop;
return Cond;
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;
Scope.Table (Scope.Last).Etyp := E_Case;
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
Scope.Table (Scope.Last).Labl := Error;
Scope.Table (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 = Tok_When or else Token = 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 > Scope.Table (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;
begin
Push_Scope_Stack;
Scope.Table (Scope.Last).Labl := Loop_Name;
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
Scope.Table (Scope.Last).Etyp := E_Loop;
Loop_Node := New_Node (N_Loop_Statement, Token_Ptr);
TF_Loop;
if No (Loop_Name) then
Set_Has_Created_Identifier (Loop_Node, True);
Set_Identifier (Loop_Node,
Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L')));
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;
begin
Push_Scope_Stack;
Scope.Table (Scope.Last).Labl := Loop_Name;
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
Scope.Table (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);
Set_Loop_Parameter_Specification
(Iter_Scheme_Node, P_Loop_Parameter_Specification);
-- 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);
TF_Loop;
Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
End_Statements (Loop_Node);
Set_Iteration_Scheme (Loop_Node, Iter_Scheme_Node);
if No (Loop_Name) then
Set_Has_Created_Identifier (Loop_Node, True);
Set_Identifier (Loop_Node,
Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L')));
else
Set_Identifier (Loop_Node, Loop_Name);
end if;
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;
begin
Push_Scope_Stack;
Scope.Table (Scope.Last).Labl := Loop_Name;
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
Scope.Table (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;
Set_Statements (Loop_Node, P_Sequence_Of_Statements (SS_Sreq));
End_Statements (Loop_Node);
Set_Iteration_Scheme (Loop_Node, Iter_Scheme_Node);
if No (Loop_Name) then
Set_Has_Created_Identifier (Loop_Node, True);
Set_Identifier (Loop_Node,
Make_Identifier (Sloc (Loop_Node), Set_Loop_Block_Name ('L')));
else
Set_Identifier (Loop_Node, Loop_Name);
end if;
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
-- 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
Loop_Param_Specification_Node :=
New_Node (N_Loop_Parameter_Specification, Token_Ptr);
Save_Scan_State (Scan_State);
ID_Node := P_Defining_Identifier;
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);
return Loop_Param_Specification_Node;
exception
when Error_Resync =>
return Error;
end P_Loop_Parameter_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;
begin
Block_Node := New_Node (N_Block_Statement, Token_Ptr);
Push_Scope_Stack;
Scope.Table (Scope.Last).Etyp := E_Name;
Scope.Table (Scope.Last).Lreq := Present (Block_Name);
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Labl := Block_Name;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
Scan; -- past DECLARE
if No (Block_Name) then
Set_Has_Created_Identifier (Block_Node, True);
Set_Identifier (Block_Node,
Make_Identifier (Sloc (Block_Node), Set_Loop_Block_Name ('B')));
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;
begin
Block_Node := New_Node (N_Block_Statement, Token_Ptr);
Push_Scope_Stack;
Scope.Table (Scope.Last).Etyp := E_Name;
Scope.Table (Scope.Last).Lreq := Present (Block_Name);
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (Scope.Last).Labl := Block_Name;
Scope.Table (Scope.Last).Sloc := Token_Ptr;
if No (Block_Name) then
Set_Has_Created_Identifier (Block_Node, True);
Set_Identifier (Block_Node,
Make_Identifier (Sloc (Block_Node), Set_Loop_Block_Name ('B')));
else
Set_Identifier (Block_Node, Block_Name);
end if;
Append_Elmt (Block_Node, Label_List);
Scope.Table (Scope.Last).Ecol := Start_Column;
Scope.Table (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;
function Missing_Semicolon_On_Exit return Boolean;
-- This function deals with the following specialized situation
--
-- when 'x' =>
-- exit [identifier]
-- when 'y' =>
--
-- This looks like a messed up EXIT WHEN, when in fact the problem
-- is a missing semicolon. It is called with Token pointing to the
-- WHEN token, and returns True if a semicolon is missing before
-- the WHEN as in the above example.
function Missing_Semicolon_On_Exit return Boolean is
State : Saved_Scan_State;
begin
if not Token_Is_At_Start_Of_Line then
return False;
elsif Scope.Table (Scope.Last).Etyp /= E_Case then
return False;
else
Save_Scan_State (State);
Scan; -- past WHEN
Scan; -- past token after WHEN
if Token = Tok_Arrow then
Restore_Scan_State (State);
return True;
else
Restore_Scan_State (State);
return False;
end if;
end if;
end Missing_Semicolon_On_Exit;
-- 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 Scope.Table (J).Etyp = E_Loop then
if Present (Scope.Table (J).Labl) then
-- Innermost loop in fact had a name, style check fails
Style.No_Exit_Name (Scope.Table (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_Exit 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);
No_Constraint;
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;
Body_Sloc : Source_Ptr;
Decls : List_Id;
Decl : Node_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;
-- Check for misplacement of later vs basic declarations in Ada 83
if Ada_83 then
Decl := First (Decls);
-- Loop through sequence of basic declarative items
Outer : while Present (Decl) loop
if Nkind (Decl) /= N_Subprogram_Body
and then Nkind (Decl) /= N_Package_Body
and then Nkind (Decl) /= N_Task_Body
and then Nkind (Decl) not in N_Body_Stub
then
Next (Decl);
-- Once a body is encountered, we only allow later declarative
-- items. The inner loop checks the rest of the list.
else
Body_Sloc := Sloc (Decl);
Inner : while Present (Decl) loop
if Nkind (Decl) not in N_Later_Decl_Item
and then Nkind (Decl) /= N_Pragma
then
if Ada_83 then
Error_Msg_Sloc := Body_Sloc;
Error_Msg_N
("(Ada 83) decl cannot appear after body#", Decl);
end if;
end if;
Next (Decl);
end loop Inner;
end if;
end loop Outer;
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 := Scope.Table (Scope.Last).Ecol;
if Style.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
Scope.Table (Scope.Last).Ecol := Start_Column;
end if;
Scope.Table (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 Scope.Table (Scope.Last).Etyp = E_Suspicious_Is
then
Scope.Table (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 = Tok_End
or else Token = Tok_EOF
or else Token in 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 := Scope.Table (Scope.Last).Sloc;
Error_Msg_Node_1 := Scope.Table (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.
if Scope.Table (Scope.Last + 1).Etyp = E_Bad_Is then
Error_Msg ("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 ("redundant THEN");
TF_Then;
end loop;
if Token = Tok_And or else Token = Tok_Or then
Error_Msg_SC ("unexpected logical operator");
Scan;
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;