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|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- P A R . C H 2 --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2013, 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
separate (Par)
package body Ch2 is
-- Local functions, used only in this chapter
procedure Scan_Pragma_Argument_Association
(Identifier_Seen : in out Boolean;
Association : out Node_Id);
-- Scans out a pragma argument association. Identifier_Seen is true on
-- entry if a previous association had an identifier, and gets set True if
-- the scanned association has an identifier (this is used to check the
-- rule that no associations without identifiers can follow an association
-- which has an identifier). The result is returned in Association.
--
-- Note: We allow attribute forms Pre'Class, Post'Class, Invariant'Class,
-- Type_Invariant'Class in place of a pragma argument identifier. Rather
-- than handle this case specially, we replace such references with
-- one of the special internal identifiers _Pre, _Post, _Invariant, or
-- _Type_Invariant, and this procedure is where this replacement occurs.
---------------------
-- 2.3 Identifier --
---------------------
-- IDENTIFIER ::= LETTER {[UNDERLINE] LETTER_OR_DIGIT}
-- LETTER_OR_DIGIT ::= IDENTIFIER_LETTER | DIGIT
-- An IDENTIFIER shall not be a reserved word
-- Error recovery: can raise Error_Resync (cannot return Error)
function P_Identifier (C : Id_Check := None) return Node_Id is
Ident_Node : Node_Id;
begin
-- All set if we do indeed have an identifier
-- Code duplication, see Par_Ch3.P_Defining_Identifier???
if Token = Tok_Identifier then
Check_Future_Keyword;
Ident_Node := Token_Node;
Scan; -- past Identifier
return Ident_Node;
-- If we have a reserved identifier, manufacture an identifier with
-- a corresponding name after posting an appropriate error message
elsif Is_Reserved_Identifier (C) then
Scan_Reserved_Identifier (Force_Msg => False);
Ident_Node := Token_Node;
Scan; -- past the node
return Ident_Node;
-- Otherwise we have junk that cannot be interpreted as an identifier
else
T_Identifier; -- to give message
raise Error_Resync;
end if;
end P_Identifier;
--------------------------
-- 2.3 Letter Or Digit --
--------------------------
-- Parsed by P_Identifier (2.3)
--------------------------
-- 2.4 Numeric Literal --
--------------------------
-- NUMERIC_LITERAL ::= DECIMAL_LITERAL | BASED_LITERAL
-- Numeric literal is returned by the scanner as either
-- Tok_Integer_Literal or Tok_Real_Literal
----------------------------
-- 2.4.1 Decimal Literal --
----------------------------
-- DECIMAL_LITERAL ::= NUMERAL [.NUMERAL] [EXPONENT]
-- Handled by scanner as part of numeric literal handing (see 2.4)
--------------------
-- 2.4.1 Numeral --
--------------------
-- NUMERAL ::= DIGIT {[UNDERLINE] DIGIT}
-- Handled by scanner as part of numeric literal handling (see 2.4)
---------------------
-- 2.4.1 Exponent --
---------------------
-- EXPONENT ::= E [+] NUMERAL | E - NUMERAL
-- Handled by scanner as part of numeric literal handling (see 2.4)
--------------------------
-- 2.4.2 Based Literal --
--------------------------
-- BASED_LITERAL ::=
-- BASE # BASED_NUMERAL [.BASED_NUMERAL] # [EXPONENT]
-- Handled by scanner as part of numeric literal handling (see 2.4)
-----------------
-- 2.4.2 Base --
-----------------
-- BASE ::= NUMERAL
-- Handled by scanner as part of numeric literal handling (see 2.4)
--------------------------
-- 2.4.2 Based Numeral --
--------------------------
-- BASED_NUMERAL ::=
-- EXTENDED_DIGIT {[UNDERLINE] EXTENDED_DIGIT}
-- Handled by scanner as part of numeric literal handling (see 2.4)
---------------------------
-- 2.4.2 Extended Digit --
---------------------------
-- EXTENDED_DIGIT ::= DIGIT | A | B | C | D | E | F
-- Handled by scanner as part of numeric literal handling (see 2.4)
----------------------------
-- 2.5 Character Literal --
----------------------------
-- CHARACTER_LITERAL ::= ' GRAPHIC_CHARACTER '
-- Handled by the scanner and returned as Tok_Char_Literal
-------------------------
-- 2.6 String Literal --
-------------------------
-- STRING LITERAL ::= "{STRING_ELEMENT}"
-- Handled by the scanner and returned as Tok_String_Literal
-- or if the string looks like an operator as Tok_Operator_Symbol.
-------------------------
-- 2.6 String Element --
-------------------------
-- STRING_ELEMENT ::= "" | non-quotation_mark_GRAPHIC_CHARACTER
-- A STRING_ELEMENT is either a pair of quotation marks ("),
-- or a single GRAPHIC_CHARACTER other than a quotation mark.
-- Handled by scanner as part of string literal handling (see 2.4)
------------------
-- 2.7 Comment --
------------------
-- A COMMENT starts with two adjacent hyphens and extends up to the
-- end of the line. A COMMENT may appear on any line of a program.
-- Handled by the scanner which simply skips past encountered comments
-----------------
-- 2.8 Pragma --
-----------------
-- PRAGMA ::= pragma IDENTIFIER
-- [(PRAGMA_ARGUMENT_ASSOCIATION {, PRAGMA_ARGUMENT_ASSOCIATION})];
-- The caller has checked that the initial token is PRAGMA
-- Error recovery: cannot raise Error_Resync
-- One special piece of processing is needed in this routine. As described
-- in the section on "Handling semicolon used in place of IS" in module
-- Parse, the parser detects the case of missing subprogram bodies to
-- allow recovery from this syntactic error. Pragma INTERFACE (and, for
-- Ada 95, pragma IMPORT) can appear in place of the body. The parser must
-- recognize the use of these two pragmas in this context, otherwise it
-- will think there are missing bodies, and try to change ; to IS, when
-- in fact the bodies ARE present, supplied by these pragmas.
function P_Pragma (Skipping : Boolean := False) return Node_Id is
Interface_Check_Required : Boolean := False;
-- Set True if check of pragma INTERFACE is required
Import_Check_Required : Boolean := False;
-- Set True if check of pragma IMPORT is required
Arg_Count : Int := 0;
-- Number of argument associations processed
Identifier_Seen : Boolean := False;
-- Set True if an identifier is encountered for a pragma argument. Used
-- to check that there are no more arguments without identifiers.
Prag_Node : Node_Id;
Prag_Name : Name_Id;
Semicolon_Loc : Source_Ptr;
Ident_Node : Node_Id;
Assoc_Node : Node_Id;
Result : Node_Id;
procedure Skip_Pragma_Semicolon;
-- Skip past semicolon at end of pragma
---------------------------
-- Skip_Pragma_Semicolon --
---------------------------
procedure Skip_Pragma_Semicolon is
begin
if Token /= Tok_Semicolon then
-- If skipping the pragma, ignore a missing semicolon
if Skipping then
null;
-- Otherwise demand a semicolon
else
T_Semicolon;
end if;
-- Scan past semicolon if present
else
Scan;
end if;
end Skip_Pragma_Semicolon;
-- Start of processing for P_Pragma
begin
Prag_Node := New_Node (N_Pragma, Token_Ptr);
Scan; -- past PRAGMA
Prag_Name := Token_Name;
if Style_Check then
Style.Check_Pragma_Name;
end if;
-- Ada 2005 (AI-284): INTERFACE is a new reserved word but it is
-- allowed as a pragma name.
if Ada_Version >= Ada_2005
and then Token = Tok_Interface
then
Prag_Name := Name_Interface;
Ident_Node := Make_Identifier (Token_Ptr, Name_Interface);
Scan; -- past INTERFACE
else
Ident_Node := P_Identifier;
end if;
Set_Pragma_Identifier (Prag_Node, Ident_Node);
-- See if special INTERFACE/IMPORT check is required
if SIS_Entry_Active then
Interface_Check_Required := (Prag_Name = Name_Interface);
Import_Check_Required := (Prag_Name = Name_Import);
else
Interface_Check_Required := False;
Import_Check_Required := False;
end if;
-- Scan arguments. We assume that arguments are present if there is
-- a left paren, or if a semicolon is missing and there is another
-- token on the same line as the pragma name.
if Token = Tok_Left_Paren
or else (Token /= Tok_Semicolon
and then not Token_Is_At_Start_Of_Line)
then
Set_Pragma_Argument_Associations (Prag_Node, New_List);
T_Left_Paren;
loop
Arg_Count := Arg_Count + 1;
Scan_Pragma_Argument_Association (Identifier_Seen, Assoc_Node);
if Arg_Count = 2
and then (Interface_Check_Required or else Import_Check_Required)
then
-- Here is where we cancel the SIS active status if this pragma
-- supplies a body for the currently active subprogram spec.
if Nkind (Expression (Assoc_Node)) in N_Direct_Name
and then Chars (Expression (Assoc_Node)) = Chars (SIS_Labl)
then
SIS_Entry_Active := False;
end if;
end if;
Append (Assoc_Node, Pragma_Argument_Associations (Prag_Node));
exit when Token /= Tok_Comma;
Scan; -- past comma
end loop;
-- If we have := for pragma Debug, it is worth special casing the
-- error message (it is easy to think of pragma Debug as taking a
-- statement, and an assignment statement is the most likely
-- candidate for this error)
if Token = Tok_Colon_Equal and then Prag_Name = Name_Debug then
Error_Msg_SC ("argument for pragma Debug must be procedure call");
Resync_To_Semicolon;
-- Normal case, we expect a right paren here
else
T_Right_Paren;
end if;
end if;
Semicolon_Loc := Token_Ptr;
-- Now we have two tasks left, we need to scan out the semicolon
-- following the pragma, and we have to call Par.Prag to process
-- the pragma. Normally we do them in this order, however, there
-- is one exception namely pragma Style_Checks where we like to
-- skip the semicolon after processing the pragma, since that way
-- the style checks for the scanning of the semicolon follow the
-- settings of the pragma.
-- You might think we could just unconditionally do things in
-- the opposite order, but there are other pragmas, notably the
-- case of pragma Source_File_Name, which assume the semicolon
-- is already scanned out.
if Prag_Name = Name_Style_Checks then
Result := Par.Prag (Prag_Node, Semicolon_Loc);
Skip_Pragma_Semicolon;
return Result;
else
Skip_Pragma_Semicolon;
return Par.Prag (Prag_Node, Semicolon_Loc);
end if;
exception
when Error_Resync =>
Resync_Past_Semicolon;
return Error;
end P_Pragma;
-- This routine is called if a pragma is encountered in an inappropriate
-- position, the pragma is scanned out and control returns to continue.
-- The caller has checked that the initial token is pragma
-- Error recovery: cannot raise Error_Resync
procedure P_Pragmas_Misplaced is
begin
while Token = Tok_Pragma loop
Error_Msg_SC ("pragma not allowed here");
Discard_Junk_Node (P_Pragma (Skipping => True));
end loop;
end P_Pragmas_Misplaced;
-- This function is called to scan out an optional sequence of pragmas.
-- If no pragmas are found, then No_List is returned.
-- Error recovery: Cannot raise Error_Resync
function P_Pragmas_Opt return List_Id is
L : List_Id;
begin
if Token = Tok_Pragma then
L := New_List;
P_Pragmas_Opt (L);
return L;
else
return No_List;
end if;
end P_Pragmas_Opt;
-- This procedure is called to scan out an optional sequence of pragmas.
-- Any pragmas found are appended to the list provided as an argument.
-- Error recovery: Cannot raise Error_Resync
procedure P_Pragmas_Opt (List : List_Id) is
P : Node_Id;
begin
while Token = Tok_Pragma loop
P := P_Pragma;
if Nkind (P) /= N_Error
and then Nam_In (Pragma_Name (P), Name_Assert, Name_Debug)
then
Error_Msg_Name_1 := Pragma_Name (P);
Error_Msg_N
("pragma% must be in declaration/statement context", P);
else
Append (P, List);
end if;
end loop;
end P_Pragmas_Opt;
--------------------------------------
-- 2.8 Pragma_Argument Association --
--------------------------------------
-- PRAGMA_ARGUMENT_ASSOCIATION ::=
-- [pragma_argument_IDENTIFIER =>] NAME
-- | [pragma_argument_IDENTIFIER =>] EXPRESSION
-- In Ada 2012, there are two more possibilities:
-- PRAGMA_ARGUMENT_ASSOCIATION ::=
-- [pragma_argument_ASPECT_MARK =>] NAME
-- | [pragma_argument_ASPECT_MARK =>] EXPRESSION
-- where the interesting allowed cases (which do not fit the syntax of the
-- first alternative above are
-- ASPECT_MARK ::=
-- Pre'Class | Post'Class | Invariant'Class | Type_Invariant'Class
-- We allow this special usage in all Ada modes, but it would be a pain to
-- allow these aspects to pervade the pragma syntax, and the representation
-- of pragma nodes internally. So what we do is to replace these
-- ASPECT_MARK forms with identifiers whose name is one of the special
-- internal names _Pre, _Post, _Invariant, or _Type_Invariant.
-- Error recovery: cannot raise Error_Resync
procedure Scan_Pragma_Argument_Association
(Identifier_Seen : in out Boolean;
Association : out Node_Id)
is
Scan_State : Saved_Scan_State;
Identifier_Node : Node_Id;
Id_Present : Boolean;
begin
Association := New_Node (N_Pragma_Argument_Association, Token_Ptr);
Set_Chars (Association, No_Name);
Id_Present := False;
-- Argument starts with identifier
if Token = Tok_Identifier then
Identifier_Node := Token_Node;
Save_Scan_State (Scan_State); -- at Identifier
Scan; -- past Identifier
if Token = Tok_Arrow then
Scan; -- past arrow
Id_Present := True;
-- Case of one of the special aspect forms
elsif Token = Tok_Apostrophe then
Scan; -- past apostrophe
-- We have apostrophe, so check for identifier'Class
if Token /= Tok_Identifier or else Token_Name /= Name_Class then
null;
-- We have identifier'Class, check for arrow
else
Scan; -- Past Class
if Token /= Tok_Arrow then
null;
-- Here we have scanned identifier'Class =>
else
Id_Present := True;
Scan; -- past arrow
case Chars (Identifier_Node) is
when Name_Pre =>
Set_Chars (Identifier_Node, Name_uPre);
when Name_Post =>
Set_Chars (Identifier_Node, Name_uPost);
when Name_Type_Invariant =>
Set_Chars (Identifier_Node, Name_uType_Invariant);
when Name_Invariant =>
Set_Chars (Identifier_Node, Name_uInvariant);
-- If it is X'Class => for some invalid X, we will give
-- an error, and forget that 'Class was present, which
-- will give better error recovery. We could do a spell
-- check here, but it seems too much work.
when others =>
Error_Msg_SC ("invalid aspect id for pragma");
end case;
end if;
end if;
end if;
-- Identifier was present
if Id_Present then
Set_Chars (Association, Chars (Identifier_Node));
Identifier_Seen := True;
-- Identifier not present after all
else
Restore_Scan_State (Scan_State); -- to Identifier
end if;
end if;
-- Diagnose error of "positional" argument for pragma appearing after
-- a "named" argument (quotes here are because that's not quite accurate
-- Ada RM terminology).
-- Since older GNAT versions did not generate this error, disable this
-- message in Relaxed_RM_Semantics mode to help legacy code using e.g.
-- codepeer.
if Identifier_Seen and not Id_Present and not Relaxed_RM_Semantics then
Error_Msg_SC ("|pragma argument identifier required here");
Error_Msg_SC ("\since previous argument had identifier (RM 2.8(4))");
end if;
if Id_Present then
Set_Expression (Association, P_Expression);
else
Set_Expression (Association, P_Expression_If_OK);
end if;
end Scan_Pragma_Argument_Association;
end Ch2;
|