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[Ada] Clean up scanner

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This patch removes some obsolete code in the scanner and related files,
and corrects some comments. Tok_Special is used only by the
preprocessor, and uses only the two characters '#' and '$'.

It might be simpler to have a single flag indicating we're scanning for
preprocessing, instead of the Special_Characters array and the
End_Of_Line_Is_Token flag, but that's for another day.

gcc/ada/

	* scans.ads: Fix obsolete comments about Tok_Special, and give
	Special_Character a predicate assuring it is one of the two
	characters used in preprocessing.
	* scng.ads: Clean up comments.
	* scng.adb: Clean up handling of Tok_Special.  Remove comment
	about '@' (target_name), which doesn't seem very helpful.
	Set_Special_Character will now blow up if given anything other
	than '#' and '$', because of the predicate on Special_Character;
	it's not clear why it used to say "when others => null;".
	Remove Comment_Is_Token, which is not used.
	* scn.ads: Remove commented-out use clause.  Remove redundant
	comment.
	* ali-util.adb: Use "is null" for do-nothing procedures.
	* gprep.adb (Post_Scan): Use "is null".
This commit is contained in:
Bob Duff 2022-06-21 09:50:06 -04:00 committed by Pierre-Marie de Rodat
parent fe6f256d5b
commit 2148f2996a
6 changed files with 36 additions and 182 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
gcc/ada/ali-util.adb
View File

@ -42,15 +42,12 @@ package body ALI.Util is
-- empty, because we don't want to report any errors when computing
-- a source checksum.
procedure Post_Scan;
procedure Post_Scan is null;
procedure Error_Msg (Msg : String; Flag_Location : Source_Ptr);
procedure Error_Msg_S (Msg : String);
procedure Error_Msg_SC (Msg : String);
procedure Error_Msg_SP (Msg : String);
procedure Error_Msg (Msg : String; Flag_Location : Source_Ptr) is null;
procedure Error_Msg_S (Msg : String) is null;
procedure Error_Msg_SC (Msg : String) is null;
procedure Error_Msg_SP (Msg : String) is null;
-- Instantiation of Styleg, needed to instantiate Scng
@ -85,47 +82,6 @@ package body ALI.Util is
return Checksum1 = Checksum2 and then Checksum1 /= Checksum_Error;
end Checksums_Match;
---------------
-- Error_Msg --
---------------
procedure Error_Msg (Msg : String; Flag_Location : Source_Ptr) is
pragma Warnings (Off, Msg);
pragma Warnings (Off, Flag_Location);
begin
null;
end Error_Msg;
-----------------
-- Error_Msg_S --
-----------------
procedure Error_Msg_S (Msg : String) is
pragma Warnings (Off, Msg);
begin
null;
end Error_Msg_S;
------------------
-- Error_Msg_SC --
------------------
procedure Error_Msg_SC (Msg : String) is
pragma Warnings (Off, Msg);
begin
null;
end Error_Msg_SC;
------------------
-- Error_Msg_SP --
------------------
procedure Error_Msg_SP (Msg : String) is
pragma Warnings (Off, Msg);
begin
null;
end Error_Msg_SP;
-----------------------
-- Get_File_Checksum --
-----------------------
@ -192,15 +148,6 @@ package body ALI.Util is
Interfaces.Reset;
end Initialize_ALI_Source;
---------------
-- Post_Scan --
---------------
procedure Post_Scan is
begin
null;
end Post_Scan;
----------------------
-- Read_Withed_ALIs --
----------------------

13
gcc/ada/gprep.adb
View File

@ -93,8 +93,8 @@ package body GPrep is
procedure Display_Copyright;
-- Display the copyright notice
procedure Post_Scan;
-- Null procedure, needed by instantiation of Scng below
procedure Post_Scan is null;
-- Needed by instantiation of Scng below
package Scanner is new Scng
(Post_Scan,
@ -327,15 +327,6 @@ package body GPrep is
New_Line (Outfile.all);
end New_EOL_To_Outfile;
---------------
-- Post_Scan --
---------------
procedure Post_Scan is
begin
null;
end Post_Scan;
----------------------------
-- Preprocess_Infile_Name --
----------------------------

19
gcc/ada/scans.ads
View File

@ -210,15 +210,11 @@ package Scans is
Tok_End_Of_Line,
-- Represents an end of line. Not used during normal compilation scans
-- where end of line is ignored. Active for preprocessor scanning and
-- also when scanning project files (where it is needed because of ???)
-- where end of line is ignored. Active for preprocessor scanning.
Tok_Special,
-- AI12-0125-03 : target name as abbreviation for LHS
-- Otherwise used only in preprocessor scanning (to represent one of
-- the characters '#', '$', '?', '@', '`', '\', '^', '~', or '_'. The
-- character value itself is stored in Scans.Special_Character.
-- Special character used by the preprocessor. The character itself is
-- stored in Special_Character below.
No_Token);
-- No_Token is used for initializing Token values to indicate that
@ -466,12 +462,9 @@ package Scans is
-- character found (i.e. a character that does not fit in Character or
-- Wide_Character).
Special_Character : Character;
-- AI12-0125-03 : '@' as target name is handled elsewhere.
-- Valid only when Token = Tok_Special. Returns one of the characters
-- '#', '$', '?', '`', '\', '^', '~', or '_'.
--
-- Why only this set? What about wide characters???
subtype Special_Preprocessor_Character is Character with
Predicate => Special_Preprocessor_Character in '#' | '$';
Special_Character : Special_Preprocessor_Character;
Comment_Id : Name_Id := No_Name;
-- Valid only when Token = Tok_Comment. Store the string that follows

6
gcc/ada/scn.ads
View File

@ -29,7 +29,7 @@
with Casing; use Casing;
with Errout; use Errout;
with Scng;
with Style; -- use Style;
with Style;
with Types; use Types;
package Scn is
@ -75,9 +75,5 @@ package Scn is
Style => Style.Style_Inst);
procedure Scan renames Scanner.Scan;
-- Scan scans out the next token, and advances the scan state accordingly
-- (see package Scans for details). If the scan encounters an illegal
-- token, then an error message is issued pointing to the bad character,
-- and Scan returns a reasonable substitute token of some kind.
end Scn;

91
gcc/ada/scng.adb
View File

@ -29,7 +29,6 @@ with Errout; use Errout;
with Hostparm; use Hostparm;
with Namet; use Namet;
with Opt; use Opt;
with Scans; use Scans;
with Sinput; use Sinput;
with Snames; use Snames;
with Stringt; use Stringt;
@ -53,9 +52,6 @@ package body Scng is
Special_Characters : array (Character) of Boolean := (others => False);
-- For characters that are Special token, the value is True
Comment_Is_Token : Boolean := False;
-- True if comments are tokens
End_Of_Line_Is_Token : Boolean := False;
-- True if End_Of_Line is a token
@ -259,9 +255,6 @@ package body Scng is
procedure Scan is
Start_Of_Comment : Source_Ptr;
-- Record start of comment position
Underline_Found : Boolean;
-- During scanning of an identifier, set to True if last character
-- scanned was an underline or other punctuation character. This
@ -1609,10 +1602,6 @@ package body Scng is
return;
end if;
-- Otherwise scan out the comment
Start_Of_Comment := Scan_Ptr;
-- Loop to scan comment (this loop runs more than once only if
-- a horizontal tab or other non-graphic character is scanned)
@ -1711,18 +1700,8 @@ package body Scng is
end if;
end loop;
-- Note that, except when comments are tokens, we do NOT
-- execute a return here, instead we fall through to reexecute
-- the scan loop to look for a token.
if Comment_Is_Token then
Name_Len := Integer (Scan_Ptr - Start_Of_Comment);
Name_Buffer (1 .. Name_Len) :=
String (Source (Start_Of_Comment .. Scan_Ptr - 1));
Comment_Id := Name_Find;
Token := Tok_Comment;
return;
end if;
-- Note that we do not return here; instead we fall through to
-- reexecute the scan loop to look for a token.
end if;
end Minus_Case;
@ -2072,14 +2051,6 @@ package body Scng is
-- Underline character
when '_' =>
if Special_Characters ('_') then
Token_Ptr := Scan_Ptr;
Scan_Ptr := Scan_Ptr + 1;
Token := Tok_Special;
Special_Character := '_';
return;
end if;
Error_Msg_S ("identifier cannot start with underline");
Name_Len := 1;
Name_Buffer (1) := '_';
@ -2132,42 +2103,19 @@ package body Scng is
Error_Illegal_Character;
end if;
-- Invalid control characters
-- Illegal characters
when ACK
| ASCII.SO
| BEL
| BS
| CAN
| DC1
| DC2
| DC3
| DC4
| DEL
| DLE
| EM
| ENQ
| EOT
| ETB
| ETX
| FS
| GS
| NAK
| NUL
| RS
| SI
| SOH
| STX
| SYN
| US
when ACK | ASCII.SO | BEL | BS | CAN | DC1 | DC2 | DC3 | DC4 | DEL
| DLE | EM | ENQ | EOT | ETB | ETX | FS | GS | NAK | NUL | RS | SI
| SOH | STX | SYN | US
| '?' | '`' | '\' | '^' | '~'
=>
Error_Illegal_Character;
-- Invalid graphic characters
-- Note that '@' is handled elsewhere, because following AI12-125
-- it denotes the target_name of an assignment.
-- Special preprocessor characters. If Set_Special_Character has been
-- called, return a Special token. Otherwise give an error.
when '#' | '$' | '?' | '`' | '\' | '^' | '~' =>
when Special_Preprocessor_Character =>
-- If Set_Special_Character has been called for this character,
-- set Scans.Special_Character and return a Special token.
@ -2710,15 +2658,6 @@ package body Scng is
end if;
end Scan;
--------------------------
-- Set_Comment_As_Token --
--------------------------
procedure Set_Comment_As_Token (Value : Boolean) is
begin
Comment_Is_Token := Value;
end Set_Comment_As_Token;
------------------------------
-- Set_End_Of_Line_As_Token --
------------------------------
@ -2732,15 +2671,9 @@ package body Scng is
-- Set_Special_Character --
---------------------------
procedure Set_Special_Character (C : Character) is
procedure Set_Special_Character (C : Special_Preprocessor_Character) is
begin
case C is
when '#' | '$' | '_' | '?' | '@' | '`' | '\' | '^' | '~' =>
Special_Characters (C) := True;
when others =>
null;
end case;
Special_Characters (C) := True;
end Set_Special_Character;
----------------------

26
gcc/ada/scng.ads
View File

@ -23,11 +23,11 @@
-- --
------------------------------------------------------------------------------
-- This package contains a generic lexical analyzer. This is used for scanning
-- Ada source files or text files with an Ada-like syntax, such as project
-- files. It is instantiated in Scn and Prj.Err.
-- This is a generic lexical analyzer, used for scanning Ada source files, and
-- also for preprocessor files.
with Casing; use Casing;
with Scans; use Scans;
with Styleg;
with Types; use Types;
@ -68,33 +68,27 @@ package Scng is
-- Scan scans out the next token, and advances the scan state accordingly
-- (see package Scan_State for details). If the scan encounters an illegal
-- token, then an error message is issued pointing to the bad character,
-- and Scan returns a reasonable substitute token of some kind.
-- For tokens Char_Literal, Identifier, Real_Literal, Integer_Literal,
-- String_Literal and Operator_Symbol, Post_Scan is called after scanning.
-- and Scan returns a reasonable substitute token. For tokens Char_Literal,
-- Identifier, Real_Literal, Integer_Literal, String_Literal and
-- Operator_Symbol, Post_Scan is called after scanning.
function Determine_Token_Casing return Casing_Type;
pragma Inline (Determine_Token_Casing);
-- Determines the casing style of the current token, which is
-- either a keyword or an identifier. See also package Casing.
procedure Set_Special_Character (C : Character);
-- Indicate that one of the following character '#', '$', '?', '`',
-- '\', '^', '_' or '~', when found is a Special token.
-- AI12-0125-03 : target name (ES) is not in this list because '@' is
-- handled as a special token as abbreviation of LHS of assignment.
procedure Set_Special_Character (C : Special_Preprocessor_Character);
-- Called when the preprocessor is active to indicate that Scan should
-- return a Special token for C.
procedure Reset_Special_Characters;
-- Indicate that there is no characters that are Special tokens., which
-- Indicate that there are no characters that are Special tokens, which
-- is the default.
procedure Set_End_Of_Line_As_Token (Value : Boolean);
-- Indicate if End_Of_Line is a token or not.
-- By default, End_Of_Line is not a token.
procedure Set_Comment_As_Token (Value : Boolean);
-- Indicate if a comment is a token or not.
-- By default, a comment is not a token.
function Set_Start_Column return Column_Number;
-- This routine is called with Scan_Ptr pointing to the first character
-- of a line. On exit, Scan_Ptr is advanced to the first non-blank