| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S C A N S -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2003 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. -- |
| -- -- |
| -- As a special exception, if other files instantiate generics from this -- |
| -- unit, or you link this unit with other files to produce an executable, -- |
| -- this unit does not by itself cause the resulting executable to be -- |
| -- covered by the GNU General Public License. This exception does not -- |
| -- however invalidate any other reasons why the executable file might be -- |
| -- covered by the GNU Public License. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| with Types; use Types; |
| with Uintp; use Uintp; |
| with Urealp; use Urealp; |
| |
| package Scans is |
| |
| -- The scanner maintains a current state in the global variables defined |
| -- in this package. The call to the Scan routine advances this state to |
| -- the next token. The state is initialized by the call to one of the |
| -- initialization routines in Sinput. |
| |
| -- The following type is used to identify token types returned by Scan. |
| -- The class column in this table indicates the token classes which |
| -- apply to the token, as defined by subsquent subtype declarations. |
| |
| -- Note: the coding in SCN depends on the fact that the first entry in |
| -- this type declaration is *not* for a reserved word. For details on |
| -- why there is this requirement, see Scn.Initialize_Scanner. |
| |
| type Token_Type is ( |
| |
| -- Token name Token type Class(es) |
| |
| Tok_Integer_Literal, -- numeric lit Literal, Lit_Or_Name |
| |
| Tok_Real_Literal, -- numeric lit Literal, Lit_Or_Name |
| |
| Tok_String_Literal, -- string lit Literal. Lit_Or_Name |
| |
| Tok_Char_Literal, -- char lit Name, Literal. Lit_Or_Name |
| |
| Tok_Operator_Symbol, -- op symbol Name, Literal, Lit_Or_Name, Desig |
| |
| Tok_Identifier, -- identifer Name, Lit_Or_Name, Desig |
| |
| Tok_Double_Asterisk, -- ** |
| |
| Tok_Ampersand, -- & Binary_Addop |
| Tok_Minus, -- - Binary_Addop, Unary_Addop |
| Tok_Plus, -- + Binary_Addop, Unary_Addop |
| |
| Tok_Asterisk, -- * Mulop |
| Tok_Mod, -- MOD Mulop |
| Tok_Rem, -- REM Mulop |
| Tok_Slash, -- / Mulop |
| |
| Tok_New, -- NEW |
| |
| Tok_Abs, -- ABS |
| Tok_Others, -- OTHERS |
| Tok_Null, -- NULL |
| |
| Tok_Dot, -- . Namext |
| Tok_Apostrophe, -- ' Namext |
| |
| Tok_Left_Paren, -- ( Namext, Consk |
| |
| Tok_Delta, -- DELTA Atkwd, Sterm, Consk |
| Tok_Digits, -- DIGITS Atkwd, Sterm, Consk |
| Tok_Range, -- RANGE Atkwd, Sterm, Consk |
| |
| Tok_Right_Paren, -- ) Sterm |
| Tok_Comma, -- , Sterm |
| |
| Tok_And, -- AND Logop, Sterm |
| Tok_Or, -- OR Logop, Sterm |
| Tok_Xor, -- XOR Logop, Sterm |
| |
| Tok_Less, -- < Relop, Sterm |
| Tok_Equal, -- = Relop, Sterm |
| Tok_Greater, -- > Relop, Sterm |
| Tok_Not_Equal, -- /= Relop, Sterm |
| Tok_Greater_Equal, -- >= Relop, Sterm |
| Tok_Less_Equal, -- <= Relop, Sterm |
| |
| Tok_In, -- IN Relop, Sterm |
| Tok_Not, -- NOT Relop, Sterm |
| |
| Tok_Box, -- <> Relop, Eterm, Sterm |
| Tok_Colon_Equal, -- := Eterm, Sterm |
| Tok_Colon, -- : Eterm, Sterm |
| Tok_Greater_Greater, -- >> Eterm, Sterm |
| |
| Tok_Abstract, -- ABSTRACT Eterm, Sterm |
| Tok_Access, -- ACCESS Eterm, Sterm |
| Tok_Aliased, -- ALIASED Eterm, Sterm |
| Tok_All, -- ALL Eterm, Sterm |
| Tok_Array, -- ARRAY Eterm, Sterm |
| Tok_At, -- AT Eterm, Sterm |
| Tok_Body, -- BODY Eterm, Sterm |
| Tok_Constant, -- CONSTANT Eterm, Sterm |
| Tok_Do, -- DO Eterm, Sterm |
| Tok_Is, -- IS Eterm, Sterm |
| Tok_Limited, -- LIMITED Eterm, Sterm |
| Tok_Of, -- OF Eterm, Sterm |
| Tok_Out, -- OUT Eterm, Sterm |
| Tok_Record, -- RECORD Eterm, Sterm |
| Tok_Renames, -- RENAMES Eterm, Sterm |
| Tok_Reverse, -- REVERSE Eterm, Sterm |
| Tok_Tagged, -- TAGGED Eterm, Sterm |
| Tok_Then, -- THEN Eterm, Sterm |
| |
| Tok_Less_Less, -- << Eterm, Sterm, After_SM |
| |
| Tok_Abort, -- ABORT Eterm, Sterm, After_SM |
| Tok_Accept, -- ACCEPT Eterm, Sterm, After_SM |
| Tok_Case, -- CASE Eterm, Sterm, After_SM |
| Tok_Delay, -- DELAY Eterm, Sterm, After_SM |
| Tok_Else, -- ELSE Eterm, Sterm, After_SM |
| Tok_Elsif, -- ELSIF Eterm, Sterm, After_SM |
| Tok_End, -- END Eterm, Sterm, After_SM |
| Tok_Exception, -- EXCEPTION Eterm, Sterm, After_SM |
| Tok_Exit, -- EXIT Eterm, Sterm, After_SM |
| Tok_Goto, -- GOTO Eterm, Sterm, After_SM |
| Tok_If, -- IF Eterm, Sterm, After_SM |
| Tok_Pragma, -- PRAGMA Eterm, Sterm, After_SM |
| Tok_Raise, -- RAISE Eterm, Sterm, After_SM |
| Tok_Requeue, -- REQUEUE Eterm, Sterm, After_SM |
| Tok_Return, -- RETURN Eterm, Sterm, After_SM |
| Tok_Select, -- SELECT Eterm, Sterm, After_SM |
| Tok_Terminate, -- TERMINATE Eterm, Sterm, After_SM |
| Tok_Until, -- UNTIL Eterm, Sterm, After_SM |
| Tok_When, -- WHEN Eterm, Sterm, After_SM |
| |
| Tok_Begin, -- BEGIN Eterm, Sterm, After_SM, Labeled_Stmt |
| Tok_Declare, -- DECLARE Eterm, Sterm, After_SM, Labeled_Stmt |
| Tok_For, -- FOR Eterm, Sterm, After_SM, Labeled_Stmt |
| Tok_Loop, -- LOOP Eterm, Sterm, After_SM, Labeled_Stmt |
| Tok_While, -- WHILE Eterm, Sterm, After_SM, Labeled_Stmt |
| |
| Tok_Entry, -- ENTRY Eterm, Sterm, Declk, Deckn, After_SM |
| Tok_Protected, -- PROTECTED Eterm, Sterm, Declk, Deckn, After_SM |
| Tok_Task, -- TASK Eterm, Sterm, Declk, Deckn, After_SM |
| Tok_Type, -- TYPE Eterm, Sterm, Declk, Deckn, After_SM |
| Tok_Subtype, -- SUBTYPE Eterm, Sterm, Declk, Deckn, After_SM |
| Tok_Use, -- USE Eterm, Sterm, Declk, Deckn, After_SM |
| |
| Tok_Function, -- FUNCTION Eterm, Sterm, Cunit, Declk, After_SM |
| Tok_Generic, -- GENERIC Eterm, Sterm, Cunit, Declk, After_SM |
| Tok_Package, -- PACKAGE Eterm, Sterm, Cunit, Declk, After_SM |
| Tok_Procedure, -- PROCEDURE Eterm, Sterm, Cunit, Declk, After_SM |
| |
| Tok_Private, -- PRIVATE Eterm, Sterm, Cunit, After_SM |
| Tok_With, -- WITH Eterm, Sterm, Cunit, After_SM |
| Tok_Separate, -- SEPARATE Eterm, Sterm, Cunit, After_SM |
| |
| Tok_EOF, -- End of file Eterm, Sterm, Cterm, After_SM |
| |
| Tok_Semicolon, -- ; Eterm, Sterm, Cterm |
| |
| Tok_Arrow, -- => Sterm, Cterm, Chtok |
| |
| Tok_Vertical_Bar, -- | Cterm, Sterm, Chtok |
| |
| Tok_Dot_Dot, -- .. Sterm, Chtok |
| |
| -- The following three entries are used only when scanning project |
| -- files. |
| |
| Tok_Project, |
| Tok_Extends, |
| Tok_External, |
| Tok_Comment, |
| |
| -- The following entry is used by the preprocessor and when scanning |
| -- project files. |
| |
| Tok_End_Of_Line, |
| |
| -- The following entry is used by the preprocessor |
| |
| Tok_Special, |
| |
| No_Token); |
| -- No_Token is used for initializing Token values to indicate that |
| -- no value has been set yet. |
| |
| -- Note: in the RM, operator symbol is a special case of string literal. |
| -- We distinguish at the lexical level in this compiler, since there are |
| -- many syntactic situations in which only an operator symbol is allowed. |
| |
| -- The following subtype declarations group the token types into classes. |
| -- These are used for class tests in the parser. |
| |
| subtype Token_Class_Numeric_Literal is |
| Token_Type range Tok_Integer_Literal .. Tok_Real_Literal; |
| -- Numeric literal |
| |
| subtype Token_Class_Literal is |
| Token_Type range Tok_Integer_Literal .. Tok_Operator_Symbol; |
| -- Literal |
| |
| subtype Token_Class_Lit_Or_Name is |
| Token_Type range Tok_Integer_Literal .. Tok_Identifier; |
| |
| subtype Token_Class_Binary_Addop is |
| Token_Type range Tok_Ampersand .. Tok_Plus; |
| -- Binary adding operator (& + -) |
| |
| subtype Token_Class_Unary_Addop is |
| Token_Type range Tok_Minus .. Tok_Plus; |
| -- Unary adding operator (+ -) |
| |
| subtype Token_Class_Mulop is |
| Token_Type range Tok_Asterisk .. Tok_Slash; |
| -- Multiplying operator |
| |
| subtype Token_Class_Logop is |
| Token_Type range Tok_And .. Tok_Xor; |
| -- Logical operator (and, or, xor) |
| |
| subtype Token_Class_Relop is |
| Token_Type range Tok_Less .. Tok_Box; |
| -- Relational operator (= /= < <= > >= not, in plus <> to catch misuse |
| -- of Pascal style not equal operator). |
| |
| subtype Token_Class_Name is |
| Token_Type range Tok_Char_Literal .. Tok_Identifier; |
| -- First token of name (4.1), |
| -- (identifier, char literal, operator symbol) |
| |
| subtype Token_Class_Desig is |
| Token_Type range Tok_Operator_Symbol .. Tok_Identifier; |
| -- Token which can be a Designator (identifier, operator symbol) |
| |
| subtype Token_Class_Namext is |
| Token_Type range Tok_Dot .. Tok_Left_Paren; |
| -- Name extension tokens. These are tokens which can appear immediately |
| -- after a name to extend it recursively (period, quote, left paren) |
| |
| subtype Token_Class_Consk is |
| Token_Type range Tok_Left_Paren .. Tok_Range; |
| -- Keywords which can start constraint |
| -- (left paren, delta, digits, range) |
| |
| subtype Token_Class_Eterm is |
| Token_Type range Tok_Colon_Equal .. Tok_Semicolon; |
| -- Expression terminators. These tokens can never appear within a simple |
| -- expression. This is used for error recovery purposes (if we encounter |
| -- an error in an expression, we simply scan to the next Eterm token). |
| |
| subtype Token_Class_Sterm is |
| Token_Type range Tok_Delta .. Tok_Dot_Dot; |
| -- Simple_Expression terminators. A Simple_Expression must be followed |
| -- by a token in this class, or an error message is issued complaining |
| -- about a missing binary operator. |
| |
| subtype Token_Class_Atkwd is |
| Token_Type range Tok_Delta .. Tok_Range; |
| -- Attribute keywords. This class includes keywords which can be used |
| -- as an Attribute_Designator, namely DELTA, DIGITS and RANGE |
| |
| subtype Token_Class_Cterm is |
| Token_Type range Tok_EOF .. Tok_Vertical_Bar; |
| -- Choice terminators. These tokens terminate a choice. This is used for |
| -- error recovery purposes (if we encounter an error in a Choice, we |
| -- simply scan to the next Cterm token). |
| |
| subtype Token_Class_Chtok is |
| Token_Type range Tok_Arrow .. Tok_Dot_Dot; |
| -- Choice tokens. These tokens signal a choice when used in an Aggregate |
| |
| subtype Token_Class_Cunit is |
| Token_Type range Tok_Function .. Tok_Separate; |
| -- Tokens which can begin a compilation unit |
| |
| subtype Token_Class_Declk is |
| Token_Type range Tok_Entry .. Tok_Procedure; |
| -- Keywords which start a declaration |
| |
| subtype Token_Class_Deckn is |
| Token_Type range Tok_Entry .. Tok_Use; |
| -- Keywords which start a declaration but can't start a compilation unit |
| |
| subtype Token_Class_After_SM is |
| Token_Type range Tok_Less_Less .. Tok_EOF; |
| -- Tokens which always, or almost always, appear after a semicolon. Used |
| -- in the Resync_Past_Semicolon routine to avoid gobbling up stuff when |
| -- a semicolon is missing. Of significance only for error recovery. |
| |
| subtype Token_Class_Labeled_Stmt is |
| Token_Type range Tok_Begin .. Tok_While; |
| -- Tokens which start labeled statements |
| |
| type Token_Flag_Array is array (Token_Type) of Boolean; |
| Is_Reserved_Keyword : constant Token_Flag_Array := Token_Flag_Array'( |
| Tok_Mod .. Tok_Rem => True, |
| Tok_New .. Tok_Null => True, |
| Tok_Delta .. Tok_Range => True, |
| Tok_And .. Tok_Xor => True, |
| Tok_In .. Tok_Not => True, |
| Tok_Abstract .. Tok_Then => True, |
| Tok_Abort .. Tok_Separate => True, |
| others => False); |
| -- Flag array used to test for reserved word |
| |
| -------------------------- |
| -- Scan State Variables -- |
| -------------------------- |
| |
| -- Note: these variables can only be referenced during the parsing of a |
| -- file. Reference to any of them from Sem or the expander is wrong. |
| |
| Scan_Ptr : Source_Ptr; |
| -- Current scan pointer location. After a call to Scan, this points |
| -- just past the end of the token just scanned. |
| |
| Token : Token_Type; |
| -- Type of current token |
| |
| Token_Ptr : Source_Ptr; |
| -- Pointer to first character of current token |
| |
| Current_Line_Start : Source_Ptr; |
| -- Pointer to first character of line containing current token |
| |
| Start_Column : Column_Number; |
| -- Starting column number (zero origin) of the first non-blank character |
| -- on the line containing the current token. This is used for error |
| -- recovery circuits which depend on looking at the column line up. |
| |
| Checksum : Word; |
| -- Used to accumulate a CRC representing the tokens in the source |
| -- file being compiled. This CRC includes only program tokens, and |
| -- excludes comments. |
| |
| First_Non_Blank_Location : Source_Ptr; |
| -- Location of first non-blank character on the line containing the |
| -- current token (i.e. the location of the character whose column number |
| -- is stored in Start_Column). |
| |
| Token_Node : Node_Id := Empty; |
| -- Node table Id for the current token. This is set only if the current |
| -- token is one for which the scanner constructs a node (i.e. it is an |
| -- identifier, operator symbol, or literal. For other token types, |
| -- Token_Node is undefined. |
| |
| Token_Name : Name_Id := No_Name; |
| -- For identifiers, this is set to the Name_Id of the identifier scanned. |
| -- For all other tokens, Token_Name is set to Error_Name. Note that it |
| -- would be possible for the caller to extract this information from |
| -- Token_Node. We set Token_Name separately for two reasons. First it |
| -- allows a quicker test for a specific identifier. Second, it allows |
| -- a version of the parser to be built that does not build tree nodes, |
| -- usable as a syntax checker. |
| |
| Prev_Token : Token_Type := No_Token; |
| -- Type of previous token |
| |
| Prev_Token_Ptr : Source_Ptr; |
| -- Pointer to first character of previous token |
| |
| Version_To_Be_Found : Boolean; |
| -- This flag is True if the scanner is still looking for an RCS version |
| -- number in a comment. Normally it is initialized to False so that this |
| -- circuit is not activated. If the -dv switch is set, then this flag is |
| -- initialized to True, and then reset when the version number is found. |
| -- We do things this way to minimize the impact on comment scanning. |
| |
| Character_Code : Char_Code; |
| -- Valid only when Token is Tok_Char_Literal. |
| |
| Real_Literal_Value : Ureal; |
| -- Valid only when Token is Tok_Real_Literal |
| |
| Int_Literal_Value : Uint; |
| -- Valid only when Token = Tok_Integer_Literal; |
| |
| String_Literal_Id : String_Id; |
| -- Id for currently scanned string value. |
| -- Valid only when Token = Tok_String_Literal or Tok_Operator_Symbol. |
| |
| Wide_Character_Found : Boolean := False; |
| -- Set True if wide character found. |
| -- Valid only when Token = Tok_String_Literal. |
| |
| Special_Character : Character; |
| -- Valid only when Token = Tok_Special |
| |
| Comment_Id : Name_Id := No_Name; |
| -- Valid only when Token = Tok_Comment. Store the string that follows |
| -- the two '-' of a comment. |
| |
| -------------------------------------------------------- |
| -- Procedures for Saving and Restoring the Scan State -- |
| -------------------------------------------------------- |
| |
| -- The following procedures can be used to save and restore the entire |
| -- scan state. They are used in cases where it is necessary to backup |
| -- the scan during the parse. |
| |
| type Saved_Scan_State is private; |
| -- Used for saving and restoring the scan state |
| |
| procedure Save_Scan_State (Saved_State : out Saved_Scan_State); |
| pragma Inline (Save_Scan_State); |
| -- Saves the current scan state for possible later restoration. Note that |
| -- there is no harm in saving the state and then never restoring it. |
| |
| procedure Restore_Scan_State (Saved_State : in Saved_Scan_State); |
| pragma Inline (Restore_Scan_State); |
| -- Restores a scan state saved by a call to Save_Scan_State. |
| -- The saved scan state must refer to the current source file. |
| |
| private |
| type Saved_Scan_State is record |
| Save_Scan_Ptr : Source_Ptr; |
| Save_Token : Token_Type; |
| Save_Token_Ptr : Source_Ptr; |
| Save_Current_Line_Start : Source_Ptr; |
| Save_Start_Column : Column_Number; |
| Save_Checksum : Word; |
| Save_First_Non_Blank_Location : Source_Ptr; |
| Save_Token_Node : Node_Id; |
| Save_Token_Name : Name_Id; |
| Save_Prev_Token : Token_Type; |
| Save_Prev_Token_Ptr : Source_Ptr; |
| end record; |
| |
| end Scans; |
