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-------------------------------------------------------------------------------
--
-- Copyright (C) 2000 Ted Dennison
--
-- This file is part of the OpenToken package.
--
-- The OpenToken package is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License as published
-- by the Free Software Foundation; either version 2, or (at your option)
-- any later version. The OpenToken package is distributed in the hope that
-- it will be useful, but WITHOUT 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 the OpenToken
-- package; see file GPL.txt. 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.
--
-- Maintainer: Ted Dennison (dennison@telepath.com)
--
-- Update History:
-- $Log: asu_example_5_10.ads,v $
-- Revision 1.1 2000/08/12 21:34:51 Ted
-- initial version
--
--
-------------------------------------------------------------------------------
with OpenToken.Token.Enumerated.List;
with OpenToken.Token.Enumerated.Analyzer;
with OpenToken.Token.Enumerated.Nonterminal;
with OpenToken.Token.Enumerated.Integer_Literal;
with OpenToken.Production.List;
with OpenToken.Production.Parser.LALR;
with OpenToken.Production.Parser.LRK_Item;
with OpenToken.Recognizer.Integer;
with OpenToken.Recognizer.Separator;
with OpenToken.Recognizer.End_Of_File;
with OpenToken.Recognizer.Character_Set;
with OpenToken.Text_Feeder.String;
with Simple_Integer_Token;
-------------------------------------------------------------------------------
-- This example is an implementation of Example 5.10 from "Compilers
-- Principles, Techniques, and Tools" by Aho, Sethi, and Ullman (aka: "The
-- Dragon Book"). It demonstrates handling of synthesized attributes
-------------------------------------------------------------------------------
package ASU_Example_5_10 is
-- The complete list of tokens, with the terminals listed first.
type Token_IDs is (Integer_ID, Left_Paren_ID, Right_Paren_ID, Plus_Sign_ID,
Multiply_ID, EOF_ID, Whitespace_ID, L_ID, E_ID, T_ID, F_ID);
-- Instantiate all the nessecary packages
package Master_Token is new OpenToken.Token.Enumerated(Token_IDs);
package Tokenizer is new Master_Token.Analyzer(Whitespace_ID);
package Token_List is new Master_Token.List;
package Nonterminal is new Master_Token.Nonterminal(Token_List);
package Production is new OpenToken.Production(Master_Token, Token_List, Nonterminal);
package Production_List is new Production.List;
package Parser is new Production.Parser(Production_List, Tokenizer);
package LALR_Parser is new Parser.LALR;
package LRK_Item is new Parser.LRK_Item (1);
-- Instantiate our tokens
package Integer_Literal is new Master_Token.Integer_Literal;
package Simple_Integer is new Simple_Integer_Token(Master_Token, Token_List, Nonterminal, Integer_Literal);
-- Allow infix operators for building productions
use type Token_List.Instance;
use type Production.Right_Hand_Side;
use type Production.Instance;
use type Production_List.Instance;
-- Define all our tokens
Times : aliased Master_Token.Class := Master_Token.Get (Multiply_ID);
Left_Paren : aliased Master_Token.Class := Master_Token.Get (Left_Paren_ID);
Right_Paren : aliased Master_Token.Class := Master_Token.Get (Right_Paren_ID);
Plus : aliased Master_Token.Class := Master_Token.Get (Plus_Sign_ID);
Int_Literal : aliased Master_Token.Class := Integer_Literal.Get (Integer_ID);
EOF : aliased Master_Token.Class := Master_Token.Get (EOF_ID);
L : aliased Simple_Integer.Class := Simple_Integer.Get (L_ID);
E : aliased Simple_Integer.Class := Simple_Integer.Get (E_ID);
T : aliased Simple_Integer.Class := Simple_Integer.Get (T_ID);
F : aliased Simple_Integer.Class := Simple_Integer.Get (F_ID);
-- Define a lexer syntax for the terminals
Syntax : constant Tokenizer.Syntax :=
(Multiply_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.Separator.Get ("*"),
New_Token => Times),
Left_Paren_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.Separator.Get ("("),
New_Token => Left_Paren),
Right_Paren_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.Separator.Get (")"),
New_Token => Right_Paren
),
Plus_Sign_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.Separator.Get ("+"),
New_Token => Plus
),
Integer_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.Integer.Get
(Allow_Signs => False),
New_Token => Int_Literal
),
EOF_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.End_Of_File.Get,
New_Token => EOF
),
Whitespace_ID => Tokenizer.Get (Recognizer => OpenToken.Recognizer.Character_Set.Get
(OpenToken.Recognizer.Character_Set.Standard_Whitespace))
);
Feeder : aliased OpenToken.Text_Feeder.String.Instance;
Analyzer : Tokenizer.Instance := Tokenizer.Initialize (Syntax, Feeder'access);
--------------------------------------------------------------------------
-- Routine to print the value of the given Single interger token.
--------------------------------------------------------------------------
procedure Print_Value (New_Token : out Nonterminal.Class;
Source : in Token_List.Instance'Class;
To_ID : in Master_Token.Token_ID);
--------------------------------------------------------------------------
-- Define the Grammar. The text in the example in the book looks something
-- like:
--
-- L -> E print (L.val)
-- E -> E + T E.val := E1.val + T.val
-- E -> T
-- T -> T * F T.val := T1.val * F.val
-- T -> F
-- F -> ( E ) F.val := E.val
-- F -> digit
--
Grammar : constant Production_List.Instance :=
L <= E & EOF + Print_Value'Access and
E <= E & Plus & T + Simple_Integer.Add_Integers and
E <= T and
T <= T & Times & F + Simple_Integer.Multiply_Integers and
T <= F and
F <= Left_Paren & E & Right_Paren + Simple_Integer.Synthesize_Second and
F <= Int_Literal;
end ASU_Example_5_10;
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