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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                        S Y S T E M . R E G E X P                         --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--                     Copyright (C) 1998-2008, AdaCore                     --

--                                                                          --

-- 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,  51  Franklin  Street,  Fifth  Floor, --

-- Boston, MA 02110-1301, 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.      --

--                                                                          --

------------------------------------------------------------------------------

--  Simple Regular expression matching

--  This package provides a simple implementation of a regular expression

--  pattern matching algorithm, using a subset of the syntax of regular

--  expressions copied from familiar Unix style utilities.

--  Note: this package is in the System hierarchy so that it can be directly

--  be used by other predefined packages. User access to this package is via

--  a renaming of this package in GNAT.Regexp (file g-regexp.ads).

with Ada.Finalization;

package System.Regexp is

   --  The regular expression must first be compiled, using the Compile

   --  function, which creates a finite state matching table, allowing

   --  very fast matching once the expression has been compiled.

   --  The following is the form of a regular expression, expressed in Ada

   --  reference manual style BNF is as follows

   --     regexp ::= term

   --     regexp ::= term | term          -- alternation (term or term ...)

   --     term ::= item

   --     term ::= item item ...          -- concatenation (item then item)

   --     item ::= elmt                   -- match elmt

   --     item ::= elmt *                 -- zero or more elmt's

   --     item ::= elmt +                 -- one or more elmt's

   --     item ::= elmt ?                 -- matches elmt or nothing

   --     elmt ::= nchr                   -- matches given character

   --     elmt ::= [nchr nchr ...]        -- matches any character listed

   --     elmt ::= [^ nchr nchr ...]      -- matches any character not listed

   --     elmt ::= [char - char]          -- matches chars in given range

   --     elmt ::= .                      -- matches any single character

   --     elmt ::= ( regexp )             -- parens used for grouping

   --     char ::= any character, including special characters

   --     nchr ::= any character except \()[].*+?^ or \char to match char

   --     ... is used to indication repetition (one or more terms)

   --  See also regexp(1) man page on Unix systems for further details

   --  A second kind of regular expressions is provided. This one is more

   --  like the wild card patterns used in file names by the Unix shell (or

   --  DOS prompt) command lines. The grammar is the following:

   --     regexp ::= term

   --     term   ::= elmt

   --     term   ::= elmt elmt ...     -- concatenation (elmt then elmt)

   --     term   ::= *                 -- any string of 0 or more characters

   --     term   ::= ?                 -- matches any character

   --     term   ::= [char char ...]   -- matches any character listed

   --     term   ::= [char - char]     -- matches any character in given range

   --     term   ::= {elmt, elmt, ...} -- alternation (matches any of elmt)

   --  Important note : This package was mainly intended to match regular

   --  expressions against file names. The whole string has to match the

   --  regular expression. If only a substring matches, then the function

   --  Match will return False.

   type Regexp is private;

   --  Private type used to represent a regular expression

   Error_In_Regexp : exception;

   --  Exception raised when an error is found in the regular expression

   function Compile

     (Pattern        : String;

      Glob           : Boolean := False;

      Case_Sensitive : Boolean := True) return Regexp;

   --  Compiles a regular expression S. If the syntax of the given

   --  expression is invalid (does not match above grammar), Error_In_Regexp

   --  is raised. If Glob is True, the pattern is considered as a 'globbing

   --  pattern', that is a pattern as given by the second grammar above.

   --  As a special case, if Pattern is the empty string it will always

   --  match.

   function Match (S : String; R : Regexp) return Boolean;

   --  True if S matches R, otherwise False. Raises Constraint_Error if

   --  R is an uninitialized regular expression value.

private

   type Regexp_Value;

   type Regexp_Access is access Regexp_Value;

   type Regexp is new Ada.Finalization.Controlled with record

      R : Regexp_Access := null;

   end record;

   pragma Finalize_Storage_Only (Regexp);

   procedure Finalize (R : in out Regexp);

   --  Free the memory occupied by R

   procedure Adjust (R : in out Regexp);

   --  Called after an assignment (do a copy of the Regexp_Access.all)

end System.Regexp;