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

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                               K R U N C H                                --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2009, 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.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

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

--  This procedure implements file name crunching

--    First, the name is divided into segments separated by minus signs and

--    underscores, then all minus signs and underscores are eliminated. If

--    this leaves the name short enough, we are done.

--    If not, then the longest segment is located (left-most if there are

--    two of equal length), and shortened by dropping its last character.

--    This is repeated until the name is short enough.

--    As an example, consider the krunch of our-strings-wide_fixed.adb

--    to fit the name into 8 characters as required by DOS:

--      our-strings-wide_fixed      22

--      our strings wide fixed      19

--      our string  wide fixed      18

--      our strin   wide fixed      17

--      our stri    wide fixed      16

--      our stri    wide fixe       15

--      our str     wide fixe       14

--      our str     wid  fixe       13

--      our str     wid  fix        12

--      ou  str     wid  fix        11

--      ou  st      wid  fix        10

--      ou  st      wi   fix         9

--      ou  st      wi   fi          8

--      Final file name: OUSTWIFX.ADB

--    A special rule applies for children of System, Ada, Gnat, and Interfaces.

--    In these cases, the following special prefix replacements occur:

--       ada-        replaced by  a-

--       gnat-       replaced by  g-

--       interfaces- replaced by  i-

--       system-     replaced by  s-

--    The rest of the name is krunched in the usual manner described above.

--    In addition, these names, as well as the names of the renamed packages

--    from the obsolescent features annex, are always krunched to 8 characters

--    regardless of the setting of Maxlen.

--    As an example of this special rule, consider ada-strings-wide_fixed.adb

--    which gets krunched as follows:

--      ada-strings-wide_fixed      22

--      a-  strings wide fixed      18

--      a-  string  wide fixed      17

--      a-  strin   wide fixed      16

--      a-  stri    wide fixed      15

--      a-  stri    wide fixe       14

--      a-  str     wide fixe       13

--      a-  str     wid  fixe       12

--      a-  str     wid  fix        11

--      a-  st      wid  fix        10

--      a-  st      wi   fix         9

--      a-  st      wi   fi          8

--      Final file name: A-STWIFX.ADB

--  Since children of units named A, G, I or S might conflict with the names

--  of predefined units, the naming rule in that case is that the first hyphen

--  is replaced by a tilde sign.

--  Note: as described below, this special treatment of predefined library

--  unit file names can be inhibited by setting the No_Predef flag.

--  Of course there is no guarantee that this algorithm results in uniquely

--  crunched names (nor, obviously, is there any algorithm which would do so)

--  In fact we run into such a case in the standard library routines with

--  children of Wide_Text_IO, so a special rule is applied to deal with this

--  clash, namely the prefix ada-wide_text_io- is replaced by a-wt- and then

--  the normal crunching rules are applied, so that for example, the unit:

--    Ada.Wide_Text_IO.Float_IO

--  has the file name

--    a-wtflio

--  More problems arise with Wide_Wide, so we replace this sequence by

--  a z (which is not used much) and also (as in the Wide_Text_IO case),

--  we replace the prefix ada.wide_wide_text_io- by a-zt- and then

--  the normal crunching rules are applied.

--  These are the only irregularity required (so far!) to keep the file names

--  unique in the standard predefined libraries.

procedure Krunch

  (Buffer        : in out String;

   Len           : in out Natural;

   Maxlen        : Natural;

   No_Predef     : Boolean;

   VMS_On_Target : Boolean := False);

pragma Elaborate_Body (Krunch);

--  The full file name is stored in Buffer (1 .. Len) on entry. The file

--  name is crunched in place and on return Len is updated, so that the

--  resulting krunched name is in Buffer (1 .. Len) where Len <= Maxlen.

--  Note that Len may be less than or equal to Maxlen on entry, in which

--  case it may be possible that Krunch does not modify Buffer. The fourth

--  parameter, No_Predef, is a switch which, if set to True, disables the

--  normal special treatment of predefined library unit file names.

--  VMS_On_Target, when True, indicates to Krunch to apply the VMS treatment

--  to the children of package A, G,I or S.

--

--  Note: the string Buffer must have a lower bound of 1, and may not

--  contain any blanks (in particular, it must not have leading blanks).