misc.sa


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------------------------->  GNU Sather - sourcefile  <-------------------------
-- Copyright (C) 2000 by K Hopper, University of Waikato, New Zealand        --
-- This file is part of the GNU Sather library. It is free software; you may --
-- redistribute  and/or modify it under the terms of the GNU Library General --
-- Public  License (LGPL)  as published  by the  Free  Software  Foundation; --
-- either version 2 of the license, or (at your option) any later version.   --
-- This  library  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 Doc/LGPL for more details.       --
-- The license text is also available from:  Free Software Foundation, Inc., --
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-------------->  Please email comments to <bug-sather@gnu.org>  <--------------


class CAST{T}

class CAST{T} is -- This class is provided to permit explicit narrowing from the general -- abstract class $OB to class T. It is a useful substitute for the one -- line typecase statement. -- -- Usage: -- thing : $OB := 3 ; -- num : INT := CAST{INT}::from(thing) ; -- -- Version 1.0 Dec 96. Copyright K Hopper, U of Waikato -- Development History -- ------------------- -- Date Who By Detail -- ---- ------ ------ -- 16 Dec 96 kh Original from standard Sather dist. create : SAME is -- This operation is used to 'get' the class name -- it won't work -- with void! return new end ; from( anything : $OB ) : T is -- This routine allows an explicit cast to make the class of anything -- to be class T. An exception is raised if anything is not of class T. typecase anything when T then return anything else SYS_ERROR::create.error(self,SYS_EXCEPT::Bad_Type, CAST_EXC::create(anything,SAME::create)) ; return void -- to keep compiler happy! end end ; end ; -- CAST{T}

class CAST_EXC < $STR

class CAST_EXC < $STR is -- This class is the class of the exception that is raised when -- a CAST{T}::from call fails. -- -- NOTE This class requires a text resource file. -- Version 1.0 Dec 96. Copyright K Hopper, U of Waikato -- Development History -- ------------------- -- Date Who By Detail -- ---- ------ ------ -- 16 Dec 96 kh Original modified from Sather dist. readonly attr ob : $OB ; readonly attr caster : $OB ; -- Mainly so that the class name -- of the cast can be determined -- for error reporting. private shared Messages : ARRAY{STR} ; private const -- local message enumeration Typecase, Attempted, Invalid ; private const Msg_Cnt : CARD := Invalid + 1 ; create( ob : $OB, caster : $OB ) : SAME is -- This creation routine merely sets the components of a new object of -- this class. me : SAME := new ; me.ob := ob ; me.caster := caster ; return me end ; str( lib : LIBCHARS ) : STR is -- This routine returns a string error message in the given repertoire -- and encoding. Note that the 'system' class returns the string -- representation of the class name as RUNES, since this is the only portable -- term -- which will need to be converted to the run-time character encoding -- during the execution of this routine. type_name : RUNES := SYS::rune_name(caster) ; if void(Messages)then Messages := lib.culture.resources.read( SYS::rune_name(self),Msg_Cnt) ; if Messages.size /= Msg_Cnt then raise SYS::str_for_tp(SYS::tp(self)) + LIBCHARS::default.Hyphen.char + Messages.size.str end end ; res : STR := FMT::create(Messages[Typecase],type_name.str,lib).str ; if void(ob) then res := res + Messages[Attempted] else ob_classname : RUNES := SYS::rune_name(ob) ; res := res + FMT::create(Messages[Invalid],ob_classname.str,lib).str end ; return res end ; str : STR is -- This routine returns a string error message in the default character -- repertoire and encoding. Note that the 'system' class returns the -- string representation of the class name as RUNES, since this is the only -- portable form -- which will need to be converted to the run-time -- character encoding during the execution of this routine. return str(LIBCHARS::default) end ; end ; -- CLASS_EXC

partial class ID

partial class ID is -- This partial class is meant to be included by types that wish to -- provide object equality as their natural, immutable identity relation. -- Version 1.0 Dec 96. Copyright K Hopper, U of Waikato -- Development History -- ------------------- -- Date Who By Detail -- ---- ------ ------ -- 16 Dec 96 kh Original from standard Sather dist. is_eq( arg : $OB ) : BOOL is -- This returns object equality! return SYS::ob_eq(self,arg) end ; -- NOTE is_lt and hash fail for immutable classes is_lt( arg : $OB ) : BOOL is -- This returns true or false depending upon the ordering of -- object identity codes as established by the compiler/run-time system. return SYS::id(self) < SYS::id(arg) end ; hash : CARD is -- This returns a consistent hash function using the value of the -- identity code as a number. return SYS::id(self).hash end ; end ; -- ID

class EXT_OB

class EXT_OB is -- This class is obsolete and appear in the required library solely -- for compatibility with the interim compiler. -- Version 1.0 Jan 97. Copyright K Hopper, U of Waikato -- Development History -- ------------------- -- Date Who By Detail -- ---- ------ ------ -- 3 Jan 97 kh Original from standard Sather dist. end ; -- EXT_OB