! :folding=indent:collapseFolds=1:

! $Id$
!
! Copyright (C) 2004 Slava Pestov.
! 
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! modification, are permitted provided that the following conditions are met:
! 
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IN: errors
USE: arithmetic
USE: combinators
USE: continuations
USE: kernel
USE: lists
USE: logic
USE: namespaces
USE: prettyprint
USE: stack
USE: stdio
USE: strings
USE: unparser
USE: vectors

! This is a very lightweight exception handling system.

: catchstack* ( -- cs ) 6 getenv ;
: catchstack ( -- cs ) catchstack* clone ;
: set-catchstack* ( cs -- ) 6 setenv ;
: set-catchstack ( cs -- ) clone set-catchstack* ;

: kernel-error? ( obj -- ? )
    dup cons? [ car fixnum? ] [ drop f ] ifte ;

: ?nth ( n list -- obj )
    over [ dup >r length min 0 max r> nth ] [ 2drop f ] ifte ;

: error# ( n -- str )
    [
        "Expired handle: "
        "Undefined word: "
        "Type check: "
        "Array range check: "
        "Underflow"
        "Bad primitive: "
        "Incompatible handle: "
        "I/O error: "
    ] ?nth ;

: ?kernel-error ( cons -- error# param )
    dup cons? [ uncons dup cons? [ car ] when ] [ f ] ifte ;

: kernel-error. ( error -- )
    ?kernel-error swap error# dup "" ? write
    dup [ . ] [ drop terpri ] ifte ;

: error. ( error -- str )
    dup kernel-error? [ kernel-error. ] [ . ] ifte ;

DEFER: >c
DEFER: throw
DEFER: default-error-handler

: init-errors ( -- )
    64 <vector> set-catchstack*
    [ 1 exit* ] >c ( last resort )
    [ default-error-handler suspend ] >c
    [ throw ] 5 setenv ( kernel calls on error ) ;