! :folding=indent:collapseFolds=1:

! $Id$
!
! Copyright (C) 2003, 2004 Slava Pestov.
! 
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! modification, are permitted provided that the following conditions are met:
! 
! 1. Redistributions of source code must retain the above copyright notice,
!    this list of conditions and the following disclaimer.
! 
! 2. Redistributions in binary form must reproduce the above copyright notice,
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IN: lists
USE: kernel
USE: namespaces

: cons@ ( x var -- )
    #! Prepend x to the list stored in var.
    [ cons ] change ;

: unique@ ( elem var -- )
    #! Prepend an element to the proper list stored in a
    #! variable if it is not already contained in the list.
    [ unique ] change ;

SYMBOL: list-buffer

: make-rlist ( quot -- list )
    #! Call a quotation. The quotation can call , to prepend
    #! objects to the list that is returned when the quotation
    #! is done.
    [ list-buffer off call list-buffer get ] with-scope ;
    inline

: make-list ( quot -- list )
    #! Return a list whose entries are in the same order that ,
    #! was called.
    make-rlist reverse ; inline

: , ( obj -- )
    #! Append an object to the currently constructing list.
    list-buffer cons@ ;

: unique, ( obj -- )
    #! Append an object to the currently constructing list, only
    #! if the object does not already occur in the list.
    list-buffer unique@ ;