! Copyright (C) 2008 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel assocs accessors ;
IN: biassocs

TUPLE: biassoc from to ;

: <biassoc> ( exemplar -- biassoc )
    [ clone ] [ clone ] bi biassoc boa ;

: <bihash> ( -- biassoc )
    H{ } <biassoc> ;

M: biassoc assoc-size from>> assoc-size ;

M: biassoc at* from>> at* ;

M: biassoc value-at* to>> at* ;

: once-at ( value key assoc -- )
    2dup key? [ 3drop ] [ set-at ] if ;

M: biassoc set-at
    [ from>> set-at ] [ swapd to>> once-at ] 3bi ;

M: biassoc delete-at
    "biassocs do not support deletion" throw ;

M: biassoc >alist
    from>> >alist ;

M: biassoc clear-assoc
    [ from>> clear-assoc ] [ to>> clear-assoc ] bi ;

INSTANCE: biassoc assoc