-- Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
-- All rights reserved.
-- Copyright (C) 2007, Gabriel Dos Reis.
-- All rights reserved.
--
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-- modification, are permitted provided that the following conditions are
-- met:
--
--     - Redistributions of source code must retain the above copyright
--       notice, this list of conditions and the following disclaimer.
--
--     - Redistributions in binary form must reproduce the above copyright
--       notice, this list of conditions and the following disclaimer in
--       the documentation and/or other materials provided with the
--       distribution.
--
--     - Neither the name of The Numerical ALgorithms Group Ltd. nor the
--       names of its contributors may be used to endorse or promote products
--       derived from this software without specific prior written permission.
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import '"vmlisp"

)package "BOOT"

--% Attributed Structures (astr)
-- For objects which are pairs where the CAR field is either just a tag
-- (an identifier) or a pair which is the tag and an association list.
 
-- Pick off the tag
ncTag x ==
   not PAIRP x => ncBug('S2CB0031,[])
   x := QCAR x
   IDENTP x => x
   not PAIRP x => ncBug('S2CB0031,[])
   QCAR x
 
-- Pick off the property list
ncAlist x ==
   not PAIRP x => ncBug('S2CB0031,[])
   x := QCAR x
   IDENTP x => NIL
   not PAIRP x => ncBug('S2CB0031,[])
   QCDR x

 --- Get the entry for key k on x's association list
ncEltQ(x,k) ==
   r := QASSQ(k,ncAlist x)
   NULL r => ncBug ('S2CB0007,[k])
   CDR r
 
-- Put (k . v) on the association list of x and return v
-- case1: ncPutQ(x,k,v) where k is a key (an identifier), v a value
--        put the pair (k . v) on the association list of x and return v
-- case2: ncPutQ(x,k,v) where k is a list of keys, v a list of values
--        equivalent to [ncPutQ(x,key,val) for key in k for val in v]
ncPutQ(x,k,v) ==
   LISTP k =>
      for key in k for val in v repeat ncPutQ(x,key,val)
      v
   r := QASSQ(k,ncAlist x)
   if NULL r then
      r := CONS( CONS(k,v), ncAlist x)
      RPLACA(x,CONS(ncTag x,r))
   else
      RPLACD(r,v)
   v