79 lines
2.8 KiB
Factor
79 lines
2.8 KiB
Factor
! :folding=indent:collapseFolds=1:
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! $Id$
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!
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! Copyright (C) 2004 Slava Pestov.
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!
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! Redistribution and use in source and binary forms, with or without
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! modification, are permitted provided that the following conditions are met:
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!
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! 1. Redistributions of source code must retain the above copyright notice,
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! this list of conditions and the following disclaimer.
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!
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! 2. Redistributions in binary form must reproduce the above copyright notice,
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! this list of conditions and the following disclaimer in the documentation
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! and/or other materials provided with the distribution.
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!
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! THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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! INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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! FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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! DEVELOPERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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! SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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! PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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! OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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! WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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! OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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! ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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IN: lists
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USE: kernel
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! An association list is a list of conses where the car of each
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! cons is a key, and the cdr is a value. See the Factor
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! Developer's Guide for details.
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: assoc? ( list -- ? )
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#! Push if the list appears to be an alist.
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dup list? [ [ cons? ] all? ] [ drop f ] ifte ;
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: assoc* ( key alist -- [ key | value ] )
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#! Looks up the key in an alist. Push the key/value pair.
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#! Most of the time you want to use assoc not assoc*.
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dup [
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2dup car car = [ nip car ] [ cdr assoc* ] ifte
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] [
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2drop f
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] ifte ;
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: assoc ( key alist -- value )
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#! Looks up the key in an alist.
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assoc* dup [ cdr ] when ;
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: remove-assoc ( key alist -- alist )
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#! Remove all key/value pairs with this key.
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[ dupd car = not ] subset nip ;
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: acons ( value key alist -- alist )
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#! Adds the key/value pair to the alist. Existing pairs with
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#! this key are not removed; the new pair simply shadows
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#! existing pairs.
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>r swons r> cons ;
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: set-assoc ( value key alist -- alist )
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#! Adds the key/value pair to the alist.
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dupd remove-assoc acons ;
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: assoc-apply ( value-alist quot-alist -- )
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#! Looks up the key of each pair in the first list in the
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#! second list to produce a quotation. The quotation is
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#! applied to the value of the pair. If there is no
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#! corresponding quotation, the value is popped off the
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#! stack.
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swap [
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over >r unswons rot assoc* dup [
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cdr call
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] [
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2drop
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] ifte r>
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] each drop ;
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