Remove old code
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USING: critbit tools.test ;
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IN: critbit.tests
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{ t } [ <critbit> empty? ] unit-test
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{ 0 } [ 0 0b11111011 direction ] unit-test
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{ 1 } [ 4 0b11111011 direction ] unit-test
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@ -1,181 +0,0 @@
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! Copyright (C) 2019 Michael Raitza
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!
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! * Crit-bit trees
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! ** Rationale
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! Critbit trees are described in [[https://cr.yp.to/critbit.html][djb's crit-bit tree]]. They are an evolution of
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! PATRICIA trees showing that fast insertion, deletion, exact searching and suffix
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! searching is possible with this data structure.
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! The strength of this datastructure, according to its author, lies in its simple
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! design and its optimisation to be machine parsable using machine word-sized
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! operations where possible. Like PATRICIA trees, crit-bit trees are
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! prefix-compressed, with internal nodes storing next decision point (the critical
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! bit) in a length field (encoded as an integer and a mask) and two successor
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! pointers. Arbitrary data objects make up its leaves.
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USING: accessors fry kernel math sequences serialize ;
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IN: critbit
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TUPLE: critbit root ;
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<PRIVATE
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: new-critbit ( class -- critbit )
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new
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f >>root ; inline
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PRIVATE>
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: <critbit> ( -- critbit )
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critbit new-critbit ;
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<PRIVATE
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TUPLE: node left right { byte# integer } { bits integer } ;
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: empty? ( tree -- ? )
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root>> f = ; inline
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: new-node ( bits byte# class -- node )
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new
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swap >>byte#
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swap >>bits ; inline
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: <node> ( bits byte# -- node )
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node new-node ;
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: get-child ( node direction -- child )
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0 = [ right>> ] [ left>> ] if ;
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: set-child ( node child direction -- node )
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0 = [ >>right ] [ >>left ] if ;
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: set-child-opposite ( node child direction -- node )
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1 swap - set-child ;
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: direction ( byte bits -- direction )
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bitor 1 + -8 shift ;
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! ** Walking the tree
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! Extract the split byte number and bit from node and return the proper child the
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! proper child corresponding to the bytestring's prefix.
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: successor ( bytes node -- bytes successor via-direction )
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2dup [ byte#>> ] [ bits>> ] bi
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[ swap ?nth [ 0 ] unless* ] dip
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direction [ get-child ] keep ;
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! Walk the tree until we find a leaf.
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: walk-critbit ( obj tree -- objbytes leaf )
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[ object>bytes ] [ root>> ] bi*
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[ dup node? ] [ successor drop ] while ;
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PRIVATE>
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: member? ( obj tree -- ? )
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dup critbit?
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[ walk-critbit = ]
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[ 2drop f ] if ;
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<PRIVATE
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! Produce a byte with all bits set except the msb from bits*.
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! See MAGIC Algorithms for rationale.
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: msb0 ( bits* -- bits )
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dup -1 shift bitor
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dup -2 shift bitor
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dup -4 shift bitor
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dup -1 shift bitnot bitand 255 bitxor ;
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: byte-diff ( newbyte oldbyte -- direction bits )
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swap over
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bitxor msb0
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[ direction ] keep ;
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: node-params ( newbytes oldbytes -- direction bits byte# )
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2dup mismatch
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[ [ '[ _ swap nth ] bi@ byte-diff ] keep ]
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! Equal prefix over full (shorter) byte sequence.
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[ [ 1 255 ] 2dip shorter length 1 - ] if* ;
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: derive-node ( obj newbytes leaf -- node direction )
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object>bytes
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node-params <node> -rot [ set-child-opposite ] keep ;
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: insert-node ( node split-node direction -- successor ? )
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[
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[ [ byte#>> ] bi@ - [ 0 < ] [ 0 = ] bi ] 2keep
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[ bits>> ] > and
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or
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] dip drop
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;
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: insertion-walk ( tree split-node new-direction -- tree )
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! FIXME Unfinished. We need obj to calculate succession :(
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rot [
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root>> dup node?
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[ ] [ 2over insert-node ] while 3drop
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] keep ;
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:: walk-on? ( split-node node -- ? )
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node node? not
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node byte#>> split-node byte#>> >
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or
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node byte#>> split-node byte#>> =
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node bits>> split-node bits>> >
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and
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or
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not ;
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:: insertion-walk ( obj split-node new-direction -- ? )
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obj obj>bytes :> objbytes
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tree root>> :> node
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[ split-node node walk-on? ] [
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node :> predecessor
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objbytes node successor :> node-direction :> node drop
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] while
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node split-node new-direction set-child
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;
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! :: insertion-successor ( objbytes bits byte# node -- split-node )
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! node node? not
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! [ node ]
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! [
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! node byte#>>
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! [ byte# > ] keep
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! byte# = node bits>> bits > and
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! or
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! ! objbytes no longer matches prefix?
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! [ node ]
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! [
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! ! FIXME: complete node insertion
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! ] if
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! ] if ;
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! :: (insert-node) ( obj tree objbytes treebytes direction bits byte# -- tree )
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! bits byte# <node>
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! direction 0 = [ obj >>right ] [ obj >>left ] if :> node
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! tree root>> [ dup node? ] [ insertion-successor]
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! ;
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! : insert-node ( obj tree objbytes treebytes -- tree )
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! 2dup node-params (insert-node)
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! ;
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PRIVATE>
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: (put) ( tree obj -- tree )
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swap dup empty?
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[ swap >>root ]
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[ [ 2dup walk-critbit
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derive-node
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! FIXME Unfinished, this node must now be inserted into the tree
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] 2keep
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2drop ! <- remove;
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! insert-node
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] if ;
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: put ( obj tree -- tree )
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dup critbit? [ (put) ] [ 2drop "Not a critbit tree" throw ] if ;
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