struct::skiplist(n)           Tcl Data Structures          struct::skiplist(n)



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NAME
       struct::skiplist - Create and manipulate skiplists

SYNOPSIS
       package require Tcl  8.2

       package require struct::skiplist  ?1.3?

       skiplistName option ?arg arg ...?

       skiplistName delete node ?node...?

       skiplistName destroy

       skiplistName insert key value

       skiplistName search node ?-key key?

       skiplistName size

       skiplistName walk cmd

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DESCRIPTION
       The ::struct::skiplist command creates a new skiplist object with an
       associated global Tcl command whose name is skiplistName. This command
       may be used to invoke various operations on the skiplist. It has the
       following general form:

       skiplistName option ?arg arg ...?
              Option and the args determine the exact behavior of the command.

       Skip lists are an alternative data structure to binary trees. They can
       be used to maintain ordered lists over any sequence of insertions and
       deletions. Skip lists use randomness to achieve probabilistic
       balancing, and as a result the algorithms for insertion and deletion in
       skip lists are much simpler and faster than those for binary trees.

       To read more about skip lists see Pugh, William.  Skip lists: a
       probabilistic alternative to balanced trees In: Communications of the
       ACM, June 1990, 33(6) 668-676.

       Currently, the key can be either a number or a string, and comparisons
       are performed with the built in greater than operator.  The following
       commands are possible for skiplist objects:

       skiplistName delete node ?node...?
              Remove the specified nodes from the skiplist.

       skiplistName destroy
              Destroy the skiplist, including its storage space and associated
              command.

       skiplistName insert key value
              Insert a node with the given key and value into the skiplist. If
              a node with that key already exists, then the that node's value
              is updated and its node level is returned. Otherwise a new node
              is created and 0 is returned.

       skiplistName search node ?-key key?
              Search for a given key in a skiplist. If not found then 0 is
              returned.  If found, then a two element list of 1 followed by
              the node's value is retuned.

       skiplistName size
              Return a count of the number of nodes in the skiplist.

       skiplistName walk cmd
              Walk the skiplist from the first node to the last. At each node,
              the command cmd will be evaluated with the key and value of the
              current node appended.

BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will undoubtedly contain
       bugs and other problems.  Please report such in the category struct ::
       skiplist of the Tcllib SF Trackers
       [http://sourceforge.net/tracker/?group_id=12883].  Please also report
       any ideas for enhancements you may have for either package and/or
       documentation.

KEYWORDS
       skiplist

CATEGORY
       Data structures

COPYRIGHT
       Copyright (c) 2000 Keith Vetter




struct                                1.3                  struct::skiplist(n)
