Ubuntu Manpage: struct::skiplist - Create and manipulate skiplists

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    Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you may  have  for
       either package and/or documentation.

KEYWORDS

       skiplist

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