struct::tree v1(n)						Tcl Data Structures						struct::tree v1(n)

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NAME

       struct::tree v1 - Create and manipulate tree objects

SYNOPSIS

       package require Tcl  8.2

       package require struct::tree  ?1.2.2?

       treeName option ?arg arg ...?

       treeName append node ?-key key? value

       treeName children node

       treeName cut node

       treeName delete node ?node ...?

       treeName depth node

       treeName destroy

       treeName exists node

       treeName get node ?-key key?

       treeName getall node

       treeName keys node

       treeName keyexists node ?-key key?

       treeName index node

       treeName insert parent index ?child ?child ...??

       treeName isleaf node

       treeName lappend node ?-key key? value

       treeName move parent index node ?node ...?

       treeName next node

       treeName numchildren node

       treeName parent node

       treeName previous node

       treeName set node ?-key key? ?value?

       treeName size ?node?

       treeName splice parent from ?to? ?child?

       treeName swap node1 node2

       treeName unset node ?-key key?

       treeName walk node ?-order order? ?-type type? -command cmd

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DESCRIPTION

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

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

       A tree is a collection of named elements, called nodes, one of which is distinguished as a root, along with a relation ("parenthood")  that
       places  a  hierarchical structure on the nodes. (Data Structures and Algorithms; Aho, Hopcroft and Ullman; Addison-Wesley, 1987).  In addi-
       tion to maintaining the node relationships, this tree implementation allows any number of keyed values to be associated with each node.

       The element names can be arbitrary strings.

       A tree is thus similar to an array, but with three important differences:

       [1]    Trees are accessed through an object command, whereas arrays are accessed as variables. (This means trees cannot be local to a  pro-
	      cedure.)

       [2]    Trees have a hierarchical structure, whereas an array is just an unordered collection.

       [3]    Each node of a tree has a separate collection of attributes and values. This is like an array where every value is a dictionary.

       The following commands are possible for tree objects:

       treeName append node ?-key key? value
	      Appends a value to one of the keyed values associated with an node. If no key is specified, the key data is assumed.

       treeName children node
	      Return a list of the children of node.

       treeName cut node
	      Removes the node specified by node from the tree, but not its children.  The children of node are made children of the parent of the
	      node, at the index at which node was located.

       treeName delete node ?node ...?
	      Remove the specified nodes from the tree.  All of the nodes' children will be removed as well to prevent orphaned nodes.

       treeName depth node
	      Return the number of steps from node node to the root node.

       treeName destroy
	      Destroy the tree, including its storage space and associated command.

       treeName exists node
	      Remove true if the specified node exists in the tree.

       treeName get node ?-key key?
	      Return the value associated with the key key for the node node. If no key is specified, the key data is assumed.

       treeName getall node
	      Returns a serialized list of key/value pairs (suitable for use with [array set]) for the node.

       treeName keys node
	      Returns a list of keys for the node.

       treeName keyexists node ?-key key?
	      Return true if the specified key exists for the node. If no key is specified, the key data is assumed.

       treeName index node
	      Returns the index of node in its parent's list of children.  For example, if a node has nodeFoo, nodeBar, and nodeBaz  as  children,
	      in that order, the index of nodeBar is 1.

       treeName insert parent index ?child ?child ...??
	      Insert  one or more nodes into the tree as children of the node parent. The nodes will be added in the order they are given. If par-
	      ent is root, it refers to the root of the tree. The new nodes will be added to the parent node's child list at the  index  given	by
	      index. The index can be end in which case the new nodes will be added after the current last child.

	      If  any of the specified children already exist in treeName, those nodes will be moved from their original location to the new loca-
	      tion indicated by this command.

	      If no child is specified, a single node will be added, and a name will be generated for the new node. The generated name is  of  the
	      form nodex, where x is a number. If names are specified they must neither contain whitespace nor colons (":").

	      The return result from this command is a list of nodes added.

       treeName isleaf node
	      Returns true if node is a leaf of the tree (if node has no children), false otherwise.

       treeName lappend node ?-key key? value
	      Appends a value (as a list) to one of the keyed values associated with an node. If no key is specified, the key data is assumed.

       treeName move parent index node ?node ...?
	      Make  the specified nodes children of parent, inserting them into the parent's child list at the index given by index. Note that the
	      command will take all nodes out of the tree before inserting them under the new parent, and that it determines the position to place
	      them  into  after  the  removal, before the re-insertion. This behaviour is important when it comes to moving one or more nodes to a
	      different index without changing their parent node.

       treeName next node
	      Return the right sibling of node, or the empty string if node was the last child of its parent.

       treeName numchildren node
	      Return the number of immediate children of node.

       treeName parent node
	      Return the parent of node.

       treeName previous node
	      Return the left sibling of node, or the empty string if node was the first child of its parent.

       treeName set node ?-key key? ?value?
	      Set or get one of the keyed values associated with a node. If no key is specified, the key data is assumed.  Each node that is added
	      to  a  tree has the value "" assigned to the key data automatically.  A node may have any number of keyed values associated with it.
	      If value is not specified, this command returns the current value assigned to the key; if value is specified, this  command  assigns
	      that value to the key.

       treeName size ?node?
	      Return a count of the number of descendants of the node node; if no node is specified, root is assumed.

       treeName splice parent from ?to? ?child?
	      Insert a node named child into the tree as a child of the node parent. If parent is root, it refers to the root of the tree. The new
	      node will be added to the parent node's child list at the index given by from.  The children of parent which are in the range of the
	      indices  from  and  to are made children of child.  If the value of to is not specified it defaults to end.  If no name is given for
	      child, a name will be generated for the new node.  The generated name is of the form nodex, where x is a number.	The return  result
	      from this command is the name of the new node.

       treeName swap node1 node2
	      Swap the position of node1 and node2 in the tree.

       treeName unset node ?-key key?
	      Remove a keyed value from the node node.	If no key is specified, the key data is assumed.

       treeName walk node ?-order order? ?-type type? -command cmd
	      Perform  a breadth-first or depth-first walk of the tree starting at the node node.  The type of walk, breadth-first or depth-first,
	      is determined by the value of type; bfs indicates breadth-first, dfs indicates depth-first.  Depth-first is the default.	The  order
	      of the walk, pre-, post-, both- or in-order is determined by the value of order; pre indicates pre-order, post indicates post-order,
	      both indicates both-order and in indicates in-order. Pre-order is the default.

	      Pre-order walking means that a parent node is visited before any of its children.  For example, a breadth-first search starting from
	      the  root will visit the root, followed by all of the root's children, followed by all of the root's grandchildren. Post-order walk-
	      ing means that a parent node is visited after any of its children. Both-order walking means that a parent node is visited before and
	      after any of its children. In-order walking means that a parent node is visited after its first child and before the second. This is
	      a generalization of in-order walking for binary trees and will do the right thing if a  binary  is  walked.  The	combination  of  a
	      breadth-first walk with in-order is illegal.

	      As the walk progresses, the command cmd will be evaluated at each node.  Percent substitution will be performed on cmd before evalu-
	      ation, just as in a bind script.	The following substitutions are recognized:

	      %%     Insert the literal % character.

	      %t     Name of the tree object.

	      %n     Name of the current node.

	      %a     Name of the action occurring; one of enter, leave, or visit.  enter actions occur during pre-order walks; leave actions occur
		     during  post-order  walks;  visit	actions  occur during in-order walks.  In a both-order walk, the command will be evaluated
		     twice for each node; the action is enter for the first evaluation, and leave for the second.

BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will undoubtedly contain bugs and other problems.  Please report such in the  category  struct
       ::  tree 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

       tree

COPYRIGHT

       Copyright (c) 2002 Andreas Kupries <andreas_kupries@users.sourceforge.net>

struct								       1.2.2							struct::tree v1(n)