                     #tocTable of Contents  
#toc0Name 
tree -  Create and manage tree data objects. 
#toc1Synopsis 
blt::tree
create 
?treeName? blt::tree destroy treeName... blt::tree names ?pattern?
#toc2Description 
The 
tree command creates tree data objects.  A tree object is
general ordered tree of nodes.  Each node has both a label and a key-value
list of data.  Data can be heterogeneous, since nodes do not have to contain
the same data keys.  It is associated with a Tcl command that you can use
to access and modify the its structure and data. Tree objects can also be
managed via a C API. 
#toc3Introduction 
 
#toc4Example 
 
#toc5Syntax 
tree create ?treeName? 
 
Creates a new tree object.  The name of the new tree is returned.  If no
treeName argument is present, then the name of the tree is automatically
generated in the form "
tree0", "tree1", etc.  If the substring "#auto" is
found in 
treeName, it is automatically substituted by a generated name.
 For example, the name 
.foo.#auto.bar will be translated to .foo.tree0.bar. A
new Tcl command (by the same name as the tree) is also created. Another
Tcl command or tree object can not already exist as 
treeName.  If the Tcl
command is deleted, the tree will also be freed.  The new tree will contain
just the root node.  Trees are by default, created in the current namespace,
not the global namespace, unless 
treeName contains a namespace qualifier,
such as "
fred::myTree". tree destroy treeName... Releases one of more trees.
 The Tcl command associated with 
treeName is also removed.  Trees are reference
counted.  The internal tree data object isn't destroyed until no one else
is using the tree. 
tree names ?pattern? Returns the names of all tree objects.
 if a 
pattern argument is given, then the only those trees whose name matches
pattern will be listed. 
#toc6Node IDs and Tags 
Nodes in a tree object may be referred
in either of two ways: by id or by tag.  Each node has a unique serial number
or id that is assigned to that node when it's created. The id of an node
never changes and id numbers are not re-used. 
A node may also have any number
of tags associated with it.  A tag is just a string of characters, and it
may take any form except that of an integer.  For example, "
x123" is valid,
but "
123" isn't.  The same tag may be associated with many different nodes.
This is commonly done to group nodes in various interesting ways. 
There
are two built-in tags: The tag 
all is implicitly associated with every node
in the tree.  It may be used to invoke operations on all the nodes in the
tree.  The tag 
root is managed automatically by the tree object. It applies
to the node current set as root. 
When specifying nodes in tree object commands,
if the specifier is an integer then it is assumed to refer to the single
node with that id. If the specifier is not an integer, then it is assumed
to refer to all of the nodes in the tree that have a tag matching the specifier.
 The symbol 
node is used below to indicate that an argument specifies either
an id that selects a single node or a tag that selects zero or more nodes.
 Many tree commands only operate on a single node at a time; if 
node is
specified in a way that names multiple items, then an error "refers to
more than one node" is generated. 
#toc7Node Modifiers 
You can also specify node
in relation to another node by appending one or more modifiers to the node
id or tag.  A modifier refers to a node in relation to the specified node.
 For example,  "
root->firstchild" selects the first subtree of the root node.
The following modifiers are available: 
firstchild  Selects the first child
of the node.   
lastchild  Selects the last child of the node.   next  Selects
the next node in preorder to the node.   
nextsibling  Selects the next sibling
of the node.   
parent  Selects the parent of the node.   previous  Selects
the previous node in preorder to the node.   
prevsibling  Selects the previous
sibling of the node.   
"label" Selects the node whose label is label.  Enclosing
label in  quotes indicates to always search for a node by its label (for
example,  even if the node is labeled "parent"). 
It's an error the node can't
be found.  For example, 
lastchild and firstchild will generate errors if
the node has no children.  The exception to this is the 
index operation.
You can use 
index to test if a modifier is valid. 
#toc8Tree Operations 
Once you
create a tree object, you can use its Tcl command  to query or modify it.
 The general form is 
treeName operation ?arg?...Both operation and its arguments determine the exact behavior of the command.
 The operations available for trees are listed below. 
treeName ancestornode1 node2 Returns the mutual ancestor of the two nodes node1 and node2.
 The ancestor can be one of the two nodes.  For example, if 
node1 and node2are the same nodes, their ancestor is 
node1. treeName apply node ?switches?
Runs commands for all nodes matching the criteria given by switches for
the subtree designated by 
node.  By default all nodes match, but you can
set switches to narrow the match.  This operation differs from 
find in two
ways: 1) Tcl commands can be invoked both pre- and post-traversal of a node
and 2) the tree is always traversed in depth first order. 
The 
-exact, -glob,
 and 
-regexp switches indicate both what kind of pattern matching to perform
and the pattern.  Pattern matching is done, by default, against each node's
label.  But if the 
-path switch is present, it will match the full path of
the node (a list containing the labels of  the node's ancestors too).  If
the 
-key switch is used, it designates the data field to be matched.   The
valid switches are listed below: 
-depth number Descend at most number (a
non-negative integer) levels If 
number is 1 this means only apply the tests
to the children of 
node. -exact string Matches each node using string.  The
node must match 
string exactly. -glob string Test each node to string using
global pattern matching.  Matching is done in a fashion similar to that
used by the C-shell. 
-invert Select non-matching nodes.  Any node that doesn'tmatch the given criteria will be selected. 
-key key If pattern matching is
selected (using the 
-exact, -glob, or -regexp switches), compare the values
of the data field keyed by 
key instead of the node's label.  If no pattern
matching switches are set, then any node with this data key will match.
-leafonly Only test nodes with no children. -nocase Ignore case when matching
patterns. 
-path Use the node's full path when comparing nodes. -precommand commandInvoke command for each matching node.  Before command is invoked, the id
of the node is appended.  You can control  processing by the return value
of 
command.  If command  generates an error, processing stops and the findoperation  returns an error.  But if 
command returns break, then  processing
stops, no error is generated.  If 
command returns  continue, then processing
stops on that subtree and continues on the next. 
-postcommand command Invoke
command for each matching node.  Before command is invoked, the id of the
node is appended.  You can control  processing by the return value of 
command.
 If 
command  generates an error, processing stops and the find operation
 returns an error.  But if 
command returns break, then  processing stops,
no error is generated.  If 
command returns  continue, then processing stops
on that subtree and continues on the next. 
-regexp string Test each node
using 
string as a regular expression pattern. -tag string Only test nodes
that have the tag 
string. treeName attach treeObject Attaches to an existing
tree object 
treeObject.  This is for cases where the tree object was previously
created via the C API.  The current tree associated with 
treeName is discarded.
 In addition, the current set of tags, notifier events, and traces are
removed. 
treeName children node Returns a list of children for node.  If
node is a leaf, then an empty string is returned. treeName copy srcNode?
destTree? destNode ?switches? Copies srcNode into destNode. Both nodes
srcNode and destNode must already exist.  If destTree argument is present,
it indicates the name of the destination tree.  By default both the source
and destination trees are the same. The valid 
switches are listed below:
-overwrite Overwrite nodes that already exist.  Normally nodes are always
created, even if there already exists a node by the same name.  This switch
indicates to add or overwrite the node's data fields. 
-recurse Recursively
copy all the subtrees of 
srcNode as well.  In this case, srcNode can't be
an ancestor of 
destNode as it would result in a cyclic copy. -tags Copy tag
inforation.  Normally the following node is copied: its  label and data
fields.  This indicates to copy tags as well. 
treeName degree node  Returns
the number of children of 
node. treeName delete node... Recursively deletes
one or more nodes from the tree.   The node and all its descendants are
removed.   The one exception is the root node.  In this case, only its descendants
are removed. The root node will remain.  Any tags or  traces on the nodes
are released. 
treeName depth node  Returns the depth of the node.  The depth
is the number of  steps from the node to the root of the tree.  The depth
of the root node is 
0. treeName dump node  Returns a list of the paths and
respective data for 
node and its descendants.  The subtree designated by
node is traversed returning the following information for each node: 1)
the node's path relative to 
node, 2) a sublist key value pairs representing
the node's data fields, and 3) a sublist of tags.   This list returned can
be used later to copy or restore the tree with the 
restore operation. treeNamedumpfile node fileName Writes a list of the paths and respective data for
node and its descendants to the given file fileName.   The subtree designated
by 
node is traversed returning the  following information for each node:
1) the node's path relative to 
node, 2) a sublist key value pairs representing
the node's data fields, and 3) a sublist of tags.   This list returned can
be used later to copy or restore the tree with the 
restore operation. treeNameexists node ?key? Indicates if node exists in the tree.  If a key argument
is present then the command also indicates if the named data field  exists.
treeName find node ?switches?  Finds for all nodes matching the criteria
given by 
switches  for the subtree designated by node.  A list of the selected
 nodes is returned.  By default all nodes match, but you can set switches
to narrow the match. 
The 
-exact, -glob,  and -regexp switches indicate both
what kind of pattern matching to perform and the pattern.  Pattern matching
is done, by default, against each node's label.  But if the 
-path switch is
present, it will match the full path of the node.  If the 
-key switch is
used, it designates the data field to be matched.   
The order in  which
the nodes are traversed is controlled by the  
-order switch. The possible
orderings are 
preorder, postorder, inorder,  and breadthfirst.  The default
is 
postorder. The valid switches are listed below: 
-addtag string  Add the
tag 
string to each selected node.   -count number Stop processing after number(a positive integer) matches.  
-depth number Descend at most number (a non-negative
integer) levels If 
number is 1 this means only apply the tests to the children
of 
node. -exact string Matches each node using string.  The node must match
string exactly. -exec command Invoke command for each matching node.  Before
command is invoked, the id of the node is appended.  You can control  processing
by the return value of 
command.  If command  generates an error, processing
stops and the 
find operation  returns an error.  But if command returns
break, then  processing stops, no error is generated.  If command returns
 
continue, then processing stops on that subtree and continues on the next.
-glob string Test each node to string using global pattern matching.  Matching
is done in a fashion similar to that used by the C-shell. 
-invert Select non-matching
nodes.  Any node that 
doesn't match the given criteria will be selected. -keykey If pattern matching is selected (using the -exact, -glob, or -regexp switches),
compare the values of the data field keyed by 
key instead of the node's
label.  If no pattern matching switches are set, then any node with this
data key will match. 
-leafonly Only test nodes with no children. -nocase Ignore
case when matching patterns. 
-order string  Traverse the tree and process
nodes according to 
string. String can be one of the following: breadthfirst 
Process the node and the subtrees at each sucessive level. Each node on
a level is processed before going to the next level. 
inorder  Recursively
process the nodes of the first subtree, the node itself, and any the remaining
subtrees. 
postorder  Recursively process all subtrees before the node. preorder 
Recursively process the node first, then any subtrees. -path Use the node's
full path when comparing nodes. 
-regexp string Test each node using stringas a regular expression pattern. 
-tag string Only test nodes that have the
tag 
string. treeName findchild node label Searches for a child node Ilabel
in 
node.  The id of the  child node is returned if found.  Otherwise -1 is
returned. 
treeName firstchild node  Returns the id of the first child in
the 
node's list of subtrees.  If node is a leaf (has no children),  then
-1 is returned. treeName get node ?key? ?defaultValue? Returns a list of
key-value pairs of data for the node.  If 
key is present, then onlyx the
value for that particular data field is returned.  It's normally an error
if 
node does not contain the data field key.  But if you provide a defaultValueargument, this value is returned instead (
node will still not contain key).
 This feature can be used to access a data field of 
node without first
testing if it exists.  This operation may trigger 
read data traces. treeNameindex node Returns the id of node.  If node is a tag, it  can only specify
one node.  If 
node does not represent a valid node id or tag, or has modifiers
that are invalid, then 
-1 is returned. treeName insert parent ?switches?
 
Inserts a new node into parent node parent.   The id of the new node is
returned. The following switches  are available: 
-at number  Inserts the
node into 
parent's list of children at  position number.  The default is
to append 
node. -data dataList Sets the value for each data field in dataListfor the  new node. 
DataList is a list of key-value pairs. -label string  Designates
the labels of the node as 
string.  By default, nodes are labeled as node0,
node1, etc. -tags tagList Adds each tag in tagList to the new node. TagListis a list of tags, so be careful if a tag has embedded space. 
treeName isproperty args   Indicates the property of a node. Both property and argsdetermine the property being tested.  Returns 
1 if true and 0 otherwise.
 The following 
property and args  are valid: ancestor node1 node2 Indicates
if 
node1 is an ancestor of node2.  before node1 node2 Indicates if node1is before 
node2 in depth first traversal.  leaf node Indicates if node is
a leaf (it has no subtrees). 
root node Indicates if node is the designated
root.  This can be changed by the 
root operation. treeName label node ?newLabel?
Returns the label of the node designated by node.  If newLabel is present,
the node is relabeled using it as the new label. 
treeName lastchild nodeReturns the id of the last child in the node's list of subtrees.  If nodeis a leaf (has no children),  then 
-1 is returned. treeName move node newParent?
switches? Moves node into newParent. Node is appended to the list children
of 
newParent.  Node can not be an ancestor of newParent.  The valid flags
for 
switches are described below. -after child  Position node after child.
 The node 
child must be a  child of newParent. -at number  Inserts node into
parent's list of children at  position number. The default is to append the
node. 
-before child  Position node before child.  The node child must be a
 child of 
newParent. treeName next node Returns the next node from nodein a preorder traversal. If 
node is the last node in the tree,  then -1 is
returned. 
treeName nextsibling node Returns the node representing the next
subtree from 
node in its parent's list of children.  If node is the last
child,  then 
-1 is returned. treeName notify args  Manages notification events
that indicate that the tree structure has  been changed. See the  
NOTIFY
OPERATIONS
  section below. 
treeName parent node Returns the parent node
of 
node.  If node is the root of the tree,  then -1 is returned. treeNamepath node Returns the full path (from root) of node. treeName position nodeReturns the position of the node in its parent's list of children. Positions
are numbered from 0. The position of the root node is always 0. 
treeNameprevious node Returns the previous node from node in a preorder traversal.
If 
node is the root of the tree,  then -1 is returned. treeName prevsiblingnode Returns the node representing the previous subtree from node in its
parent's list of children.  If 
node is the first child,  then -1 is returned.
treeName restore node dataString switches Performs the inverse function
of the 
dump operation, restoring nodes to the tree. The format of dataStringis exactly what is  returned by the 
dump operation.  It's a list containing
information for each node to be restored.  The information consists of 1)
the relative path of the node, 2) a sublist of key value pairs representing
the  node's data, and 3) a list of tags for the node.  Nodes are created
 starting from 
node. Nodes can be listed in any order.  If a node's  path
describes ancestor nodes that do not already exist, they are  automatically
created.  The valid 
switches are listed below: -overwrite Overwrite nodes
that already exist.  Normally nodes are always created, even if there already
exists a node by the same name.  This switch indicates to add or overwrite
the node's data fields. 
treeName restorefile node fileName switches Performs
the inverse function of the 
dumpfile operation, restoring nodes to the
tree from the file 
fileName. The format of  fileName is exactly what is
returned by the 
dumpfile operation.   It's a list containing information
for each node to be restored.   The information consists of 1) the relative
path of the node, 2)  a sublist of key value pairs representing the node's
data, and 3)  a list of tags for the node.  Nodes are created  starting
from 
node. Nodes can be listed in any order.  If a node's  path describes
ancestor nodes that do not already exist, they are  automatically created.
 The valid 
switches are listed below: -overwrite Overwrite nodes that already
exist.  Normally nodes are always created, even if there already exists
a node by the same name.  This switch indicates to add or overwrite the
node's data fields. 
treeName root ?node? Returns the id of the root node.
 Normally this is node 
0.  If a node argument is provided, it will become
the new root of the tree. This lets you temporarily work within a subset
of the tree. Changing root affects operations such as 
next, path, previous,
etc. 
treeName set node key value ?key value...? Sets one or more data fields
in 
node. Node may  be a tag that represents several nodes.  Key is the name
of the data field to be set and 
value is its respective value.  This operation
may trigger 
write and create data traces. treeName size node Returns the
number of nodes in the subtree. This includes the node and all its descendants.
 The size of a leaf node is 1. 
treeName sort node ?switches?  -ascii  Compare
strings using the ASCII  collation order. 
-command string Use command stringas a comparison command.  To compare two elements, evaluate a Tcl script
consisting of command with the two elements appended as additional arguments.
 The script should return an integer less than, equal to, or greater than
zero if the first element is to be considered less than, equal to, or greater
than the second, respectively. 
-decreasing Sort in decreasing order (largest
items come first). 
-dictionary Compare strings using a dictionary-style comparison.
 This is the same  as 
-ascii except (a) case is ignored except as a tie-breaker
and (b)  if two strings contain embedded numbers, the numbers compare as
integers, not characters.  For example, in 
-dictionary mode, bigBoy sorts
between bigbang and bigboy, and x10y sorts between x9y and x11y. 
-integerCompare the nodes as integers.   -key string Sort based upon the node's data
field keyed by 
string. Normally nodes are sorted according to their label.
 
-path Compare the full path of each node.  The default is to compare only
its label. 
-real Compare the nodes as real numbers. -recurse Recursively sort
the entire subtree rooted at 
node. -reorder  Recursively sort subtrees for
each node.  
Warning.  Unlike the normal flat sort, where a list of nodes
is returned, this will reorder the tree.   
treeName tag args Manages tags
for the tree object. See the  
TAG OPERATIONS  section below. 
treeName traceargs Manages traces for data fields in the tree object. Traces cause Tcl
commands to be executed whenever a data field of a node is created, read,
written, or unset.  Traces can be set for a specific node or a tag, representing
possibly many nodes. See the  
TRACE OPERATIONS  section below. 
treeName unsetnode key... Removes one or more data fields from node. Node may  be a tag that
represents several nodes.  
Key is the name of the data field to be removed.
 It's not an error is 
node does not contain key.   This operation may trigger
unset data traces. #toc9Tag Operations 
Tags are a general means of selecting and
marking nodes in the tree. A tag is just a string of characters, and it
may take any form except that of an integer.  The same tag may be associated
with many different nodes.   
There are two built-in tags: The tag 
all is
implicitly associated with every node in the tree.  It may be used to invoke
operations on all the nodes in the tree.  The tag 
root is managed automatically
by the tree object.  It specifies the node that is currently set as the
root of the tree. 
Most tree operations use tags.  And several operations
let you operate on multiple nodes at once.  For example, you can use the
set operation with the tag all to set a data field in  for all nodes in
the tree. 
Tags are invoked by the 
tag operation.  The general form is treeName tag operation ?arg?...Both operation and its arguments determine the exact behavior of the command.
 The operations available for tags are listed below. 
treeName tag add stringnode... Adds the tag string to one of more nodes. treeName tag delete stringnode... Deletes the tag string from one or more nodes.   treeName tag forgetstring Removes the tag string from all nodes.  It's not an error if no nodes
are tagged as 
string. treeName tag names ?node? Returns a list of tags used
by the tree.  If a 
node argument is present, only those tags used by nodeare returned. 
treeName tag nodes string Returns a list of nodes that have
the tag 
string.  If no node is tagged as string, then an empty string is
returned. 
#toc10Trace Operations 
Data fields can be traced much in the same way
that you can trace Tcl variables.  Data traces cause Tcl commands to be
executed whenever a particular data field of a node is created, read, written,
or unset. A trace can apply to one or more nodes.  You can trace a specific
node by using its id, or a group of nodes by a their tag. 
The tree's 
get,
set, and unset operations can  trigger various traces.  The get operation
can cause  a 
read  trace to fire.  The set operation causes a write  trace
to fire.  And if the data field is written for the first time, you will
also get a 
create trace. The unset operation triggers unset traces. Data
traces are invoked by the 
trace operation.  The general form is treeName trace operation ?arg?...Both operation and its arguments determine the exact behavior of the command.
 The operations available for traces are listed below. 
treeName trace createnode key ops command Creates a trace for node on data field key.  Node can
refer to more than one node (for example, the tag 
all). If node is a tag,
any node with that tag can possibly trigger a trace, invoking 
command. 
 
Command is command prefix, typically a procedure name. Whenever a trace
is triggered, four arguments are appended to 
command before it is invoked:
treeName, id of the node, key and, ops. Note that no nodes need have the
field 
key.   A trace identifier in the form "trace0", "trace1", etc. is returned.
  
Ops indicates which operations are of interest, and consists of one or
more of the following letters: 
r Invoke command whenever key is read. Both
read and write traces are temporarily disabled when 
command is executed.
w Invoke command whenever key is written.  Both read and write traces are
temporarily disabled when 
command is executed. c Invoke command whenever
key is created. u  Invoke command whenever key is unset.  Data fields are
typically unset with the 
unset command.   Data fields are also  unset when
the tree is released, but all traces are disabled prior to that. 
treeNametrace delete traceId... Deletes one of more traces.  TraceId is the trace identifier
returned by the 
trace create operation. treeName trace info traceId  Returns
information about the trace 
traceId.  TraceId is a trace identifier previously
returned by the 
trace create operation. It's the same information specified
for the 
trace create operation. It consists of the node id or tag, data
field key, a string of letters indicating the operations that are traced
(it's in the same form as 
ops) and, the command prefix. treeName trace namesReturns a list of identifers for all the current traces. #toc11Notify Operations 
Tree
objects can be shared among many clients, such as a 
hiertable widget.  Any
client can create or delete nodes, sorting the tree, etc.  You can request
to be notified whenever these events occur.  Notify events cause Tcl commands
to be executed whenever the tree structure is changed.   
Notifications are
handled by the 
notify operation.  The general form is treeName notify operation ?arg?...Both operation and its arguments determine the exact behavior of the command.
 The operations available for events are listed below. 
treeName notify create?
switches? command ?args?...   Creates a notifier for the tree.  A notify identifier
in the form "
notify0", "notify1", etc.  is returned. Command and args are
saved and invoked whenever the tree structure is changed (according to
switches). Two arguments are appended to command and args before it's invoked:
the id of the node and a string representing the type of event that occured.
One of more switches can be set to indicate the events that are of interest.
 The valid switches are as follows: 
-create  Invoke command whenever a new
node has been added. 
-delete Invoke command whenever a node has been deleted.
-move Invoke command whenever a node has been moved. -sort Invoke commandwhenever the tree has been sorted and reordered. 
-relabel Invoke commandwhenever a node has been relabeled. 
-allevents Invoke command whenever any
of the above events occur. 
-whenidle When an event occurs don't invoke commandimmediately, but queue it to be run the next time the event loop is entered
and there  are no events to process.  If subsequent events occur before
 the event loop is entered, 
command will still be  invoked only once. treeNamenotify delete notifyId  Deletes one or more notifiers from the tree.  NotifyIdis the notifier identifier returned by the 
notify create operation. treeNamenotify info notifyId Returns information about the notify event notifyId.
 
NotifyId is a notify identifier previously returned by the notify createoperation. It's the same information specified for the 
notify create operation.
It consists of the notify id, a sublist of event flags (it's in the same
form as 
flags) and, the command prefix. treeName notify names Returns a
list of identifers for all the current notifiers. 
#toc12C Language API 
Blt_TreeApply,
 Blt_TreeApplyBFS,  Blt_TreeApplyDFS,  Blt_TreeChangeRoot,  Blt_TreeCreate,
 Blt_TreeCreateEventHandler,  Blt_TreeCreateNode,  Blt_TreeCreateTrace,
 Blt_TreeDeleteEventHandler,  Blt_TreeDeleteNode,  Blt_TreeDeleteTrace,
 Blt_TreeExists,  Blt_TreeFindChild,  Blt_TreeFirstChild,  Blt_TreeFirstKey,
 Blt_TreeGetNode,  Blt_TreeGetToken,  Blt_TreeGetValue,  Blt_TreeIsAncestor,
 Blt_TreeIsBefore,  Blt_TreeIsLeaf,  Blt_TreeLastChild,  Blt_TreeMoveNode,
 Blt_TreeName,  Blt_TreeNextKey,  Blt_TreeNextNode,  Blt_TreeNextSibling,
 Blt_TreeNodeDegree,  Blt_TreeNodeDepth,  Blt_TreeNodeId,  Blt_TreeNodeLabel,
 Blt_TreeNodeParent,  Blt_TreePrevNode,  Blt_TreePrevSibling,  Blt_TreeRelabelNode,
 Blt_TreeReleaseToken,  Blt_TreeRootNode,  Blt_TreeSetValue,  Blt_TreeSize,
 Blt_TreeSortNode, and Blt_TreeUnsetValue. 
#toc13Keywords 
tree, hiertable, widget
Table of Contents #sect0Name #sect1Synopsis #sect2Description #sect3Introduction #sect4Example #sect5Syntax #sect6Node IDs and Tags #sect7Node Modifiers #sect8Tree Operations #sect9Tag Operations #sect10Trace Operations #sect11Notify Operations #sect12C Language API #sect13Keywords 