tree(n) BLT Built-In Commands tree(n)______________________________________________________________________________NAME
tree - Create and manage tree data objects.
SYNOPSIS
blt::tree create ?treeName?
blt::tree destroy treeName...
blt::tree names ?pattern?
_________________________________________________________________DESCRIPTION
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.
INTRODUCTIONEXAMPLESYNTAX
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 cre‐
ated. 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.
NODE 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 currently 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.
NODE 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.
TREE 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 oper‐
ation and its arguments determine the exact behavior of the command.
The operations available for trees are listed below.
treeName ancestor node1 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 node2 are 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. By default each
pattern will be compared with the node label. You can set more
than one of these switches. If any of the patterns match (logi‐
cal or), the node matches. If the -key switch is used, it des‐
ignates 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 match‐
ing. 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.
-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. The
node's full path is a list of labels, starting from
the root of each ancestor and the node itself.
-precommand 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 gen‐
erated. 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 gen‐
erated. 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? parentNode ?switches?
Copies srcNode into parentNode. Both nodes srcNode and parentN‐
ode must already exist. The id of the new node is returned. You
can copy from one tree to another. If a 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:
-label string
Label destNode as string. By default, destNode has the
same label as srcNode.
-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.
treeName dumpfile 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 sub‐
list of tags. This list returned can be used later to copy or
restore the tree with the restore operation.
treeName exists 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. By default each
pattern will be compared with the node label. You can set more
than one of these switches. If any of the patterns match (logi‐
cal or), the node matches. If the -key switch is used, it des‐
ignates 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 gen‐
erated. 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 match‐
ing. 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.
-key key Compare the values of the data field keyed by key
instead of the node's label. If no pattern is given
(-exact, -glob, or -regexp switches), 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 string as 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 sub‐
trees. 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 defaultValue argument,
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.
treeName index 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:
-after child
Position node after child. The node child must be a
child of parent.
-at number
Inserts the node into parent's list of children at
position number. The default is to append node.
-before child
Position node before child. The node child must be a
child of parent.
-data dataList
Sets the value for each data field in dataList for 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.
-node id Designates the id for the node. Normally new ids are
automatically generated. This allows you to create a
node with a specific id. It is an error if the id is
already used by another node in the tree.
-tags tagList
Adds each tag in tagList to the new node. TagList is a
list of tags, so be careful if a tag has embedded
space.
treeName is property args
Indicates the property of a node. Both property and args deter‐
mine the property being tested. Returns 1 if true and 0 other‐
wise. The following property and args are valid:
ancestor node1 node2
Indicates if node1 is an ancestor of node2.
before node1 node2
Indicates if node1 is before node2 in depth first tra‐
versal.
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 node
Returns the id of the last child in the node's list of subtrees.
If node is 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 posi‐
tion 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 node in 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 struc‐
ture 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.
treeName path node
Returns the full path (from root) of node.
treeName position node
Returns the position of the node in its parent's list of chil‐
dren. Positions are numbered from 0. The position of the root
node is always 0.
treeName previous node
Returns the previous node from node in a preorder traversal. If
node is the root of the tree, then -1 is returned.
treeName prevsibling node
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 dataString is exactly what is
returned by the dump operation. It's a list containing informa‐
tion 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, restor‐
ing 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, pre‐
vious, 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 string as a comparison command. To com‐
pare 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 ele‐
ment 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.
-integer Compare 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 sec‐
tion below.
treeName trace args
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 spe‐
cific node or a tag, representing possibly many nodes. See the
TRACE OPERATIONS section below.
treeName unset node 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.
TAG 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 string node...
Adds the tag string to one of more nodes.
treeName tag delete string node...
Deletes the tag string from one or more nodes.
treeName tag forget string
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 node are 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.
TRACE 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 create node 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 iden‐
tifier 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.
treeName trace 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 opera‐
tion. 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 names
Returns a list of identifers for all the current traces.
NOTIFY OPERATIONS
Tree objects can be shared among many clients, such as a hiertable wid‐
get. 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 struc‐
ture 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 command whenever the tree has been sorted and
reordered.
-relabel Invoke command whenever a node has been relabeled.
-allevents
Invoke command whenever any of the above events occur.
-whenidle When an event occurs don't invoke command immediately,
but queue it to be run the next time the event loop is
entered and there are no events to process. If subse‐
quent events occur before the event loop is entered,
command will still be invoked only once.
treeName notify delete notifyId
Deletes one or more notifiers from the tree. NotifyId is the
notifier identifier returned by the notify create operation.
treeName notify info notifyId
Returns information about the notify event notifyId. NotifyId
is a notify identifier previously returned by the notify create
operation. 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.
C 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_TreeGetTo‐
ken, Blt_TreeGetValue, Blt_TreeIsAncestor, Blt_TreeIsBefore,
Blt_TreeIsLeaf, Blt_TreeLastChild, Blt_TreeMoveNode, Blt_TreeName,
Blt_TreeNextKey, Blt_TreeNextNode, Blt_TreeNextSibling, Blt_TreeNodeDe‐
gree, Blt_TreeNodeDepth, Blt_TreeNodeId, Blt_TreeNodeLabel, Blt_TreeN‐
odeParent, Blt_TreePrevNode, Blt_TreePrevSibling, Blt_TreeRelabelNode,
Blt_TreeReleaseToken, Blt_TreeRootNode, Blt_TreeSetValue, Blt_TreeSize,
Blt_TreeSortNode, and Blt_TreeUnsetValue.
KEYWORDS
tree, hiertable, widget
BLT 2.4 tree(n)
