Table of Contents
tree - Create and manage tree data objects.
blt::tree
create ?treeName?
blt::tree destroy treeName...
blt::tree names ?pattern?
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.
- 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.
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.
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.
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 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. 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'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.
- -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 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.
- 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 sublist 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. 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.
- -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.
- -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 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 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:
- -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 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.
- -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
determine 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 node1
is 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 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 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 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 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.
- 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 children. 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
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 string
as 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.
- -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
section 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 specific 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.
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.
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 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.
- 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 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 names
- Returns a list of identifers for all the current traces.
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 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 subsequent 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.
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.
tree, hiertable, widget
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