N:blt tree
From Linux Man Pages
tree - Create and manage tree data objects.
Contents |
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.
INTRODUCTION
EXAMPLE
SYNTAX
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 refer-
ence 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 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. 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 (logical or), the node matches. 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 val-
ues 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, start-
ing 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 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? parentNode ?switches?
Copies srcNode into parentNode. Both nodes srcNode and parentNode 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 indi-
cates 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 opera-
tion.
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 (logical or), the node matches. 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 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 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:
-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 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 ances-
tor 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 OPERA-
TIONS 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 file-
Name. The format of fileName is exactly what is returned by the dumpfile operation. It's a list contain-
ing 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 ances-
tor 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 con-
sisting 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 con-
sidered 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.
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 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 com-
mand 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.
NOTIFY 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 represent-
ing 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 pre-
fix.
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_TreeCreateEven-
tHandler, 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.
KEYWORDS
tree, hiertable, widget