--- name: "struct_tree1" section: "3tcl" platform: "linux" package: "tcllib" version: "2.0+dfsg-4" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/struct_tree1" --- # struct\_tree1(3tcl) Create and manipulate tree objects ``` ``` ## NAME struct::tree\_v1 - Create and manipulate tree objects ## SYNOPSIS package require **Tcl 8.5 9** package require **struct::tree ?1.2.3?** **treeName** **option** ?*arg arg ...*? *treeName* **append** *node* ?-key *key*? *value* *treeName* **children** *node* *treeName* **cut** *node* *treeName* **delete** *node* ?*node* ...? *treeName* **depth** *node* *treeName* **destroy** *treeName* **exists** *node* *treeName* **get** *node* ?**-key** *key*? *treeName* **getall** *node* *treeName* **keys** *node* *treeName* **keyexists** *node* ?-key *key*? *treeName* **index** *node* *treeName* **insert** *parent* *index* ?*child* ?*child* ...?? *treeName* **isleaf** *node* *treeName* **lappend** *node* ?-key *key*? *value* *treeName* **move** *parent* *index* *node* ?*node* ...? *treeName* **next** *node* *treeName* **numchildren** *node* *treeName* **parent** *node* *treeName* **previous** *node* *treeName* **set** *node* ?**-key** *key*? ?*value*? *treeName* **size** ?*node*? *treeName* **splice** *parent* *from* ?*to*? ?*child*? *treeName* **swap** *node1* *node2* *treeName* **unset** *node* ?**-key** *key*? *treeName* **walk** *node* ?**-order** *order*? ?**-type** *type*? **-command** *cmd* ``` ``` ## DESCRIPTION The **::struct::tree** command creates a new tree object with an associated global Tcl command whose name is *treeName*. This command may be used to invoke various operations on the tree. It has the following general form: - **treeName** **option** ?*arg arg ...*? *Option* and the *arg*s determine the exact behavior of the command. A tree is a collection of named elements, called nodes, one of which is distinguished as a root, along with a relation ("parenthood") that places a hierarchical structure on the nodes. (Data Structures and Algorithms; Aho, Hopcroft and Ullman; Addison-Wesley, 1987). In addition to maintaining the node relationships, this tree implementation allows any number of keyed values to be associated with each node. The element names can be arbitrary strings. A tree is thus similar to an array, but with three important differences: - \[1\] Trees are accessed through an object command, whereas arrays are accessed as variables. (This means trees cannot be local to a procedure.) - \[2\] Trees have a hierarchical structure, whereas an array is just an unordered collection. - \[3\] Each node of a tree has a separate collection of attributes and values. This is like an array where every value is a dictionary. The following commands are possible for tree objects: - *treeName* **append** *node* ?-key *key*? *value* Appends a *value* to one of the keyed values associated with an node. If no *key* is specified, the key **data** is assumed. - *treeName* **children** *node* Return a list of the children of *node*. - *treeName* **cut** *node* Removes the node specified by *node* from the tree, but not its children. The children of *node* are made children of the parent of the *node*, at the index at which *node* was located. - *treeName* **delete** *node* ?*node* ...? Removes the specified nodes from the tree. All of the nodes' children will be removed as well to prevent orphaned nodes. - *treeName* **depth** *node* Return the number of steps from node *node* to the root node. - *treeName* **destroy** Destroy the tree, including its storage space and associated command. - *treeName* **exists** *node* Returns true if the specified node exists in the tree. - *treeName* **get** *node* ?**-key** *key*? Return the value associated with the key *key* for the node *node*. If no key is specified, the key **data** is assumed. - *treeName* **getall** *node* Returns a serialized list of key/value pairs (suitable for use with \[**array set**\]) for the *node*. - *treeName* **keys** *node* Returns a list of keys for the *node*. - *treeName* **keyexists** *node* ?-key *key*? Return true if the specified *key* exists for the *node*. If no *key* is specified, the key **data** is assumed. - *treeName* **index** *node* Returns the index of *node* in its parent's list of children. For example, if a node has *nodeFoo*, *nodeBar*, and *nodeBaz* as children, in that order, the index of *nodeBar* is 1. - *treeName* **insert** *parent* *index* ?*child* ?*child* ...?? Insert one or more nodes into the tree as children of the node *parent*. The nodes will be added in the order they are given. If *parent* is **root**, it refers to the root of the tree. The new nodes will be added to the *parent* node's child list at the index given by *index*. The *index* can be **end** in which case the new nodes will be added after the current last child. If any of the specified children already exist in *treeName*, those nodes will be moved from their original location to the new location indicated by this command. If no *child* is specified, a single node will be added, and a name will be generated for the new node. The generated name is of the form *node***x**, where **x** is a number. If names are specified they must neither contain whitespace nor colons (":"). The return result from this command is a list of nodes added. - *treeName* **isleaf** *node* Returns true if *node* is a leaf of the tree (if *node* has no children), false otherwise. - *treeName* **lappend** *node* ?-key *key*? *value* Appends a *value* (as a list) to one of the keyed values associated with an *node*. If no *key* is specified, the key **data** is assumed. - *treeName* **move** *parent* *index* *node* ?*node* ...? Make the specified nodes children of *parent*, inserting them into the parent's child list at the index given by *index*. Note that the command will take all nodes out of the tree before inserting them under the new parent, and that it determines the position to place them into after the removal, before the re-insertion. This behaviour is important when it comes to moving one or more nodes to a different index without changing their parent node. - *treeName* **next** *node* Return the right sibling of *node*, or the empty string if *node* was the last child of its parent. - *treeName* **numchildren** *node* Return the number of immediate children of *node*. - *treeName* **parent** *node* Return the parent of *node*. - *treeName* **previous** *node* Return the left sibling of *node*, or the empty string if *node* was the first child of its parent. - *treeName* **set** *node* ?**-key** *key*? ?*value*? Set or get one of the keyed values associated with a node. If no key is specified, the key **data** is assumed. Each node that is added to a tree has the value "" assigned to the key **data** automatically. A node may have any number of keyed values associated with it. If *value* is not specified, this command returns the current value assigned to the key; if *value* is specified, this command assigns that value to the key. - *treeName* **size** ?*node*? Return a count of the number of descendants of the node *node*; if no node is specified, **root** is assumed. - *treeName* **splice** *parent* *from* ?*to*? ?*child*? Insert a node named *child* into the tree as a child of the node *parent*. If *parent* is **root**, it refers to the root of the tree. The new node will be added to the parent node's child list at the index given by *from*. The children of *parent* which are in the range of the indices *from* and *to* are made children of *child*. If the value of *to* is not specified it defaults to **end**. If no name is given for *child*, a name will be generated for the new node. The generated name is of the form *node***x**, where **x** is a number. The return result from this command is the name of the new node. - *treeName* **swap** *node1* *node2* Swap the position of *node1* and *node2* in the tree. - *treeName* **unset** *node* ?**-key** *key*? Removes a keyed value from the node *node*. If no key is specified, the key **data** is assumed. - *treeName* **walk** *node* ?**-order** *order*? ?**-type** *type*? **-command** *cmd* Perform a breadth-first or depth-first walk of the tree starting at the node *node*. The type of walk, breadth-first or depth-first, is determined by the value of *type*; **bfs** indicates breadth-first, **dfs** indicates depth-first. Depth-first is the default. The order of the walk, pre-, post-, both- or in-order is determined by the value of *order*; **pre** indicates pre-order, **post** indicates post-order, **both** indicates both-order and **in** indicates in-order. Pre-order is the default. Pre-order walking means that a parent node is visited before any of its children. For example, a breadth-first search starting from the root will visit the root, followed by all of the root's children, followed by all of the root's grandchildren. Post-order walking means that a parent node is visited after any of its children. Both-order walking means that a parent node is visited before *and* after any of its children. In-order walking means that a parent node is visited after its first child and before the second. This is a generalization of in-order walking for binary trees and will do the right thing if a binary is walked. The combination of a breadth-first walk with in-order is illegal. As the walk progresses, the command *cmd* will be evaluated at each node. Percent substitution will be performed on *cmd* before evaluation, just as in a **bind** script. The following substitutions are recognized: - **%%** Insert the literal % character. - **%t** Name of the tree object. - **%n** Name of the current node. - **%a** Name of the action occurring; one of **enter**, **leave**, or **visit**. **enter** actions occur during pre-order walks; **leave** actions occur during post-order walks; **visit** actions occur during in-order walks. In a both-order walk, the command will be evaluated twice for each node; the action is **enter** for the first evaluation, and **leave** for the second. ## BUGS, IDEAS, FEEDBACK This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category *struct :: tree* of the *Tcllib Trackers* \[http://core.tcl.tk/tcllib/reportlist\]. Please also report any ideas for enhancements you may have for either package and/or documentation. When proposing code changes, please provide *unified diffs*, i.e the output of **diff -u**. Note further that *attachments* are strongly preferred over inlined patches. Attachments can be made by going to the **Edit** form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar. ## KEYWORDS tree ## CATEGORY Data structures ## COPYRIGHT ``` Copyright (c) 2002 Andreas Kupries ```