Table of Contents

## Name

Blt_Tree - Tree data object.

## Synopsis

    #include <bltTree.h>

    struct Blt_Tree {
    Tcl_Alloc(size)

    Tcl_Free(ptr)

    char *
    Tcl_Realloc(ptr, size)

## Arguments

int size`` `` (in)
`` `` Size in bytes of the memory block to allocate.

char *ptr`` `` (in)
`` `` Pointer to memory block to free or realloc.

## Description

These procedures provide a platform and compiler independent interface for memory allocation. Programs that need to transfer ownership of memory blocks between Tcl and other modules should use these routines rather than the native malloc() and free() routines provided by the C run-time library.

Tcl_Alloc returns a pointer to a block of at least size bytes suitably aligned for any use.

Tcl_Free makes the space referred to by ptr available for further allocation.

Tcl_Realloc changes the size of the block pointed to by ptr to size bytes and returns a pointer to the new block. The contents will be unchanged up to the lesser of the new and old sizes. The returned location may be different from ptr.

## Tree Object Routines

The following library routines allow you to create and destroy tree objects. Each tree object has a name that uniquely identifies it. Tree objects can also be shared. For example, the tree and hiertable commands may access the same tree data object. Each client grabs a token associated with the tree. When all tokens are released the tree data object is automatically destroyed.

Blt_TreeCreate
  Create a tree data object and optionally obtains a token associated with it.
Blt_TreeExists
  Indicates if a tree by a given name exists.
Blt_TreeGetToken
  Obtains a token for an existing tree data object.
Blt_TreeReleaseToken
  Releases a token for a tree data object. The tree object is deleted when all outstanding tokens have been released.
Blt_TreeName
  Returns the name of the tree object.
Blt_TreeChangeRoot
  Specifies a node as the new root to a tree.

## Treenode Routines

Tree objects initially contain only a root node. You can add or delete nodes with the following routines.

Blt_TreeCreateNode
  Creates a new child node for a given parent in the tree.
Blt_TreeDeleteNode
  Deletes a node and its children.
Blt_TreeNodeId
  Returns the unique node identifier for a node.
Blt_TreeGetNode
  Gets a node based upon its identifier.
Blt_TreeFindChild
  Searches for a child node given by its label in a parent node.
Blt_TreeNodeLabel
  Returns the current label for a node.
Blt_TreeRelabelNode
  Resets a node's label.
Blt_TreeNodePath
  Returns the fullpath to a node.
Blt_TreeNodeDepth
  Returns the depth of the node.
Blt_TreeNodeDegree
  Returns the number of children for a node.
Blt_TreeIsLeaf
  Indicates if a node has no children.
Blt_TreeIsBefore
  Indicates if a node is before another node in depth-first search order.
Blt_TreeIsAncestor
  Indicates if a node is an ancestor or another.
Blt_TreeSortNode
  Sorts the children of a node.
Blt_TreeSize
  Returns the number of nodes in a node and its descendants.
Blt_TreeMoveNode

## Node Navigation

Each node can have zero or more children nodes. These routines let you navigate the tree hierarchy.

Blt_TreeNodeParent
  Returns the parent node.
Blt_TreeFirstChild
  Returns the first child of a parent node.
Blt_TreeLastChild
  Returns the last child of a parent node.
Blt_TreeNextSibling
  Returns the next sibling node in the parent's list of children.
Blt_TreePrevSibling
  Returns the previous sibling node in the parent's list of children.
Blt_TreeRootNode
  Returns the root node of the tree.
Blt_TreeNextNode
  Returns the next node in depth-first order.
Blt_TreePrevNode
  Returns the previous node in depth-first order.
Blt_TreeEndNode
  Returns the last node in the tree as determined by depth-first order.
Blt_TreeApply
  Walks through a node and all it descendants, applying a given callback procedure.
Blt_TreeApplyDFS
  Walks through a node and all it descendants in depth-first search order, applying a given callback procedure.
Blt_TreeApplyBFS
  Walks through a node and all it descendants in breadth-first search order, applying a given callback procedure.

## Node Data Values

Data values can be stored at any node. Values have by both a string key and a Tcl_Obj value. Data value keys do not have to be homogenous across all nodes (i.e. nodes do not have to contain the same keys). There is also a special node array data type.

Blt_TreeGetValue
  Gets the node data value given by a key.
Blt_TreeValueExists
  Indicates if a node data value given by a key exists.
Blt_TreeSetValue
  Sets a node's value of a key.
Blt_TreeUnsetValue
  Remove the node data value and key.
Blt_TreeGetArrayValue
  Gets the node data array value given by a key and an array index.
Blt_TreeSetArrayValue
  Sets the node data array value given by a key and an array index.
Blt_TreeUnsetArrayValue
  Remove the node data array value.
Blt_TreeArrayValueExists
  Determines if an array element by a given index exists.
Blt_TreeFirstKey
  Returns the key of the first value in the node.
Blt_TreeNextKey
  Returns the key of the next value in the node.
Blt_TreePrivateValue
  Lock the value to current client, making it private.
Blt_TreePublicValue
  Unlock the value so that all clients can access it.
Blt_TreeGetKey

## Node Traces

Blt_TreeCreateTrace
  Sets up a trace callback to be invoked when the node value is read, set, or unset.
Blt_TreeDeleteTrace
  Deletes an existing trace.

## Node Events

Blt_TreeCreateEventHandler
  Sets up a callback to be invoked when events (create, delete, relabel, etc) take place on a node.
Blt_TreeDeleteEventHandler
  Deletes an existing node callback.

## Keywords

alloc, allocation, free, malloc, memory, realloc

Table of Contents

- Name
- Synopsis
- Arguments
- Description
- Tree Object Routines
- Treenode Routines
- Node Navigation
- Node Data Values
- Node Traces
- Node Events
- Keywords