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n_cst_treenode

Description

Tree list instance object. Each element in a balanced binary tree is an instance of n_cst_treenode. N_cst_treenode contains balance information as well as functions to copy nodes and balance the tree.

Ancestry

Figure

Library

  • PFCAPSRV.PBL
  • PFEAPSRV.PBL

Usage

Use n_cst_treenode to create nodes for use with n_cst_tree.

To use n_cst_treenode:

  1. Declare a variable for your list (an instance variable in this example):

    n_cst_tree inv_tree

  2. Declare variables for tree nodes (local variables in this example):

    n_cst_treenode lnv_node

  3. Create the node instance:

    lnv_node = CREATE n_cst_treenode

You can also call the n_cst_tree of_Create function to create a tree node instance.

  1. Access the node’s key and data values as appropriate:

    lnv_node.of_SetKey(sle_1.text)
lnv_node.of_SetData(sle_1.text)

  2. Call tree processing functions as appropriate:

    li_return = inv_tree.of_Add(lnv_node)

See also

Instance variables

N_cst_treenode includes instance variables:

Instance variable Description Data type Access Usage
ii_balance Current tree balance Integer Protected Set with of_SetBalance

Functions

N_cst_treenode includes precoded object functions:
of_CopyTo of_SetBalance
of_GetBalance

of_CopyTo

Description

Copies the data and key of the passed node into the current node.

Access

Public

Syntax

instancename.of_CopyTo ( targetnode )
Argument Description
instancename Instance name of n_cst_treenode
targetnode N_cst_treenode instance whose data and key are copied to instancename (passed by reference)

Return value

Integer. Returns 1 if the function succeeds and -1 if an error occurs.

Usage

If you extend n_cst_treenode, be sure to override this function to copy all added data elements as well as the ia_key and ia_data instance variables.

Examples

This example calls the of_CopyTo function:

n_cst_treenode  lnv_node, lnv_temp, lnv_copy
Long  ll_return
Any  la_data

lnv_temp = CREATE n_cst_treenode

lnv_temp.of_SetKey(sle_2.text)
ll_return = inv_tree.of_Find(lnv_node, lnv_temp)
IF ll_return < 1 THEN
   MessageBox("Not Found",  &
      "The specified node was not found")
   Return
END IF
lnv_copy = CREATE n_cst_treenode
ll_return = lnv_node.of_CopyTo(lnv_copy)
IF ll_return = 1 THEN
   lnv_copy.of_GetData(la_data)
   MessageBox("Success",   &
      "Node copied successfully~r~n"  &
         + "Data is: " + String(la_data))
END IF

of_GetBalance

Description

Retrieves the current balance of a tree list.

Access

Public

Syntax

instancename.of_GetBalance ( )
Argument Description
instancename Instance name of n_cst_treenode

Return value

Integer. Returns values as follows:

  • 1 Right branch is one level higher than the left
  • 0 Tree is balanced
  • -1 Left branch is one level higher than the right

Usage

Internal.

Examples

This example calls the of_GetBalance function:

...
choose case anv_currentnode.of_GetBalance()
   case 1
      anv_currentnode.of_SetBalance(0)
      ab_height = false
...

of_SetBalance

Description

Sets the current balance in a tree list.

Access

Public

Syntax

instancename.of_SetBalance ( balancelevel )
Argument Description
instancename Instance name of n_cst_treenode
balancelevel Integer specifying the balance level. Valid values are:
• 1 Right branch is one level higher than the left
• 0 Tree is balanced
• -1 Left branch is one level higher than the right

Return value

Integer. Returns 1 if the function succeeds and -1 if an error occurs.

Examples

This example calls the of_SetBalance function:

...
anv_newnode.of_SetBalance(0)
anv_currentnode = anv_newnode
...