N-ary Trees

N-ary Trees — trees of data with any number of branches

Types and Values

Includes

#include <glib.h>

Description

The GNode struct and its associated functions provide a N-ary tree data structure, where nodes in the tree can contain arbitrary data.

To create a new tree use g_node_new().

To insert a node into a tree use g_node_insert(), g_node_insert_before(), g_node_append() and g_node_prepend().

To create a new node and insert it into a tree use g_node_insert_data(), g_node_insert_data_after(), g_node_insert_data_before(), g_node_append_data() and g_node_prepend_data().

To reverse the children of a node use g_node_reverse_children().

To find a node use g_node_get_root(), g_node_find(), g_node_find_child(), g_node_child_index(), g_node_child_position(), g_node_first_child(), g_node_last_child(), g_node_nth_child(), g_node_first_sibling(), g_node_prev_sibling(), g_node_next_sibling() or g_node_last_sibling().

To get information about a node or tree use G_NODE_IS_LEAF(), G_NODE_IS_ROOT(), g_node_depth(), g_node_n_nodes(), g_node_n_children(), g_node_is_ancestor() or g_node_max_height().

To traverse a tree, calling a function for each node visited in the traversal, use g_node_traverse() or g_node_children_foreach().

To remove a node or subtree from a tree use g_node_unlink() or g_node_destroy().

Functions

g_node_new ()

GNode *
g_node_new (gpointer data);

Creates a new GNode containing the given data. Used to create the first node in a tree.

Parameters

data

the data of the new node

 

Returns

a new GNode


g_node_copy ()

GNode *
g_node_copy (GNode *node);

Recursively copies a GNode (but does not deep-copy the data inside the nodes, see g_node_copy_deep() if you need that).

Parameters

node

a GNode

 

Returns

a new GNode containing the same data pointers


GCopyFunc ()

gpointer
(*GCopyFunc) (gconstpointer src,
              gpointer data);

A function of this signature is used to copy the node data when doing a deep-copy of a tree.

Parameters

src

A pointer to the data which should be copied.

[not nullable]

data

Additional data

 

Returns

A pointer to the copy.

[not nullable]

Since: 2.4


g_node_copy_deep ()

GNode *
g_node_copy_deep (GNode *node,
                  GCopyFunc copy_func,
                  gpointer data);

Recursively copies a GNode and its data.

Parameters

node

a GNode

 

copy_func

the function which is called to copy the data inside each node, or NULL to use the original data.

 

data

data to pass to copy_func

 

Returns

a new GNode containing copies of the data in node .

Since: 2.4


g_node_insert ()

GNode *
g_node_insert (GNode *parent,
               gint position,
               GNode *node);

Inserts a GNode beneath the parent at the given position.

Parameters

parent

the GNode to place node under

 

position

the position to place node at, with respect to its siblings If position is -1, node is inserted as the last child of parent

 

node

the GNode to insert

 

Returns

the inserted GNode


g_node_insert_before ()

GNode *
g_node_insert_before (GNode *parent,
                      GNode *sibling,
                      GNode *node);

Inserts a GNode beneath the parent before the given sibling.

Parameters

parent

the GNode to place node under

 

sibling

the sibling GNode to place node before. If sibling is NULL, the node is inserted as the last child of parent .

 

node

the GNode to insert

 

Returns

the inserted GNode


g_node_insert_after ()

GNode *
g_node_insert_after (GNode *parent,
                     GNode *sibling,
                     GNode *node);

Inserts a GNode beneath the parent after the given sibling.

Parameters

parent

the GNode to place node under

 

sibling

the sibling GNode to place node after. If sibling is NULL, the node is inserted as the first child of parent .

 

node

the GNode to insert

 

Returns

the inserted GNode


g_node_append()

#define             g_node_append(parent, node)

Inserts a GNode as the last child of the given parent.

Parameters

parent

the GNode to place the new GNode under

 

node

the GNode to insert

 

Returns

the inserted GNode


g_node_prepend ()

GNode *
g_node_prepend (GNode *parent,
                GNode *node);

Inserts a GNode as the first child of the given parent.

Parameters

parent

the GNode to place the new GNode under

 

node

the GNode to insert

 

Returns

the inserted GNode


g_node_insert_data()

#define             g_node_insert_data(parent, position, data)

Inserts a new GNode at the given position.

Parameters

parent

the GNode to place the new GNode under

 

position

the position to place the new GNode at. If position is -1, the new GNode is inserted as the last child of parent

 

data

the data for the new GNode

 

Returns

the new GNode


g_node_insert_data_after()

#define             g_node_insert_data_after(parent, sibling, data)

Inserts a new GNode after the given sibling.

Parameters

parent

the GNode to place the new GNode under

 

sibling

the sibling GNode to place the new GNode after

 

data

the data for the new GNode

 

Returns

the new GNode


g_node_insert_data_before()

#define             g_node_insert_data_before(parent, sibling, data)

Inserts a new GNode before the given sibling.

Parameters

parent

the GNode to place the new GNode under

 

sibling

the sibling GNode to place the new GNode before

 

data

the data for the new GNode

 

Returns

the new GNode


g_node_append_data()

#define             g_node_append_data(parent, data)

Inserts a new GNode as the last child of the given parent.

Parameters

parent

the GNode to place the new GNode under

 

data

the data for the new GNode

 

Returns

the new GNode


g_node_prepend_data()

#define             g_node_prepend_data(parent, data)

Inserts a new GNode as the first child of the given parent.

Parameters

parent

the GNode to place the new GNode under

 

data

the data for the new GNode

 

Returns

the new GNode


g_node_reverse_children ()

void
g_node_reverse_children (GNode *node);

Reverses the order of the children of a GNode. (It doesn't change the order of the grandchildren.)

Parameters

node

a GNode.

 

g_node_traverse ()

void
g_node_traverse (GNode *root,
                 GTraverseType order,
                 GTraverseFlags flags,
                 gint max_depth,
                 GNodeTraverseFunc func,
                 gpointer data);

Traverses a tree starting at the given root GNode. It calls the given function for each node visited. The traversal can be halted at any point by returning TRUE from func .

Parameters

root

the root GNode of the tree to traverse

 

order

the order in which nodes are visited - G_IN_ORDER, G_PRE_ORDER, G_POST_ORDER, or G_LEVEL_ORDER.

 

flags

which types of children are to be visited, one of G_TRAVERSE_ALL, G_TRAVERSE_LEAVES and G_TRAVERSE_NON_LEAVES

 

max_depth

the maximum depth of the traversal. Nodes below this depth will not be visited. If max_depth is -1 all nodes in the tree are visited. If depth is 1, only the root is visited. If depth is 2, the root and its children are visited. And so on.

 

func

the function to call for each visited GNode

 

data

user data to pass to the function

 

GNodeTraverseFunc ()

gboolean
(*GNodeTraverseFunc) (GNode *node,
                      gpointer data);

Specifies the type of function passed to g_node_traverse(). The function is called with each of the nodes visited, together with the user data passed to g_node_traverse(). If the function returns TRUE, then the traversal is stopped.

Parameters

node

a GNode.

 

data

user data passed to g_node_traverse().

 

Returns

TRUE to stop the traversal.


g_node_children_foreach ()

void
g_node_children_foreach (GNode *node,
                         GTraverseFlags flags,
                         GNodeForeachFunc func,
                         gpointer data);

Calls a function for each of the children of a GNode. Note that it doesn't descend beneath the child nodes.

Parameters

node

a GNode

 

flags

which types of children are to be visited, one of G_TRAVERSE_ALL, G_TRAVERSE_LEAVES and G_TRAVERSE_NON_LEAVES

 

func

the function to call for each visited node

 

data

user data to pass to the function

 

GNodeForeachFunc ()

void
(*GNodeForeachFunc) (GNode *node,
                     gpointer data);

Specifies the type of function passed to g_node_children_foreach(). The function is called with each child node, together with the user data passed to g_node_children_foreach().

Parameters

node

a GNode.

 

data

user data passed to g_node_children_foreach().

 

g_node_get_root ()

GNode *
g_node_get_root (GNode *node);

Gets the root of a tree.

Parameters

node

a GNode

 

Returns

the root of the tree


g_node_find ()

GNode *
g_node_find (GNode *root,
             GTraverseType order,
             GTraverseFlags flags,
             gpointer data);

Finds a GNode in a tree.

Parameters

root

the root GNode of the tree to search

 

order

the order in which nodes are visited - G_IN_ORDER, G_PRE_ORDER, G_POST_ORDER, or G_LEVEL_ORDER

 

flags

which types of children are to be searched, one of G_TRAVERSE_ALL, G_TRAVERSE_LEAVES and G_TRAVERSE_NON_LEAVES

 

data

the data to find

 

Returns

the found GNode, or NULL if the data is not found


g_node_find_child ()

GNode *
g_node_find_child (GNode *node,
                   GTraverseFlags flags,
                   gpointer data);

Finds the first child of a GNode with the given data.

Parameters

node

a GNode

 

flags

which types of children are to be searched, one of G_TRAVERSE_ALL, G_TRAVERSE_LEAVES and G_TRAVERSE_NON_LEAVES

 

data

the data to find

 

Returns

the found child GNode, or NULL if the data is not found


g_node_child_index ()

gint
g_node_child_index (GNode *node,
                    gpointer data);

Gets the position of the first child of a GNode which contains the given data.

Parameters

node

a GNode

 

data

the data to find

 

Returns

the index of the child of node which contains data , or -1 if the data is not found


g_node_child_position ()

gint
g_node_child_position (GNode *node,
                       GNode *child);

Gets the position of a GNode with respect to its siblings. child must be a child of node . The first child is numbered 0, the second 1, and so on.

Parameters

node

a GNode

 

child

a child of node

 

Returns

the position of child with respect to its siblings


g_node_first_child()

#define             g_node_first_child(node)

Gets the first child of a GNode.

Parameters

node

a GNode

 

Returns

the first child of node , or NULL if node is NULL or has no children


g_node_last_child ()

GNode *
g_node_last_child (GNode *node);

Gets the last child of a GNode.

Parameters

node

a GNode (must not be NULL)

 

Returns

the last child of node , or NULL if node has no children


g_node_nth_child ()

GNode *
g_node_nth_child (GNode *node,
                  guint n);

Gets a child of a GNode, using the given index. The first child is at index 0. If the index is too big, NULL is returned.

Parameters

node

a GNode

 

n

the index of the desired child

 

Returns

the child of node at index n


g_node_first_sibling ()

GNode *
g_node_first_sibling (GNode *node);

Gets the first sibling of a GNode. This could possibly be the node itself.

Parameters

node

a GNode

 

Returns

the first sibling of node


g_node_next_sibling()

#define             g_node_next_sibling(node)

Gets the next sibling of a GNode.

Parameters

node

a GNode

 

Returns

the next sibling of node , or NULL if node is the last node or NULL


g_node_prev_sibling()

#define             g_node_prev_sibling(node)

Gets the previous sibling of a GNode.

Parameters

node

a GNode

 

Returns

the previous sibling of node , or NULL if node is the first node or NULL


g_node_last_sibling ()

GNode *
g_node_last_sibling (GNode *node);

Gets the last sibling of a GNode. This could possibly be the node itself.

Parameters

node

a GNode

 

Returns

the last sibling of node


G_NODE_IS_LEAF()

#define	 G_NODE_IS_LEAF(node) (((GNode*) (node))->children == NULL)

Returns TRUE if a GNode is a leaf node.

Parameters

node

a GNode

 

Returns

TRUE if the GNode is a leaf node (i.e. it has no children)


G_NODE_IS_ROOT()

#define             G_NODE_IS_ROOT(node)

Returns TRUE if a GNode is the root of a tree.

Parameters

node

a GNode

 

Returns

TRUE if the GNode is the root of a tree (i.e. it has no parent or siblings)


g_node_depth ()

guint
g_node_depth (GNode *node);

Gets the depth of a GNode.

If node is NULL the depth is 0. The root node has a depth of 1. For the children of the root node the depth is 2. And so on.

Parameters

node

a GNode

 

Returns

the depth of the GNode


g_node_n_nodes ()

guint
g_node_n_nodes (GNode *root,
                GTraverseFlags flags);

Gets the number of nodes in a tree.

Parameters

root

a GNode

 

flags

which types of children are to be counted, one of G_TRAVERSE_ALL, G_TRAVERSE_LEAVES and G_TRAVERSE_NON_LEAVES

 

Returns

the number of nodes in the tree


g_node_n_children ()

guint
g_node_n_children (GNode *node);

Gets the number of children of a GNode.

Parameters

node

a GNode

 

Returns

the number of children of node


g_node_is_ancestor ()

gboolean
g_node_is_ancestor (GNode *node,
                    GNode *descendant);

Returns TRUE if node is an ancestor of descendant . This is true if node is the parent of descendant , or if node is the grandparent of descendant etc.

Parameters

node

a GNode

 

descendant

a GNode

 

Returns

TRUE if node is an ancestor of descendant


g_node_max_height ()

guint
g_node_max_height (GNode *root);

Gets the maximum height of all branches beneath a GNode. This is the maximum distance from the GNode to all leaf nodes.

If root is NULL, 0 is returned. If root has no children, 1 is returned. If root has children, 2 is returned. And so on.

Parameters

root

a GNode

 

Returns

the maximum height of the tree beneath root


g_node_unlink ()

void
g_node_unlink (GNode *node);

Unlinks a GNode from a tree, resulting in two separate trees.

Parameters

node

the GNode to unlink, which becomes the root of a new tree

 

g_node_destroy ()

void
g_node_destroy (GNode *root);

Removes root and its children from the tree, freeing any memory allocated.

Parameters

root

the root of the tree/subtree to destroy

 

Types and Values

struct GNode

struct GNode {
  gpointer data;
  GNode	  *next;
  GNode	  *prev;
  GNode	  *parent;
  GNode	  *children;
};

The GNode struct represents one node in a n-ary tree.

Members

gpointer data;

contains the actual data of the node.

 

GNode *next;

points to the node's next sibling (a sibling is another GNode with the same parent).

 

GNode *prev;

points to the node's previous sibling.

 

GNode *parent;

points to the parent of the GNode, or is NULL if the GNode is the root of the tree.

 

GNode *children;

points to the first child of the GNode. The other children are accessed by using the next pointer of each child.

 

enum GTraverseType

Specifies the type of traveral performed by g_tree_traverse(), g_node_traverse() and g_node_find(). The different orders are illustrated here:

  • In order: A, B, C, D, E, F, G, H, I

  • Pre order: F, B, A, D, C, E, G, I, H

  • Post order: A, C, E, D, B, H, I, G, F

  • Level order: F, B, G, A, D, I, C, E, H

Members

G_IN_ORDER

vists a node's left child first, then the node itself, then its right child. This is the one to use if you want the output sorted according to the compare function.

 

G_PRE_ORDER

visits a node, then its children.

 

G_POST_ORDER

visits the node's children, then the node itself.

 

G_LEVEL_ORDER

is not implemented for balanced binary trees. For n-ary trees, it vists the root node first, then its children, then its grandchildren, and so on. Note that this is less efficient than the other orders.

 

enum GTraverseFlags

Specifies which nodes are visited during several of the tree functions, including g_node_traverse() and g_node_find().

Members

G_TRAVERSE_LEAVES

only leaf nodes should be visited. This name has been introduced in 2.6, for older version use G_TRAVERSE_LEAFS.

 

G_TRAVERSE_NON_LEAVES

only non-leaf nodes should be visited. This name has been introduced in 2.6, for older version use G_TRAVERSE_NON_LEAFS.

 

G_TRAVERSE_ALL

all nodes should be visited.

 

G_TRAVERSE_MASK

a mask of all traverse flags.

 

G_TRAVERSE_LEAFS

identical to G_TRAVERSE_LEAVES.

 

G_TRAVERSE_NON_LEAFS

identical to G_TRAVERSE_NON_LEAVES.