## N-ary Trees

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

## Synopsis

    #include <glib.h>

                        GNode;
    GNode*              g_node_new                          (gpointer data);
    GNode*              g_node_copy                         (GNode *node);
    gpointer            (*GCopyFunc)                        (gconstpointer src,
                                                             gpointer data);
    GNode*              g_node_copy_deep                    (GNode *node,
                                                             GCopyFunc copy_func,
                                                             gpointer data);

    GNode*              g_node_insert                       (GNode *parent,
                                                             gint position,
                                                             GNode *node);
    GNode*              g_node_insert_before                (GNode *parent,
                                                             GNode *sibling,
                                                             GNode *node);
    GNode*              g_node_insert_after                 (GNode *parent,
                                                             GNode *sibling,
                                                             GNode *node);
    #define             g_node_append                       (parent, node)
    GNode*              g_node_prepend                      (GNode *parent,
                                                             GNode *node);

    #define             g_node_insert_data                  (parent, position, data)
    #define             g_node_insert_data_before           (parent, sibling, data)
    #define             g_node_append_data                  (parent, data)
    #define             g_node_prepend_data                 (parent, data)

    void                g_node_reverse_children             (GNode *node);
    void                g_node_traverse                     (GNode *root,
                                                             GTraverseType order,
                                                             GTraverseFlags flags,
                                                             gint max_depth,
                                                             GNodeTraverseFunc func,
                                                             gpointer data);
    enum                GTraverseFlags;
    gboolean            (*GNodeTraverseFunc)                (GNode *node,
                                                             gpointer data);
    void                g_node_children_foreach             (GNode *node,
                                                             GTraverseFlags flags,
                                                             GNodeForeachFunc func,
                                                             gpointer data);
    void                (*GNodeForeachFunc)                 (GNode *node,
                                                             gpointer data);

    GNode*              g_node_get_root                     (GNode *node);
    GNode*              g_node_find                         (GNode *root,
                                                             GTraverseType order,
                                                             GTraverseFlags flags,
                                                             gpointer data);
    GNode*              g_node_find_child                   (GNode *node,
                                                             GTraverseFlags flags,
                                                             gpointer data);
    gint                g_node_child_index                  (GNode *node,
                                                             gpointer data);
    gint                g_node_child_position               (GNode *node,
                                                             GNode *child);
    #define             g_node_first_child                  (node)
    GNode*              g_node_last_child                   (GNode *node);
    GNode*              g_node_nth_child                    (GNode *node,
                                                             guint n);
    GNode*              g_node_first_sibling                (GNode *node);
    #define             g_node_next_sibling                 (node)
    #define             g_node_prev_sibling                 (node)
    GNode*              g_node_last_sibling                 (GNode *node);

    #define             G_NODE_IS_LEAF                      (node)
    #define             G_NODE_IS_ROOT                      (node)
    guint               g_node_depth                        (GNode *node);
    guint               g_node_n_nodes                      (GNode *root,
                                                             GTraverseFlags flags);
    guint               g_node_n_children                   (GNode *node);
    gboolean            g_node_is_ancestor                  (GNode *node,
                                                             GNode *descendant);
    guint               g_node_max_height                   (GNode *root);

    void                g_node_unlink                       (GNode *node);
    void                g_node_destroy                      (GNode *root);

    void                g_node_push_allocator               (gpointer dummy);
    void                g_node_pop_allocator                (void);

## 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_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()`.

## Details

### GNode

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

The GNode struct represents one node in a N-ary Tree. fields

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

### 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.

`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).

`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.

`src` : | A pointer to the data which should be copied.
`data` : | Additional data.
Returns : | A pointer to the copy.

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.

`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.

`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.

`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.

`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.

`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.

`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.

`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_before()

    #define             g_node_insert_data_before(parent, sibling, data)

Inserts a new GNode before the given sibling.

`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.

`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.

`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.)

`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`.

`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.

### enum GTraverseFlags

    typedef enum
    {
      G_TRAVERSE_LEAVES     = 1 << 0,
      G_TRAVERSE_NON_LEAVES = 1 << 1,
      G_TRAVERSE_ALL        = G_TRAVERSE_LEAVES | G_TRAVERSE_NON_LEAVES,
      G_TRAVERSE_MASK       = 0x03,
      G_TRAVERSE_LEAFS      = G_TRAVERSE_LEAVES,
      G_TRAVERSE_NON_LEAFS  = G_TRAVERSE_NON_LEAVES
    } GTraverseFlags;

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

`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`.

### 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.

`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.

`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()`.

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`node` : | a GNode.
Returns : | the next sibling of `node`, or `NULL` if `node` is `NULL`.

### g_node_prev_sibling()

    #define             g_node_prev_sibling(node)

Gets the previous sibling of a GNode.

`node` : | a GNode.
Returns : | the previous sibling of `node`, or `NULL` if `node` is `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.

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`node` : | the GNode to unlink, which becomes the root of a new tree.

### g_node_destroy ()

    void                g_node_destroy                      (GNode *root);

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

`root` : | the root of the tree/subtree to destroy.

### g_node_push_allocator ()

    void                g_node_push_allocator               (gpointer dummy);

### Warning

`g_node_push_allocator` has been deprecated since version 2.10 and should not be used in newly-written code. It does nothing, since GNode has been converted to the slice allocator

Sets the allocator to use to allocate GNode elements. Use `g_node_pop_allocator()` to restore the previous allocator.

Note that this function is not available if GLib has been compiled with `--disable-mem-pools`

`dummy` : | the GAllocator to use when allocating GNode elements.

### g_node_pop_allocator ()

    void                g_node_pop_allocator                (void);

### Warning

`g_node_pop_allocator` has been deprecated since version 2.10 and should not be used in newly-written code. It does nothing, since GNode has been converted to the slice allocator

Restores the previous GAllocator, used when allocating GNode elements.

Note that this function is not available if GLib has been compiled with `--disable-mem-pools`