glib 树

原文地址： http://hi.baidu.com/study_together/blog/item/0ffc733c224211cf7c1e7138.html

编译：gcc -g -Wall -O0 fuck.c -o fuck `pkg-config --libs --cflags glib-2.0`

1

树的基本操作

这里是在树中可以执行的一些基本操作：

#include <glib.h>
#include <stdio.h>

int main(int argc, char** argv) {
    GTree* t = g_tree_new((GCompareFunc)g_ascii_strcasecmp);
    g_tree_insert(t, "c", "Chicago");
    printf("The tree height is %d because there's only one node\n", g_tree_height(t));
    g_tree_insert(t, "b", "Boston");
    g_tree_insert(t, "d", "Detroit");
    printf("Height is %d since c is root; b and d are children\n", g_tree_height(t));
    printf("There are %d nodes in the tree\n", g_tree_nnodes(t));
    g_tree_remove(t, "d");
    printf("After remove(), there are %d nodes in the tree\n", g_tree_nnodes(t));
    g_tree_destroy(t);
    return 0;
}


***** Output *****

The tree height is 1 because there's only one node
Height is 2 since c is root; b and d are children
There are 3 nodes in the tree
After remove(), there are 2 nodes in the tree

2

替换和提取

在前面的 GHashTable 部分已经看到了 replace 和 steal 函数名， 关于 GTree 的函数也是如此。

g_tree_replace 会同时替换一个 GTree 条目的键和值，不同于 g_tree_insert，如果要插入的键是重复的，则它只是将值替换。

不需要调用任何 GDestroyNotify 函数，g_tree_steal 就可以删除一个节点。 这里是一个示例：

#include <glib.h>
#include <stdio.h>

void key_d(gpointer data) {
    printf("Key %s destroyed\n", data);
}
void value_d(gpointer data) {
    printf("Value %s destroyed\n", data);
}
int main(int argc, char** argv) {
    GTree* t = g_tree_new_full((GCompareDataFunc)g_ascii_strcasecmp,
            NULL, (GDestroyNotify)key_d, (GDestroyNotify)value_d);
    g_tree_insert(t, "c", "Chicago");
    g_tree_insert(t, "b", "Boston");
    g_tree_insert(t, "d", "Detroit");
    printf(">Replacing 'b', should get destroy callbacks\n");
    g_tree_replace(t, "b", "Billings");
    printf(">Stealing 'b', no destroy notifications will occur\n");
    g_tree_steal(t, "b");
    printf(">Destroying entire tree now\n");
    g_tree_destroy(t);
    return 0;
}


***** Output *****

>Replacing 'b', should get destroy callbacks
Value Boston destroyed
Key b destroyed
>Stealing 'b', no destroy notifications will occur
>Destroying entire tree now
Key d destroyed
Value Detroit destroyed
Key c destroyed
Value Chicago destroyed

3

查找数据

GTree 具备只查找键或者同时查找键和值的方法。这与在 GHashTable 部分中接触到的非常类似；

有一个 lookup 以及一个 lookup_extended。这里是一个示例：

#include <glib.h>
#include <stdio.h>

int main(int argc, char** argv) {
    GTree* t = g_tree_new((GCompareFunc)g_ascii_strcasecmp);
    g_tree_insert(t, "c", "Chicago");
    g_tree_insert(t, "b", "Boston");
    g_tree_insert(t, "d", "Detroit");
    printf("The data at 'b' is %s\n", g_tree_lookup(t, "b"));
    printf("%s\n",  g_tree_lookup(t, "a") ? "My goodness!" : "As expected, couldn't find 'a'");

    gpointer* key = NULL;
    gpointer* value = NULL;
    g_tree_lookup_extended(t, "c", (gpointer*)&key, (gpointer*)&value);
    printf("The data at '%s' is %s\n", key, value);
    gboolean found = g_tree_lookup_extended(t, "a", (gpointer*)&key, (gpointer*)&value);
    printf("%s\n", found ? "My goodness!" : "As expected, couldn't find 'a'");

    g_tree_destroy(t);
    return 0;
}


***** Output *****

The data at 'b' is Boston
As expected, couldn't find 'a'
The data at 'c' is Chicago
As expected, couldn't find 'a'

4

使用 foreach 列出树

GTree 提供了一个 g_tree_foreach 函数，用来以有序的顺序遍历整棵对。这里是一个示例：

#include <glib.h>
#include <stdio.h>

gboolean iter_all(gpointer key, gpointer value, gpointer data) {
    printf("%s, %s\n", key, value);
    return FALSE;
}
gboolean iter_some(gpointer key, gpointer value, gpointer data) {
    printf("%s, %s\n", key, value);
    return g_ascii_strcasecmp(key, "b") == 0;
}
int main(int argc, char** argv) {
    GTree* t = g_tree_new((GCompareFunc)g_ascii_strcasecmp);
    g_tree_insert(t, "d", "Detroit");
    g_tree_insert(t, "a", "Atlanta");
    g_tree_insert(t, "c", "Chicago");
    g_tree_insert(t, "b", "Boston");
    printf("Iterating all nodes\n");
    g_tree_foreach(t, (GTraverseFunc)iter_all, NULL);
    printf("Iterating some of the nodes\n");
    g_tree_foreach(t, (GTraverseFunc)iter_some, NULL);
    g_tree_destroy(t);
    return 0;
}


***** Output *****

Iterating all nodes
a, Atlanta
b, Boston
c, Chicago
d, Detroit
Iterating some of the nodes
a, Atlanta
b, Boston

5

搜索

可以使用 g_tree_foreach 搜索条目，如果知道键，可以使用 g_tree_lookup。 不过，要进行更复杂地搜索，可以使用 g_tree_search 函数。

这里是其工作方式：

#include <glib.h>
#include <stdio.h>

gint finder(gpointer key, gpointer user_data) {
    int len = strlen((char*)key);
    if (len == 3) {
        return 0;
    }
    return (len < 3) ? 1 : -1;
}
int main(int argc, char** argv) {
    GTree* t = g_tree_new((GCompareFunc)g_ascii_strcasecmp);
    g_tree_insert(t, "dddd", "Detroit");
    g_tree_insert(t, "a", "Annandale");
    g_tree_insert(t, "ccc", "Cleveland");
    g_tree_insert(t, "bb", "Boston");
    gpointer value = g_tree_search(t, (GCompareFunc)finder, NULL);
    printf("Located value %s; its key is 3 characters long\n", value);
    g_tree_destroy(t);
    return 0;
}



***** Output *****

Located value Cleveland; its key is 3 characters long

6

不只是二叉：n-叉 树

GLib n-叉 树实现基于 GNode 数据结构；以前所述，它允许每个父节点有多个子节点。 好像很少会用到它，不过，完整起见，这里给出一个用法示例：

#include <glib.h>
#include <stdio.h>

gboolean iter(GNode* n, gpointer data) {
    printf("%s ", n->data);
    return FALSE;
}
int main(int argc, char** argv) {
    GNode* root = g_node_new("Atlanta");
    g_node_append(root, g_node_new("Detroit"));
    GNode* portland = g_node_prepend(root, g_node_new("Portland"));
    printf(">Some cities to start with\n");
    g_node_traverse(root, G_PRE_ORDER, G_TRAVERSE_ALL, -1, iter, NULL);
    printf("\n>Inserting Coos Bay before Portland\n");
    g_node_insert_data_before(root, portland, "Coos Bay");
    g_node_traverse(root, G_PRE_ORDER, G_TRAVERSE_ALL, -1, iter, NULL);
    printf("\n>Reversing the child nodes\n");
    g_node_reverse_children(root);
    g_node_traverse(root, G_PRE_ORDER, G_TRAVERSE_ALL, -1, iter, NULL);
    printf("\n>Root node is %s\n", g_node_get_root(portland)->data);
    printf(">Portland node index is %d\n", g_node_child_index(root, "Portland"));
    g_node_destroy(root);
    return 0;
}


***** Output *****

>Some cities to start with
Atlanta Portland Detroit
>Inserting Coos Bay before Portland
Atlanta Coos Bay Portland Detroit
>Reversing the child nodes
Atlanta Detroit Portland Coos Bay
>Root node is Atlanta
>Portland node index is 1

完