Glib学习（3） 双端队列 Double-ended Queues
在数据结构中两种重要的类型就是队列和栈，而什么又是双端队列呢？
双端队列是一个限定插入和删除操作的数据结构，具有队列和栈的性质。
(deque，全名double-ended queue)是一种具有队列和栈的性质的数据结构。双端队列中的元素可以从两端弹出，其限定插入和删除操作在表的两端进行。
也就是说双端队列是队列和栈的集合，通过规则来灵活的实现队列和栈的功能。
下面还是先贴出来GLib Reference Manual网址
http://web.mit.edu/barnowl/share/gtk-doc/html/glib/glib-Double-ended-Queues.html#g-queue-copy
GQueue结构体及其相关函数提供了一个标准的队列数据结构。在内部,GQueue使用和glist相同的数据结构来存储元素。可以存储一个int型的数据，或者使用类型转换宏 Type Conversion Macros，去转换成任何数据类型的指针。
创建一个队列使用g_queue_new()
初始化一个静态的队列使用G_QUEUE_INIT 或者 g_queue_init()
这里就涉及到new和init的区别了，在操作系统中，通过动态申请内存，分配在堆上的使用new实现，分配在栈上的使用init实现。在编程的区别就是new的方法可以在程序中动态实现，init在编译之前就已经知道在哪里了。
添加元素使用 g_queue_push_head(), g_queue_push_head_link(), g_queue_push_tail() 和 g_queue_push_tail_link()
删除元素使用 g_queue_pop_head() 和 g_queue_pop_tail()
释放全部队列使用 g_queue_free()
下面看一下结构体
GQueue
typedef struct {
GList *head;
GList *tail;
guint length;
} GQueue;
head指向队列的第一个元素
tail指向队列的最后一个元素
length是队列的元素个数
下面是队列提供的函数
Synopsis
#include <glib.h>
GQueue;
GQueue* g_queue_new (void);
void g_queue_free (GQueue *queue);
#define G_QUEUE_INIT
void g_queue_init (GQueue *queue);
void g_queue_clear (GQueue *queue);
gboolean g_queue_is_empty (GQueue *queue);
guint g_queue_get_length (GQueue *queue);
void g_queue_reverse (GQueue *queue);
GQueue* g_queue_copy (GQueue *queue);
void g_queue_foreach (GQueue *queue,
GFunc func,
gpointer user_data);
GList* g_queue_find (GQueue *queue,
gconstpointer data);
GList* g_queue_find_custom (GQueue *queue,
gconstpointer data,
GCompareFunc func);
void g_queue_sort (GQueue *queue,
GCompareDataFunc compare_func,
gpointer user_data);
void g_queue_push_head (GQueue *queue,
gpointer data);
void g_queue_push_tail (GQueue *queue,
gpointer data);
void g_queue_push_nth (GQueue *queue,
gpointer data,
gint n);
gpointer g_queue_pop_head (GQueue *queue);
gpointer g_queue_pop_tail (GQueue *queue);
gpointer g_queue_pop_nth (GQueue *queue,
guint n);
gpointer g_queue_peek_head (GQueue *queue);
gpointer g_queue_peek_tail (GQueue *queue);
gpointer g_queue_peek_nth (GQueue *queue,
guint n);
gint g_queue_index (GQueue *queue,
gconstpointer data);
void g_queue_remove (GQueue *queue,
gconstpointer data);
void g_queue_remove_all (GQueue *queue,
gconstpointer data);
void g_queue_insert_before (GQueue *queue,
GList *sibling,
gpointer data);
void g_queue_insert_after (GQueue *queue,
GList *sibling,
gpointer data);
void g_queue_insert_sorted (GQueue *queue,
gpointer data,
GCompareDataFunc func,
gpointer user_data);
void g_queue_push_head_link (GQueue *queue,
GList *link_);
void g_queue_push_tail_link (GQueue *queue,
GList *link_);
void g_queue_push_nth_link (GQueue *queue,
gint n,
GList *link_);
GList* g_queue_pop_head_link (GQueue *queue);
GList* g_queue_pop_tail_link (GQueue *queue);
GList* g_queue_pop_nth_link (GQueue *queue,
guint n);
GList* g_queue_peek_head_link (GQueue *queue);
GList* g_queue_peek_tail_link (GQueue *queue);
GList* g_queue_peek_nth_link (GQueue *queue,
guint n);
gint g_queue_link_index (GQueue *queue,
GList *link_);
void g_queue_unlink (GQueue *queue,
GList *link_);
void g_queue_delete_link (GQueue *queue,
GList *link_);
下面提供一段测试代码，
#include <stdio.h>
#include <glib.h>
//#include <glib/gprintf.h>
struct map {
int key;
char *value;
} m[10] = {
{0,"zero"},
{1,"one"},
{2,"two"},
{3,"three"},
{4,"four"},
{5,"five"},
{6,"six"},
{7,"seven"},
{8,"eight"},
{9,"nine"},
};
typedef struct map map;
static void
myPrintInt(gpointer p1, gpointer fmt)
{
g_printf(fmt, *(gint *)p1);
}
static void
myPrintStr(gpointer p1, gpointer fmt)
{
g_printf(fmt, (gchar *)p1);
}
static void
test_queue_1(void)
{
// GQueue* g_queue_new(void); 创建队列
GQueue *queue = g_queue_new();
// gboolean g_queue_is_empty(GQueue *queue); 判断队列是否为空，空返回1
gboolean b = g_queue_is_empty(queue);
g_printf("The queue should be empty now.\t\tResult: %s.\n", b ? "YES" : "NO");
// void g_queue_push_tail(GQueue *queue, gpointer data); 将数据data压入队列尾部
gint i;
for (i = 0; i < sizeof (m) / sizeof (m[0]); i++)
g_queue_push_tail(queue, m[i].value);
// void g_queue_foreach(GQueue *queue, GFunc func, gpointer user_data); 调用函数func遍历队列元素，user_data是函数的参数
g_printf("Now the queue[after push tail] :\n");
g_queue_foreach(queue, myPrintStr, "%s, ");//打印字符串的形式输出队列的数据，因为之前是将map中的value，即字符串数据保存到了队列中
g_printf("\n");
// guint g_queue_get_length(GQueue *queue); 得到队列元素的个数
g_printf("The lenght should be '%d' now.\t\tResult: %d.\n", 10, g_queue_get_length(queue));
// void g_queue_reverse(GQueue *queue); 翻转队列的元素
g_queue_reverse(queue);
g_printf("Now the queue[after reverse] :\n");
g_queue_foreach(queue, myPrintStr, "%s, ");
g_printf("\n");
// gpointer g_queue_pop_head(GQueue *queue); 从头部取出一个数据
g_printf("The head should be '%s' now.\t\tResult: %s.\n", "nine", (gchar *)g_queue_pop_head(queue));
// gpointer g_queue_pop_tail(GQueue *queue); 从尾部取出一个数据
g_printf("The tail should be '%s' now.\t\tResult: %s.\n", "zero", (gchar *)g_queue_pop_tail(queue));
g_printf("Now the queue[after pop head and tail] :\n");
g_queue_foreach(queue, myPrintStr, "%s, ");
g_printf("\n");
// gpointer g_queue_pop_nth(GQueue *queue, guint n); 将第n个数据取出
g_printf("The head should be '%s' now.\t\tResult: %s.\n", "eight", (gchar *)g_queue_pop_nth(queue, 0));
// void g_queue_push_head(GQueue *queue, gpointer data); 将数据data压入队列头
g_queue_push_head(queue, "zero");
g_queue_push_head(queue, "eight");
// void g_queue_push_nth(GQueue *queue, gpointer data, gint n); 将data插入第n个位置
g_queue_push_nth(queue, "nine", 2);
g_printf("Now the queue[after push 'zero' 'eight' 'nine'] :\n");
g_queue_foreach(queue, myPrintStr, "%s, ");
g_printf("\n");
// gpointer g_queue_peek_head(GQueue *queue); 查看头数据，不取出
g_printf("The head should be '%s' now.\t\tResult: %s.\n", "eight", (gchar *)g_queue_peek_head(queue));
// gpointer g_queue_peek_tail(GQueue *queue); 查看尾数据，不取出
g_printf("The tail should be '%s' now.\t\tResult: %s.\n", "one", (gchar *)g_queue_peek_tail(queue));
// gpointer g_queue_peek_nth(GQueue *queue, guint n); 查看第n个数据，不取出
g_printf("The head should be '%s' now.\t\tResult: %s.\n", "eight", (gchar *)g_queue_peek_nth(queue, 0));
/*
// void g_queue_clear(GQueue *queue); 清理队列，如果数据是动态申请的， 在调用这个函数之前需要先释放数据，这个函数是与init配套使用的，new配套使用free
g_queue_clear(queue);
g_printf("Now the queue[after clear] :\n");
g_queue_foreach(queue, myPrintStr, "%s, ");
g_printf("\n");
*/
// void g_queue_free(GQueue *queue); 释放队列
g_queue_free(queue);
}
static gint
sort(gconstpointer p1, gconstpointer p2, gpointer user_data)//正向排序规则
{
gint32 a, b;
a = *(gint*)(p1);
b = *(gint*)(p2);
return (a > b ? +1 : a == b ? 0 : -1);
}
static gint
myCompareInt(gconstpointer p1, gconstpointer p2)//比较大小
{
const int *a = p1;
const int *b = p2;
return *a - *b;
}
static gint
sort_r(gconstpointer p1, gconstpointer p2, gpointer user_data)//逆向排序规则
{
gint32 a, b;
a = *(gint*)(p1);
b = *(gint*)(p2);
return (a < b ? +1 : a == b ? 0 : -1);
}
static void
test_queue_2(void)
{
GQueue *queue = NULL;
/*
// void g_queue_init(GQueue *queue); 在栈中申请队列
g_queue_init(queue);
*/
queue = g_queue_new();
// void g_queue_insert_sorted(GQueue *queue, gpointer data, GCompareDataFunc func gpointer user_data); 按照func规则进行插入队列
gint i;
for (i = 0; i < sizeof (m) / sizeof (m[0]); i++)
g_queue_insert_sorted(queue, &m[i].key, sort_r, NULL);
g_printf("Now the queue[after insert sorted] :\n");
for (i = 0; i < queue->length; i++)
g_printf("%d, ", *(gint *)g_queue_peek_nth(queue, i));
g_printf("\n");
// void g_queue_remove(GQueue *queue, gconstpointer data); 将队列中的data数据移除，只移除第一次出现的数据
g_queue_remove(queue, &m[3].key);
g_printf("Now the queue[after remove '%d'] :\n", m[3].key);
for (i = 0; i < queue->length; i++)
g_printf("%d, ", *(gint *)g_queue_peek_nth(queue, i));
g_printf("\n");
// GList* g_queue_find_custom(GQueue *queue, gconstpointer data, GCompareFunc func); 通过比较函数func查找数据data
// void g_queue_insert_before(GQueue *queue, GList *sibling, gpointer data); 将数据data插入到sibling前面
// void g_queue_insert_after(GQueue *queue, GList *sibling, gpointer data); 将数据data插入到sibling后面
g_queue_insert_before(queue, g_queue_find_custom(queue, &m[5].key, myCompareInt), &m[3].key);
g_queue_insert_after(queue, g_queue_find_custom(queue, &m[5].key, myCompareInt), &m[3].key);
g_printf("Now the queue[after insert '%d' around '%d'] :\n", m[3].key, m[5].key);
g_queue_foreach(queue, myPrintInt, "%d, ");
g_printf("\n");
// void g_queue_sort(GQueue *queue, GCompareDataFunc compare, gpointer user_data); 通过比较函数compare进行排序
g_queue_sort(queue, sort, NULL);
g_printf("Now the queue[sorted] :\n");
g_queue_foreach(queue, myPrintInt, "%d, ");
g_printf("\n");
// GQueue* g_queue_copy(GQueue *queue); 复制队列，同样，也只是指针的复制，并没有实际复制数据
GQueue *q = g_queue_copy(queue);
g_printf("Now the queue[copy] :\n");
g_queue_foreach(q, myPrintInt, "%d, ");
g_printf("\n");
// void g_queue_remove_all(GQueue *queue, gconstpointer data); 删除队列中所有的data数据
g_queue_remove_all(q, &m[3].key);
g_printf("Now the queue[remove '%d'] :\n", m[3].key);
g_queue_foreach(q, myPrintInt, "%d, ");
g_printf("\n");
g_queue_free(q);
g_queue_free(queue);
}
int
main(void)
{
printf("BEGIN:\n************************************************************\n");
printf("\n------------------------------------------------------------\ntest_queue_1:\n");
test_queue_1();
printf("------------------------------------------------------------\n");
printf("\n------------------------------------------------------------\ntest_queue_2:\n");
test_queue_2();
printf("------------------------------------------------------------\n");
printf("\n************************************************************\nDONE\n");
return 0;
}
linux@ubuntu:~/16021/glibdemo$ gcc -o Double_ended_Queues Double_ended_Queues.c -lglib-2.0 Double_ended_Queues.c: In function ‘test_queue_2’: Double_ended_Queues.c:183:17: warning: initialization makes pointer from integer without a cast [enabled by default] linux@ubuntu:~/16021/glibdemo$ ./Double_ended_Queues BEGIN: ************************************************************ ------------------------------------------------------------ test_queue_1: The queue should be empty now. Result: YES. Now the queue[after push tail] : zero, one, two, three, four, five, six, seven, eight, nine, The lenght should be '10' now. Result: 10. Now the queue[after reverse] : nine, eight, seven, six, five, four, three, two, one, zero, The head should be 'nine' now. Result: nine. The tail should be 'zero' now. Result: zero. Now the queue[after pop head and tail] : eight, seven, six, five, four, three, two, one, The head should be 'eight' now. Result: eight. Now the queue[after push 'zero' 'eight' 'nine'] : eight, zero, nine, seven, six, five, four, three, two, one, The head should be 'eight' now. Result: eight. The tail should be 'one' now. Result: one. The head should be 'eight' now. Result: eight. ------------------------------------------------------------ ------------------------------------------------------------ test_queue_2: Now the queue[after insert sorted] : 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, Now the queue[after remove '3'] : 9, 8, 7, 6, 5, 4, 2, 1, 0, Now the queue[after insert '3' around '5'] : 9, 8, 7, 6, 3, 5, 3, 4, 2, 1, 0, Now the queue[sorted] : 0, 1, 2, 3, 3, 4, 5, 6, 7, 8, 9, Now the queue[copy] : 0, 1, 2, 3, 3, 4, 5, 6, 7, 8, 9, Now the queue[remove '3'] : 0, 1, 2, 4, 5, 6, 7, 8, 9, ------------------------------------------------------------ ************************************************************ DONE linux@ubuntu:~/16021/glibdemo$
好了，常用的函数基本就这些，明天按照顺序应该是序列，但是序列往往用在数据库的主键上，而每个数据库有没有统一的规则，所以应用并不多，暂时先不进行研究，顺序进行hash的研究。