GLib 库学习笔记

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

int main() {
    GObject *a = NULL, *b = NULL, *c = NULL;
    GObjectClass *a_class = NULL, *b_class = NULL, *c_class = NULL;

    // GObject 库新建类实例的方式
    a = g_object_new(G_TYPE_OBJECT, NULL);
    b = g_object_new(G_TYPE_OBJECT, NULL);
    c = g_object_new(G_TYPE_OBJECT, NULL);

    // GObject 库获取实例类型信息的方式
    a_class = G_OBJECT_GET_CLASS(a);
    b_class = G_OBJECT_GET_CLASS(b);
    c_class = G_OBJECT_GET_CLASS(c);

    printf("a -> %p\nb -> %p\nc -> %p\n", a, b, c);
    printf("a_class -> %p\nb_class -> %p\nc_class -> %p\n", a_class, b_class,
           c_class);

    // GObject 库释放实例的方式
    g_object_unref(a);
    g_object_unref(b);
    g_object_unref(c);

    return 0;
}

> cmake .. -G "MinGW Makefiles" && mingw32-make && ../bin/hello
a -> 0000013E80285A80
b -> 0000013E80285580
c -> 0000013E80285AA0
a_class -> 0000013E8029C6F0
b_class -> 0000013E8029C6F0
c_class -> 0000013E8029C6F0

#ifndef __SAMPLE_STRING_H__
#define __SAMPLE_STRING_H__

#include <glib-object.h>

G_BEGIN_DECLS // 必需，表示开始声明类型及其成员方法

// 惯例，使用 <命名空间>_TYPE_<类名> 宏表示此类型的“代号”
#define SAMPLE_TYPE_STRING (sample_string_get_type())

// 宏，声明类型名并且定义 sample_string_get_type() 函数等
// 参数分别为：类型名、成员函数前缀、命名空间、去除命名空间后的类型名、父类类名
G_DECLARE_FINAL_TYPE(SampleString, sample_string, SAMPLE, STRING, GObject)

// 构造函数
SampleString *sample_string_new(gsize capacity);

// 构造函数的“重载”
SampleString *sample_string_new_with_text(const gchar *const restrict text,
                                          gsize capacity);

G_END_DECLS // 必需，结束声明类型及其成员方法

#endif  // __SAMPLE_STRING_H__

#include "sample-string.h"

// 属性的枚举值（或唯一 ID）
enum {
    SAMPLE_STRING_TEXT = 1,
    SAMPLE_STRING_LENGTH = 2,
    SAMPLE_STRING_CAPACITY = 3,
};

// 必需，定义 SampleString 类型
struct _SampleString {
    GObject parent_instance; // 必需，且必须为第一个字段

    gchar *array;           // 字符串数组
    gsize length;           // 文本长度
    gsize capacity;         // 当前容量
};

// 宏，自动完成 SampleStringClass 的定义等任务
// 参数分别为：类型名、成员函数前缀、父类“类型代号”
G_DEFINE_TYPE(SampleString, sample_string, G_TYPE_OBJECT);

// 所有属性的写入都会调用此函数完成
static void sample_string_set_property(GObject *object, guint property_id,
                                       const GValue *value, GParamSpec *pspec) {
    // 带检查的类型转换
    // SAMPLE_STRING() 宏函数由 G_DECLARE_FINAL_TYPE 宏定义
    SampleString *this = SAMPLE_STRING(object);

    switch (property_id) {
        case SAMPLE_STRING_TEXT: {
            // 写入 Text 属性
            gchar *temp = g_value_dup_string(value);
            if (strlen(temp) > this->capacity) {
                this->capacity = strlen(temp);
                this->array = g_realloc(this->array, this->capacity);
            }
            memcpy(this->array, temp, this->capacity);
            g_free(temp);
            this->length = strlen(temp);
            break;
        }
        case SAMPLE_STRING_CAPACITY: {
            // 写入 Capacity 属性
            // 注意，下文注册此属性时的 flag 含有 G_PARAM_CONSTRUCT_ONLY
            this->capacity = g_value_get_uint64(value);
            break;
        }
        default: {
            // 其余属性不可写，或不存在此属性编号
            G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec);
            break;
        }
    }
    g_print("sample_string_set_property() finished.\n");
}

// 所有属性的读取都会调用此函数完成
static void sample_string_get_property(GObject *object, guint property_id,
                                       GValue *value, GParamSpec *pspec) {
    SampleString *this = SAMPLE_STRING(object);
    switch (property_id) {
        case SAMPLE_STRING_TEXT: {
            // 读取 Text 属性
            g_value_set_string(value, this->array);
            break;
        }
        case SAMPLE_STRING_LENGTH: {
            // 读取 Length 属性
            g_value_set_uint64(value, this->length);
            break;
        }
        case SAMPLE_STRING_CAPACITY: {
            // 读取 Capacity 属性
            g_value_set_uint64(value, this->capacity);
            break;
        }
        default: {
            // 没有其它属性了
            G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec);
            break;
        }
    }
    g_print("sample_string_get_property() finished.\n");
}

// 当调用 g_object_unref() 时，触发此函数
static void sample_string_dispose(GObject *object) {

    // 必需，sample_string_parent_class 变量由 G_DEFINE_TYPE 宏定义，因此仅能在此文件内使用
    // 触发父类的 dispose() 方法
    G_OBJECT_CLASS(sample_string_parent_class)->dispose(object);

    g_print("sample_string_dispose() finished.\n");
}

// 当引用计数归 0 时，触发此函数
static void sample_string_finalize(GObject *object) {
    SampleString *this = SAMPLE_STRING(object);
    g_free(this->array);

    // 必需，触发父类的 finalize() 方法
    G_OBJECT_CLASS(sample_string_parent_class)->finalize(object);

    g_print("sample_string_finalize() finished.\n");
}

// 必需，初始化函数
static void sample_string_init(SampleString *this) {
    g_print("sample_string_init() finished.\n");
}

// 当实例构造完毕后触发
static void sample_string_constructed(GObject *object) {
    SampleString *this = SAMPLE_STRING(object);

    this->array = g_new(gchar, this->capacity);

    // 必需，触发父类的 constructed() 方法
    G_OBJECT_CLASS(sample_string_parent_class)->constructed(object);
}

// 必需，类型信息对象初始化函数
// SampleStringClass 类型由 G_DECLARE_FINAL_TYPE 宏声明
static void sample_string_class_init(SampleStringClass *class) {
    GObjectClass *object_class = G_OBJECT_CLASS(class);
    GParamSpec *temp = NULL;

    // 注册函数，虚函数（抽象方法）就是通过这种方式实现的
    object_class->constructed = sample_string_constructed;
    object_class->set_property = sample_string_set_property;
    object_class->get_property = sample_string_get_property;
    object_class->dispose = sample_string_dispose;
    object_class->finalize = sample_string_finalize;

    // 注册属性
    // G_PARAM_READWRITE 代表可读可写
    // G_PARAM_CONSTRUCT_ONLY 代表仅在构造实例时才可写
    temp = g_param_spec_string("text", "Text", "Text stored inside the struct.",
                               NULL, G_PARAM_READWRITE);
    g_object_class_install_property(object_class, SAMPLE_STRING_TEXT, temp);

    temp = g_param_spec_uint64("length", "Length", "Text length.", 0,
                               G_MAXUINT64, 0, G_PARAM_READABLE);
    g_object_class_install_property(object_class, SAMPLE_STRING_LENGTH, temp);

    temp = g_param_spec_uint64("capacity", "Capacity", "Text capacity.", 0,
                               G_MAXUINT64, 0,
                               G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY);
    g_object_class_install_property(object_class, SAMPLE_STRING_CAPACITY, temp);

    g_print("sample_string_class_init() finished.\n");
}

// 构造函数的定义
SampleString *sample_string_new(gsize capacity) {
    SampleString *this =
        // g_object_new() 函数的最后一个参数必须为 NULL
        g_object_new(SAMPLE_TYPE_STRING, "capacity", capacity, NULL);
    return this;
}

// 构造函数“重载”的定义
SampleString *sample_string_new_with_text(const gchar *const restrict text,
                                          gsize capacity) {
    GValue value = G_VALUE_INIT;
    SampleString *this =
        g_object_new(SAMPLE_TYPE_STRING, "capacity", capacity, NULL);
    g_value_init(&value, G_TYPE_STRING);
    g_value_set_string(&value, text);
    g_object_set_property(G_OBJECT(this), "text", &value);
    return this;
}

#include <glib-object.h>

#include "sample-string.h"

// 尝试获取三种属性的值
int main() {
    GValue text = G_VALUE_INIT, length = G_VALUE_INIT, capacity = G_VALUE_INIT;
    SampleString *a = sample_string_new_with_text("1145141919810", 20);

    g_value_init(&text, G_TYPE_STRING);
    g_object_get_property(G_OBJECT(a), "text", &text);
    g_print("a->text = %s\n", g_value_get_string(&text));

    g_value_init(&length, G_TYPE_UINT64);
    g_object_get_property(G_OBJECT(a), "length", &length);
    g_print("a->length = %llu\n", g_value_get_uint64(&length));

    g_value_init(&capacity, G_TYPE_UINT64);
    g_object_get_property(G_OBJECT(a), "capacity", &capacity);
    g_print("a->capacity = %llu\n", g_value_get_uint64(&capacity));

    g_object_unref(a);

    return 0;
}

cmake .. -G "MinGW Makefiles" && mingw32-make && ../bin/hello
sample_string_class_init() finished.
sample_string_init() finished.
sample_string_set_property() finished.
sample_string_set_property() finished.
sample_string_get_property() finished.
a->text = 1145141919810
sample_string_get_property() finished.
a->length = 13
sample_string_get_property() finished.
a->capacity = 20
sample_string_dispose() finished.
sample_string_finalize() finished.

#ifndef __SAMPLE_LIST_H__
#define __SAMPLE_LIST_H__

#include <glib-object.h>

G_BEGIN_DECLS

// 声明可派生类
G_DECLARE_DERIVABLE_TYPE(SampleList, sample_list, SAMPLE, LIST, GObject)

// 存储 SampleList 类信息的结构体
struct _SampleListClass {
    GObjectClass parent_class;

    // 虚函数
    void (*push_front)(SampleList *const restrict this, gint item);
    void (*push_back)(SampleList *const restrict this, gint item);
    void (*pop_front)(SampleList *const restrict this);
    void (*pop_back)(SampleList *const restrict this);
};

// 成员函数的声明，其内部实现应当调用虚函数
void sample_list_push_back(SampleList *const restrict this, gint item);

void sample_list_pop_back(SampleList *const restrict this);

G_END_DECLS

#endif  // __SAMPLE_LIST_H__

#include "sample-list.h"

typedef struct {
    gsize length;
    gsize capacity;
    gint *array;
} SampleListPrivate;  // 注意，此结构体名称有特定要求

// 也可以使用 G_DEFINE_TYPE 宏
// 若使用 G_DEFINE_TYPE_WITH_PRIVATE 宏，则私有变量必须定义在 <类型名>Private 结构体内
G_DEFINE_TYPE_WITH_PRIVATE(SampleList, sample_list, G_TYPE_OBJECT);

// 成员函数的实现
void sample_list_push_back(SampleList *const restrict this, gint item) {
    SampleListClass *class = NULL;

    // 类型检查
    // SAMPLE_IS_LIST() 函数由 G_DECLARE_DERIVABLE_TYPE 宏定义
    g_return_if_fail(SAMPLE_IS_LIST(this));

    class = SAMPLE_LIST_GET_CLASS(this);

    // 虚函数必须被实现
    g_return_if_fail(class->push_back != NULL);

    class->push_back(this, item);
}

void sample_list_pop_back(SampleList *const restrict this) {
    SampleListClass *class = NULL;
    g_return_if_fail(SAMPLE_IS_LIST(this));
    class = SAMPLE_LIST_GET_CLASS(this);
    g_return_if_fail(class->pop_back != NULL);
    class->pop_back(this);
}

// 实例初始化函数
static void sample_list_init(SampleList *this) {
    SampleListPrivate *private = sample_list_get_instance_private(this);
    private->length = 0;
    private->capacity = 10;
    private->array = g_new(gint, 10);
}

// 存储类信息的实例初始化函数
static void sample_list_class_init(SampleListClass *class) {
    // 如果赋值为 NULL，则为纯虚函数
    // 也可以给出虚函数的默认实现
    class->pop_back = NULL;
    class->pop_front = NULL;
    class->push_back = NULL;
    class->push_front = NULL;
}

#ifndef __SAMPLE_I_COMPARABLE_H__
#define __SAMPLE_I_COMPARABLE_H__

#include <glib-object.h>

G_BEGIN_DECLS

// 可选
#define SAMPLE_TYPE_ICOMPARABLE sample_icomparable_get_type()

// 声明接口
// 参数分别为：接口名、接口方法前缀、命名空间、去命名空间后的接口名、实现此接口的类型必需也实现某接口或继承自某类
G_DECLARE_INTERFACE(SampleIComparable, sample_icomparable, SAMPLE, ICOMPARABLE,
                    GObject)

// 必需，_SampleIComparableInterface 结构体被 G_DECLARE_INTERFACE 宏声明但未定义
// 类型名规则：_<接口名>Interface
struct _SampleIComparableInterface {
    GTypeInterface parent_iface;    // 接口也有“父类”，注意父类类型是 GTypeInterface

    // 通过类似公有虚函数的方式来声明接口方法
    void (*compare)(SampleIComparable *this,
                    SampleIComparable *item,
                    gint *const restrict result);
};

// 接口不公开内部方法就没有意义了
void sample_icomparable_compare(SampleIComparable *this,
                                SampleIComparable *item,
                                gint *const restrict result);

G_END_DECLS

#endif  // __SAMPLE_I_COMPARABLE_H__

#include "sample-icomparable.h"

// 定义接口
G_DEFINE_INTERFACE(SampleIComparable, sample_icomparable, G_TYPE_OBJECT)

static void sample_icomparable_default_init(SampleIComparableInterface *interface) {
    // GObject 库的特色，接口也可以有属性和私有变量等
}

void sample_icomparable_compare(SampleIComparable *this,
                                SampleIComparable *item,
                                gint *const restrict result) {
    SampleIComparableInterface *interface = NULL;

    // 类型检查
    g_return_if_fail(SAMPLE_IS_ICOMPARABLE(this));
    g_return_if_fail(result != NULL);

    interface = SAMPLE_ICOMPARABLE_GET_IFACE(this);

    // 必需实现接口声明的方法
    g_return_if_fail(interface->compare != NULL);

    interface->compare(this, item, result);
}

#ifndef __SAMPLE_I_COMPARABLE_H__
#define __SAMPLE_I_COMPARABLE_H__

#include <glib-object.h>

G_BEGIN_DECLS

#define SAMPLE_TYPE_ICOMPARABLE (sample_icomparable_get_type())

G_DECLARE_INTERFACE(SampleIComparable, sample_icomparable, SAMPLE, ICOMPARABLE,
                    GObject)

struct _SampleIComparableInterface {
    GTypeInterface parent_iface;

    void (*compare)(SampleIComparable *this, SampleIComparable *item,
                    gint *const restrict result);
};

void sample_icomparable_compare(SampleIComparable *this,
                                SampleIComparable *item,
                                gint *const restrict result);

G_END_DECLS

#endif  // __SAMPLE_I_COMPARABLE_H__

#include "sample-icomparable.h"

G_DEFINE_INTERFACE(SampleIComparable, sample_icomparable, G_TYPE_OBJECT)

static void sample_icomparable_default_init(
    SampleIComparableInterface *interface) {}

void sample_icomparable_compare(SampleIComparable *this,
                                SampleIComparable *item,
                                gint *const restrict result) {
    SampleIComparableInterface *interface = NULL;

    g_return_if_fail(SAMPLE_IS_ICOMPARABLE(this));
    g_return_if_fail(result != NULL);

    interface = SAMPLE_ICOMPARABLE_GET_IFACE(this);
    g_return_if_fail(interface->compare != NULL);
    interface->compare(this, item, result);
}

#ifndef __SAMPLE_STRING_H__
#define __SAMPLE_STRING_H__

#include <glib-object.h>

G_BEGIN_DECLS

#define SAMPLE_TYPE_STRING (sample_string_get_type())

G_DECLARE_FINAL_TYPE(SampleString, sample_string, SAMPLE, STRING, GObject)

SampleString *sample_string_new(gsize capacity);

SampleString *sample_string_new_with_text(const gchar *const restrict text,
                                          gsize capacity);

void sample_string_compare(SampleString *this, SampleString *item,
                           gint *const restrict result);

G_END_DECLS

#endif  // __SAMPLE_STRING_H__

#include "sample-string.h"

#include "sample-icomparable.h"

enum {
    SAMPLE_STRING_TEXT = 1,
    SAMPLE_STRING_LENGTH = 2,
    SAMPLE_STRING_CAPACITY = 3,
};

struct _SampleString {
    GObject parent_instance;

    gchar *array;
    gsize length;
    gsize capacity;
};

static void sample_icomparable_interface_init(
    SampleIComparableInterface *interface);

G_DEFINE_TYPE_WITH_CODE(
    SampleString, sample_string, G_TYPE_OBJECT,
    G_IMPLEMENT_INTERFACE(SAMPLE_TYPE_ICOMPARABLE,
                          sample_icomparable_interface_init))

// 注意参数类型
static void compare(SampleIComparable *this, SampleIComparable *item,
                    gint *const restrict result) {
    SampleString *a = SAMPLE_STRING(this), *b = SAMPLE_STRING(item);
    *result = a->length - b->length;
}

static void sample_icomparable_interface_init(
    SampleIComparableInterface *interface) {
    interface->compare = compare;
}

static void sample_string_set_property(GObject *object, guint property_id,
                                       const GValue *value, GParamSpec *pspec) {
    SampleString *this = SAMPLE_STRING(object);
    switch (property_id) {
        case SAMPLE_STRING_TEXT: {
            gchar *temp = g_value_dup_string(value);
            if (strlen(temp) > this->capacity) {
                this->capacity = strlen(temp);
                this->array = g_realloc(this->array, this->capacity);
            }
            memcpy(this->array, temp, this->capacity);
            g_free(temp);
            this->length = strlen(temp);
            break;
        }
        case SAMPLE_STRING_CAPACITY: {
            this->capacity = g_value_get_uint64(value);
            break;
        }
        default: {
            G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec);
            break;
        }
    }
    g_print("sample_string_set_property() finished.\n");
}

static void sample_string_get_property(GObject *object, guint property_id,
                                       GValue *value, GParamSpec *pspec) {
    SampleString *this = SAMPLE_STRING(object);
    switch (property_id) {
        case SAMPLE_STRING_TEXT: {
            g_value_set_string(value, this->array);
            break;
        }
        case SAMPLE_STRING_LENGTH: {
            g_value_set_uint64(value, this->length);
            break;
        }
        case SAMPLE_STRING_CAPACITY: {
            g_value_set_uint64(value, this->capacity);
            break;
        }
        default: {
            G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec);
            break;
        }
    }
    g_print("sample_string_get_property() finished.\n");
}

static void sample_string_dispose(GObject *object) {
    G_OBJECT_CLASS(sample_string_parent_class)->dispose(object);
    g_print("sample_string_dispose() finished.\n");
}

static void sample_string_finalize(GObject *object) {
    SampleString *this = SAMPLE_STRING(object);
    g_free(this->array);
    G_OBJECT_CLASS(sample_string_parent_class)->finalize(object);
    g_print("sample_string_finalize() finished.\n");
}

static void sample_string_init(SampleString *this) {
    g_print("sample_string_init() finished.\n");
}

static void sample_string_constructed(GObject *object) {
    SampleString *this = SAMPLE_STRING(object);

    this->array = g_new(gchar, this->capacity);
}

static void sample_string_class_init(SampleStringClass *class) {
    GObjectClass *object_class = G_OBJECT_CLASS(class);
    GParamSpec *temp = NULL;

    object_class->constructed = sample_string_constructed;
    object_class->set_property = sample_string_set_property;
    object_class->get_property = sample_string_get_property;
    object_class->dispose = sample_string_dispose;
    object_class->finalize = sample_string_finalize;

    temp = g_param_spec_string("text", "Text", "Text stored inside the struct.",
                               NULL, G_PARAM_READWRITE);
    g_object_class_install_property(object_class, SAMPLE_STRING_TEXT, temp);
    temp = g_param_spec_uint64("length", "Length", "Text length.", 0,
                               G_MAXUINT64, 0, G_PARAM_READABLE);
    g_object_class_install_property(object_class, SAMPLE_STRING_LENGTH, temp);
    temp = g_param_spec_uint64("capacity", "Capacity", "Text capacity.", 0,
                               G_MAXUINT64, 0,
                               G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY);
    g_object_class_install_property(object_class, SAMPLE_STRING_CAPACITY, temp);

    g_print("sample_string_class_init() finished.\n");
}

SampleString *sample_string_new(gsize capacity) {
    SampleString *this =
        g_object_new(SAMPLE_TYPE_STRING, "capacity", capacity, NULL);
    return this;
}

SampleString *sample_string_new_with_text(const gchar *const restrict text,
                                          gsize capacity) {
    GValue value = G_VALUE_INIT;
    SampleString *this =
        g_object_new(SAMPLE_TYPE_STRING, "capacity", capacity, NULL);
    g_value_init(&value, G_TYPE_STRING);
    g_value_set_string(&value, text);
    g_object_set_property(G_OBJECT(this), "text", &value);
    return this;
}

void sample_string_compare(SampleString *this, SampleString *item,
                           gint *const restrict result) {
    SampleIComparable *a = NULL, *b = NULL;

    g_return_if_fail(result != NULL);

    a = SAMPLE_ICOMPARABLE(this);
    b = SAMPLE_ICOMPARABLE(item);
    compare(a, b, result);
}

#include <glib-object.h>

#include "sample-icomparable.h"
#include "sample-string.h"

int main() {
    gint result = 0;
    SampleString *a = sample_string_new_with_text("1145141919810", 20),
                 *b = sample_string_new_with_text("1919810", 20);

    // 注意，调用的不是 SampleString 类的成员函数
    sample_icomparable_compare(SAMPLE_ICOMPARABLE(a), SAMPLE_ICOMPARABLE(b),
                               &result);

    g_print("result = %d\n", result);
}

> cmake .. -G "MinGW Makefiles" && mingw32-make && ../bin/hello
sample_string_class_init() finished.
sample_string_init() finished.
sample_string_set_property() finished.
sample_string_set_property() finished.
sample_string_init() finished.
sample_string_set_property() finished.
sample_string_set_property() finished.
result = 6

SampleString *str = g_object_new(SAMPLE_TYPE_STRING, NULL);

// 初始化
GValue a = G_VALUE_INIT, b = G_VALUE_INIT;
g_value_init(&a, SAMPLE_TYPE_STRING);   // 第二个参数填“类型代号”，可以是自定义类型
g_value_init(&b, SAMPLE_TYPE_STRING);

g_value_set_object(&a, str);            // 根据类型调用 set_<类型>() 方法
g_value_copy(&a, &b);                   // 拷贝
str = g_value_get_object(&b);           // 取出拷贝值

// 减少三次引用计数
g_object_unref(str);
g_object_unref(str);
g_object_unref(str);

> cmake .. -G "MinGW Makefiles" && mingw32-make && ../bin/hello
sample_string_class_init() finished.
sample_string_init() finished.
sample_string_set_property() finished.
sample_string_dispose() finished.
sample_string_finalize() finished.