cmake_demo/main.c

#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <assert.h>

#define VIRTUAL  
#define PRIVATE static 

#define ASSERT_CALL_VIRTUAL_METHOD() assert(!("can't call abstract method"))


struct _virtual_table
{
    VIRTUAL double (*area)(void *self, void *parent);
    VIRTUAL void (*draw)(void *self, void *parent);
};

double virtual_area(void *self, void *parent)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

void virtual_draw(void *self, void *parent)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

struct _virtual_table *virtual_new(void)
{
    struct _virtual_table *vtb = calloc(1, sizeof(struct _virtual_table));
    if (vtb == NULL)
    {
        return NULL;
    }
    vtb->area = virtual_area;
    vtb->draw = virtual_draw;
    return vtb;
}

struct _shape
{
    struct _virtual_table vtb;
};

double shape_area(void *self, void *parent)
{
    double area = 0;
    struct _shape *pthis = (struct _shape *)parent;
    area = pthis->vtb.area(self, NULL);
    return area;
}

void shape_draw(void *self, void *parent)
{
    struct _shape *pthis = (struct _shape *)parent;
    pthis->vtb.draw(self, NULL);
}

PRIVATE double _shape_area(void *self, void *parent)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

PRIVATE void _shape_draw(void *self, void *parent)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

struct _shape *shape_new(void)
{
    struct _shape *shape = calloc(1, sizeof(struct _shape));
    if(shape == NULL)
    {
        return NULL;
    }
    static struct _virtual_table vtb = {
        .area = (double (*)(void *self, void *parent))_shape_area, 
        .draw = (void (*)(void *self, void *parent))_shape_draw
    };
    shape->vtb = vtb;
    return shape;
}

#if 0
void shape_free(struct _shape * self)
{
    if (self != NULL)
    {
        free(self);
    }
}
#endif

struct _rect
{
    int invalid;

    // super
    struct _shape shape;
    // struct _shape;
    // struct _virtual_table vtb;

    // attribute
    double width, height;

    // method
    // void (*area)(void *self);
    // void (*draw)(void *self);
};

double rect_area(struct _rect *self, void *parent)
{
    double area = self->width * self->height;
    printf("rect area = %0.2f\n", area);
    return area;
}

void rect_draw(struct _rect *self, void *parent)
{
    printf("rect draw\n");
}

struct _rect *rect_new(double width, double height)
{
    struct _rect *rect = calloc(1, sizeof(struct _rect));
    if (rect == NULL)
    {
        return NULL;
    }
    rect->width = width;
    rect->height = height;

    static struct _virtual_table vtb = {
        .area = (double (*)(void *self, void *parent))rect_area,
        .draw = (void (*)(void *self, void *parent))rect_draw
    };

    rect->shape.vtb = vtb;
    // rect->vtb = vtb;
    return rect;
}

struct _circle
{
    int invalid;

    // super
    struct _shape shape;
    // struct _shape;
    // struct _virtual_table vtb;

    // attribute
    double radius;

    // method
    // void (*area)(void *self);
    // void (*draw)(void *self);
};

double circle_area(struct _circle *self, void *parent)
{
    double area = 3.14 * self->radius * self->radius;
    printf("circle area = %0.2f\n", area);
    return area;
}
void circle_draw(struct _circle *self, void *parent)
{
    printf("circle draw\n");
}

struct _circle *circle_new(double radius)
{
    struct _circle *circle = calloc(1, sizeof(struct _circle));
    if (circle == NULL)
    {
        return NULL;
    }
    circle->radius = radius;

    static struct _virtual_table vtb = {
        .area = (double (*)(void *self, void *parent))circle_area,
        .draw = (void (*)(void *self, void *parent))circle_draw,
    };

    // circle->vtb = vtb;
    circle->shape.vtb = vtb;
    return circle;
}

struct _copper_cash
{
    struct _shape shape;
    struct _rect *rect;
    struct _circle *circle;

    double price;
};

double copper_cash_area(struct _copper_cash *self, void *parent)
{
    double circle_area = self->circle->shape.vtb.area(self->circle, self->circle);
    double rect_area = self->rect->shape.vtb.area(self->rect, self->rect);
    double area = circle_area - rect_area;

    printf("copper cash area = %0.2f\n", circle_area - rect_area);
    return area;
}

void copper_cash_draw(struct _copper_cash *self, void *parent)
{
    printf("copper cash draw\n");
}


struct _copper_cash *copper_cash_new(double width, double height, double radius)
{
    struct _copper_cash *cc = calloc(1, sizeof(struct _copper_cash));
    if (cc == NULL)
    {
        return NULL;
    }

    struct _rect *rect = rect_new(width, height);
    if(rect == NULL)
    {
        return NULL;
    }
    cc->rect = rect;

    struct _circle *circle = circle_new(radius);
    if (circle == NULL)
    {
        return NULL;
    }
    cc->circle = circle;
    cc->price = 100;

    static struct _virtual_table vtb = {
        .area = (double (*)(void *self, void *parent))copper_cash_area,
        .draw = (void (*)(void *self, void *parent))copper_cash_draw,
    };
    cc->shape.vtb = vtb;
    return cc;
}

int main(int argc, char *argv[])
{
    struct _rect *rect = rect_new(4, 5);
    rect_area(rect, rect);
    rect_draw(rect, rect);

    struct _circle *circle = circle_new(3);
    circle_area(circle, circle);
    circle_draw(circle, circle);

    printf("----- rect & circle -----\n");
    shape_area(rect, &rect->shape);
    shape_draw(rect, &rect->shape);

    shape_area(circle, &circle->shape);
    shape_draw(circle, &circle->shape);

    printf("----- [2] rect & circle -----\n");
    struct _rect *rect2 = (struct _rect *)rect_new(2, 3);
    shape_area(rect2, &rect2->shape);
    shape_draw(rect2, &rect2->shape);

    struct _circle *circle2 = (struct _circle *)circle_new(1);
    shape_area(circle2, &circle->shape);
    shape_draw(circle2, &circle->shape);

    // printf("----- [2] shape -----\n");
    // struct _shape *shape = shape_new();
    // shape_area(shape, shape);
    // shape_draw(shape, shape);

    printf("----- copper_cash -----\n");
    struct _copper_cash *cc = copper_cash_new(2, 2, 4);
    shape_area(cc, &cc->shape);
    shape_draw(cc, &cc->shape);

    return 0;
}