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// https://doc.rust-lang.org/rust-by-example/std/box.html
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stc/ccommon.h>
struct {
double x;
double y;
} typedef Point;
// A Rectangle can be specified by where its top left and bottom right
// corners are in space
struct {
Point top_left;
Point bottom_right;
} typedef Rectangle;
#define i_val Point
#define i_opt c_no_cmp
#include <stc/cbox.h> // cbox_Point
#define i_val Rectangle
#define i_opt c_no_cmp
#include <stc/cbox.h> // cbox_Rectangle
// Box in box:
#define i_val_bind cbox_Point // NB: adviced to use i_val_arc when value is a cbox or csptr!
// it will auto-set i_drop, i_from, i_cmp for you.
#define i_opt c_no_cmp
#define i_tag BoxPoint
#include <stc/cbox.h> // cbox_BoxPoint
Point origin(void) {
return (Point){ .x=0.0, .y=0.0 };
}
cbox_Point boxed_origin(void) {
// Allocate this point on the heap, and return a pointer to it
return cbox_Point_new((Point){ .x=0.0, .y=0.0 });
}
int main(void) {
// (all the type annotations are superfluous)
// Stack allocated variables
Point point = origin();
Rectangle rectangle = (Rectangle){
.top_left = origin(),
.bottom_right = (Point){ .x=3.0, .y=-4.0 }
};
// Heap allocated rectangle
c_auto (cbox_Rectangle, boxed_rectangle)
c_auto (cbox_Point, boxed_point)
c_auto (cbox_BoxPoint, box_in_a_box)
{
boxed_rectangle = cbox_Rectangle_new((Rectangle){
.top_left = origin(),
.bottom_right = (Point){ .x=3.0, .y=-4.0 }
});
// The output of functions can be boxed
boxed_point = cbox_Point_new(origin());
// Double indirection
box_in_a_box = cbox_BoxPoint_new(boxed_origin());
printf("Point occupies %zu bytes on the stack\n",
sizeof(point));
printf("Rectangle occupies %zu bytes on the stack\n",
sizeof(rectangle));
// box size == pointer size
printf("Boxed point occupies %zu bytes on the stack\n",
sizeof(boxed_point));
printf("Boxed rectangle occupies %zu bytes on the stack\n",
sizeof(boxed_rectangle));
printf("Boxed box occupies %zu bytes on the stack\n",
sizeof(box_in_a_box));
// Copy the data contained in `boxed_point` into `unboxed_point`
Point unboxed_point = *boxed_point.get;
printf("Unboxed point occupies %zu bytes on the stack\n",
sizeof(unboxed_point));
}
}
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