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const std = @import("std");
/// Interface type, holding a pointer to the object and the interface function pointers.
const Iter = struct {
ptr: *anyopaque,
next_fn: *const fn (*anyopaque) ?i32,
/// Convenience wrapper to call vtable function.
pub fn next(self: Iter) ?i32 {
return self.next_fn(self.ptr);
}
};
const UpIter = struct {
end: i32,
now: i32 = 0,
/// Create an Inter interface object from UpIter.
pub fn iter(self: *UpIter) Iter {
return Iter{ .ptr = self, .next_fn = next };
}
pub fn next(ptr: *anyopaque) ?i32 {
const self: *UpIter = @alignCast(@ptrCast(ptr));
if (self.now < self.end) {
self.now += 1;
return self.now;
} else {
return null;
}
}
};
/// Function example taking an Iter interface object.
fn run_iter(iter: Iter) void {
while (iter.next()) |v| {
std.debug.print("{},", .{v});
}
std.debug.print("\n", .{});
}
pub fn main() void {
var uit = UpIter{ .end = 10 };
run_iter(uit.iter());
}
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