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@willcrichton willcrichton/goodvector.rs Secret
Created Feb 4, 2018

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#![feature(allocator_api)]
use std::heap::{Heap, Layout, Alloc};
use std::slice;
struct Vec2 {
data: Box<[isize]>,
length: usize,
capacity: usize,
}
impl Vec2 {
fn new() -> Vec2 {
let v = Vec2 {
data: Box::new([0]),
length: 0,
capacity: 1,
};
return v;
}
fn push(&mut self, n: isize) {
if self.length == self.capacity {
let new_capacity = self.capacity * 2;
let mut new_data = unsafe {
let ptr = Heap::default()
.alloc(Layout::array::<isize>(new_capacity).unwrap())
.unwrap() as *mut isize;
Box::from_raw(slice::from_raw_parts_mut(ptr, new_capacity))
};
for i in 0..self.length {
new_data[i] = self.data[i];
}
self.data = new_data;
self.capacity = new_capacity;
}
self.data[self.length] = n;
self.length += 1;
}
}
fn main() {
let mut vec: Vec2 = Vec2::new();
vec.push(107);
vec.push(110);
let n: &isize = &vec.data[0];
}
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