openethereum/src/vector.rs

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Rust
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2015-11-26 19:09:14 +01:00
use std::ptr;
pub trait InsertSlice<T> {
fn insert_slice(&mut self, index: usize, elements: &[T]);
}
/// based on `insert` function implementation from standard library
impl<T> InsertSlice<T> for Vec<T> {
fn insert_slice(&mut self, index: usize, elements: &[T]) {
let e_len = elements.len();
if e_len == 0 {
return;
}
let len = self.len();
assert!(index <= len);
// space for the new element
self.reserve(e_len);
unsafe {
{
let p = self.as_mut_ptr().offset(index as isize);
let ep = elements.as_ptr().offset(0);
// shift everything by e_len, to make space
ptr::copy(p, p.offset(e_len as isize), len - index);
// write new element
ptr::copy(ep, p, e_len);
}
self.set_len(len + e_len);
}
}
}