rlp uses insert_slice

This commit is contained in:
debris 2015-11-26 19:09:14 +01:00
parent 716c907dc2
commit 0b9620f3ec
3 changed files with 46 additions and 19 deletions

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@ -5,6 +5,7 @@ pub mod hash;
pub mod uint;
pub mod bytes;
pub mod rlp;
pub mod vector;
#[test]
fn it_works() {

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@ -48,6 +48,7 @@ use std::cell::Cell;
use std::collections::LinkedList;
use std::error::Error as StdError;
use bytes::{ToBytes, FromBytes, FromBytesError};
use vector::InsertSlice;
/// rlp container
#[derive(Debug)]
@ -455,16 +456,9 @@ impl BasicEncoder {
}
/// inserts list prefix at given position
/// TODO: optimise it, so it does not copy an array
/// TODO: optimise it further?
fn insert_list_len_at_pos(&mut self, len: usize, pos: usize) -> () {
// new bytes
let mut res: Vec<u8> = vec![];
// reserve a space equal at least current space + space for length
res.reserve(self.bytes.len() + 1);
{
let (before_slice, after_slice) = self.bytes.split_at(pos);
res.extend(before_slice);
let mut res = vec![];
match len {
0...55 => res.push(0xc0u8 + len as u8),
_ => {
@ -473,9 +467,7 @@ impl BasicEncoder {
}
};
res.extend(after_slice);
}
self.bytes = res;
self.bytes.insert_slice(pos, &res);
}
/// get encoded value

34
src/vector.rs Normal file
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@ -0,0 +1,34 @@
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);
}
}
}