rlp uses insert_slice
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@ -5,6 +5,7 @@ pub mod hash;
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pub mod uint;
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pub mod bytes;
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pub mod rlp;
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pub mod vector;
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#[test]
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fn it_works() {
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30
src/rlp.rs
30
src/rlp.rs
@ -48,6 +48,7 @@ use std::cell::Cell;
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use std::collections::LinkedList;
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use std::error::Error as StdError;
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use bytes::{ToBytes, FromBytes, FromBytesError};
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use vector::InsertSlice;
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/// rlp container
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#[derive(Debug)]
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@ -455,27 +456,18 @@ impl BasicEncoder {
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}
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/// inserts list prefix at given position
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/// TODO: optimise it, so it does not copy an array
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/// TODO: optimise it further?
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fn insert_list_len_at_pos(&mut self, len: usize, pos: usize) -> () {
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// new bytes
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let mut res: Vec<u8> = vec![];
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// reserve a space equal at least current space + space for length
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res.reserve(self.bytes.len() + 1);
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{
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let (before_slice, after_slice) = self.bytes.split_at(pos);
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res.extend(before_slice);
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let mut res = vec![];
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match len {
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0...55 => res.push(0xc0u8 + len as u8),
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_ => {
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res.push(0x7fu8 + len.to_bytes_len() as u8);
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res.extend(len.to_bytes());
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}
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};
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match len {
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0...55 => res.push(0xc0u8 + len as u8),
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_ => {
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res.push(0x7fu8 + len.to_bytes_len() as u8);
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res.extend(len.to_bytes());
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}
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};
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res.extend(after_slice);
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}
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self.bytes = res;
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self.bytes.insert_slice(pos, &res);
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}
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/// get encoded value
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34
src/vector.rs
Normal file
34
src/vector.rs
Normal file
@ -0,0 +1,34 @@
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use std::ptr;
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pub trait InsertSlice<T> {
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fn insert_slice(&mut self, index: usize, elements: &[T]);
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}
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/// based on `insert` function implementation from standard library
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impl<T> InsertSlice<T> for Vec<T> {
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fn insert_slice(&mut self, index: usize, elements: &[T]) {
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let e_len = elements.len();
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if e_len == 0 {
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return;
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}
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let len = self.len();
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assert!(index <= len);
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// space for the new element
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self.reserve(e_len);
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unsafe {
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{
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let p = self.as_mut_ptr().offset(index as isize);
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let ep = elements.as_ptr().offset(0);
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// shift everything by e_len, to make space
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ptr::copy(p, p.offset(e_len as isize), len - index);
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// write new element
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ptr::copy(ep, p, e_len);
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}
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self.set_len(len + e_len);
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}
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}
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}
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