openethereum/util/rlp/src/stream.rs

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// Copyright 2015-2017 Parity Technologies
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::borrow::Borrow;
use byteorder::{ByteOrder, BigEndian};
use elastic_array::{ElasticArray16, ElasticArray1024};
use traits::Encodable;
#[derive(Debug, Copy, Clone)]
struct ListInfo {
position: usize,
current: usize,
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max: Option<usize>,
}
impl ListInfo {
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fn new(position: usize, max: Option<usize>) -> ListInfo {
ListInfo {
position: position,
current: 0,
max: max,
}
}
}
/// Appendable rlp encoder.
pub struct RlpStream {
unfinished_lists: ElasticArray16<ListInfo>,
buffer: ElasticArray1024<u8>,
finished_list: bool,
}
impl Default for RlpStream {
fn default() -> Self {
RlpStream::new()
}
}
impl RlpStream {
/// Initializes instance of empty `Stream`.
pub fn new() -> Self {
RlpStream {
unfinished_lists: ElasticArray16::new(),
buffer: ElasticArray1024::new(),
finished_list: false,
}
}
/// Initializes the `Stream` as a list.
pub fn new_list(len: usize) -> Self {
let mut stream = RlpStream::new();
stream.begin_list(len);
stream
}
/// Appends value to the end of stream, chainable.
///
/// ```rust
/// extern crate rlp;
/// use rlp::*;
///
/// fn main () {
/// let mut stream = RlpStream::new_list(2);
/// stream.append(&"cat").append(&"dog");
/// let out = stream.out();
/// assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
/// }
/// ```
pub fn append<'a, E>(&'a mut self, value: &E) -> &'a mut Self where E: Encodable {
self.finished_list = false;
value.rlp_append(self);
if !self.finished_list {
self.note_appended(1);
}
self
}
/// Appends list of values to the end of stream, chainable.
pub fn append_list<'a, E, K>(&'a mut self, values: &[K]) -> &'a mut Self where E: Encodable, K: Borrow<E> {
self.begin_list(values.len());
for value in values {
self.append(value.borrow());
}
self
}
/// Appends value to the end of stream, but do not count it as an appended item.
/// It's useful for wrapper types
pub fn append_internal<'a, E>(&'a mut self, value: &E) -> &'a mut Self where E: Encodable {
value.rlp_append(self);
self
}
/// Declare appending the list of given size, chainable.
///
/// ```rust
/// extern crate rlp;
/// use rlp::*;
///
/// fn main () {
/// let mut stream = RlpStream::new_list(2);
/// stream.begin_list(2).append(&"cat").append(&"dog");
/// stream.append(&"");
/// let out = stream.out();
/// assert_eq!(out, vec![0xca, 0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g', 0x80]);
/// }
/// ```
pub fn begin_list(&mut self, len: usize) -> &mut RlpStream {
self.finished_list = false;
match len {
0 => {
// we may finish, if the appended list len is equal 0
self.buffer.push(0xc0u8);
self.note_appended(1);
self.finished_list = true;
},
_ => {
// payload is longer than 1 byte only for lists > 55 bytes
// by pushing always this 1 byte we may avoid unnecessary shift of data
self.buffer.push(0);
let position = self.buffer.len();
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self.unfinished_lists.push(ListInfo::new(position, Some(len)));
},
}
// return chainable self
self
}
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/// Declare appending the list of unknown size, chainable.
pub fn begin_unbounded_list(&mut self) -> &mut RlpStream {
self.finished_list = false;
// payload is longer than 1 byte only for lists > 55 bytes
// by pushing always this 1 byte we may avoid unnecessary shift of data
self.buffer.push(0);
let position = self.buffer.len();
self.unfinished_lists.push(ListInfo::new(position, None));
// return chainable self
self
}
/// Apends null to the end of stream, chainable.
///
/// ```rust
/// extern crate rlp;
/// use rlp::*;
///
/// fn main () {
/// let mut stream = RlpStream::new_list(2);
/// stream.append_empty_data().append_empty_data();
/// let out = stream.out();
/// assert_eq!(out, vec![0xc2, 0x80, 0x80]);
/// }
/// ```
pub fn append_empty_data(&mut self) -> &mut RlpStream {
// self push raw item
self.buffer.push(0x80);
// try to finish and prepend the length
self.note_appended(1);
// return chainable self
self
}
/// Appends raw (pre-serialised) RLP data. Use with caution. Chainable.
pub fn append_raw<'a>(&'a mut self, bytes: &[u8], item_count: usize) -> &'a mut RlpStream {
// push raw items
self.buffer.append_slice(bytes);
// try to finish and prepend the length
self.note_appended(item_count);
// return chainable self
self
}
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/// Appends raw (pre-serialised) RLP data. Checks for size oveflow.
pub fn append_raw_checked<'a>(&'a mut self, bytes: &[u8], item_count: usize, max_size: usize) -> bool {
if self.estimate_size(bytes.len()) > max_size {
return false;
}
self.append_raw(bytes, item_count);
true
}
/// Calculate total RLP size for appended payload.
pub fn estimate_size<'a>(&'a self, add: usize) -> usize {
let total_size = self.buffer.len() + add;
let mut base_size = total_size;
for list in &self.unfinished_lists[..] {
let len = total_size - list.position;
if len > 55 {
let leading_empty_bytes = (len as u64).leading_zeros() as usize / 8;
let size_bytes = 8 - leading_empty_bytes;
base_size += size_bytes;
}
}
base_size
}
/// Returns current RLP size in bytes for the data pushed into the list.
pub fn len<'a>(&'a self) -> usize {
self.estimate_size(0)
}
/// Clear the output stream so far.
///
/// ```rust
/// extern crate rlp;
/// use rlp::*;
///
/// fn main () {
/// let mut stream = RlpStream::new_list(3);
/// stream.append(&"cat");
/// stream.clear();
/// stream.append(&"dog");
/// let out = stream.out();
/// assert_eq!(out, vec![0x83, b'd', b'o', b'g']);
/// }
pub fn clear(&mut self) {
// clear bytes
self.buffer.clear();
// clear lists
self.unfinished_lists.clear();
}
/// Returns true if stream doesnt expect any more items.
///
/// ```rust
/// extern crate rlp;
/// use rlp::*;
///
/// fn main () {
/// let mut stream = RlpStream::new_list(2);
/// stream.append(&"cat");
/// assert_eq!(stream.is_finished(), false);
/// stream.append(&"dog");
/// assert_eq!(stream.is_finished(), true);
/// let out = stream.out();
/// assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
/// }
pub fn is_finished(&self) -> bool {
self.unfinished_lists.len() == 0
}
/// Get raw encoded bytes
pub fn as_raw(&self) -> &[u8] {
//&self.encoder.bytes
&self.buffer
}
/// Streams out encoded bytes.
///
/// panic! if stream is not finished.
pub fn out(self) -> Vec<u8> {
match self.is_finished() {
//true => self.encoder.out().into_vec(),
true => self.buffer.into_vec(),
false => panic!()
}
}
/// Try to finish lists
fn note_appended(&mut self, inserted_items: usize) -> () {
if self.unfinished_lists.len() == 0 {
return;
}
let back = self.unfinished_lists.len() - 1;
let should_finish = match self.unfinished_lists.get_mut(back) {
None => false,
Some(ref mut x) => {
x.current += inserted_items;
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match x.max {
Some(ref max) if x.current > *max => panic!("You cannot append more items then you expect!"),
Some(ref max) => x.current == *max,
_ => false,
}
}
};
if should_finish {
let x = self.unfinished_lists.pop().unwrap();
let len = self.buffer.len() - x.position;
self.encoder().insert_list_payload(len, x.position);
self.note_appended(1);
}
self.finished_list = should_finish;
}
pub fn encoder(&mut self) -> BasicEncoder {
BasicEncoder::new(self)
}
/// Drain the object and return the underlying ElasticArray.
pub fn drain(self) -> ElasticArray1024<u8> {
match self.is_finished() {
true => self.buffer,
false => panic!()
}
}
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/// Finalize current ubnbound list. Panics if no unbounded list has been opened.
pub fn complete_unbounded_list(&mut self) {
let list = self.unfinished_lists.pop().expect("No open list.");
if list.max.is_some() {
panic!("List type mismatch.");
}
let len = self.buffer.len() - list.position;
self.encoder().insert_list_payload(len, list.position);
self.note_appended(1);
}
}
pub struct BasicEncoder<'a> {
buffer: &'a mut ElasticArray1024<u8>,
}
impl<'a> BasicEncoder<'a> {
fn new(stream: &'a mut RlpStream) -> Self {
BasicEncoder {
buffer: &mut stream.buffer
}
}
fn insert_size(&mut self, size: usize, position: usize) -> u8 {
let size = size as u32;
let leading_empty_bytes = size.leading_zeros() as usize / 8;
let size_bytes = 4 - leading_empty_bytes as u8;
let mut buffer = [0u8; 4];
BigEndian::write_u32(&mut buffer, size);
self.buffer.insert_slice(position, &buffer[leading_empty_bytes..]);
size_bytes as u8
}
/// Inserts list prefix at given position
fn insert_list_payload(&mut self, len: usize, pos: usize) {
// 1 byte was already reserved for payload earlier
match len {
0...55 => {
self.buffer[pos - 1] = 0xc0u8 + len as u8;
},
_ => {
let inserted_bytes = self.insert_size(len, pos);
self.buffer[pos - 1] = 0xf7u8 + inserted_bytes;
}
};
}
/// Pushes encoded value to the end of buffer
pub fn encode_value(&mut self, value: &[u8]) {
match value.len() {
// just 0
0 => self.buffer.push(0x80u8),
// byte is its own encoding if < 0x80
1 if value[0] < 0x80 => self.buffer.push(value[0]),
// (prefix + length), followed by the string
len @ 1 ... 55 => {
self.buffer.push(0x80u8 + len as u8);
self.buffer.append_slice(value);
}
// (prefix + length of length), followed by the length, followd by the string
len => {
self.buffer.push(0);
let position = self.buffer.len();
let inserted_bytes = self.insert_size(len, position);
self.buffer[position - 1] = 0xb7 + inserted_bytes;
self.buffer.append_slice(value);
}
}
}
}