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#![deny(missing_docs)]
extern crate crypto;
extern crate byteorder;
#[macro_use]
extern crate log;
mod window;
mod hashing;
pub mod string_diff;
use std::collections::HashMap;
use std::fs::File;
use std::io::{self, Read, Write, Seek, SeekFrom};
use std::slice::Iter;
use std::fmt;
use std::mem;
use std::string::FromUtf8Error;
use byteorder::{NetworkEndian, ByteOrder};
#[derive(Debug, PartialEq)]
pub struct BlockHashes {
hashes: HashMap<u32, Vec<(usize, [u8; 16])>>,
block_size: usize,
file_size: usize
}
#[derive(PartialEq)]
pub struct Insert {
position: usize,
data: Vec<u8>
}
#[derive(PartialEq)]
pub struct Delete {
position: usize,
len: usize
}
#[derive(Debug, PartialEq)]
pub struct Diff {
inserts: Vec<Insert>,
deletes: Vec<Delete>
}
struct Window<R: Read> {
front: Vec<u8>,
back: Vec<u8>,
block_size: usize,
offset: usize,
bytes_read: usize,
reader: R
}
impl Diff {
#[inline]
pub fn new() -> Diff {
Diff {
inserts: Vec::new(),
deletes: Vec::new()
}
}
fn add_insert(&mut self, position: usize, mut data: Vec<u8>) {
if let Some(tail) = self.inserts.last_mut() {
if tail.position + tail.data.len() == position {
tail.data.append(&mut data);
return;
}
}
self.inserts.push(Insert {
position: position,
data: data
});
}
fn add_delete(&mut self, position: usize, len: usize) {
if let Some(tail) = self.deletes.last_mut() {
if tail.position == position {
tail.len += len;
return;
}
}
self.deletes.push(Delete {
position: position,
len: len
});
}
pub fn inserts(&self) -> Iter<Insert> {
self.inserts.iter()
}
pub fn deletes(&self) -> Iter<Delete> {
self.deletes.iter()
}
pub fn is_empty(&self) -> bool {
self.deletes.is_empty() && self.inserts.is_empty()
}
pub fn apply_to_string(&self, string: &str) -> Result<String, FromUtf8Error> {
let mut old_bytes = string.bytes();
let mut new_bytes = Vec::new();
let mut index = 0;
for insert in self.inserts() {
while index < insert.position {
new_bytes.push(old_bytes.next().unwrap().clone());
index += 1;
}
new_bytes.append(&mut insert.data.clone());
index += insert.data.len();
}
while let Some(byte) = old_bytes.next() {
new_bytes.push(byte);
}
let old_bytes = mem::replace(&mut new_bytes, Vec::new());
let mut old_bytes = old_bytes.into_iter();
index = 0;
for delete in self.deletes() {
while index < delete.position {
new_bytes.push(old_bytes.next().unwrap());
index += 1;
}
for _ in 0..delete.len {
old_bytes.next();
}
}
while let Some(byte) = old_bytes.next() {
new_bytes.push(byte);
}
String::from_utf8(new_bytes)
}
pub fn apply(&self, file: &mut File) -> io::Result<()> {
let mut new_bytes = Vec::new();
try!(file.seek(SeekFrom::Start(0)));
let mut old_bytes = file.try_clone().unwrap().bytes();
let mut index = 0;
for insert in self.inserts.iter() {
while index < insert.position {
new_bytes.push(try!(old_bytes.next().unwrap()).clone());
index += 1;
}
new_bytes.extend_from_slice(&insert.data[..]);
index += insert.data.len();
}
while let Some(byte) = old_bytes.next() {
new_bytes.push(try!(byte));
}
let old_bytes = mem::replace(&mut new_bytes, Vec::new());
let mut old_bytes = old_bytes.into_iter();
index = 0;
for delete in self.deletes.iter() {
while index < delete.position {
new_bytes.push(old_bytes.next().unwrap());
index += 1;
}
for _ in 0..delete.len {
old_bytes.next();
}
}
while let Some(byte) = old_bytes.next() {
new_bytes.push(byte);
}
try!(file.seek(SeekFrom::Start(0)));
try!(file.set_len(new_bytes.len() as u64));
file.write_all(new_bytes.as_slice())
}
pub fn compress_to<W: Write>(&self, writer: &mut W) -> io::Result<()> {
let mut int_buf = [0;4];
NetworkEndian::write_u32(&mut int_buf, self.inserts.len() as u32);
try!(writer.write(&mut int_buf));
for insert in self.inserts.iter() {
try!(insert.compress_to(writer));
}
NetworkEndian::write_u32(&mut int_buf, self.deletes.len() as u32);
try!(writer.write(&mut int_buf));
for delete in self.deletes.iter() {
try!(delete.compress_to(writer));
}
Ok(())
}
pub fn expand_from<R: Read>(reader: &mut R) -> io::Result<Diff> {
let mut int_buf = [0;4];
trace!("Reading insert length");
try!(reader.read_exact(&mut int_buf));
let insert_len = NetworkEndian::read_u32(&int_buf);
trace!("Insert length was: {}", insert_len);
let inserts = (0..insert_len).map(|_|Insert::expand_from(reader).unwrap()).collect();
trace!("Read inserts");
trace!("Reading delete length");
try!(reader.read_exact(&mut int_buf));
let delete_len = NetworkEndian::read_u32(&int_buf);
trace!("Delete length was: {}", delete_len);
let deletes = (0..delete_len).map(|_|Delete::expand_from(reader).unwrap()).collect();
trace!("Read deletes");
Ok(Diff {
inserts: inserts,
deletes: deletes
})
}
}
impl fmt::Debug for Insert {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "Insert({}, '{}')", self.position, String::from_utf8_lossy(&self.data).replace('\r', "").replace('\n', "\\n"))
}
}
impl fmt::Debug for Delete {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "Delete({}, {})", self.position, self.len)
}
}
impl Insert {
#[inline]
pub fn get_position(&self) -> usize {
self.position
}
#[inline]
pub fn get_data(&self) -> &Vec<u8> {
&self.data
}
pub fn compress_to<W: Write>(&self, writer: &mut W) -> io::Result<()> {
let mut int_buf = [0;4];
NetworkEndian::write_u32(&mut int_buf, self.position as u32);
try!(writer.write(&int_buf));
NetworkEndian::write_u32(&mut int_buf, self.data.len() as u32);
try!(writer.write(&int_buf));
try!(writer.write(&self.data));
Ok(())
}
pub fn expand_from<R: Read>(reader: &mut R) -> io::Result<Insert> {
let mut int_buf = [0;4];
try!(reader.read_exact(&mut int_buf));
let position = NetworkEndian::read_u32(&int_buf);
try!(reader.read_exact(&mut int_buf));
let data_len = NetworkEndian::read_u32(&int_buf) as usize;
let mut data = Vec::with_capacity(data_len);
data.resize(data_len, 0);
try!(reader.read_exact(&mut data));
Ok(Insert{
position: position as usize,
data: data
})
}
}
impl Delete {
#[inline]
pub fn get_position(&self) -> usize {
self.position
}
#[inline]
pub fn get_length(&self) -> usize {
self.len
}
pub fn compress_to<W: Write>(&self, writer: &mut W) -> io::Result<()> {
let mut int_buf = [0;4];
NetworkEndian::write_u32(&mut int_buf, self.position as u32);
try!(writer.write(&int_buf));
NetworkEndian::write_u32(&mut int_buf, self.len as u32);
try!(writer.write(&int_buf));
Ok(())
}
pub fn expand_from<R: Read>(reader: &mut R) -> io::Result<Delete> {
let mut int_buf = [0;4];
try!(reader.read_exact(&mut int_buf));
let position = NetworkEndian::read_u32(&int_buf);
try!(reader.read_exact(&mut int_buf));
let len = NetworkEndian::read_u32(&int_buf);
Ok(Delete{
position: position as usize,
len: len as usize,
})
}
}
#[cfg(test)]
mod test {
use super::Diff;
#[test]
fn applying_diff_to_string() {
let string = "Mr. and Mrs. Dursley, of number four, Privet Drive, were proud to say that they were perfectly normal, thank you very much. They were the last people you'd expect to be involved in anything strange or mysterious, because they just didn't hold with such nonsense.";
let mut diff = Diff::new();
diff.add_insert(2, vec![115]);
diff.add_insert(37, vec![116, 121]);
diff.add_insert(98, vec![97, 98]);
diff.add_insert(253, vec![109]);
diff.add_delete(35, 1);
diff.add_delete(181, 34);
diff.add_delete(219, 1);
let result = diff.apply_to_string(string).unwrap();
assert_eq!(result, "Mrs. and Mrs. Dursley, of number forty, Privet Drive, were proud to say that they were perfectly abnormal, thank you very much. They were the last people you'd expect to be involved, because they just didn't hold with much nonsense.".to_string());
}
}