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use std::io;
use std::fmt;
use std::cmp;
use super::*;
/// A `BufferedReader` that duplicates the underlying `BufferedReader`
/// without consuming any of the data.
///
/// Note: this will likely cause the underlying stream to buffer as
/// much data as you read. Thus, it should only be used for peeking
/// at the underlying `BufferedReader`.
pub struct BufferedReaderDup<'a, C> {
reader: Box<'a + BufferedReader<C>>,
// The number of bytes that have been consumed.
cursor: usize,
// The user settable cookie.
cookie: C,
}
impl<'a, C> fmt::Debug for BufferedReaderDup<'a, C> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("BufferedReaderDup")
.field("cursor", &self.cursor)
.field("reader", &self.reader)
.finish()
}
}
impl<'a> BufferedReaderDup<'a, ()> {
/// Instantiate a new memory-based reader. `buffer` contains the
/// reader's contents.
pub fn new(reader: Box<'a + BufferedReader<()>>) -> Self {
Self::with_cookie(reader, ())
}
}
impl<'a, C> BufferedReaderDup<'a, C> {
/// Like `new()`, but sets a cookie, which can be retrieved using
/// the `cookie_ref` and `cookie_mut` methods, and set using
/// the `cookie_set` method.
pub fn with_cookie(reader: Box<'a + BufferedReader<C>>, cookie: C) -> Self {
BufferedReaderDup {
reader: reader,
cursor: 0,
cookie: cookie,
}
}
/// Returns the number of bytes that have been consumed by this
/// reader.
pub fn total_out(&self) -> usize {
return self.cursor;
}
/// Resets the cursor to the beginning of the stream.
pub fn rewind(&mut self) {
self.cursor = 0;
}
}
impl<'a, C> io::Read for BufferedReaderDup<'a, C> {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
let data = self.reader.data(self.cursor + buf.len())?;
assert!(data.len() >= self.cursor);
let data = &data[self.cursor..];
let amount = cmp::min(buf.len(), data.len());
buf.copy_from_slice(&data[..amount]);
self.cursor += amount;
Ok(amount)
}
}
impl<'a, C> BufferedReader<C> for BufferedReaderDup<'a, C> {
fn buffer(&self) -> &[u8] {
let data = self.reader.buffer();
assert!(data.len() >= self.cursor);
&data[self.cursor..]
}
fn data(&mut self, amount: usize) -> Result<&[u8], io::Error> {
let data = self.reader.data(self.cursor + amount)?;
assert!(data.len() >= self.cursor);
Ok(&data[self.cursor..])
}
fn consume(&mut self, amount: usize) -> &[u8] {
let data = self.reader.buffer();
assert!(data.len() >= self.cursor + amount);
let data = &data[self.cursor..];
self.cursor += amount;
data
}
fn data_consume(&mut self, amount: usize) -> Result<&[u8], io::Error> {
let data = self.reader.data(self.cursor + amount)?;
assert!(data.len() >= self.cursor);
let data = &data[self.cursor..];
self.cursor += cmp::min(data.len(), amount);
Ok(data)
}
fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
let data = self.reader.data_hard(self.cursor + amount)?;
assert!(data.len() >= self.cursor + amount);
let data = &data[self.cursor..];
self.cursor += amount;
Ok(data)
}
fn get_mut(&mut self) -> Option<&mut BufferedReader<C>> {
Some(&mut self.reader)
}
fn get_ref(&self) -> Option<&BufferedReader<C>> {
Some(&self.reader)
}
fn into_inner<'b>(self: Box<Self>) -> Option<Box<BufferedReader<C> + 'b>>
where Self: 'b {
Some(self.reader)
}
fn cookie_set(&mut self, cookie: C) -> C {
use std::mem;
mem::replace(&mut self.cookie, cookie)
}
fn cookie_ref(&self) -> &C {
&self.cookie
}
fn cookie_mut(&mut self) -> &mut C {
&mut self.cookie
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn buffered_reader_memory_test () {
let data : &[u8] = include_bytes!("buffered-reader-test.txt");
let reader = BufferedReaderMemory::new(data);
let mut reader = BufferedReaderDup::new(Box::new(reader));
buffered_reader_test_data_check(&mut reader);
let consumed = reader.total_out();
assert_eq!(consumed, data.len());
// Since we haven't consumed the inner buffer, this should
// still work.
let mut reader = Box::new(reader).into_inner().unwrap();
// Try to read consumed + 1 bytes (which shouldn't be
// possible).
assert_eq!(consumed, reader.data(consumed + 1).unwrap().len());
buffered_reader_test_data_check(&mut reader);
}
// Test that buffer() returns the same data as data().
#[test]
fn buffer_test() {
// Test vector. A BufferedReaderDup returns all unconsumed
// data. So, use a relatively small buffer size.
let size = DEFAULT_BUF_SIZE;
let mut input = Vec::with_capacity(size);
let mut v = 0u8;
for _ in 0..size {
input.push(v);
if v == std::u8::MAX {
v = 0;
} else {
v += 1;
}
}
let reader = BufferedReaderMemory::new(&input[..]);
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