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|
use std::io;
use std::fmt;
use std::cmp;
use std::io::{Error, ErrorKind};
use super::*;
/// Wraps a memory buffer.
///
/// Although it is possible to use `Generic` to wrap a
/// buffer, this implementation is optimized for a memory buffer, and
/// avoids double buffering.
#[derive(Debug)]
pub struct Memory<'a, C: fmt::Debug + Sync + Send> {
buffer: &'a [u8],
// The next byte to read in the buffer.
cursor: usize,
// The user settable cookie.
cookie: C,
}
assert_send_and_sync!(Memory<'_, C>
where C: fmt::Debug);
impl<'a, C: fmt::Debug + Sync + Send> fmt::Display for Memory<'a, C> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Memory ({} of {} bytes read)",
self.cursor, self.buffer.len())
}
}
impl<'a> Memory<'a, ()> {
/// Instantiates a new `Memory`.
///
/// `buffer` contains the `Memory`'s contents.
pub fn new(buffer: &'a [u8]) -> Self {
Self::with_cookie(buffer, ())
}
}
impl<'a, C: fmt::Debug + Sync + Send> Memory<'a, C> {
/// Like `new()`, but sets a cookie.
///
/// The cookie can be retrieved using the `cookie_ref` and
/// `cookie_mut` methods, and set using the `cookie_set` method.
pub fn with_cookie(buffer: &'a [u8], cookie: C) -> Self {
Memory {
buffer,
cursor: 0,
cookie,
}
}
/// Returns the number of bytes that have been consumed by this
/// reader.
pub fn total_out(&self) -> usize {
self.cursor
}
#[allow(dead_code)]
pub(crate) fn source_buffer(&self) -> &[u8] {
self.buffer
}
}
impl<'a, C: fmt::Debug + Sync + Send> io::Read for Memory<'a, C> {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
let amount = cmp::min(buf.len(), self.buffer.len() - self.cursor);
buf[0..amount].copy_from_slice(
&self.buffer[self.cursor..self.cursor+amount]);
self.consume(amount);
Ok(amount)
}
}
impl<'a, C: fmt::Debug + Sync + Send> BufferedReader<C> for Memory<'a, C> {
fn buffer(&self) -> &[u8] {
&self.buffer[self.cursor..]
}
fn data(&mut self, _amount: usize) -> Result<&[u8], io::Error> {
assert!(self.cursor <= self.buffer.len());
Ok(&self.buffer[self.cursor..])
}
fn consume(&mut self, amount: usize) -> &[u8] {
// The caller can't consume more than is buffered!
assert!(amount <= self.buffer.len() - self.cursor,
"Attempt to consume {} bytes, but buffer only has {} bytes!",
amount, self.buffer.len() - self.cursor);
self.cursor += amount;
assert!(self.cursor <= self.buffer.len());
&self.buffer[self.cursor - amount..]
}
fn data_consume(&mut self, amount: usize) -> Result<&[u8], io::Error> {
let amount = cmp::min(amount, self.buffer.len() - self.cursor);
return Ok(self.consume(amount));
}
fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
if self.buffer.len() - self.cursor < amount {
return Err(Error::new(ErrorKind::UnexpectedEof, "EOF"));
}
return Ok(self.consume(amount));
}
fn get_mut(&mut self) -> Option<&mut dyn BufferedReader<C>> {
None
}
fn get_ref(&self) -> Option<&dyn BufferedReader<C>> {
None
}
fn into_inner<'b>(self: Box<Self>) -> Option<Box<dyn BufferedReader<C> + 'b>>
where Self: 'b {
None
}
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 mut bio = Memory::new(crate::BUFFERED_READER_TEST_DATA);
buffered_reader_test_data_check(&mut bio);
}
// Test that buffer() returns the same data as data().
#[test]
fn buffer_test() {
// Test vector. A Memory 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 mut reader = Memory::new(&input[..]);
for i in 0..input.len() {
let data = reader.data(default_buf_size() + 1).unwrap().to_vec();
assert!(!data.is_empty());
assert_eq!(data, reader.buffer());
// And, we may as well check to make sure we read the
// right data.
assert_eq!(data, &input[i..i+data.len()]);
// Consume one byte and see what happens.
reader.consume(1);
}
}
}
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