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|
//! Stackable writers.
#[cfg(feature = "compression-bzip2")]
mod writer_bzip2;
#[cfg(feature = "compression-bzip2")]
pub use self::writer_bzip2::BZ;
#[cfg(feature = "compression-deflate")]
mod writer_deflate;
#[cfg(feature = "compression-deflate")]
pub use self::writer_deflate::{ZIP, ZLIB};
use std::fmt;
use std::io;
use symmetric;
use {
Result,
SymmetricAlgorithm,
};
/// A stack of writers.
///
/// We use trait objects as the unit of composition. This is a
/// compiler limitation, we may use impl trait in the future.
pub type Stack<'a, C> = Box<'a + Stackable<'a, C>>;
/// Makes a writer stackable and provides convenience functions.
pub trait Stackable<'a, C> : io::Write + fmt::Debug {
/// Recovers the inner stackable.
///
/// This can fail if the current `Stackable` has buffered data
/// that hasn't been written to the underlying `Stackable`.
fn into_inner(self: Box<Self>) -> Result<Option<Stack<'a, C>>>;
/// Pops the stackable from the stack, detaching it.
///
/// Returns the detached stack.
fn pop(&mut self) -> Result<Option<Stack<'a, C>>>;
/// Sets the inner stackable.
fn mount(&mut self, new: Stack<'a, C>);
/// Returns a mutable reference to the inner `Writer`, if
/// any.
///
/// It is a very bad idea to write any data from the inner
/// `Writer`, but it can sometimes be useful to get the cookie.
fn inner_mut(&mut self) -> Option<&mut Stackable<'a, C>>;
/// Returns a reference to the inner `Writer`.
fn inner_ref(&self) -> Option<&Stackable<'a, C>>;
/// Sets the cookie and returns the old value.
fn cookie_set(&mut self, cookie: C) -> C;
/// Returns a reference to the cookie.
fn cookie_ref(&self) -> &C;
/// Returns a mutable reference to the cookie.
fn cookie_mut(&mut self) -> &mut C;
/// Writes a byte.
fn write_u8(&mut self, b: u8) -> io::Result<()> {
let b : [u8; 1] = [b; 1];
self.write_all(&b[..])
}
/// Writes a big endian `u16`.
fn write_be_u16(&mut self, n: u16) -> io::Result<()> {
let b : [u8; 2] = [ ((n >> 8) & 0xFF) as u8, (n & 0xFF) as u8 ];
self.write_all(&b[..])
}
/// Writes a big endian `u32`.
fn write_be_u32(&mut self, n: u32) -> io::Result<()> {
let b : [u8; 4] = [ (n >> 24) as u8, ((n >> 16) & 0xFF) as u8,
((n >> 8) & 0xFF) as u8, (n & 0xFF) as u8 ];
self.write_all(&b[..])
}
}
/// Make a `Box<Stackable>` look like a Stackable.
impl <'a, C> Stackable<'a, C> for Stack<'a, C> {
fn into_inner(self: Box<Self>) -> Result<Option<Stack<'a, C>>> {
(*self).into_inner()
}
/// Recovers the inner stackable.
fn pop(&mut self) -> Result<Option<Stack<'a, C>>> {
self.as_mut().pop()
}
/// Sets the inner stackable.
fn mount(&mut self, new: Stack<'a, C>) {
self.as_mut().mount(new);
}
fn inner_mut(&mut self) -> Option<&mut Stackable<'a, C>> {
self.as_mut().inner_mut()
}
fn inner_ref(&self) -> Option<&Stackable<'a, C>> {
self.as_ref().inner_ref()
}
fn cookie_set(&mut self, cookie: C) -> C {
self.as_mut().cookie_set(cookie)
}
fn cookie_ref(&self) -> &C {
self.as_ref().cookie_ref()
}
fn cookie_mut(&mut self) -> &mut C {
self.as_mut().cookie_mut()
}
}
/// Maps a function over the stack of writers.
#[allow(dead_code)]
pub fn map<C, F>(head: &Stackable<C>, mut fun: F)
where F: FnMut(&Stackable<C>) -> bool {
let mut ow = Some(head);
while let Some(w) = ow {
if ! fun(w) {
break;
}
ow = w.inner_ref()
}
}
/// Maps a function over the stack of mutable writers.
#[allow(dead_code)]
pub fn map_mut<C, F>(head: &mut Stackable<C>, mut fun: F)
where F: FnMut(&mut Stackable<C>) -> bool {
let mut ow = Some(head);
while let Some(w) = ow {
if ! fun(w) {
break;
}
ow = w.inner_mut()
}
}
/// Dumps the writer stack.
#[allow(dead_code)]
pub fn dump<C>(head: &Stackable<C>) {
let mut depth = 0;
map(head, |w| {
eprintln!("{}: {:?}", depth, w);
depth += 1;
true
});
}
pub struct Identity<'a, C> {
inner: Option<Stack<'a, C>>,
co
|