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//! Implement push-based [`Write`] trait for both compressing and decompressing.
use std::io::{self, Write};
use zstd_safe;
use crate::dict::{DecoderDictionary, EncoderDictionary};
use crate::stream::{raw, zio};
#[cfg(test)]
mod tests;
/// An encoder that compress and forward data to another writer.
///
/// This allows to compress a stream of data
/// (good for files or heavy network stream).
///
/// Don't forget to call [`finish()`] before dropping it!
///
/// Alternatively, you can call [`auto_finish()`] to use an
/// [`AutoFinishEncoder`] that will finish on drop.
///
/// Note: The zstd library has its own internal input buffer (~128kb).
///
/// [`finish()`]: #method.finish
/// [`auto_finish()`]: #method.auto_finish
/// [`AutoFinishEncoder`]: AutoFinishEncoder
pub struct Encoder<'a, W: Write> {
// output writer (compressed data)
writer: zio::Writer<W, raw::Encoder<'a>>,
}
/// A decoder that decompress and forward data to another writer.
///
/// Note that you probably want to `flush()` after writing your stream content.
/// You can use [`auto_flush()`] to automatically flush the writer on drop.
///
/// [`auto_flush()`]: Decoder::auto_flush
pub struct Decoder<'a, W: Write> {
// output writer (decompressed data)
writer: zio::Writer<W, raw::Decoder<'a>>,
}
/// A wrapper around an `Encoder<W>` that finishes the stream on drop.
///
/// This can be created by the [`auto_finish()`] method on the [`Encoder`].
///
/// [`auto_finish()`]: Encoder::auto_finish
/// [`Encoder`]: Encoder
pub struct AutoFinishEncoder<
'a,
W: Write,
F: FnMut(io::Result<W>) = Box<dyn Send + FnMut(io::Result<W>)>,
> {
// We wrap this in an option to take it during drop.
encoder: Option<Encoder<'a, W>>,
on_finish: Option<F>,
}
/// A wrapper around a `Decoder<W>` that flushes the stream on drop.
///
/// This can be created by the [`auto_flush()`] method on the [`Decoder`].
///
/// [`auto_flush()`]: Decoder::auto_flush
/// [`Decoder`]: Decoder
pub struct AutoFlushDecoder<
'a,
W: Write,
F: FnMut(io::Result<()>) = Box<dyn Send + FnMut(io::Result<()>)>,
> {
// We wrap this in an option to take it during drop.
decoder: Option<Decoder<'a, W>>,
on_flush: Option<F>,
}
impl<'a, W: Write, F: FnMut(io::Result<()>)> AutoFlushDecoder<'a, W, F> {
fn new(decoder: Decoder<'a, W>, on_flush: F) -> Self {
AutoFlushDecoder {
decoder: Some(decoder),
on_flush: Some(on_flush),
}
}
/// Acquires a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.decoder.as_ref().unwrap().get_ref()
}
/// Acquires a mutable reference to the underlying writer.
///
/// Note that mutation of the writer may result in surprising results if
/// this decoder is continued to be used.
///
/// Mostly used for testing purposes.
pub fn get_mut(&mut self) -> &mut W {
self.decoder.as_mut().unwrap().get_mut()
}
}
impl<W, F> Drop for AutoFlushDecoder<'_, W, F>
where
W: Write,
F: FnMut(io::Result<()>),
{
fn drop(&mut self) {
let mut decoder = self.decoder.take().unwrap();
let result = decoder.flush();
if let Some(mut on_finish) = self.on_flush.take() {
on_finish(result);
}
}
}
impl<W: Write, F: FnMut(io::Result<()>)> Write for AutoFlushDecoder<'_, W, F> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.decoder.as_mut().unwrap().write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.decoder.as_mut().unwrap().flush()
}
}
impl<'a, W: Write, F: FnMut(io::Result<W>)> AutoFinishEncoder<'a, W, F> {
fn new(encoder: Encoder<'a, W>, on_finish: F) -> Self {
AutoFinishEncoder {
encoder: Some(encoder),
on_finish: Some(on_finish),
}
}
/// Acquires a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.encoder.as_ref().unwrap().get_ref()
}
/// Acquires a mutable reference to the underlying writer.
///
/// Note that mutation of the writer may result in surprising results if
/// this encoder is continued to be used.
///
/// Mostly used for testing purposes.
pub fn get_mut(&mut self) -> &mut W {
self.encoder.as_mut().unwrap().get_mut()
}
}
impl<W: Write, F: FnMut(io::Result<W>)> Drop for AutoFinishEncoder<'_, W, F> {
fn drop(&mut self) {
let result = self.encoder.take().unwrap().finish();
if let Some(mut on_finish) = self.on_finish.take() {
on_finish(result);
}
}
}
impl<W: Write, F: FnMut(io::Result<W>)> Write for AutoFinishEncoder<'_, W, F> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.encoder.as_mut().unwrap().write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.encoder.as_mut().unwrap().flush()
}
}
impl<W: Write> Encoder<'static, W> {
/// Creates a new encoder.
///
/// `level`: compression level (1-22).
///
/// A level of `0` uses zstd's default (currently `3`).
pub fn new(writer: W, level: i32) -> io::Result<Self> {
Self::with_dictionary(writer, level, &[])
}
/// Creates a new encoder, using an existing dictionary.
///
/// (Provides better compression ratio for small files,
/// but requires the dictionary to be present during decompression.)
///
/// A level of `0` uses zstd's default (currently `3`).
pub fn with_dictionary(
writer: W,
level: i32,
dictionary: &[u8],
) -> io::Result<Self> {
let encoder = raw::Encoder::with_dictionary(level, dictionary)?;
let writer = zio::Writer::new(writer, encoder);
Ok(Encoder { writer })
}
}
impl<'a, W: Write> Encoder<'a, W> {
/// Creates an encoder that uses the provided context to compress a stream.
pub fn with_context(
writer: W,
context: &'a mut zstd_safe::CCtx<'static>,
) -> Self {
Self {
writer: zio::Writer::new(
writer,
raw::Encoder::with_context(context),
),
}
}
/// Creates a new encoder, using an existing prepared `EncoderDictionary`.
///
/// (Provides better compression ratio for small files,
/// but requires the dictionary to be present during decompression.)
pub fn with_prepared_dictionary<'b>(
writer: W,
dictionary: &EncoderDictionary<'b>,
) -> io::Result<Self>
where
'b: 'a,
{
let encoder = raw::Encoder::with_prepared_dictionary(dictionary)?;
let writer = zio::Writer::new(writer, encoder);
Ok(Encoder { writer })
}
/// Creates a new encoder, using a ref prefix
pub fn with_ref_prefix<'b>(
writer: W,
level: i32,
ref_prefix: &'b [u8],
) -> io::Result<Self>
where
'b: 'a,
{
let encoder = raw::Encoder::with_ref_prefix(level, ref_prefix)?;
let writer = zio::Writer::new(writer, encoder);
Ok(Encoder { writer })
}
/// Returns a wrapper around `self` that will finish the stream on drop.
pub fn auto_finish(self) -> AutoFinishEncoder<'a, W> {
AutoFinishEncoder {
encoder: Some(self),
on_finish: None,
}
}
/// Returns an encoder that will finish the stream on drop.
///
/// Calls the given callback with the result from `finish()`. This runs during drop so it's
/// important that the provided callback doesn't panic.
pub fn on_finish<F: FnMut(io::Result<W>)>(
self,
f: F,
) -> AutoFinishEncoder<'a, W, F> {
AutoFinishEncoder::new(self, f)
}
/// Acquires a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.writer.writer()
}
/// Acquires a mutable reference to the underlying writer.
///
/// Note that mutation of the writer may result in surprising results if
/// this encoder is continued to be used.
pub fn get_mut(&mut self) -> &mut W {
self.writer.writer_mut()
}
/// **Required**: Finishes the stream.
///
/// You *need* to finish the stream when you're done writing, either with
/// this method or with [`try_finish(self)`](#method.try_finish).
///
/// This returns the inner writer in case you need it.
///
/// To get back `self` in case an error happened, use `try_finish`.
///
/// **Note**: If you don't want (or can't) call `finish()` manually after
/// writing your data, consider using `auto_finish()` to get an
/// `AutoFinishEncoder`.
pub fn finish(self) -> io::Result<W> {
self.try_finish().map_err(|(_, err)| err)
}
/// **Required**: Attempts to finish the stream.
///
/// You *need* to finish the stream when you're done writing, either with
/// this method or with [`finish(self)`](#method.finish).
///
/// This returns the inner writer if the finish was successful, or the
/// object plus an error if it wasn't.
///
/// `write` on this object will panic after `try_finish` has been called,
/// even if it fails.
pub fn try_finish(mut self) -> Result<W, (Self, io::Error)> {
match self.writer.finish() {
// Return the writer, because why not
Ok(()) => Ok(self.writer.into_inner().0),
Err(e) => Err((self, e)),
}
}
/// Attempts to finish the stream.
///
/// You *need* to finish the stream when you're done writing, either with
/// this method or with [`finish(self)`](#method.finish).
pub fn do_finish(&mut self) -> io::Result<()> {
self.writer.finish()
}
/// Return a recommendation for the size of data to write at once.
pub fn recommended_input_size() -> usize {
zstd_safe::CCtx::in_size()
}
crate::encoder_common!(writer);
}
impl<'a, W: Write> Write for Encoder<'a, W> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.writer.write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.writer.flush()
}
}
impl<W: Write> Decoder<'static, W> {
/// Creates a new decoder.
pub fn new(writer: W) -> io::Result<Self> {
Self::with_dictionary(writer, &[])
}
/// Creates a new decoder, using an existing dictionary.
///
/// (Provides better compression ratio for small files,
/// but requires the dictionary to be present during decompression.)
pub fn with_dictionary(writer: W, dictionary: &[u8]) -> io::Result<Self> {
let decoder = raw::Decoder::with_dictionary(dictionary)?;
let writer = zio::Writer::new(writer, decoder);
Ok(Decoder { writer })
}
}
impl<'a, W: Write> Decoder<'a, W> {
/// Creates a new decoder, using an existing prepared `DecoderDictionary`.
///
/// (Provides better compression ratio for small files,
/// but requires the dictionary to be present during decompression.)
pub fn with_prepared_dictionary<'b>(
writer: W,
dictionary: &DecoderDictionary<'b>,
) -> io::Result<Self>
where
'b: 'a,
{
let decoder = raw::Decoder::with_prepared_dictionary(dictionary)?;
let writer = zio::Writer::new(writer, decoder);
Ok(Decoder { writer })
}
/// Acquires a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.writer.writer()
}
/// Acquires a mutable reference to the underlying writer.
///
/// Note that mutation of the writer may result in surprising results if
/// this decoder is continued to be used.
pub fn get_mut(&mut self) -> &mut W {
self.writer.writer_mut()
}
/// Returns the inner `Write`.
pub fn into_inner(self) -> W {
self.writer.into_inner().0
}
/// Return a recommendation for the size of data to write at once.
pub fn recommended_input_size() -> usize {
zstd_safe::DCtx::in_size()
}
/// Returns a wrapper around `self` that will flush the stream on drop.
pub fn auto_flush(self) -> AutoFlushDecoder<'a, W> {
AutoFlushDecoder {
decoder: Some(self),
on_flush: None,
}
}
/// Returns a decoder that will flush the stream on drop.
///
/// Calls the given callback with the result from `flush()`. This runs during drop so it's
/// important that the provided callback doesn't panic.
pub fn on_flush<F: FnMut(io::Result<()>)>(
self,
f: F,
) -> AutoFlushDecoder<'a, W, F> {
AutoFlushDecoder::new(self, f)
}
crate::decoder_common!(writer);
}
impl<W: Write> Write for Decoder<'_, W> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.writer.write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.writer.flush()
}
}
fn _assert_traits() {
fn _assert_send<T: Send>(_: T) {}
_assert_send(Decoder::new(Vec::new()));
_assert_send(Encoder::new(Vec::new(), 1));
_assert_send(Decoder::new(Vec::new()).unwrap().auto_flush());
_assert_send(Encoder::new(Vec::new(), 1).unwrap().auto_finish());
}