jubako 0.4.0

The reference implementation of the Jubako container format
Documentation 
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use crate::bases::*;
use std::io::Read;
use std::sync::Arc;

use super::ByteRegion;

/// A `Read` struct on top of bytes contained in Jubako
///
/// A `ByteStream` allow to read from a [ByteRegion].
#[derive(Debug)]
pub struct ByteStream {
    source: Arc<dyn Source>,
    region: Region,
    offset: Offset,
}

impl ByteStream {
    pub(crate) fn new_from_parts(source: Arc<dyn Source>, region: Region, offset: Offset) -> Self {
        Self {
            source,
            region,
            offset,
        }
    }

    /// The size of the data left to be read
    pub fn size_left(&self) -> u64 {
        (self.region.end() - self.offset).into_u64()
    }

    /// The full size of the ByteStream
    pub fn size(&self) -> u64 {
        self.region.size().into_u64()
    }

    /// The current offset in the ByteStream
    pub fn offset(&self) -> u64 {
        (self.offset - self.region.begin()).into_u64()
    }
}

impl Read for ByteStream {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        let max_len = std::cmp::min(
            buf.len() as u64,
            (self.region.end() - self.offset).into_u64(),
        ) as usize;
        let buf = &mut buf[..max_len];
        match self.source.read(self.offset, buf) {
            Ok(s) => {
                self.offset += s;
                Ok(s)
            }
            Err(e) => Err(std::io::Error::other(e)),
        }
    }
}

impl From<ByteRegion> for ByteStream {
    fn from(bregion: ByteRegion) -> Self {
        Self::new_from_parts(bregion.source, bregion.region, Offset::zero())
    }
}