fast_stream 0.0.1

stream
Documentation 
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use crate::stream::Stream;
use std::fmt::Error;
use std::io;
use std::io::{ErrorKind, Seek, SeekFrom};

#[allow(dead_code)]
pub trait Pin {
    fn restore(&mut self) -> io::Result<&mut Self>;
    fn pin(&mut self) -> io::Result<u64>;
    fn un_pin(&mut self) -> io::Result<u64>;
    fn un_pin_size(&mut self, size: u64) -> io::Result<&mut Self>;
    fn set_position(&mut self, position: u64) -> io::Result<&mut Self>;
    fn position(&mut self) -> io::Result<u64>;
}
impl<T: Seek> Pin for Stream<T> {
    fn restore(&mut self) -> io::Result<&mut Self> {
        self.inner.seek(SeekFrom::Start(0))?;
        Ok(self)
    }
    fn pin(&mut self) -> io::Result<u64> {
        let current = self.stream_position()?;
        self.pins.push(current);
        Ok(current)
    }

    fn un_pin(&mut self) -> io::Result<u64> {
        if let Some(pos) = self.pins.pop() {
            self.seek(SeekFrom::Start(pos))?;
            return Ok(pos);
        }
        Err(io::Error::new(ErrorKind::NotFound, Error::default()))
    }
    /*
    恢复到pin+size位置
     */
    fn un_pin_size(&mut self, size: u64) -> io::Result<&mut Self> {
        let current_position = self.inner.stream_position()?;
        if let Some(position) = self.pins.pop() {
            if current_position - position != size {
                self.inner.seek(SeekFrom::Start(position + size))?;
            }
        }
        Ok(self)
    }

    fn set_position(&mut self, position: u64) -> io::Result<&mut Self> {
        self.seek(SeekFrom::Start(position))?;
        Ok(self)
    }
    fn position(&mut self) -> io::Result<u64> {
        self.stream_position()
    }
}