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use std::cell::{Ref, RefCell}; use std::fmt::{self, Debug, Formatter}; use std::io::{self, ErrorKind, Read, Seek, SeekFrom}; #[cfg(feature = "nightly")] use std::io::{Initializer, IoSliceMut}; use std::rc::Rc; pub struct RcRefCellU8Reader<T: AsRef<[u8]> + ?Sized> { data: Rc<RefCell<T>>, pos: usize, } impl<T: AsRef<[u8]> + ?Sized> Debug for RcRefCellU8Reader<T> { #[inline] fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> { impl_debug_for_struct!(RcRefCellU8Reader, f, self, let .data = self.data.as_ref().borrow().as_ref(), .pos); } } impl<T: AsRef<[u8]> + ?Sized> RcRefCellU8Reader<T> { #[inline] pub fn new(data: Rc<RefCell<T>>) -> RcRefCellU8Reader<T> { RcRefCellU8Reader { data, pos: 0, } } } impl<T: AsRef<[u8]> + ?Sized> Read for RcRefCellU8Reader<T> { fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> { let data: Ref<T> = (*self.data).borrow(); let data: &[u8] = &data.as_ref()[self.pos..]; let data_len = data.len(); let buf_len = buf.len(); let len = if data_len > buf_len { let data = &data[..buf_len]; buf.copy_from_slice(data); buf_len } else { buf[..data_len].copy_from_slice(data); data_len }; self.pos += len; Ok(len) } #[cfg(feature = "nightly")] #[inline] fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { let mut nread = 0; for buf in bufs { let n = self.read(buf)?; nread += n; if n < buf.len() { break; } } Ok(nread) } #[cfg(feature = "nightly")] #[inline] unsafe fn initializer(&self) -> Initializer { Initializer::nop() } } impl<T: AsRef<[u8]> + ?Sized> Seek for RcRefCellU8Reader<T> { fn seek(&mut self, style: SeekFrom) -> Result<u64, io::Error> { let (base_pos, offset) = match style { SeekFrom::Start(n) => { let n = if n > usize::max_value() as u64 { usize::max_value() } else { n as usize }; self.pos = n; return Ok(n as u64); } SeekFrom::End(n) => { ( { let data: Ref<T> = (*self.data).borrow(); let data: &[u8] = &data.as_ref()[self.pos..]; data.len() }, n, ) } SeekFrom::Current(n) => (self.pos, n), }; let offset = if offset > isize::max_value() as i64 { isize::max_value() } else if offset < isize::min_value() as i64 { isize::min_value() } else { offset as isize }; let new_pos = if offset >= 0 { base_pos.checked_add(offset as usize) } else { base_pos.checked_sub((offset.wrapping_neg()) as usize) }; match new_pos { Some(n) => { self.pos = n; Ok(self.pos as u64) } None => { Err(io::Error::new( ErrorKind::InvalidInput, "invalid seek to a negative or overflowing position", )) } } } #[cfg(feature = "nightly")] #[inline] fn stream_len(&mut self) -> Result<u64, io::Error> { let data_len = { let data: Ref<T> = (*self.data).borrow(); let data: &[u8] = &data.as_ref()[self.pos..]; data.len() }; Ok(data_len as u64) } #[cfg(feature = "nightly")] #[inline] fn stream_position(&mut self) -> Result<u64, io::Error> { Ok(self.pos as u64) } }