src/libstd/io/impls.rs - third_party/rust - Git at Google

 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 use cmp;
 use io::{self, SeekFrom, Read, Initializer, Write, Seek, BufRead, Error, ErrorKind};
 use fmt;
 use mem;

 // =============================================================================
 // Forwarding implementations

 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, R: Read + ?Sized> Read for &'a mut R {
     #[inline]
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         (**self).read(buf)
     }

     #[inline]
     unsafe fn initializer(&self) -> Initializer {
         (**self).initializer()
     }

     #[inline]
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
         (**self).read_to_end(buf)
     }

     #[inline]
     fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
         (**self).read_to_string(buf)
     }

     #[inline]
     fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
         (**self).read_exact(buf)
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, W: Write + ?Sized> Write for &'a mut W {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }

     #[inline]
     fn flush(&mut self) -> io::Result<()> { (**self).flush() }

     #[inline]
     fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
         (**self).write_all(buf)
     }

     #[inline]
     fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
         (**self).write_fmt(fmt)
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
     #[inline]
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
     #[inline]
     fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }

     #[inline]
     fn consume(&mut self, amt: usize) { (**self).consume(amt) }

     #[inline]
     fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
         (**self).read_until(byte, buf)
     }

     #[inline]
     fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
         (**self).read_line(buf)
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl<R: Read + ?Sized> Read for Box<R> {
     #[inline]
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         (**self).read(buf)
     }

     #[inline]
     unsafe fn initializer(&self) -> Initializer {
         (**self).initializer()
     }

     #[inline]
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
         (**self).read_to_end(buf)
     }

     #[inline]
     fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
         (**self).read_to_string(buf)
     }

     #[inline]
     fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
         (**self).read_exact(buf)
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write + ?Sized> Write for Box<W> {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }

     #[inline]
     fn flush(&mut self) -> io::Result<()> { (**self).flush() }

     #[inline]
     fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
         (**self).write_all(buf)
     }

     #[inline]
     fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
         (**self).write_fmt(fmt)
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<S: Seek + ?Sized> Seek for Box<S> {
     #[inline]
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<B: BufRead + ?Sized> BufRead for Box<B> {
     #[inline]
     fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }

     #[inline]
     fn consume(&mut self, amt: usize) { (**self).consume(amt) }

     #[inline]
     fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
         (**self).read_until(byte, buf)
     }

     #[inline]
     fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
         (**self).read_line(buf)
     }
 }

 // =============================================================================
 // In-memory buffer implementations

 /// Read is implemented for `&[u8]` by copying from the slice.
 ///
 /// Note that reading updates the slice to point to the yet unread part.
 /// The slice will be empty when EOF is reached.
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> Read for &'a [u8] {
     #[inline]
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         let amt = cmp::min(buf.len(), self.len());
         let (a, b) = self.split_at(amt);

         // First check if the amount of bytes we want to read is small:
         // `copy_from_slice` will generally expand to a call to `memcpy`, and
         // for a single byte the overhead is significant.
         if amt == 1 {
             buf[0] = a[0];
         } else {
             buf[..amt].copy_from_slice(a);
         }

         *self = b;
         Ok(amt)
     }

     #[inline]
     unsafe fn initializer(&self) -> Initializer {
         Initializer::nop()
     }

     #[inline]
     fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
         if buf.len() > self.len() {
             return Err(Error::new(ErrorKind::UnexpectedEof,
                                   "failed to fill whole buffer"));
         }
         let (a, b) = self.split_at(buf.len());

         // First check if the amount of bytes we want to read is small:
         // `copy_from_slice` will generally expand to a call to `memcpy`, and
         // for a single byte the overhead is significant.
         if buf.len() == 1 {
             buf[0] = a[0];
         } else {
             buf.copy_from_slice(a);
         }

         *self = b;
         Ok(())
     }

     #[inline]
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
         buf.extend_from_slice(*self);
         let len = self.len();
         *self = &self[len..];
         Ok(len)
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> BufRead for &'a [u8] {
     #[inline]
     fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }

     #[inline]
     fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
 }

 /// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
 /// its data.
 ///
 /// Note that writing updates the slice to point to the yet unwritten part.
 /// The slice will be empty when it has been completely overwritten.
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> Write for &'a mut [u8] {
     #[inline]
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         let amt = cmp::min(data.len(), self.len());
         let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
         a.copy_from_slice(&data[..amt]);
         *self = b;
         Ok(amt)
     }

     #[inline]
     fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
         if self.write(data)? == data.len() {
             Ok(())
         } else {
             Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
         }
     }

     #[inline]
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }

 /// Write is implemented for `Vec<u8>` by appending to the vector.
 /// The vector will grow as needed.
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Write for Vec<u8> {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.extend_from_slice(buf);
         Ok(buf.len())
     }

     #[inline]
     fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
         self.extend_from_slice(buf);
         Ok(())
     }

     #[inline]
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }

 #[cfg(test)]
 mod tests {
     use io::prelude::*;
     use test;

     #[bench]
     fn bench_read_slice(b: &mut test::Bencher) {
         let buf = [5; 1024];
         let mut dst = [0; 128];

         b.iter(|| {
             let mut rd = &buf[..];
             for _ in 0..8 {
                 let _ = rd.read(&mut dst);
                 test::black_box(&dst);
             }
         })
     }

     #[bench]
     fn bench_write_slice(b: &mut test::Bencher) {
         let mut buf = [0; 1024];
         let src = [5; 128];

         b.iter(|| {
             let mut wr = &mut buf[..];
             for _ in 0..8 {
                 let _ = wr.write_all(&src);
                 test::black_box(&wr);
             }
         })
     }

     #[bench]
     fn bench_read_vec(b: &mut test::Bencher) {
         let buf = vec![5; 1024];
         let mut dst = [0; 128];

         b.iter(|| {
             let mut rd = &buf[..];
             for _ in 0..8 {
                 let _ = rd.read(&mut dst);
                 test::black_box(&dst);
             }
         })
     }

     #[bench]
     fn bench_write_vec(b: &mut test::Bencher) {
         let mut buf = Vec::with_capacity(1024);
         let src = [5; 128];

         b.iter(|| {
             let mut wr = &mut buf[..];
             for _ in 0..8 {
                 let _ = wr.write_all(&src);
                 test::black_box(&wr);
             }
         })
     }
 }
	// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	use cmp;
	use io::{self, SeekFrom, Read, Initializer, Write, Seek, BufRead, Error, ErrorKind};
	use fmt;
	use mem;

	// =============================================================================
	// Forwarding implementations

	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a, R: Read + ?Sized> Read for &'a mut R {
	#[inline]
	fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
	(**self).read(buf)
	}

	#[inline]
	unsafe fn initializer(&self) -> Initializer {
	(**self).initializer()
	}

	#[inline]
	fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
	(**self).read_to_end(buf)
	}

	#[inline]
	fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
	(**self).read_to_string(buf)
	}

	#[inline]
	fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
	(**self).read_exact(buf)
	}
	}
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a, W: Write + ?Sized> Write for &'a mut W {
	#[inline]
	fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }

	#[inline]
	fn flush(&mut self) -> io::Result<()> { (**self).flush() }

	#[inline]
	fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
	(**self).write_all(buf)
	}

	#[inline]
	fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
	(**self).write_fmt(fmt)
	}
	}
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
	#[inline]
	fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
	}
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
	#[inline]
	fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }

	#[inline]
	fn consume(&mut self, amt: usize) { (**self).consume(amt) }

	#[inline]
	fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
	(**self).read_until(byte, buf)
	}

	#[inline]
	fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
	(**self).read_line(buf)
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl<R: Read + ?Sized> Read for Box<R> {
	#[inline]
	fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
	(**self).read(buf)
	}

	#[inline]
	unsafe fn initializer(&self) -> Initializer {
	(**self).initializer()
	}

	#[inline]
	fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
	(**self).read_to_end(buf)
	}

	#[inline]
	fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
	(**self).read_to_string(buf)
	}

	#[inline]
	fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
	(**self).read_exact(buf)
	}
	}
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<W: Write + ?Sized> Write for Box<W> {
	#[inline]
	fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }

	#[inline]
	fn flush(&mut self) -> io::Result<()> { (**self).flush() }

	#[inline]
	fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
	(**self).write_all(buf)
	}

	#[inline]
	fn write_fmt(&mut self, fmt: fmt::Arguments) -> io::Result<()> {
	(**self).write_fmt(fmt)
	}
	}
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<S: Seek + ?Sized> Seek for Box<S> {
	#[inline]
	fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
	}
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<B: BufRead + ?Sized> BufRead for Box<B> {
	#[inline]
	fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }

	#[inline]
	fn consume(&mut self, amt: usize) { (**self).consume(amt) }

	#[inline]
	fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
	(**self).read_until(byte, buf)
	}

	#[inline]
	fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
	(**self).read_line(buf)
	}
	}

	// =============================================================================
	// In-memory buffer implementations

	/// Read is implemented for `&[u8]` by copying from the slice.
	///
	/// Note that reading updates the slice to point to the yet unread part.
	/// The slice will be empty when EOF is reached.
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a> Read for &'a [u8] {
	#[inline]
	fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
	let amt = cmp::min(buf.len(), self.len());
	let (a, b) = self.split_at(amt);

	// First check if the amount of bytes we want to read is small:
	// `copy_from_slice` will generally expand to a call to `memcpy`, and
	// for a single byte the overhead is significant.
	if amt == 1 {
	buf[0] = a[0];
	} else {
	buf[..amt].copy_from_slice(a);
	}

	*self = b;
	Ok(amt)
	}

	#[inline]
	unsafe fn initializer(&self) -> Initializer {
	Initializer::nop()
	}

	#[inline]
	fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
	if buf.len() > self.len() {
	return Err(Error::new(ErrorKind::UnexpectedEof,
	"failed to fill whole buffer"));
	}
	let (a, b) = self.split_at(buf.len());

	// First check if the amount of bytes we want to read is small:
	// `copy_from_slice` will generally expand to a call to `memcpy`, and
	// for a single byte the overhead is significant.
	if buf.len() == 1 {
	buf[0] = a[0];
	} else {
	buf.copy_from_slice(a);
	}

	*self = b;
	Ok(())
	}

	#[inline]
	fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
	buf.extend_from_slice(*self);
	let len = self.len();
	*self = &self[len..];
	Ok(len)
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a> BufRead for &'a [u8] {
	#[inline]
	fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }

	#[inline]
	fn consume(&mut self, amt: usize) { *self = &self[amt..]; }
	}

	/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
	/// its data.
	///
	/// Note that writing updates the slice to point to the yet unwritten part.
	/// The slice will be empty when it has been completely overwritten.
	#[stable(feature = "rust1", since = "1.0.0")]
	impl<'a> Write for &'a mut [u8] {
	#[inline]
	fn write(&mut self, data: &[u8]) -> io::Result<usize> {
	let amt = cmp::min(data.len(), self.len());
	let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
	a.copy_from_slice(&data[..amt]);
	*self = b;
	Ok(amt)
	}

	#[inline]
	fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
	if self.write(data)? == data.len() {
	Ok(())
	} else {
	Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
	}
	}

	#[inline]
	fn flush(&mut self) -> io::Result<()> { Ok(()) }
	}

	/// Write is implemented for `Vec<u8>` by appending to the vector.
	/// The vector will grow as needed.
	#[stable(feature = "rust1", since = "1.0.0")]
	impl Write for Vec<u8> {
	#[inline]
	fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
	self.extend_from_slice(buf);
	Ok(buf.len())
	}

	#[inline]
	fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
	self.extend_from_slice(buf);
	Ok(())
	}

	#[inline]
	fn flush(&mut self) -> io::Result<()> { Ok(()) }
	}

	#[cfg(test)]
	mod tests {
	use io::prelude::*;
	use test;

	#[bench]
	fn bench_read_slice(b: &mut test::Bencher) {
	let buf = [5; 1024];
	let mut dst = [0; 128];

	b.iter(\|\| {
	let mut rd = &buf[..];
	for _ in 0..8 {
	let _ = rd.read(&mut dst);
	test::black_box(&dst);
	}
	})
	}

	#[bench]
	fn bench_write_slice(b: &mut test::Bencher) {
	let mut buf = [0; 1024];
	let src = [5; 128];

	b.iter(\|\| {
	let mut wr = &mut buf[..];
	for _ in 0..8 {
	let _ = wr.write_all(&src);
	test::black_box(&wr);
	}
	})
	}

	#[bench]
	fn bench_read_vec(b: &mut test::Bencher) {
	let buf = vec![5; 1024];
	let mut dst = [0; 128];

	b.iter(\|\| {
	let mut rd = &buf[..];
	for _ in 0..8 {
	let _ = rd.read(&mut dst);
	test::black_box(&dst);
	}
	})
	}

	#[bench]
	fn bench_write_vec(b: &mut test::Bencher) {
	let mut buf = Vec::with_capacity(1024);
	let src = [5; 128];

	b.iter(\|\| {
	let mut wr = &mut buf[..];
	for _ in 0..8 {
	let _ = wr.write_all(&src);
	test::black_box(&wr);
	}
	})
	}
	}