Implement Show for types in std::io::{buffered,util}

src/libstd/io/buffered.rs

@@ -13,6 +13,7 @@
 //! Buffering wrappers for I/O traits
 
 use cmp;
+use fmt;
 use io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
 use iter::{IteratorExt, ExactSizeIterator};
 use ops::Drop;
@@ -51,6 +52,13 @@ pub struct BufferedReader<R> {
     cap: uint,
 }
 
+impl<R> fmt::Show for BufferedReader<R> where R: fmt::Show {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "BufferedReader {{ reader: {:?}, buffer: {}/{} }}",
+               self.inner, self.cap - self.pos, self.buf.len())
+    }
+}
+
 impl<R: Reader> BufferedReader<R> {
     /// Creates a new `BufferedReader` with the specified buffer capacity
     pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
@@ -148,6 +156,13 @@ pub struct BufferedWriter<W> {
     pos: uint
 }
 
+impl<W> fmt::Show for BufferedWriter<W> where W: fmt::Show {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "BufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
+               self.inner.as_ref().unwrap(), self.pos, self.buf.len())
+    }
+}
+
 impl<W: Writer> BufferedWriter<W> {
     /// Creates a new `BufferedWriter` with the specified buffer capacity
     pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
@@ -235,6 +250,13 @@ pub struct LineBufferedWriter<W> {
     inner: BufferedWriter<W>,
 }
 
+impl<W> fmt::Show for LineBufferedWriter<W> where W: fmt::Show {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "LineBufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
+               self.inner.inner, self.inner.pos, self.inner.buf.len())
+    }
+}
+
 impl<W: Writer> LineBufferedWriter<W> {
     /// Creates a new `LineBufferedWriter`
     pub fn new(inner: W) -> LineBufferedWriter<W> {
@@ -318,6 +340,17 @@ pub struct BufferedStream<S> {
     inner: BufferedReader<InternalBufferedWriter<S>>
 }
 
+impl<S> fmt::Show for BufferedStream<S> where S: fmt::Show {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let reader = &self.inner;
+        let writer = &self.inner.inner.0;
+        write!(fmt, "BufferedStream {{ stream: {:?}, write_buffer: {}/{}, read_buffer: {}/{} }}",
+               writer.inner,
+               writer.pos, writer.buf.len(),
+               reader.cap - reader.pos, reader.buf.len())
+    }
+}
+
 impl<S: Stream> BufferedStream<S> {
     /// Creates a new buffered stream with explicitly listed capacities for the
     /// reader/writer buffer.

src/libstd/io/util.rs

@@ -16,6 +16,7 @@ use io;
 use slice::bytes::MutableByteVector;
 
 /// Wraps a `Reader`, limiting the number of bytes that can be read from it.
+#[derive(Show)]
 pub struct LimitReader<R> {
     limit: uint,
     inner: R
@@ -77,7 +78,7 @@ impl<R: Buffer> Buffer for LimitReader<R> {
 }
 
 /// A `Writer` which ignores bytes written to it, like /dev/null.
-#[derive(Copy)]
+#[derive(Copy, Show)]
 pub struct NullWriter;
 
 impl Writer for NullWriter {
@@ -86,7 +87,7 @@ impl Writer for NullWriter {
 }
 
 /// A `Reader` which returns an infinite stream of 0 bytes, like /dev/zero.
-#[derive(Copy)]
+#[derive(Copy, Show)]
 pub struct ZeroReader;
 
 impl Reader for ZeroReader {
@@ -107,7 +108,7 @@ impl Buffer for ZeroReader {
 }
 
 /// A `Reader` which is always at EOF, like /dev/null.
-#[derive(Copy)]
+#[derive(Copy, Show)]
 pub struct NullReader;
 
 impl Reader for NullReader {
@@ -128,18 +129,19 @@ impl Buffer for NullReader {
 ///
 /// The `Writer`s are delegated to in order. If any `Writer` returns an error,
 /// that error is returned immediately and remaining `Writer`s are not called.
-pub struct MultiWriter {
-    writers: Vec<Box<Writer+'static>>
+#[derive(Show)]
+pub struct MultiWriter<W> {
+    writers: Vec<W>
 }
 
-impl MultiWriter {
+impl<W> MultiWriter<W> where W: Writer {
     /// Creates a new `MultiWriter`
-    pub fn new(writers: Vec<Box<Writer+'static>>) -> MultiWriter {
+    pub fn new(writers: Vec<W>) -> MultiWriter<W> {
         MultiWriter { writers: writers }
     }
 }
 
-impl Writer for MultiWriter {
+impl<W> Writer for MultiWriter<W> where W: Writer {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::IoResult<()> {
         for writer in self.writers.iter_mut() {
@@ -159,7 +161,7 @@ impl Writer for MultiWriter {
 
 /// A `Reader` which chains input from multiple `Reader`s, reading each to
 /// completion before moving onto the next.
-#[derive(Clone)]
+#[derive(Clone, Show)]
 pub struct ChainedReader<I, R> {
     readers: I,
     cur_reader: Option<R>,
@@ -198,6 +200,7 @@ impl<R: Reader, I: Iterator<Item=R>> Reader for ChainedReader<I, R> {
 
 /// A `Reader` which forwards input from another `Reader`, passing it along to
 /// a `Writer` as well. Similar to the `tee(1)` command.
+#[derive(Show)]
 pub struct TeeReader<R, W> {
     reader: R,
     writer: W,
@@ -239,7 +242,7 @@ pub fn copy<R: Reader, W: Writer>(r: &mut R, w: &mut W) -> io::IoResult<()> {
 }
 
 /// An adaptor converting an `Iterator<u8>` to a `Reader`.
-#[derive(Clone)]
+#[derive(Clone, Show)]
 pub struct IterReader<T> {
     iter: T,
 }