1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Buffering wrappers for I/O traits
14 use container::Container;
15 use io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
18 use option::{Some, None, Option};
19 use result::{Ok, Err};
20 use slice::{OwnedVector, ImmutableVector, MutableVector};
23 /// Wraps a Reader and buffers input from it
25 /// It can be excessively inefficient to work directly with a `Reader` or
26 /// `Writer`. Every call to `read` or `write` on `TcpStream` results in a
27 /// system call, for example. This module provides structures that wrap
28 /// `Readers`, `Writers`, and `Streams` and buffer input and output to them.
33 /// use std::io::{BufferedReader, File};
35 /// let file = File::open(&Path::new("message.txt"));
36 /// let mut reader = BufferedReader::new(file);
38 /// let mut buf = [0, ..100];
39 /// match reader.read(buf) {
40 /// Ok(nread) => println!("Read {} bytes", nread),
41 /// Err(e) => println!("error reading: {}", e)
44 pub struct BufferedReader<R> {
52 impl<R: Reader> BufferedReader<R> {
53 /// Creates a new `BufferedReader` with the specified buffer capacity
54 pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
55 // It's *much* faster to create an uninitialized buffer than it is to
56 // fill everything in with 0. This buffer is entirely an implementation
57 // detail and is never exposed, so we're safe to not initialize
58 // everything up-front. This allows creation of BufferedReader instances
59 // to be very cheap (large mallocs are not nearly as expensive as large
61 let mut buf = slice::with_capacity(cap);
62 unsafe { buf.set_len(cap); }
72 /// Creates a new `BufferedReader` with a default buffer capacity
73 pub fn new(inner: R) -> BufferedReader<R> {
74 BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
77 /// Gets a reference to the underlying reader.
79 /// This type does not expose the ability to get a mutable reference to the
80 /// underlying reader because that could possibly corrupt the buffer.
81 pub fn get_ref<'a>(&'a self) -> &'a R { &self.inner }
83 /// Unwraps this buffer, returning the underlying reader.
85 /// Note that any leftover data in the internal buffer is lost.
86 pub fn unwrap(self) -> R { self.inner }
89 impl<R: Reader> Buffer for BufferedReader<R> {
90 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> {
91 if self.pos == self.cap {
92 self.cap = try!(self.inner.read(self.buf));
95 Ok(self.buf.slice(self.pos, self.cap))
98 fn consume(&mut self, amt: uint) {
100 assert!(self.pos <= self.cap);
104 impl<R: Reader> Reader for BufferedReader<R> {
105 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
107 let available = try!(self.fill_buf());
108 let nread = cmp::min(available.len(), buf.len());
109 slice::bytes::copy_memory(buf, available.slice_to(nread));
117 /// Wraps a Writer and buffers output to it
119 /// This writer will be flushed when it is dropped.
124 /// # #[allow(unused_must_use)];
125 /// use std::io::{BufferedWriter, File};
127 /// let file = File::open(&Path::new("message.txt"));
128 /// let mut writer = BufferedWriter::new(file);
130 /// writer.write_str("hello, world");
133 pub struct BufferedWriter<W> {
134 priv inner: Option<W>,
139 impl<W: Writer> BufferedWriter<W> {
140 /// Creates a new `BufferedWriter` with the specified buffer capacity
141 pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
142 // See comments in BufferedReader for why this uses unsafe code.
143 let mut buf = slice::with_capacity(cap);
144 unsafe { buf.set_len(cap); }
152 /// Creates a new `BufferedWriter` with a default buffer capacity
153 pub fn new(inner: W) -> BufferedWriter<W> {
154 BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
157 fn flush_buf(&mut self) -> IoResult<()> {
159 let ret = self.inner.get_mut_ref().write(self.buf.slice_to(self.pos));
167 /// Gets a reference to the underlying writer.
169 /// This type does not expose the ability to get a mutable reference to the
170 /// underlying reader because that could possibly corrupt the buffer.
171 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
173 /// Unwraps this buffer, returning the underlying writer.
175 /// The buffer is flushed before returning the writer.
176 pub fn unwrap(mut self) -> W {
177 // FIXME(#12628): is failing the right thing to do if flushing fails?
178 self.flush_buf().unwrap();
179 self.inner.take_unwrap()
183 impl<W: Writer> Writer for BufferedWriter<W> {
184 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
185 if self.pos + buf.len() > self.buf.len() {
186 try!(self.flush_buf());
189 if buf.len() > self.buf.len() {
190 self.inner.get_mut_ref().write(buf)
192 let dst = self.buf.mut_slice_from(self.pos);
193 slice::bytes::copy_memory(dst, buf);
194 self.pos += buf.len();
199 fn flush(&mut self) -> IoResult<()> {
200 self.flush_buf().and_then(|()| self.inner.get_mut_ref().flush())
205 impl<W: Writer> Drop for BufferedWriter<W> {
207 if self.inner.is_some() {
208 // FIXME(#12628): should this error be ignored?
209 let _ = self.flush_buf();
214 /// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
215 /// `'\n'`) is detected.
217 /// This writer will be flushed when it is dropped.
218 pub struct LineBufferedWriter<W> {
219 priv inner: BufferedWriter<W>,
222 impl<W: Writer> LineBufferedWriter<W> {
223 /// Creates a new `LineBufferedWriter`
224 pub fn new(inner: W) -> LineBufferedWriter<W> {
225 // Lines typically aren't that long, don't use a giant buffer
227 inner: BufferedWriter::with_capacity(1024, inner)
231 /// Gets a reference to the underlying writer.
233 /// This type does not expose the ability to get a mutable reference to the
234 /// underlying reader because that could possibly corrupt the buffer.
235 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
237 /// Unwraps this buffer, returning the underlying writer.
239 /// The internal buffer is flushed before returning the writer.
240 pub fn unwrap(self) -> W { self.inner.unwrap() }
243 impl<W: Writer> Writer for LineBufferedWriter<W> {
244 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
245 match buf.iter().rposition(|&b| b == '\n' as u8) {
247 try!(self.inner.write(buf.slice_to(i + 1)));
248 try!(self.inner.flush());
249 try!(self.inner.write(buf.slice_from(i + 1)));
252 None => self.inner.write(buf),
256 fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
259 struct InternalBufferedWriter<W>(BufferedWriter<W>);
261 impl<W> InternalBufferedWriter<W> {
262 fn get_mut_ref<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
263 let InternalBufferedWriter(ref mut w) = *self;
268 impl<W: Reader> Reader for InternalBufferedWriter<W> {
269 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
270 self.get_mut_ref().inner.get_mut_ref().read(buf)
274 /// Wraps a Stream and buffers input and output to and from it.
276 /// The output half will be flushed when this stream is dropped.
281 /// # #[allow(unused_must_use)];
282 /// use std::io::{BufferedStream, File};
284 /// let file = File::open(&Path::new("message.txt"));
285 /// let mut stream = BufferedStream::new(file);
287 /// stream.write("hello, world".as_bytes());
290 /// let mut buf = [0, ..100];
291 /// match stream.read(buf) {
292 /// Ok(nread) => println!("Read {} bytes", nread),
293 /// Err(e) => println!("error reading: {}", e)
296 pub struct BufferedStream<S> {
297 priv inner: BufferedReader<InternalBufferedWriter<S>>
300 impl<S: Stream> BufferedStream<S> {
301 /// Creates a new buffered stream with explicitly listed capacities for the
302 /// reader/writer buffer.
303 pub fn with_capacities(reader_cap: uint, writer_cap: uint, inner: S)
304 -> BufferedStream<S> {
305 let writer = BufferedWriter::with_capacity(writer_cap, inner);
306 let internal_writer = InternalBufferedWriter(writer);
307 let reader = BufferedReader::with_capacity(reader_cap,
309 BufferedStream { inner: reader }
312 /// Creates a new buffered stream with the default reader/writer buffer
314 pub fn new(inner: S) -> BufferedStream<S> {
315 BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
319 /// Gets a reference to the underlying stream.
321 /// This type does not expose the ability to get a mutable reference to the
322 /// underlying reader because that could possibly corrupt the buffer.
323 pub fn get_ref<'a>(&'a self) -> &'a S {
324 let InternalBufferedWriter(ref w) = self.inner.inner;
328 /// Unwraps this buffer, returning the underlying stream.
330 /// The internal buffer is flushed before returning the stream. Any leftover
331 /// data in the read buffer is lost.
332 pub fn unwrap(self) -> S {
333 let InternalBufferedWriter(w) = self.inner.inner;
338 impl<S: Stream> Buffer for BufferedStream<S> {
339 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
340 fn consume(&mut self, amt: uint) { self.inner.consume(amt) }
343 impl<S: Stream> Reader for BufferedStream<S> {
344 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
349 impl<S: Stream> Writer for BufferedStream<S> {
350 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
351 self.inner.inner.get_mut_ref().write(buf)
353 fn flush(&mut self) -> IoResult<()> {
354 self.inner.inner.get_mut_ref().flush()
364 use super::super::mem::{MemReader, MemWriter, BufReader};
365 use Harness = self::test::BenchHarness;
367 /// A type, free to create, primarily intended for benchmarking creation of
368 /// wrappers that, just for construction, don't need a Reader/Writer that
369 /// does anything useful. Is equivalent to `/dev/null` in semantics.
370 #[deriving(Clone,Eq,Ord)]
371 pub struct NullStream;
373 impl Reader for NullStream {
374 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
375 Err(io::standard_error(io::EndOfFile))
379 impl Writer for NullStream {
380 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
383 /// A dummy reader intended at testing short-reads propagation.
384 pub struct ShortReader {
385 priv lengths: ~[uint],
388 impl Reader for ShortReader {
389 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
390 match self.lengths.shift() {
392 None => Err(io::standard_error(io::EndOfFile))
398 fn test_buffered_reader() {
399 let inner = MemReader::new(~[0, 1, 2, 3, 4]);
400 let mut reader = BufferedReader::with_capacity(2, inner);
402 let mut buf = [0, 0, 0];
403 let nread = reader.read(buf);
404 assert_eq!(Ok(2), nread);
405 assert_eq!(buf.as_slice(), &[0, 1, 0]);
408 let nread = reader.read(buf);
409 assert_eq!(Ok(1), nread);
410 assert_eq!(buf.as_slice(), &[2]);
412 let mut buf = [0, 0, 0];
413 let nread = reader.read(buf);
414 assert_eq!(Ok(1), nread);
415 assert_eq!(buf.as_slice(), &[3, 0, 0]);
417 let nread = reader.read(buf);
418 assert_eq!(Ok(1), nread);
419 assert_eq!(buf.as_slice(), &[4, 0, 0]);
421 assert!(reader.read(buf).is_err());
425 fn test_buffered_writer() {
426 let inner = MemWriter::new();
427 let mut writer = BufferedWriter::with_capacity(2, inner);
429 writer.write([0, 1]).unwrap();
430 assert_eq!(writer.get_ref().get_ref(), &[]);
432 writer.write([2]).unwrap();
433 assert_eq!(writer.get_ref().get_ref(), &[0, 1]);
435 writer.write([3]).unwrap();
436 assert_eq!(writer.get_ref().get_ref(), &[0, 1]);
438 writer.flush().unwrap();
439 assert_eq!(&[0, 1, 2, 3], writer.get_ref().get_ref());
441 writer.write([4]).unwrap();
442 writer.write([5]).unwrap();
443 assert_eq!(&[0, 1, 2, 3], writer.get_ref().get_ref());
445 writer.write([6]).unwrap();
446 assert_eq!(&[0, 1, 2, 3, 4, 5],
447 writer.get_ref().get_ref());
449 writer.write([7, 8]).unwrap();
450 assert_eq!(&[0, 1, 2, 3, 4, 5, 6],
451 writer.get_ref().get_ref());
453 writer.write([9, 10, 11]).unwrap();
454 assert_eq!(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
455 writer.get_ref().get_ref());
457 writer.flush().unwrap();
458 assert_eq!(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
459 writer.get_ref().get_ref());
463 fn test_buffered_writer_inner_flushes() {
464 let mut w = BufferedWriter::with_capacity(3, MemWriter::new());
465 w.write([0, 1]).unwrap();
466 assert_eq!(&[], w.get_ref().get_ref());
468 assert_eq!(&[0, 1], w.get_ref());
471 // This is just here to make sure that we don't infinite loop in the
472 // newtype struct autoderef weirdness
474 fn test_buffered_stream() {
477 impl io::Writer for S {
478 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
481 impl io::Reader for S {
482 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
483 Err(io::standard_error(io::EndOfFile))
487 let mut stream = BufferedStream::new(S);
489 assert!(stream.read(buf).is_err());
490 stream.write(buf).unwrap();
491 stream.flush().unwrap();
495 fn test_read_until() {
496 let inner = MemReader::new(~[0, 1, 2, 1, 0]);
497 let mut reader = BufferedReader::with_capacity(2, inner);
498 assert_eq!(reader.read_until(0), Ok(~[0]));
499 assert_eq!(reader.read_until(2), Ok(~[1, 2]));
500 assert_eq!(reader.read_until(1), Ok(~[1]));
501 assert_eq!(reader.read_until(8), Ok(~[0]));
502 assert!(reader.read_until(9).is_err());
506 fn test_line_buffer() {
507 let mut writer = LineBufferedWriter::new(MemWriter::new());
508 writer.write([0]).unwrap();
509 assert_eq!(writer.get_ref().get_ref(), &[]);
510 writer.write([1]).unwrap();
511 assert_eq!(writer.get_ref().get_ref(), &[]);
512 writer.flush().unwrap();
513 assert_eq!(writer.get_ref().get_ref(), &[0, 1]);
514 writer.write([0, '\n' as u8, 1, '\n' as u8, 2]).unwrap();
515 assert_eq!(writer.get_ref().get_ref(),
516 &[0, 1, 0, '\n' as u8, 1, '\n' as u8]);
517 writer.flush().unwrap();
518 assert_eq!(writer.get_ref().get_ref(),
519 &[0, 1, 0, '\n' as u8, 1, '\n' as u8, 2]);
520 writer.write([3, '\n' as u8]).unwrap();
521 assert_eq!(writer.get_ref().get_ref(),
522 &[0, 1, 0, '\n' as u8, 1, '\n' as u8, 2, 3, '\n' as u8]);
526 fn test_read_line() {
527 let in_buf = MemReader::new(bytes!("a\nb\nc").to_owned());
528 let mut reader = BufferedReader::with_capacity(2, in_buf);
529 assert_eq!(reader.read_line(), Ok(~"a\n"));
530 assert_eq!(reader.read_line(), Ok(~"b\n"));
531 assert_eq!(reader.read_line(), Ok(~"c"));
532 assert!(reader.read_line().is_err());
537 let in_buf = MemReader::new(bytes!("a\nb\nc").to_owned());
538 let mut reader = BufferedReader::with_capacity(2, in_buf);
539 let mut it = reader.lines();
540 assert_eq!(it.next(), Some(Ok(~"a\n")));
541 assert_eq!(it.next(), Some(Ok(~"b\n")));
542 assert_eq!(it.next(), Some(Ok(~"c")));
543 assert_eq!(it.next(), None);
547 fn test_short_reads() {
548 let inner = ShortReader{lengths: ~[0, 1, 2, 0, 1, 0]};
549 let mut reader = BufferedReader::new(inner);
550 let mut buf = [0, 0];
551 assert_eq!(reader.read(buf), Ok(0));
552 assert_eq!(reader.read(buf), Ok(1));
553 assert_eq!(reader.read(buf), Ok(2));
554 assert_eq!(reader.read(buf), Ok(0));
555 assert_eq!(reader.read(buf), Ok(1));
556 assert_eq!(reader.read(buf), Ok(0));
557 assert!(reader.read(buf).is_err());
561 fn read_char_buffered() {
562 let buf = [195u8, 159u8];
563 let mut reader = BufferedReader::with_capacity(1, BufReader::new(buf));
564 assert_eq!(reader.read_char(), Ok('ß'));
569 let buf = [195u8, 159u8, 'a' as u8];
570 let mut reader = BufferedReader::with_capacity(1, BufReader::new(buf));
571 let mut it = reader.chars();
572 assert_eq!(it.next(), Some(Ok('ß')));
573 assert_eq!(it.next(), Some(Ok('a')));
574 assert_eq!(it.next(), None);
578 fn bench_buffered_reader(bh: &mut Harness) {
580 BufferedReader::new(NullStream)
585 fn bench_buffered_writer(bh: &mut Harness) {
587 BufferedWriter::new(NullStream)
592 fn bench_buffered_stream(bh: &mut Harness) {
594 BufferedStream::new(NullStream);