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 /*! Utility implementations of Reader and Writer */
17 use slice::bytes::MutableByteVector;
19 /// Wraps a `Reader`, limiting the number of bytes that can be read from it.
20 pub struct LimitReader<R> {
25 impl<R: Reader> LimitReader<R> {
26 /// Creates a new `LimitReader`
27 pub fn new(r: R, limit: uint) -> LimitReader<R> {
28 LimitReader { limit: limit, inner: r }
31 /// Consumes the `LimitReader`, returning the underlying `Reader`.
32 pub fn unwrap(self) -> R { self.inner }
34 /// Returns the number of bytes that can be read before the `LimitReader`
39 /// The reader may reach EOF after reading fewer bytes than indicated by
40 /// this method if the underlying reader reaches EOF.
41 pub fn limit(&self) -> uint { self.limit }
44 impl<R: Reader> Reader for LimitReader<R> {
45 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
47 return Err(io::standard_error(io::EndOfFile));
50 let len = cmp::min(self.limit, buf.len());
51 self.inner.read(buf.mut_slice_to(len)).map(|len| {
58 impl<R: Buffer> Buffer for LimitReader<R> {
59 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
60 let amt = try!(self.inner.fill_buf());
61 let buf = amt.slice_to(cmp::min(amt.len(), self.limit));
63 Err(io::standard_error(io::EndOfFile))
69 fn consume(&mut self, amt: uint) {
71 self.inner.consume(amt);
76 /// A `Writer` which ignores bytes written to it, like /dev/null.
77 pub struct NullWriter;
79 impl Writer for NullWriter {
81 fn write(&mut self, _buf: &[u8]) -> io::IoResult<()> { Ok(()) }
84 /// A `Reader` which returns an infinite stream of 0 bytes, like /dev/zero.
85 pub struct ZeroReader;
87 impl Reader for ZeroReader {
89 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
95 impl Buffer for ZeroReader {
96 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
97 static DATA: [u8, ..64] = [0, ..64];
100 fn consume(&mut self, _amt: uint) {}
103 /// A `Reader` which is always at EOF, like /dev/null.
104 pub struct NullReader;
106 impl Reader for NullReader {
108 fn read(&mut self, _buf: &mut [u8]) -> io::IoResult<uint> {
109 Err(io::standard_error(io::EndOfFile))
113 impl Buffer for NullReader {
114 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
115 Err(io::standard_error(io::EndOfFile))
117 fn consume(&mut self, _amt: uint) {}
120 /// A `Writer` which multiplexes writes to a set of `Writers`.
121 pub struct MultiWriter {
122 writers: Vec<Box<Writer>>
126 /// Creates a new `MultiWriter`
127 pub fn new(writers: Vec<Box<Writer>>) -> MultiWriter {
128 MultiWriter { writers: writers }
132 impl Writer for MultiWriter {
134 fn write(&mut self, buf: &[u8]) -> io::IoResult<()> {
135 let mut ret = Ok(());
136 for writer in self.writers.mut_iter() {
137 ret = ret.and(writer.write(buf));
143 fn flush(&mut self) -> io::IoResult<()> {
144 let mut ret = Ok(());
145 for writer in self.writers.mut_iter() {
146 ret = ret.and(writer.flush());
152 /// A `Reader` which chains input from multiple `Readers`, reading each to
153 /// completion before moving onto the next.
154 pub struct ChainedReader<I, R> {
156 cur_reader: Option<R>,
159 impl<R: Reader, I: Iterator<R>> ChainedReader<I, R> {
160 /// Creates a new `ChainedReader`
161 pub fn new(mut readers: I) -> ChainedReader<I, R> {
162 let r = readers.next();
163 ChainedReader { readers: readers, cur_reader: r }
167 impl<R: Reader, I: Iterator<R>> Reader for ChainedReader<I, R> {
168 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
170 let err = match self.cur_reader {
173 Ok(len) => return Ok(len),
174 Err(ref e) if e.kind == io::EndOfFile => None,
180 self.cur_reader = self.readers.next();
182 Some(e) => return Err(e),
186 Err(io::standard_error(io::EndOfFile))
190 /// A `Reader` which forwards input from another `Reader`, passing it along to
191 /// a `Writer` as well. Similar to the `tee(1)` command.
192 pub struct TeeReader<R, W> {
197 impl<R: Reader, W: Writer> TeeReader<R, W> {
198 /// Creates a new `TeeReader`
199 pub fn new(r: R, w: W) -> TeeReader<R, W> {
200 TeeReader { reader: r, writer: w }
203 /// Consumes the `TeeReader`, returning the underlying `Reader` and
205 pub fn unwrap(self) -> (R, W) {
206 let TeeReader { reader, writer } = self;
211 impl<R: Reader, W: Writer> Reader for TeeReader<R, W> {
212 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
213 self.reader.read(buf).and_then(|len| {
214 self.writer.write(buf.slice_to(len)).map(|()| len)
219 /// Copies all data from a `Reader` to a `Writer`.
220 pub fn copy<R: Reader, W: Writer>(r: &mut R, w: &mut W) -> io::IoResult<()> {
221 let mut buf = [0, ..super::DEFAULT_BUF_SIZE];
223 let len = match r.read(buf) {
225 Err(ref e) if e.kind == io::EndOfFile => return Ok(()),
226 Err(e) => return Err(e),
228 try!(w.write(buf.slice_to(len)));
232 /// A `Reader` which converts an `Iterator<u8>` into a `Reader`.
233 pub struct IterReader<T> {
237 impl<T: Iterator<u8>> IterReader<T> {
238 /// Create a new `IterReader` which will read from the specified `Iterator`.
239 pub fn new(iter: T) -> IterReader<T> {
246 impl<T: Iterator<u8>> Reader for IterReader<T> {
248 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
250 for (slot, elt) in buf.mut_iter().zip(self.iter.by_ref()) {
255 Err(io::standard_error(io::EndOfFile))
264 use io::{MemReader, MemWriter, BufReader};
271 fn test_limit_reader_unlimited() {
272 let mut r = MemReader::new(vec!(0, 1, 2));
274 let mut r = LimitReader::new(r.by_ref(), 4);
275 assert_eq!(vec!(0, 1, 2), r.read_to_end().unwrap());
280 fn test_limit_reader_limited() {
281 let mut r = MemReader::new(vec!(0, 1, 2));
283 let mut r = LimitReader::new(r.by_ref(), 2);
284 assert_eq!(vec!(0, 1), r.read_to_end().unwrap());
286 assert_eq!(vec!(2), r.read_to_end().unwrap());
290 fn test_limit_reader_limit() {
291 let r = MemReader::new(vec!(0, 1, 2));
292 let mut r = LimitReader::new(r, 3);
293 assert_eq!(3, r.limit());
294 assert_eq!(0, r.read_byte().unwrap());
295 assert_eq!(2, r.limit());
296 assert_eq!(vec!(1, 2), r.read_to_end().unwrap());
297 assert_eq!(0, r.limit());
301 fn test_null_writer() {
302 let mut s = NullWriter;
303 let buf = vec![0, 0, 0];
304 s.write(buf.as_slice()).unwrap();
309 fn test_zero_reader() {
310 let mut s = ZeroReader;
311 let mut buf = vec![1, 2, 3];
312 assert_eq!(s.read(buf.as_mut_slice()), Ok(3));
313 assert_eq!(vec![0, 0, 0], buf);
317 fn test_null_reader() {
318 let mut r = NullReader;
319 let mut buf = vec![0];
320 assert!(r.read(buf.as_mut_slice()).is_err());
324 fn test_multi_writer() {
325 static mut writes: uint = 0;
326 static mut flushes: uint = 0;
329 impl Writer for TestWriter {
330 fn write(&mut self, _buf: &[u8]) -> io::IoResult<()> {
331 unsafe { writes += 1 }
335 fn flush(&mut self) -> io::IoResult<()> {
336 unsafe { flushes += 1 }
341 let mut multi = MultiWriter::new(vec!(box TestWriter as Box<Writer>,
342 box TestWriter as Box<Writer>));
343 multi.write([1, 2, 3]).unwrap();
344 assert_eq!(2, unsafe { writes });
345 assert_eq!(0, unsafe { flushes });
346 multi.flush().unwrap();
347 assert_eq!(2, unsafe { writes });
348 assert_eq!(2, unsafe { flushes });
352 fn test_chained_reader() {
353 let rs = vec!(MemReader::new(vec!(0, 1)), MemReader::new(vec!()),
354 MemReader::new(vec!(2, 3)));
355 let mut r = ChainedReader::new(rs.move_iter());
356 assert_eq!(vec!(0, 1, 2, 3), r.read_to_end().unwrap());
360 fn test_tee_reader() {
361 let mut r = TeeReader::new(MemReader::new(vec!(0, 1, 2)),
363 assert_eq!(vec!(0, 1, 2), r.read_to_end().unwrap());
364 let (_, w) = r.unwrap();
365 assert_eq!(vec!(0, 1, 2), w.unwrap());
370 let mut r = MemReader::new(vec!(0, 1, 2, 3, 4));
371 let mut w = MemWriter::new();
372 copy(&mut r, &mut w).unwrap();
373 assert_eq!(vec!(0, 1, 2, 3, 4), w.unwrap());
377 fn limit_reader_buffer() {
378 let data = "0123456789\n0123456789\n";
379 let mut r = BufReader::new(data.as_bytes());
381 let mut r = LimitReader::new(r.by_ref(), 3);
382 assert_eq!(r.read_line(), Ok("012".to_string()));
383 assert_eq!(r.limit(), 0);
384 assert_eq!(r.read_line().err().unwrap().kind, io::EndOfFile);
387 let mut r = LimitReader::new(r.by_ref(), 9);
388 assert_eq!(r.read_line(), Ok("3456789\n".to_string()));
389 assert_eq!(r.limit(), 1);
390 assert_eq!(r.read_line(), Ok("0".to_string()));
393 let mut r = LimitReader::new(r.by_ref(), 100);
394 assert_eq!(r.read_char(), Ok('1'));
395 assert_eq!(r.limit(), 99);
396 assert_eq!(r.read_line(), Ok("23456789\n".to_string()));
401 fn test_iter_reader() {
402 let mut r = IterReader::new(range(0u8, 8));
403 let mut buf = [0, 0, 0];
404 let len = r.read(buf).unwrap();
406 assert!(buf == [0, 1, 2]);
408 let len = r.read(buf).unwrap();
410 assert!(buf == [3, 4, 5]);
412 let len = r.read(buf).unwrap();
414 assert!(buf == [6, 7, 5]);
416 assert_eq!(r.read(buf).unwrap_err().kind, io::EndOfFile);