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 */
16 use slice::bytes::MutableByteVector;
18 /// Wraps a `Reader`, limiting the number of bytes that can be read from it.
19 pub struct LimitReader<R> {
24 impl<R: Reader> LimitReader<R> {
25 /// Creates a new `LimitReader`
26 pub fn new(r: R, limit: uint) -> LimitReader<R> {
27 LimitReader { limit: limit, inner: r }
30 /// Consumes the `LimitReader`, returning the underlying `Reader`.
31 pub fn unwrap(self) -> R { self.inner }
33 /// Returns the number of bytes that can be read before the `LimitReader`
38 /// The reader may reach EOF after reading fewer bytes than indicated by
39 /// this method if the underlying reader reaches EOF.
40 pub fn limit(&self) -> uint { self.limit }
43 impl<R: Reader> Reader for LimitReader<R> {
44 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
46 return Err(io::standard_error(io::EndOfFile));
49 let len = cmp::min(self.limit, buf.len());
50 let res = self.inner.read(buf[mut ..len]);
52 Ok(len) => self.limit -= len,
59 impl<R: Buffer> Buffer for LimitReader<R> {
60 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
61 let amt = try!(self.inner.fill_buf());
62 let buf = amt[..cmp::min(amt.len(), self.limit)];
64 Err(io::standard_error(io::EndOfFile))
70 fn consume(&mut self, amt: uint) {
71 // Don't let callers reset the limit by passing an overlarge value
72 let amt = cmp::min(amt, self.limit);
74 self.inner.consume(amt);
79 /// A `Writer` which ignores bytes written to it, like /dev/null.
80 pub struct NullWriter;
82 impl Writer for NullWriter {
84 fn write(&mut self, _buf: &[u8]) -> io::IoResult<()> { Ok(()) }
87 /// A `Reader` which returns an infinite stream of 0 bytes, like /dev/zero.
88 pub struct ZeroReader;
90 impl Reader for ZeroReader {
92 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
98 impl Buffer for ZeroReader {
99 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
100 static DATA: [u8, ..64] = [0, ..64];
104 fn consume(&mut self, _amt: uint) {}
107 /// A `Reader` which is always at EOF, like /dev/null.
108 pub struct NullReader;
110 impl Reader for NullReader {
112 fn read(&mut self, _buf: &mut [u8]) -> io::IoResult<uint> {
113 Err(io::standard_error(io::EndOfFile))
117 impl Buffer for NullReader {
118 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
119 Err(io::standard_error(io::EndOfFile))
121 fn consume(&mut self, _amt: uint) {}
124 /// A `Writer` which multiplexes writes to a set of `Writer`s.
126 /// The `Writer`s are delegated to in order. If any `Writer` returns an error,
127 /// that error is returned immediately and remaining `Writer`s are not called.
128 pub struct MultiWriter {
129 writers: Vec<Box<Writer+'static>>
133 /// Creates a new `MultiWriter`
134 pub fn new(writers: Vec<Box<Writer+'static>>) -> MultiWriter {
135 MultiWriter { writers: writers }
139 impl Writer for MultiWriter {
141 fn write(&mut self, buf: &[u8]) -> io::IoResult<()> {
142 for writer in self.writers.iter_mut() {
143 try!(writer.write(buf));
149 fn flush(&mut self) -> io::IoResult<()> {
150 for writer in self.writers.iter_mut() {
151 try!(writer.flush());
157 /// A `Reader` which chains input from multiple `Reader`s, reading each to
158 /// completion before moving onto the next.
159 pub struct ChainedReader<I, R> {
161 cur_reader: Option<R>,
164 impl<R: Reader, I: Iterator<R>> ChainedReader<I, R> {
165 /// Creates a new `ChainedReader`
166 pub fn new(mut readers: I) -> ChainedReader<I, R> {
167 let r = readers.next();
168 ChainedReader { readers: readers, cur_reader: r }
172 impl<R: Reader, I: Iterator<R>> Reader for ChainedReader<I, R> {
173 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
175 let err = match self.cur_reader {
178 Ok(len) => return Ok(len),
179 Err(ref e) if e.kind == io::EndOfFile => None,
185 self.cur_reader = self.readers.next();
187 Some(e) => return Err(e),
191 Err(io::standard_error(io::EndOfFile))
195 /// A `Reader` which forwards input from another `Reader`, passing it along to
196 /// a `Writer` as well. Similar to the `tee(1)` command.
197 pub struct TeeReader<R, W> {
202 impl<R: Reader, W: Writer> TeeReader<R, W> {
203 /// Creates a new `TeeReader`
204 pub fn new(r: R, w: W) -> TeeReader<R, W> {
205 TeeReader { reader: r, writer: w }
208 /// Consumes the `TeeReader`, returning the underlying `Reader` and
210 pub fn unwrap(self) -> (R, W) {
211 let TeeReader { reader, writer } = self;
216 impl<R: Reader, W: Writer> Reader for TeeReader<R, W> {
217 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
218 self.reader.read(buf).and_then(|len| {
219 self.writer.write(buf[mut ..len]).map(|()| len)
224 /// Copies all data from a `Reader` to a `Writer`.
225 pub fn copy<R: Reader, W: Writer>(r: &mut R, w: &mut W) -> io::IoResult<()> {
226 let mut buf = [0, ..super::DEFAULT_BUF_SIZE];
228 let len = match r.read(&mut buf) {
230 Err(ref e) if e.kind == io::EndOfFile => return Ok(()),
231 Err(e) => return Err(e),
233 try!(w.write(buf[..len]));
237 /// An adaptor converting an `Iterator<u8>` to a `Reader`.
238 pub struct IterReader<T> {
242 impl<T: Iterator<u8>> IterReader<T> {
243 /// Creates a new `IterReader` which will read from the specified
245 pub fn new(iter: T) -> IterReader<T> {
246 IterReader { iter: iter }
250 impl<T: Iterator<u8>> Reader for IterReader<T> {
252 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
254 for (slot, elt) in buf.iter_mut().zip(self.iter.by_ref()) {
258 if len == 0 && buf.len() != 0 {
259 Err(io::standard_error(io::EndOfFile))
268 use io::{MemReader, BufReader, ByRefReader};
275 fn test_limit_reader_unlimited() {
276 let mut r = MemReader::new(vec!(0, 1, 2));
278 let mut r = LimitReader::new(r.by_ref(), 4);
279 assert_eq!(vec!(0, 1, 2), r.read_to_end().unwrap());
284 fn test_limit_reader_limited() {
285 let mut r = MemReader::new(vec!(0, 1, 2));
287 let mut r = LimitReader::new(r.by_ref(), 2);
288 assert_eq!(vec!(0, 1), r.read_to_end().unwrap());
290 assert_eq!(vec!(2), r.read_to_end().unwrap());
294 fn test_limit_reader_limit() {
295 let r = MemReader::new(vec!(0, 1, 2));
296 let mut r = LimitReader::new(r, 3);
297 assert_eq!(3, r.limit());
298 assert_eq!(0, r.read_byte().unwrap());
299 assert_eq!(2, r.limit());
300 assert_eq!(vec!(1, 2), r.read_to_end().unwrap());
301 assert_eq!(0, r.limit());
305 fn test_limit_reader_overlong_consume() {
306 let mut r = MemReader::new(vec![0, 1, 2, 3, 4, 5]);
307 let mut r = LimitReader::new(r.by_ref(), 1);
309 assert_eq!(vec![], r.read_to_end().unwrap());
313 fn test_null_writer() {
314 let mut s = NullWriter;
315 let buf = vec![0, 0, 0];
316 s.write(buf.as_slice()).unwrap();
321 fn test_zero_reader() {
322 let mut s = ZeroReader;
323 let mut buf = vec![1, 2, 3];
324 assert_eq!(s.read(buf.as_mut_slice()), Ok(3));
325 assert_eq!(vec![0, 0, 0], buf);
329 fn test_null_reader() {
330 let mut r = NullReader;
331 let mut buf = vec![0];
332 assert!(r.read(buf.as_mut_slice()).is_err());
336 fn test_multi_writer() {
337 static mut writes: uint = 0;
338 static mut flushes: uint = 0;
341 impl Writer for TestWriter {
342 fn write(&mut self, _buf: &[u8]) -> io::IoResult<()> {
343 unsafe { writes += 1 }
347 fn flush(&mut self) -> io::IoResult<()> {
348 unsafe { flushes += 1 }
353 let mut multi = MultiWriter::new(vec!(box TestWriter as Box<Writer>,
354 box TestWriter as Box<Writer>));
355 multi.write(&[1, 2, 3]).unwrap();
356 assert_eq!(2, unsafe { writes });
357 assert_eq!(0, unsafe { flushes });
358 multi.flush().unwrap();
359 assert_eq!(2, unsafe { writes });
360 assert_eq!(2, unsafe { flushes });
364 fn test_chained_reader() {
365 let rs = vec!(MemReader::new(vec!(0, 1)), MemReader::new(vec!()),
366 MemReader::new(vec!(2, 3)));
367 let mut r = ChainedReader::new(rs.into_iter());
368 assert_eq!(vec!(0, 1, 2, 3), r.read_to_end().unwrap());
372 fn test_tee_reader() {
373 let mut r = TeeReader::new(MemReader::new(vec!(0, 1, 2)),
375 assert_eq!(vec!(0, 1, 2), r.read_to_end().unwrap());
376 let (_, w) = r.unwrap();
377 assert_eq!(vec!(0, 1, 2), w);
382 let mut r = MemReader::new(vec!(0, 1, 2, 3, 4));
383 let mut w = Vec::new();
384 copy(&mut r, &mut w).unwrap();
385 assert_eq!(vec!(0, 1, 2, 3, 4), w);
389 fn limit_reader_buffer() {
390 let data = "0123456789\n0123456789\n";
391 let mut r = BufReader::new(data.as_bytes());
393 let mut r = LimitReader::new(r.by_ref(), 3);
394 assert_eq!(r.read_line(), Ok("012".to_string()));
395 assert_eq!(r.limit(), 0);
396 assert_eq!(r.read_line().err().unwrap().kind, io::EndOfFile);
399 let mut r = LimitReader::new(r.by_ref(), 9);
400 assert_eq!(r.read_line(), Ok("3456789\n".to_string()));
401 assert_eq!(r.limit(), 1);
402 assert_eq!(r.read_line(), Ok("0".to_string()));
405 let mut r = LimitReader::new(r.by_ref(), 100);
406 assert_eq!(r.read_char(), Ok('1'));
407 assert_eq!(r.limit(), 99);
408 assert_eq!(r.read_line(), Ok("23456789\n".to_string()));
413 fn test_iter_reader() {
414 let mut r = IterReader::new(range(0u8, 8));
415 let mut buf = [0, 0, 0];
416 let len = r.read(&mut buf).unwrap();
418 assert!(buf == [0, 1, 2]);
420 let len = r.read(&mut buf).unwrap();
422 assert!(buf == [3, 4, 5]);
424 let len = r.read(&mut buf).unwrap();
426 assert!(buf == [6, 7, 5]);
428 assert_eq!(r.read(&mut buf).unwrap_err().kind, io::EndOfFile);
432 fn iter_reader_zero_length() {
433 let mut r = IterReader::new(range(0u8, 8));
435 assert_eq!(Ok(0), r.read(&mut buf));