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 into_inner(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.slice_to_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.
81 pub struct NullWriter;
83 impl Writer for NullWriter {
85 fn write(&mut self, _buf: &[u8]) -> io::IoResult<()> { Ok(()) }
88 /// A `Reader` which returns an infinite stream of 0 bytes, like /dev/zero.
90 pub struct ZeroReader;
92 impl Reader for ZeroReader {
94 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
100 impl Buffer for ZeroReader {
101 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
102 static DATA: [u8; 64] = [0; 64];
106 fn consume(&mut self, _amt: uint) {}
109 /// A `Reader` which is always at EOF, like /dev/null.
111 pub struct NullReader;
113 impl Reader for NullReader {
115 fn read(&mut self, _buf: &mut [u8]) -> io::IoResult<uint> {
116 Err(io::standard_error(io::EndOfFile))
120 impl Buffer for NullReader {
121 fn fill_buf<'a>(&'a mut self) -> io::IoResult<&'a [u8]> {
122 Err(io::standard_error(io::EndOfFile))
124 fn consume(&mut self, _amt: uint) {}
127 /// A `Writer` which multiplexes writes to a set of `Writer`s.
129 /// The `Writer`s are delegated to in order. If any `Writer` returns an error,
130 /// that error is returned immediately and remaining `Writer`s are not called.
131 pub struct MultiWriter {
132 writers: Vec<Box<Writer+'static>>
136 /// Creates a new `MultiWriter`
137 pub fn new(writers: Vec<Box<Writer+'static>>) -> MultiWriter {
138 MultiWriter { writers: writers }
142 impl Writer for MultiWriter {
144 fn write(&mut self, buf: &[u8]) -> io::IoResult<()> {
145 for writer in self.writers.iter_mut() {
146 try!(writer.write(buf));
152 fn flush(&mut self) -> io::IoResult<()> {
153 for writer in self.writers.iter_mut() {
154 try!(writer.flush());
160 /// A `Reader` which chains input from multiple `Reader`s, reading each to
161 /// completion before moving onto the next.
163 pub struct ChainedReader<I, R> {
165 cur_reader: Option<R>,
168 impl<R: Reader, I: Iterator<Item=R>> ChainedReader<I, R> {
169 /// Creates a new `ChainedReader`
170 pub fn new(mut readers: I) -> ChainedReader<I, R> {
171 let r = readers.next();
172 ChainedReader { readers: readers, cur_reader: r }
176 impl<R: Reader, I: Iterator<Item=R>> Reader for ChainedReader<I, R> {
177 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
179 let err = match self.cur_reader {
182 Ok(len) => return Ok(len),
183 Err(ref e) if e.kind == io::EndOfFile => None,
189 self.cur_reader = self.readers.next();
191 Some(e) => return Err(e),
195 Err(io::standard_error(io::EndOfFile))
199 /// A `Reader` which forwards input from another `Reader`, passing it along to
200 /// a `Writer` as well. Similar to the `tee(1)` command.
201 pub struct TeeReader<R, W> {
206 impl<R: Reader, W: Writer> TeeReader<R, W> {
207 /// Creates a new `TeeReader`
208 pub fn new(r: R, w: W) -> TeeReader<R, W> {
209 TeeReader { reader: r, writer: w }
212 /// Consumes the `TeeReader`, returning the underlying `Reader` and
214 pub fn into_inner(self) -> (R, W) {
215 let TeeReader { reader, writer } = self;
220 impl<R: Reader, W: Writer> Reader for TeeReader<R, W> {
221 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
222 self.reader.read(buf).and_then(|len| {
223 self.writer.write(buf[mut ..len]).map(|()| len)
228 /// Copies all data from a `Reader` to a `Writer`.
229 pub fn copy<R: Reader, W: Writer>(r: &mut R, w: &mut W) -> io::IoResult<()> {
230 let mut buf = [0; super::DEFAULT_BUF_SIZE];
232 let len = match r.read(&mut buf) {
234 Err(ref e) if e.kind == io::EndOfFile => return Ok(()),
235 Err(e) => return Err(e),
237 try!(w.write(buf[..len]));
241 /// An adaptor converting an `Iterator<u8>` to a `Reader`.
243 pub struct IterReader<T> {
247 impl<T: Iterator<Item=u8>> IterReader<T> {
248 /// Creates a new `IterReader` which will read from the specified
250 pub fn new(iter: T) -> IterReader<T> {
251 IterReader { iter: iter }
255 impl<T: Iterator<Item=u8>> Reader for IterReader<T> {
257 fn read(&mut self, buf: &mut [u8]) -> io::IoResult<uint> {
259 for (slot, elt) in buf.iter_mut().zip(self.iter.by_ref()) {
263 if len == 0 && buf.len() != 0 {
264 Err(io::standard_error(io::EndOfFile))
275 use io::{MemReader, ByRefReader};
280 fn test_limit_reader_unlimited() {
281 let mut r = MemReader::new(vec!(0, 1, 2));
283 let mut r = LimitReader::new(r.by_ref(), 4);
284 assert_eq!(vec!(0, 1, 2), r.read_to_end().unwrap());
289 fn test_limit_reader_limited() {
290 let mut r = MemReader::new(vec!(0, 1, 2));
292 let mut r = LimitReader::new(r.by_ref(), 2);
293 assert_eq!(vec!(0, 1), r.read_to_end().unwrap());
295 assert_eq!(vec!(2), r.read_to_end().unwrap());
299 fn test_limit_reader_limit() {
300 let r = MemReader::new(vec!(0, 1, 2));
301 let mut r = LimitReader::new(r, 3);
302 assert_eq!(3, r.limit());
303 assert_eq!(0, r.read_byte().unwrap());
304 assert_eq!(2, r.limit());
305 assert_eq!(vec!(1, 2), r.read_to_end().unwrap());
306 assert_eq!(0, r.limit());
310 fn test_limit_reader_overlong_consume() {
311 let mut r = MemReader::new(vec![0, 1, 2, 3, 4, 5]);
312 let mut r = LimitReader::new(r.by_ref(), 1);
314 assert_eq!(vec![], r.read_to_end().unwrap());
318 fn test_null_writer() {
319 let mut s = NullWriter;
320 let buf = vec![0, 0, 0];
321 s.write(buf.as_slice()).unwrap();
326 fn test_zero_reader() {
327 let mut s = ZeroReader;
328 let mut buf = vec![1, 2, 3];
329 assert_eq!(s.read(buf.as_mut_slice()), Ok(3));
330 assert_eq!(vec![0, 0, 0], buf);
334 fn test_null_reader() {
335 let mut r = NullReader;
336 let mut buf = vec![0];
337 assert!(r.read(buf.as_mut_slice()).is_err());
341 fn test_multi_writer() {
342 static mut writes: uint = 0;
343 static mut flushes: uint = 0;
346 impl Writer for TestWriter {
347 fn write(&mut self, _buf: &[u8]) -> io::IoResult<()> {
348 unsafe { writes += 1 }
352 fn flush(&mut self) -> io::IoResult<()> {
353 unsafe { flushes += 1 }
358 let mut multi = MultiWriter::new(vec!(box TestWriter as Box<Writer>,
359 box TestWriter as Box<Writer>));
360 multi.write(&[1, 2, 3]).unwrap();
361 assert_eq!(2, unsafe { writes });
362 assert_eq!(0, unsafe { flushes });
363 multi.flush().unwrap();
364 assert_eq!(2, unsafe { writes });
365 assert_eq!(2, unsafe { flushes });
369 fn test_chained_reader() {
370 let rs = vec!(MemReader::new(vec!(0, 1)), MemReader::new(vec!()),
371 MemReader::new(vec!(2, 3)));
372 let mut r = ChainedReader::new(rs.into_iter());
373 assert_eq!(vec!(0, 1, 2, 3), r.read_to_end().unwrap());
377 fn test_tee_reader() {
378 let mut r = TeeReader::new(MemReader::new(vec!(0, 1, 2)),
380 assert_eq!(vec!(0, 1, 2), r.read_to_end().unwrap());
381 let (_, w) = r.into_inner();
382 assert_eq!(vec!(0, 1, 2), w);
387 let mut r = MemReader::new(vec!(0, 1, 2, 3, 4));
388 let mut w = Vec::new();
389 copy(&mut r, &mut w).unwrap();
390 assert_eq!(vec!(0, 1, 2, 3, 4), w);
394 fn limit_reader_buffer() {
395 let r = &mut b"0123456789\n0123456789\n";
397 let mut r = LimitReader::new(r.by_ref(), 3);
398 assert_eq!(r.read_line(), Ok("012".to_string()));
399 assert_eq!(r.limit(), 0);
400 assert_eq!(r.read_line().err().unwrap().kind, io::EndOfFile);
403 let mut r = LimitReader::new(r.by_ref(), 9);
404 assert_eq!(r.read_line(), Ok("3456789\n".to_string()));
405 assert_eq!(r.limit(), 1);
406 assert_eq!(r.read_line(), Ok("0".to_string()));
409 let mut r = LimitReader::new(r.by_ref(), 100);
410 assert_eq!(r.read_char(), Ok('1'));
411 assert_eq!(r.limit(), 99);
412 assert_eq!(r.read_line(), Ok("23456789\n".to_string()));
417 fn test_iter_reader() {
418 let mut r = IterReader::new(range(0u8, 8));
419 let mut buf = [0, 0, 0];
420 let len = r.read(&mut buf).unwrap();
422 assert!(buf == [0, 1, 2]);
424 let len = r.read(&mut buf).unwrap();
426 assert!(buf == [3, 4, 5]);
428 let len = r.read(&mut buf).unwrap();
430 assert!(buf == [6, 7, 5]);
432 assert_eq!(r.read(&mut buf).unwrap_err().kind, io::EndOfFile);
436 fn iter_reader_zero_length() {
437 let mut r = IterReader::new(range(0u8, 8));
439 assert_eq!(Ok(0), r.read(&mut buf));