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85aaf69f | 1 | // Copyright 2015 The Rust Project Developers. See the COPYRIGHT |
1a4d82fc JJ |
2 | // file at the top-level directory of this distribution and at |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
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. | |
1a4d82fc | 10 | |
85aaf69f | 11 | //! Traits, helpers, and type definitions for core I/O functionality. |
c1a9b12d SL |
12 | //! |
13 | //! The `std::io` module contains a number of common things you'll need | |
14 | //! when doing input and output. The most core part of this module is | |
15 | //! the [`Read`][read] and [`Write`][write] traits, which provide the | |
16 | //! most general interface for reading and writing input and output. | |
17 | //! | |
18 | //! [read]: trait.Read.html | |
19 | //! [write]: trait.Write.html | |
20 | //! | |
21 | //! # Read and Write | |
22 | //! | |
23 | //! Because they are traits, they're implemented by a number of other types, | |
24 | //! and you can implement them for your types too. As such, you'll see a | |
25 | //! few different types of I/O throughout the documentation in this module: | |
26 | //! `File`s, `TcpStream`s, and somtimes even `Vec<T>`s. For example, `Read` | |
27 | //! adds a `read()` method, which we can use on `File`s: | |
28 | //! | |
29 | //! ``` | |
30 | //! use std::io; | |
31 | //! use std::io::prelude::*; | |
32 | //! use std::fs::File; | |
33 | //! | |
34 | //! # fn foo() -> io::Result<()> { | |
35 | //! let mut f = try!(File::open("foo.txt")); | |
36 | //! let mut buffer = [0; 10]; | |
37 | //! | |
38 | //! // read up to 10 bytes | |
39 | //! try!(f.read(&mut buffer)); | |
40 | //! | |
41 | //! println!("The bytes: {:?}", buffer); | |
42 | //! # Ok(()) | |
43 | //! # } | |
44 | //! ``` | |
45 | //! | |
46 | //! `Read` and `Write` are so important, implementors of the two traits have a | |
47 | //! nickname: readers and writers. So you'll sometimes see 'a reader' instead | |
48 | //! of 'a type that implements the `Read` trait'. Much easier! | |
49 | //! | |
50 | //! ## Seek and BufRead | |
51 | //! | |
52 | //! Beyond that, there are two important traits that are provided: [`Seek`][seek] | |
53 | //! and [`BufRead`][bufread]. Both of these build on top of a reader to control | |
54 | //! how the reading happens. `Seek` lets you control where the next byte is | |
55 | //! coming from: | |
56 | //! | |
57 | //! ``` | |
58 | //! use std::io; | |
59 | //! use std::io::prelude::*; | |
60 | //! use std::io::SeekFrom; | |
61 | //! use std::fs::File; | |
62 | //! | |
63 | //! # fn foo() -> io::Result<()> { | |
64 | //! let mut f = try!(File::open("foo.txt")); | |
65 | //! let mut buffer = [0; 10]; | |
66 | //! | |
67 | //! // skip to the last 10 bytes of the file | |
68 | //! try!(f.seek(SeekFrom::End(-10))); | |
69 | //! | |
70 | //! // read up to 10 bytes | |
71 | //! try!(f.read(&mut buffer)); | |
72 | //! | |
73 | //! println!("The bytes: {:?}", buffer); | |
74 | //! # Ok(()) | |
75 | //! # } | |
76 | //! ``` | |
77 | //! | |
78 | //! [seek]: trait.Seek.html | |
79 | //! [bufread]: trait.BufRead.html | |
80 | //! | |
81 | //! `BufRead` uses an internal buffer to provide a number of other ways to read, but | |
82 | //! to show it off, we'll need to talk about buffers in general. Keep reading! | |
83 | //! | |
84 | //! ## BufReader and BufWriter | |
85 | //! | |
86 | //! Byte-based interfaces are unwieldy and can be inefficient, as we'd need to be | |
87 | //! making near-constant calls to the operating system. To help with this, | |
88 | //! `std::io` comes with two structs, `BufReader` and `BufWriter`, which wrap | |
89 | //! readers and writers. The wrapper uses a buffer, reducing the number of | |
90 | //! calls and providing nicer methods for accessing exactly what you want. | |
91 | //! | |
92 | //! For example, `BufReader` works with the `BufRead` trait to add extra | |
93 | //! methods to any reader: | |
94 | //! | |
95 | //! ``` | |
96 | //! use std::io; | |
97 | //! use std::io::prelude::*; | |
98 | //! use std::io::BufReader; | |
99 | //! use std::fs::File; | |
100 | //! | |
101 | //! # fn foo() -> io::Result<()> { | |
102 | //! let f = try!(File::open("foo.txt")); | |
103 | //! let mut reader = BufReader::new(f); | |
104 | //! let mut buffer = String::new(); | |
105 | //! | |
106 | //! // read a line into buffer | |
107 | //! try!(reader.read_line(&mut buffer)); | |
108 | //! | |
109 | //! println!("{}", buffer); | |
110 | //! # Ok(()) | |
111 | //! # } | |
112 | //! ``` | |
113 | //! | |
114 | //! `BufWriter` doesn't add any new ways of writing, it just buffers every call | |
115 | //! to [`write()`][write]: | |
116 | //! | |
117 | //! ``` | |
118 | //! use std::io; | |
119 | //! use std::io::prelude::*; | |
120 | //! use std::io::BufWriter; | |
121 | //! use std::fs::File; | |
122 | //! | |
123 | //! # fn foo() -> io::Result<()> { | |
124 | //! let f = try!(File::create("foo.txt")); | |
125 | //! { | |
126 | //! let mut writer = BufWriter::new(f); | |
127 | //! | |
128 | //! // write a byte to the buffer | |
129 | //! try!(writer.write(&[42])); | |
130 | //! | |
131 | //! } // the buffer is flushed once writer goes out of scope | |
132 | //! | |
133 | //! # Ok(()) | |
134 | //! # } | |
135 | //! ``` | |
136 | //! | |
137 | //! [write]: trait.Write.html#tymethod.write | |
138 | //! | |
139 | //! ## Standard input and output | |
140 | //! | |
141 | //! A very common source of input is standard input: | |
142 | //! | |
143 | //! ``` | |
144 | //! use std::io; | |
145 | //! | |
146 | //! # fn foo() -> io::Result<()> { | |
147 | //! let mut input = String::new(); | |
148 | //! | |
149 | //! try!(io::stdin().read_line(&mut input)); | |
150 | //! | |
151 | //! println!("You typed: {}", input.trim()); | |
152 | //! # Ok(()) | |
153 | //! # } | |
154 | //! ``` | |
155 | //! | |
156 | //! And a very common source of output is standard output: | |
157 | //! | |
158 | //! ``` | |
159 | //! use std::io; | |
160 | //! use std::io::prelude::*; | |
161 | //! | |
162 | //! # fn foo() -> io::Result<()> { | |
163 | //! try!(io::stdout().write(&[42])); | |
164 | //! # Ok(()) | |
165 | //! # } | |
166 | //! ``` | |
167 | //! | |
168 | //! Of course, using `io::stdout()` directly is less comon than something like | |
169 | //! `println!`. | |
170 | //! | |
171 | //! ## Iterator types | |
172 | //! | |
173 | //! A large number of the structures provided by `std::io` are for various | |
174 | //! ways of iterating over I/O. For example, `Lines` is used to split over | |
175 | //! lines: | |
176 | //! | |
177 | //! ``` | |
178 | //! use std::io; | |
179 | //! use std::io::prelude::*; | |
180 | //! use std::io::BufReader; | |
181 | //! use std::fs::File; | |
182 | //! | |
183 | //! # fn foo() -> io::Result<()> { | |
184 | //! let f = try!(File::open("foo.txt")); | |
185 | //! let mut reader = BufReader::new(f); | |
186 | //! | |
187 | //! for line in reader.lines() { | |
188 | //! let line = try!(line); | |
189 | //! println!("{}", line); | |
190 | //! } | |
191 | //! | |
192 | //! # Ok(()) | |
193 | //! # } | |
194 | //! ``` | |
195 | //! | |
196 | //! ## Functions | |
197 | //! | |
198 | //! There are a number of [functions][functions] that offer access to various | |
199 | //! features. For example, we can use three of these functions to copy everything | |
200 | //! from standard input to standard output: | |
201 | //! | |
202 | //! ``` | |
203 | //! use std::io; | |
204 | //! | |
205 | //! # fn foo() -> io::Result<()> { | |
206 | //! try!(io::copy(&mut io::stdin(), &mut io::stdout())); | |
207 | //! # Ok(()) | |
208 | //! # } | |
209 | //! ``` | |
210 | //! | |
211 | //! [functions]: #functions | |
212 | //! | |
213 | //! ## io::Result | |
214 | //! | |
215 | //! Last, but certainly not least, is [`io::Result`][result]. This type is used | |
216 | //! as the return type of many `std::io` functions that can cause an error, and | |
217 | //! can be returned from your own functions as well. Many of the examples in this | |
218 | //! module use the [`try!`][try] macro: | |
219 | //! | |
220 | //! ``` | |
221 | //! use std::io; | |
222 | //! | |
223 | //! fn read_input() -> io::Result<()> { | |
224 | //! let mut input = String::new(); | |
225 | //! | |
226 | //! try!(io::stdin().read_line(&mut input)); | |
227 | //! | |
228 | //! println!("You typed: {}", input.trim()); | |
229 | //! | |
230 | //! Ok(()) | |
231 | //! } | |
232 | //! ``` | |
233 | //! | |
234 | //! The return type of `read_input()`, `io::Result<()>`, is a very common type | |
235 | //! for functions which don't have a 'real' return value, but do want to return | |
236 | //! errors if they happen. In this case, the only purpose of this function is | |
237 | //! to read the line and print it, so we use use `()`. | |
238 | //! | |
239 | //! [result]: type.Result.html | |
240 | //! [try]: macro.try!.html | |
1a4d82fc | 241 | |
c34b1796 | 242 | #![stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 243 | |
85aaf69f | 244 | use cmp; |
d9579d0f | 245 | use rustc_unicode::str as core_str; |
c34b1796 | 246 | use error as std_error; |
1a4d82fc | 247 | use fmt; |
c1a9b12d | 248 | use iter::{Iterator}; |
1a4d82fc | 249 | use marker::Sized; |
85aaf69f SL |
250 | use ops::{Drop, FnOnce}; |
251 | use option::Option::{self, Some, None}; | |
1a4d82fc | 252 | use result::Result::{Ok, Err}; |
85aaf69f | 253 | use result; |
1a4d82fc | 254 | use string::String; |
c34b1796 | 255 | use str; |
1a4d82fc JJ |
256 | use vec::Vec; |
257 | ||
85aaf69f SL |
258 | pub use self::buffered::{BufReader, BufWriter, BufStream, LineWriter}; |
259 | pub use self::buffered::IntoInnerError; | |
260 | pub use self::cursor::Cursor; | |
261 | pub use self::error::{Result, Error, ErrorKind}; | |
262 | pub use self::util::{copy, sink, Sink, empty, Empty, repeat, Repeat}; | |
c34b1796 AL |
263 | pub use self::stdio::{stdin, stdout, stderr, _print, Stdin, Stdout, Stderr}; |
264 | pub use self::stdio::{StdoutLock, StderrLock, StdinLock}; | |
265 | #[doc(no_inline, hidden)] | |
266 | pub use self::stdio::{set_panic, set_print}; | |
267 | ||
85aaf69f | 268 | pub mod prelude; |
1a4d82fc | 269 | mod buffered; |
85aaf69f SL |
270 | mod cursor; |
271 | mod error; | |
272 | mod impls; | |
62682a34 | 273 | mod lazy; |
85aaf69f | 274 | mod util; |
c34b1796 | 275 | mod stdio; |
1a4d82fc | 276 | |
85aaf69f | 277 | const DEFAULT_BUF_SIZE: usize = 64 * 1024; |
1a4d82fc | 278 | |
85aaf69f SL |
279 | // A few methods below (read_to_string, read_line) will append data into a |
280 | // `String` buffer, but we need to be pretty careful when doing this. The | |
281 | // implementation will just call `.as_mut_vec()` and then delegate to a | |
282 | // byte-oriented reading method, but we must ensure that when returning we never | |
283 | // leave `buf` in a state such that it contains invalid UTF-8 in its bounds. | |
284 | // | |
285 | // To this end, we use an RAII guard (to protect against panics) which updates | |
286 | // the length of the string when it is dropped. This guard initially truncates | |
287 | // the string to the prior length and only after we've validated that the | |
288 | // new contents are valid UTF-8 do we allow it to set a longer length. | |
289 | // | |
290 | // The unsafety in this function is twofold: | |
291 | // | |
292 | // 1. We're looking at the raw bytes of `buf`, so we take on the burden of UTF-8 | |
293 | // checks. | |
294 | // 2. We're passing a raw buffer to the function `f`, and it is expected that | |
295 | // the function only *appends* bytes to the buffer. We'll get undefined | |
296 | // behavior if existing bytes are overwritten to have non-UTF-8 data. | |
c34b1796 AL |
297 | fn append_to_string<F>(buf: &mut String, f: F) -> Result<usize> |
298 | where F: FnOnce(&mut Vec<u8>) -> Result<usize> | |
85aaf69f SL |
299 | { |
300 | struct Guard<'a> { s: &'a mut Vec<u8>, len: usize } | |
d9579d0f | 301 | impl<'a> Drop for Guard<'a> { |
85aaf69f SL |
302 | fn drop(&mut self) { |
303 | unsafe { self.s.set_len(self.len); } | |
1a4d82fc JJ |
304 | } |
305 | } | |
1a4d82fc | 306 | |
85aaf69f SL |
307 | unsafe { |
308 | let mut g = Guard { len: buf.len(), s: buf.as_mut_vec() }; | |
309 | let ret = f(g.s); | |
310 | if str::from_utf8(&g.s[g.len..]).is_err() { | |
c34b1796 | 311 | ret.and_then(|_| { |
62682a34 | 312 | Err(Error::new(ErrorKind::InvalidData, |
c34b1796 | 313 | "stream did not contain valid UTF-8")) |
85aaf69f SL |
314 | }) |
315 | } else { | |
316 | g.len = g.s.len(); | |
317 | ret | |
318 | } | |
1a4d82fc JJ |
319 | } |
320 | } | |
321 | ||
c34b1796 AL |
322 | // This uses an adaptive system to extend the vector when it fills. We want to |
323 | // avoid paying to allocate and zero a huge chunk of memory if the reader only | |
324 | // has 4 bytes while still making large reads if the reader does have a ton | |
325 | // of data to return. Simply tacking on an extra DEFAULT_BUF_SIZE space every | |
326 | // time is 4,500 times (!) slower than this if the reader has a very small | |
327 | // amount of data to return. | |
328 | fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize> { | |
329 | let start_len = buf.len(); | |
330 | let mut len = start_len; | |
331 | let mut new_write_size = 16; | |
332 | let ret; | |
85aaf69f | 333 | loop { |
c34b1796 AL |
334 | if len == buf.len() { |
335 | if new_write_size < DEFAULT_BUF_SIZE { | |
336 | new_write_size *= 2; | |
337 | } | |
c1a9b12d | 338 | buf.resize(len + new_write_size, 0); |
85aaf69f | 339 | } |
c34b1796 AL |
340 | |
341 | match r.read(&mut buf[len..]) { | |
342 | Ok(0) => { | |
343 | ret = Ok(len - start_len); | |
344 | break; | |
345 | } | |
346 | Ok(n) => len += n, | |
85aaf69f | 347 | Err(ref e) if e.kind() == ErrorKind::Interrupted => {} |
c34b1796 AL |
348 | Err(e) => { |
349 | ret = Err(e); | |
350 | break; | |
351 | } | |
85aaf69f | 352 | } |
1a4d82fc | 353 | } |
c34b1796 AL |
354 | |
355 | buf.truncate(len); | |
356 | ret | |
1a4d82fc JJ |
357 | } |
358 | ||
c1a9b12d | 359 | /// The `Read` trait allows for reading bytes from a source. |
85aaf69f | 360 | /// |
c1a9b12d | 361 | /// Implementors of the `Read` trait are sometimes called 'readers'. |
1a4d82fc | 362 | /// |
c1a9b12d SL |
363 | /// Readers are defined by one required method, `read()`. Each call to `read` |
364 | /// will attempt to pull bytes from this source into a provided buffer. A | |
365 | /// number of other methods are implemented in terms of `read()`, giving | |
366 | /// implementors a number of ways to read bytes while only needing to implement | |
367 | /// a single method. | |
368 | /// | |
369 | /// Readers are intended to be composable with one another. Many implementors | |
370 | /// throughout `std::io` take and provide types which implement the `Read` | |
371 | /// trait. | |
372 | /// | |
373 | /// # Examples | |
374 | /// | |
375 | /// [`File`][file]s implement `Read`: | |
376 | /// | |
377 | /// [file]: ../std/fs/struct.File.html | |
378 | /// | |
379 | /// ``` | |
380 | /// use std::io; | |
381 | /// use std::io::prelude::*; | |
382 | /// use std::fs::File; | |
383 | /// | |
384 | /// # fn foo() -> io::Result<()> { | |
385 | /// let mut f = try!(File::open("foo.txt")); | |
386 | /// let mut buffer = [0; 10]; | |
387 | /// | |
388 | /// // read up to 10 bytes | |
389 | /// try!(f.read(&mut buffer)); | |
390 | /// | |
391 | /// let mut buffer = vec![0; 10]; | |
392 | /// // read the whole file | |
393 | /// try!(f.read_to_end(&mut buffer)); | |
394 | /// | |
395 | /// // read into a String, so that you don't need to do the conversion. | |
396 | /// let mut buffer = String::new(); | |
397 | /// try!(f.read_to_string(&mut buffer)); | |
398 | /// | |
399 | /// // and more! See the other methods for more details. | |
400 | /// # Ok(()) | |
401 | /// # } | |
402 | /// ``` | |
c34b1796 | 403 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
404 | pub trait Read { |
405 | /// Pull some bytes from this source into the specified buffer, returning | |
406 | /// how many bytes were read. | |
407 | /// | |
408 | /// This function does not provide any guarantees about whether it blocks | |
409 | /// waiting for data, but if an object needs to block for a read but cannot | |
410 | /// it will typically signal this via an `Err` return value. | |
411 | /// | |
412 | /// If the return value of this method is `Ok(n)`, then it must be | |
413 | /// guaranteed that `0 <= n <= buf.len()`. A nonzero `n` value indicates | |
9346a6ac | 414 | /// that the buffer `buf` has been filled in with `n` bytes of data from this |
85aaf69f SL |
415 | /// source. If `n` is `0`, then it can indicate one of two scenarios: |
416 | /// | |
417 | /// 1. This reader has reached its "end of file" and will likely no longer | |
418 | /// be able to produce bytes. Note that this does not mean that the | |
419 | /// reader will *always* no longer be able to produce bytes. | |
420 | /// 2. The buffer specified was 0 bytes in length. | |
421 | /// | |
422 | /// No guarantees are provided about the contents of `buf` when this | |
423 | /// function is called, implementations cannot rely on any property of the | |
424 | /// contents of `buf` being true. It is recommended that implementations | |
425 | /// only write data to `buf` instead of reading its contents. | |
1a4d82fc | 426 | /// |
85aaf69f | 427 | /// # Errors |
1a4d82fc | 428 | /// |
85aaf69f SL |
429 | /// If this function encounters any form of I/O or other error, an error |
430 | /// variant will be returned. If an error is returned then it must be | |
431 | /// guaranteed that no bytes were read. | |
c1a9b12d SL |
432 | /// |
433 | /// # Examples | |
434 | /// | |
435 | /// [`File`][file]s implement `Read`: | |
436 | /// | |
437 | /// [file]: ../std/fs/struct.File.html | |
438 | /// | |
439 | /// ``` | |
440 | /// use std::io; | |
441 | /// use std::io::prelude::*; | |
442 | /// use std::fs::File; | |
443 | /// | |
444 | /// # fn foo() -> io::Result<()> { | |
445 | /// let mut f = try!(File::open("foo.txt")); | |
446 | /// let mut buffer = [0; 10]; | |
447 | /// | |
448 | /// // read 10 bytes | |
449 | /// try!(f.read(&mut buffer[..])); | |
450 | /// # Ok(()) | |
451 | /// # } | |
452 | /// ``` | |
c34b1796 | 453 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 454 | fn read(&mut self, buf: &mut [u8]) -> Result<usize>; |
1a4d82fc | 455 | |
85aaf69f | 456 | /// Read all bytes until EOF in this source, placing them into `buf`. |
1a4d82fc | 457 | /// |
85aaf69f | 458 | /// All bytes read from this source will be appended to the specified buffer |
9346a6ac AL |
459 | /// `buf`. This function will continuously call `read` to append more data to |
460 | /// `buf` until `read` returns either `Ok(0)` or an error of | |
461 | /// non-`ErrorKind::Interrupted` kind. | |
1a4d82fc | 462 | /// |
9346a6ac | 463 | /// If successful, this function will return the total number of bytes read. |
1a4d82fc | 464 | /// |
85aaf69f | 465 | /// # Errors |
1a4d82fc | 466 | /// |
85aaf69f SL |
467 | /// If this function encounters an error of the kind |
468 | /// `ErrorKind::Interrupted` then the error is ignored and the operation | |
469 | /// will continue. | |
1a4d82fc | 470 | /// |
85aaf69f SL |
471 | /// If any other read error is encountered then this function immediately |
472 | /// returns. Any bytes which have already been read will be appended to | |
473 | /// `buf`. | |
c1a9b12d SL |
474 | /// |
475 | /// # Examples | |
476 | /// | |
477 | /// [`File`][file]s implement `Read`: | |
478 | /// | |
479 | /// [file]: ../std/fs/struct.File.html | |
480 | /// | |
481 | /// ``` | |
482 | /// use std::io; | |
483 | /// use std::io::prelude::*; | |
484 | /// use std::fs::File; | |
485 | /// | |
486 | /// # fn foo() -> io::Result<()> { | |
487 | /// let mut f = try!(File::open("foo.txt")); | |
488 | /// let mut buffer = Vec::new(); | |
489 | /// | |
490 | /// // read the whole file | |
491 | /// try!(f.read_to_end(&mut buffer)); | |
492 | /// # Ok(()) | |
493 | /// # } | |
494 | /// ``` | |
c34b1796 AL |
495 | #[stable(feature = "rust1", since = "1.0.0")] |
496 | fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize> { | |
85aaf69f | 497 | read_to_end(self, buf) |
1a4d82fc JJ |
498 | } |
499 | ||
85aaf69f | 500 | /// Read all bytes until EOF in this source, placing them into `buf`. |
1a4d82fc | 501 | /// |
c34b1796 AL |
502 | /// If successful, this function returns the number of bytes which were read |
503 | /// and appended to `buf`. | |
504 | /// | |
85aaf69f | 505 | /// # Errors |
1a4d82fc | 506 | /// |
85aaf69f SL |
507 | /// If the data in this stream is *not* valid UTF-8 then an error is |
508 | /// returned and `buf` is unchanged. | |
1a4d82fc | 509 | /// |
c1a9b12d SL |
510 | /// See [`read_to_end()`][readtoend] for other error semantics. |
511 | /// | |
512 | /// [readtoend]: #method.read_to_end | |
513 | /// | |
514 | /// # Examples | |
515 | /// | |
516 | /// [`File`][file]s implement `Read`: | |
517 | /// | |
518 | /// [file]: ../std/fs/struct.File.html | |
519 | /// | |
520 | /// ``` | |
521 | /// use std::io; | |
522 | /// use std::io::prelude::*; | |
523 | /// use std::fs::File; | |
524 | /// | |
525 | /// # fn foo() -> io::Result<()> { | |
526 | /// let mut f = try!(File::open("foo.txt")); | |
527 | /// let mut buffer = String::new(); | |
528 | /// | |
529 | /// try!(f.read_to_string(&mut buffer)); | |
530 | /// # Ok(()) | |
531 | /// # } | |
532 | /// ``` | |
c34b1796 AL |
533 | #[stable(feature = "rust1", since = "1.0.0")] |
534 | fn read_to_string(&mut self, buf: &mut String) -> Result<usize> { | |
85aaf69f SL |
535 | // Note that we do *not* call `.read_to_end()` here. We are passing |
536 | // `&mut Vec<u8>` (the raw contents of `buf`) into the `read_to_end` | |
537 | // method to fill it up. An arbitrary implementation could overwrite the | |
538 | // entire contents of the vector, not just append to it (which is what | |
539 | // we are expecting). | |
540 | // | |
541 | // To prevent extraneously checking the UTF-8-ness of the entire buffer | |
542 | // we pass it to our hardcoded `read_to_end` implementation which we | |
543 | // know is guaranteed to only read data into the end of the buffer. | |
544 | append_to_string(buf, |b| read_to_end(self, b)) | |
1a4d82fc JJ |
545 | } |
546 | ||
9346a6ac | 547 | /// Creates a "by reference" adaptor for this instance of `Read`. |
1a4d82fc | 548 | /// |
85aaf69f SL |
549 | /// The returned adaptor also implements `Read` and will simply borrow this |
550 | /// current reader. | |
c1a9b12d SL |
551 | /// |
552 | /// # Examples | |
553 | /// | |
554 | /// [`File`][file]s implement `Read`: | |
555 | /// | |
556 | /// [file]: ../std/fs/struct.File.html | |
557 | /// | |
558 | /// ``` | |
559 | /// use std::io; | |
560 | /// use std::io::Read; | |
561 | /// use std::fs::File; | |
562 | /// | |
563 | /// # fn foo() -> io::Result<()> { | |
564 | /// let mut f = try!(File::open("foo.txt")); | |
565 | /// let mut buffer = Vec::new(); | |
566 | /// let mut other_buffer = Vec::new(); | |
567 | /// | |
568 | /// { | |
569 | /// let reference = f.by_ref(); | |
570 | /// | |
571 | /// // read at most 5 bytes | |
572 | /// try!(reference.take(5).read_to_end(&mut buffer)); | |
573 | /// | |
574 | /// } // drop our &mut reference so we can use f again | |
575 | /// | |
576 | /// // original file still usable, read the rest | |
577 | /// try!(f.read_to_end(&mut other_buffer)); | |
578 | /// # Ok(()) | |
579 | /// # } | |
580 | /// ``` | |
c34b1796 AL |
581 | #[stable(feature = "rust1", since = "1.0.0")] |
582 | fn by_ref(&mut self) -> &mut Self where Self: Sized { self } | |
1a4d82fc | 583 | |
9346a6ac | 584 | /// Transforms this `Read` instance to an `Iterator` over its bytes. |
1a4d82fc | 585 | /// |
85aaf69f SL |
586 | /// The returned type implements `Iterator` where the `Item` is `Result<u8, |
587 | /// R::Err>`. The yielded item is `Ok` if a byte was successfully read and | |
588 | /// `Err` otherwise for I/O errors. EOF is mapped to returning `None` from | |
589 | /// this iterator. | |
c1a9b12d SL |
590 | /// |
591 | /// # Examples | |
592 | /// | |
593 | /// [`File`][file]s implement `Read`: | |
594 | /// | |
595 | /// [file]: ../std/fs/struct.File.html | |
596 | /// | |
597 | /// ``` | |
598 | /// use std::io; | |
599 | /// use std::io::prelude::*; | |
600 | /// use std::fs::File; | |
601 | /// | |
602 | /// # fn foo() -> io::Result<()> { | |
603 | /// let mut f = try!(File::open("foo.txt")); | |
604 | /// | |
605 | /// for byte in f.bytes() { | |
606 | /// println!("{}", byte.unwrap()); | |
607 | /// } | |
608 | /// # Ok(()) | |
609 | /// # } | |
610 | /// ``` | |
c34b1796 AL |
611 | #[stable(feature = "rust1", since = "1.0.0")] |
612 | fn bytes(self) -> Bytes<Self> where Self: Sized { | |
85aaf69f | 613 | Bytes { inner: self } |
1a4d82fc JJ |
614 | } |
615 | ||
9346a6ac | 616 | /// Transforms this `Read` instance to an `Iterator` over `char`s. |
1a4d82fc | 617 | /// |
d9579d0f | 618 | /// This adaptor will attempt to interpret this reader as a UTF-8 encoded |
85aaf69f SL |
619 | /// sequence of characters. The returned iterator will return `None` once |
620 | /// EOF is reached for this reader. Otherwise each element yielded will be a | |
621 | /// `Result<char, E>` where `E` may contain information about what I/O error | |
622 | /// occurred or where decoding failed. | |
1a4d82fc | 623 | /// |
85aaf69f SL |
624 | /// Currently this adaptor will discard intermediate data read, and should |
625 | /// be avoided if this is not desired. | |
c1a9b12d SL |
626 | /// |
627 | /// # Examples | |
628 | /// | |
629 | /// [`File`][file]s implement `Read`: | |
630 | /// | |
631 | /// [file]: ../std/fs/struct.File.html | |
632 | /// | |
633 | /// ``` | |
634 | /// #![feature(io)] | |
635 | /// use std::io; | |
636 | /// use std::io::prelude::*; | |
637 | /// use std::fs::File; | |
638 | /// | |
639 | /// # fn foo() -> io::Result<()> { | |
640 | /// let mut f = try!(File::open("foo.txt")); | |
641 | /// | |
642 | /// for c in f.chars() { | |
643 | /// println!("{}", c.unwrap()); | |
644 | /// } | |
645 | /// # Ok(()) | |
646 | /// # } | |
647 | /// ``` | |
c34b1796 AL |
648 | #[unstable(feature = "io", reason = "the semantics of a partial read/write \ |
649 | of where errors happen is currently \ | |
650 | unclear and may change")] | |
651 | fn chars(self) -> Chars<Self> where Self: Sized { | |
85aaf69f | 652 | Chars { inner: self } |
1a4d82fc JJ |
653 | } |
654 | ||
9346a6ac | 655 | /// Creates an adaptor which will chain this stream with another. |
1a4d82fc | 656 | /// |
85aaf69f SL |
657 | /// The returned `Read` instance will first read all bytes from this object |
658 | /// until EOF is encountered. Afterwards the output is equivalent to the | |
659 | /// output of `next`. | |
c1a9b12d SL |
660 | /// |
661 | /// # Examples | |
662 | /// | |
663 | /// [`File`][file]s implement `Read`: | |
664 | /// | |
665 | /// [file]: ../std/fs/struct.File.html | |
666 | /// | |
667 | /// ``` | |
668 | /// use std::io; | |
669 | /// use std::io::prelude::*; | |
670 | /// use std::fs::File; | |
671 | /// | |
672 | /// # fn foo() -> io::Result<()> { | |
673 | /// let mut f1 = try!(File::open("foo.txt")); | |
674 | /// let mut f2 = try!(File::open("bar.txt")); | |
675 | /// | |
676 | /// let mut handle = f1.chain(f2); | |
677 | /// let mut buffer = String::new(); | |
678 | /// | |
679 | /// // read the value into a String. We could use any Read method here, | |
680 | /// // this is just one example. | |
681 | /// try!(handle.read_to_string(&mut buffer)); | |
682 | /// # Ok(()) | |
683 | /// # } | |
684 | /// ``` | |
c34b1796 AL |
685 | #[stable(feature = "rust1", since = "1.0.0")] |
686 | fn chain<R: Read>(self, next: R) -> Chain<Self, R> where Self: Sized { | |
85aaf69f | 687 | Chain { first: self, second: next, done_first: false } |
1a4d82fc JJ |
688 | } |
689 | ||
9346a6ac | 690 | /// Creates an adaptor which will read at most `limit` bytes from it. |
1a4d82fc | 691 | /// |
85aaf69f SL |
692 | /// This function returns a new instance of `Read` which will read at most |
693 | /// `limit` bytes, after which it will always return EOF (`Ok(0)`). Any | |
694 | /// read errors will not count towards the number of bytes read and future | |
695 | /// calls to `read` may succeed. | |
c1a9b12d SL |
696 | /// |
697 | /// # Examples | |
698 | /// | |
699 | /// [`File`][file]s implement `Read`: | |
700 | /// | |
701 | /// [file]: ../std/fs/struct.File.html | |
702 | /// | |
703 | /// ``` | |
704 | /// use std::io; | |
705 | /// use std::io::prelude::*; | |
706 | /// use std::fs::File; | |
707 | /// | |
708 | /// # fn foo() -> io::Result<()> { | |
709 | /// let mut f = try!(File::open("foo.txt")); | |
710 | /// let mut buffer = [0; 5]; | |
711 | /// | |
712 | /// // read at most five bytes | |
713 | /// let mut handle = f.take(5); | |
714 | /// | |
715 | /// try!(handle.read(&mut buffer)); | |
716 | /// # Ok(()) | |
717 | /// # } | |
718 | /// ``` | |
c34b1796 AL |
719 | #[stable(feature = "rust1", since = "1.0.0")] |
720 | fn take(self, limit: u64) -> Take<Self> where Self: Sized { | |
85aaf69f | 721 | Take { inner: self, limit: limit } |
1a4d82fc JJ |
722 | } |
723 | ||
85aaf69f SL |
724 | /// Creates a reader adaptor which will write all read data into the given |
725 | /// output stream. | |
1a4d82fc | 726 | /// |
85aaf69f SL |
727 | /// Whenever the returned `Read` instance is read it will write the read |
728 | /// data to `out`. The current semantics of this implementation imply that | |
729 | /// a `write` error will not report how much data was initially read. | |
c1a9b12d SL |
730 | /// |
731 | /// # Examples | |
732 | /// | |
733 | /// [`File`][file]s implement `Read`: | |
734 | /// | |
735 | /// [file]: ../std/fs/struct.File.html | |
736 | /// | |
737 | /// ``` | |
738 | /// #![feature(io)] | |
739 | /// use std::io; | |
740 | /// use std::io::prelude::*; | |
741 | /// use std::fs::File; | |
742 | /// | |
743 | /// # fn foo() -> io::Result<()> { | |
744 | /// let mut f = try!(File::open("foo.txt")); | |
745 | /// let mut buffer1 = Vec::with_capacity(10); | |
746 | /// let mut buffer2 = Vec::with_capacity(10); | |
747 | /// | |
748 | /// // write the output to buffer1 as we read | |
749 | /// let mut handle = f.tee(&mut buffer1); | |
750 | /// | |
751 | /// try!(handle.read(&mut buffer2)); | |
752 | /// # Ok(()) | |
753 | /// # } | |
754 | /// ``` | |
c34b1796 AL |
755 | #[unstable(feature = "io", reason = "the semantics of a partial read/write \ |
756 | of where errors happen is currently \ | |
757 | unclear and may change")] | |
758 | fn tee<W: Write>(self, out: W) -> Tee<Self, W> where Self: Sized { | |
85aaf69f | 759 | Tee { reader: self, writer: out } |
1a4d82fc | 760 | } |
85aaf69f | 761 | } |
1a4d82fc | 762 | |
85aaf69f SL |
763 | /// A trait for objects which are byte-oriented sinks. |
764 | /// | |
c1a9b12d SL |
765 | /// Implementors of the `Write` trait are sometimes called 'writers'. |
766 | /// | |
767 | /// Writers are defined by two required methods, `write()` and `flush()`: | |
768 | /// | |
769 | /// * The `write()` method will attempt to write some data into the object, | |
770 | /// returning how many bytes were successfully written. | |
771 | /// | |
772 | /// * The `flush()` method is useful for adaptors and explicit buffers | |
773 | /// themselves for ensuring that all buffered data has been pushed out to the | |
774 | /// 'true sink'. | |
775 | /// | |
776 | /// Writers are intended to be composable with one another. Many implementors | |
777 | /// throughout `std::io` take and provide types which implement the `Write` | |
778 | /// trait. | |
779 | /// | |
780 | /// # Examples | |
781 | /// | |
782 | /// ``` | |
783 | /// use std::io::prelude::*; | |
784 | /// use std::fs::File; | |
85aaf69f | 785 | /// |
c1a9b12d SL |
786 | /// # fn foo() -> std::io::Result<()> { |
787 | /// let mut buffer = try!(File::create("foo.txt")); | |
85aaf69f | 788 | /// |
c1a9b12d SL |
789 | /// try!(buffer.write(b"some bytes")); |
790 | /// # Ok(()) | |
791 | /// # } | |
792 | /// ``` | |
c34b1796 | 793 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
794 | pub trait Write { |
795 | /// Write a buffer into this object, returning how many bytes were written. | |
1a4d82fc | 796 | /// |
85aaf69f SL |
797 | /// This function will attempt to write the entire contents of `buf`, but |
798 | /// the entire write may not succeed, or the write may also generate an | |
799 | /// error. A call to `write` represents *at most one* attempt to write to | |
800 | /// any wrapped object. | |
1a4d82fc | 801 | /// |
85aaf69f | 802 | /// Calls to `write` are not guaranteed to block waiting for data to be |
62682a34 | 803 | /// written, and a write which would otherwise block can be indicated through |
85aaf69f | 804 | /// an `Err` variant. |
1a4d82fc | 805 | /// |
85aaf69f SL |
806 | /// If the return value is `Ok(n)` then it must be guaranteed that |
807 | /// `0 <= n <= buf.len()`. A return value of `0` typically means that the | |
808 | /// underlying object is no longer able to accept bytes and will likely not | |
809 | /// be able to in the future as well, or that the buffer provided is empty. | |
1a4d82fc | 810 | /// |
85aaf69f | 811 | /// # Errors |
1a4d82fc | 812 | /// |
85aaf69f SL |
813 | /// Each call to `write` may generate an I/O error indicating that the |
814 | /// operation could not be completed. If an error is returned then no bytes | |
815 | /// in the buffer were written to this writer. | |
1a4d82fc | 816 | /// |
85aaf69f SL |
817 | /// It is **not** considered an error if the entire buffer could not be |
818 | /// written to this writer. | |
c1a9b12d SL |
819 | /// |
820 | /// # Examples | |
821 | /// | |
822 | /// ``` | |
823 | /// use std::io::prelude::*; | |
824 | /// use std::fs::File; | |
825 | /// | |
826 | /// # fn foo() -> std::io::Result<()> { | |
827 | /// let mut buffer = try!(File::create("foo.txt")); | |
828 | /// | |
829 | /// try!(buffer.write(b"some bytes")); | |
830 | /// # Ok(()) | |
831 | /// # } | |
832 | /// ``` | |
c34b1796 | 833 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 834 | fn write(&mut self, buf: &[u8]) -> Result<usize>; |
1a4d82fc | 835 | |
85aaf69f SL |
836 | /// Flush this output stream, ensuring that all intermediately buffered |
837 | /// contents reach their destination. | |
1a4d82fc | 838 | /// |
85aaf69f | 839 | /// # Errors |
1a4d82fc | 840 | /// |
85aaf69f SL |
841 | /// It is considered an error if not all bytes could be written due to |
842 | /// I/O errors or EOF being reached. | |
c1a9b12d SL |
843 | /// |
844 | /// # Examples | |
845 | /// | |
846 | /// ``` | |
847 | /// use std::io::prelude::*; | |
848 | /// use std::io::BufWriter; | |
849 | /// use std::fs::File; | |
850 | /// | |
851 | /// # fn foo() -> std::io::Result<()> { | |
852 | /// let mut buffer = BufWriter::new(try!(File::create("foo.txt"))); | |
853 | /// | |
854 | /// try!(buffer.write(b"some bytes")); | |
855 | /// try!(buffer.flush()); | |
856 | /// # Ok(()) | |
857 | /// # } | |
858 | /// ``` | |
c34b1796 | 859 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 860 | fn flush(&mut self) -> Result<()>; |
1a4d82fc | 861 | |
85aaf69f | 862 | /// Attempts to write an entire buffer into this write. |
1a4d82fc | 863 | /// |
85aaf69f SL |
864 | /// This method will continuously call `write` while there is more data to |
865 | /// write. This method will not return until the entire buffer has been | |
866 | /// successfully written or an error occurs. The first error generated from | |
867 | /// this method will be returned. | |
1a4d82fc JJ |
868 | /// |
869 | /// # Errors | |
870 | /// | |
85aaf69f | 871 | /// This function will return the first error that `write` returns. |
c1a9b12d SL |
872 | /// |
873 | /// # Examples | |
874 | /// | |
875 | /// ``` | |
876 | /// use std::io::prelude::*; | |
877 | /// use std::fs::File; | |
878 | /// | |
879 | /// # fn foo() -> std::io::Result<()> { | |
880 | /// let mut buffer = try!(File::create("foo.txt")); | |
881 | /// | |
882 | /// try!(buffer.write_all(b"some bytes")); | |
883 | /// # Ok(()) | |
884 | /// # } | |
885 | /// ``` | |
c34b1796 | 886 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 887 | fn write_all(&mut self, mut buf: &[u8]) -> Result<()> { |
9346a6ac | 888 | while !buf.is_empty() { |
85aaf69f SL |
889 | match self.write(buf) { |
890 | Ok(0) => return Err(Error::new(ErrorKind::WriteZero, | |
c34b1796 | 891 | "failed to write whole buffer")), |
85aaf69f SL |
892 | Ok(n) => buf = &buf[n..], |
893 | Err(ref e) if e.kind() == ErrorKind::Interrupted => {} | |
894 | Err(e) => return Err(e), | |
895 | } | |
896 | } | |
897 | Ok(()) | |
898 | } | |
1a4d82fc JJ |
899 | |
900 | /// Writes a formatted string into this writer, returning any error | |
901 | /// encountered. | |
902 | /// | |
c1a9b12d SL |
903 | /// This method is primarily used to interface with the |
904 | /// [`format_args!`][formatargs] macro, but it is rare that this should | |
905 | /// explicitly be called. The [`write!`][write] macro should be favored to | |
906 | /// invoke this method instead. | |
907 | /// | |
908 | /// [formatargs]: ../std/macro.format_args!.html | |
909 | /// [write]: ../std/macro.write!.html | |
1a4d82fc | 910 | /// |
c1a9b12d SL |
911 | /// This function internally uses the [`write_all`][writeall] method on |
912 | /// this trait and hence will continuously write data so long as no errors | |
913 | /// are received. This also means that partial writes are not indicated in | |
914 | /// this signature. | |
915 | /// | |
916 | /// [writeall]: #method.write_all | |
85aaf69f | 917 | /// |
1a4d82fc JJ |
918 | /// # Errors |
919 | /// | |
920 | /// This function will return any I/O error reported while formatting. | |
c1a9b12d SL |
921 | /// |
922 | /// # Examples | |
923 | /// | |
924 | /// ``` | |
925 | /// use std::io::prelude::*; | |
926 | /// use std::fs::File; | |
927 | /// | |
928 | /// # fn foo() -> std::io::Result<()> { | |
929 | /// let mut buffer = try!(File::create("foo.txt")); | |
930 | /// | |
931 | /// // this call | |
932 | /// try!(write!(buffer, "{:.*}", 2, 1.234567)); | |
933 | /// // turns into this: | |
934 | /// try!(buffer.write_fmt(format_args!("{:.*}", 2, 1.234567))); | |
935 | /// # Ok(()) | |
936 | /// # } | |
937 | /// ``` | |
c34b1796 | 938 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
939 | fn write_fmt(&mut self, fmt: fmt::Arguments) -> Result<()> { |
940 | // Create a shim which translates a Write to a fmt::Write and saves | |
1a4d82fc | 941 | // off I/O errors. instead of discarding them |
85aaf69f | 942 | struct Adaptor<'a, T: ?Sized + 'a> { |
1a4d82fc | 943 | inner: &'a mut T, |
85aaf69f | 944 | error: Result<()>, |
1a4d82fc JJ |
945 | } |
946 | ||
85aaf69f | 947 | impl<'a, T: Write + ?Sized> fmt::Write for Adaptor<'a, T> { |
1a4d82fc | 948 | fn write_str(&mut self, s: &str) -> fmt::Result { |
85aaf69f | 949 | match self.inner.write_all(s.as_bytes()) { |
1a4d82fc JJ |
950 | Ok(()) => Ok(()), |
951 | Err(e) => { | |
952 | self.error = Err(e); | |
953 | Err(fmt::Error) | |
954 | } | |
955 | } | |
956 | } | |
957 | } | |
958 | ||
959 | let mut output = Adaptor { inner: self, error: Ok(()) }; | |
960 | match fmt::write(&mut output, fmt) { | |
961 | Ok(()) => Ok(()), | |
962 | Err(..) => output.error | |
963 | } | |
964 | } | |
1a4d82fc | 965 | |
9346a6ac | 966 | /// Creates a "by reference" adaptor for this instance of `Write`. |
1a4d82fc | 967 | /// |
85aaf69f SL |
968 | /// The returned adaptor also implements `Write` and will simply borrow this |
969 | /// current writer. | |
c1a9b12d SL |
970 | /// |
971 | /// # Examples | |
972 | /// | |
973 | /// ``` | |
974 | /// use std::io::Write; | |
975 | /// use std::fs::File; | |
976 | /// | |
977 | /// # fn foo() -> std::io::Result<()> { | |
978 | /// let mut buffer = try!(File::create("foo.txt")); | |
979 | /// | |
980 | /// let reference = buffer.by_ref(); | |
981 | /// | |
982 | /// // we can use reference just like our original buffer | |
983 | /// try!(reference.write_all(b"some bytes")); | |
984 | /// # Ok(()) | |
985 | /// # } | |
986 | /// ``` | |
c34b1796 AL |
987 | #[stable(feature = "rust1", since = "1.0.0")] |
988 | fn by_ref(&mut self) -> &mut Self where Self: Sized { self } | |
1a4d82fc | 989 | |
85aaf69f SL |
990 | /// Creates a new writer which will write all data to both this writer and |
991 | /// another writer. | |
992 | /// | |
993 | /// All data written to the returned writer will both be written to `self` | |
994 | /// as well as `other`. Note that the error semantics of the current | |
995 | /// implementation do not precisely track where errors happen. For example | |
996 | /// an error on the second call to `write` will not report that the first | |
997 | /// call to `write` succeeded. | |
c1a9b12d SL |
998 | /// |
999 | /// # Examples | |
1000 | /// | |
1001 | /// ``` | |
1002 | /// #![feature(io)] | |
1003 | /// use std::io::prelude::*; | |
1004 | /// use std::fs::File; | |
1005 | /// | |
1006 | /// # fn foo() -> std::io::Result<()> { | |
1007 | /// let mut buffer1 = try!(File::create("foo.txt")); | |
1008 | /// let mut buffer2 = Vec::new(); | |
1009 | /// | |
1010 | /// // write the output to buffer1 as we read | |
1011 | /// let mut handle = buffer1.broadcast(&mut buffer2); | |
1012 | /// | |
1013 | /// try!(handle.write(b"some bytes")); | |
1014 | /// # Ok(()) | |
1015 | /// # } | |
1016 | /// ``` | |
c34b1796 AL |
1017 | #[unstable(feature = "io", reason = "the semantics of a partial read/write \ |
1018 | of where errors happen is currently \ | |
1019 | unclear and may change")] | |
1020 | fn broadcast<W: Write>(self, other: W) -> Broadcast<Self, W> | |
1021 | where Self: Sized | |
1022 | { | |
85aaf69f | 1023 | Broadcast { first: self, second: other } |
1a4d82fc JJ |
1024 | } |
1025 | } | |
1026 | ||
c1a9b12d SL |
1027 | /// The `Seek` trait provides a cursor which can be moved within a stream of |
1028 | /// bytes. | |
1a4d82fc | 1029 | /// |
85aaf69f SL |
1030 | /// The stream typically has a fixed size, allowing seeking relative to either |
1031 | /// end or the current offset. | |
c1a9b12d SL |
1032 | /// |
1033 | /// # Examples | |
1034 | /// | |
1035 | /// [`File`][file]s implement `Seek`: | |
1036 | /// | |
1037 | /// [file]: ../std/fs/struct.File.html | |
1038 | /// | |
1039 | /// ``` | |
1040 | /// use std::io; | |
1041 | /// use std::io::prelude::*; | |
1042 | /// use std::fs::File; | |
1043 | /// use std::io::SeekFrom; | |
1044 | /// | |
1045 | /// # fn foo() -> io::Result<()> { | |
1046 | /// let mut f = try!(File::open("foo.txt")); | |
1047 | /// | |
1048 | /// // move the cursor 42 bytes from the start of the file | |
1049 | /// try!(f.seek(SeekFrom::Start(42))); | |
1050 | /// # Ok(()) | |
1051 | /// # } | |
1052 | /// ``` | |
c34b1796 | 1053 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1054 | pub trait Seek { |
c1a9b12d | 1055 | /// Seek to an offset, in bytes, in a stream. |
85aaf69f | 1056 | /// |
c1a9b12d SL |
1057 | /// A seek beyond the end of a stream is allowed, but implementation |
1058 | /// defined. | |
85aaf69f SL |
1059 | /// |
1060 | /// The behavior when seeking past the end of the stream is implementation | |
1061 | /// defined. | |
1062 | /// | |
c1a9b12d SL |
1063 | /// If the seek operation completed successfully, |
1064 | /// this method returns the new position from the start of the stream. | |
1065 | /// That position can be used later with `SeekFrom::Start`. | |
85aaf69f SL |
1066 | /// |
1067 | /// # Errors | |
1068 | /// | |
c1a9b12d | 1069 | /// Seeking to a negative offset is considered an error. |
c34b1796 | 1070 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1071 | fn seek(&mut self, pos: SeekFrom) -> Result<u64>; |
1a4d82fc JJ |
1072 | } |
1073 | ||
85aaf69f SL |
1074 | /// Enumeration of possible methods to seek within an I/O object. |
1075 | #[derive(Copy, PartialEq, Eq, Clone, Debug)] | |
c34b1796 | 1076 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1077 | pub enum SeekFrom { |
1078 | /// Set the offset to the provided number of bytes. | |
c34b1796 | 1079 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1080 | Start(u64), |
1a4d82fc | 1081 | |
85aaf69f SL |
1082 | /// Set the offset to the size of this object plus the specified number of |
1083 | /// bytes. | |
1084 | /// | |
1085 | /// It is possible to seek beyond the end of an object, but is an error to | |
1086 | /// seek before byte 0. | |
c34b1796 | 1087 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1088 | End(i64), |
1a4d82fc | 1089 | |
85aaf69f SL |
1090 | /// Set the offset to the current position plus the specified number of |
1091 | /// bytes. | |
1092 | /// | |
1093 | /// It is possible to seek beyond the end of an object, but is an error to | |
1094 | /// seek before byte 0. | |
c34b1796 | 1095 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1096 | Current(i64), |
1a4d82fc JJ |
1097 | } |
1098 | ||
85aaf69f | 1099 | fn read_until<R: BufRead + ?Sized>(r: &mut R, delim: u8, buf: &mut Vec<u8>) |
c34b1796 AL |
1100 | -> Result<usize> { |
1101 | let mut read = 0; | |
85aaf69f SL |
1102 | loop { |
1103 | let (done, used) = { | |
1104 | let available = match r.fill_buf() { | |
1105 | Ok(n) => n, | |
1106 | Err(ref e) if e.kind() == ErrorKind::Interrupted => continue, | |
1107 | Err(e) => return Err(e) | |
1108 | }; | |
c1a9b12d | 1109 | match available.iter().position(|x| *x == delim) { |
85aaf69f SL |
1110 | Some(i) => { |
1111 | buf.push_all(&available[..i + 1]); | |
1112 | (true, i + 1) | |
1113 | } | |
1114 | None => { | |
1115 | buf.push_all(available); | |
1116 | (false, available.len()) | |
1117 | } | |
1118 | } | |
1119 | }; | |
1120 | r.consume(used); | |
c34b1796 | 1121 | read += used; |
85aaf69f | 1122 | if done || used == 0 { |
c34b1796 | 1123 | return Ok(read); |
1a4d82fc JJ |
1124 | } |
1125 | } | |
1126 | } | |
1127 | ||
c1a9b12d SL |
1128 | /// A `BufRead` is a type of `Read`er which has an internal buffer, allowing it |
1129 | /// to perform extra ways of reading. | |
1130 | /// | |
1131 | /// For example, reading line-by-line is inefficient without using a buffer, so | |
1132 | /// if you want to read by line, you'll need `BufRead`, which includes a | |
1133 | /// [`read_line()`][readline] method as well as a [`lines()`][lines] iterator. | |
1134 | /// | |
1135 | /// [readline]: #method.read_line | |
1136 | /// [lines]: #method.lines | |
1137 | /// | |
1138 | /// # Examples | |
1139 | /// | |
1140 | /// A locked standard input implements `BufRead`: | |
1141 | /// | |
1142 | /// ``` | |
1143 | /// use std::io; | |
1144 | /// use std::io::prelude::*; | |
1145 | /// | |
1146 | /// let stdin = io::stdin(); | |
1147 | /// for line in stdin.lock().lines() { | |
1148 | /// println!("{}", line.unwrap()); | |
1149 | /// } | |
1150 | /// ``` | |
1151 | /// | |
1152 | /// If you have something that implements `Read`, you can use the [`BufReader` | |
1153 | /// type][bufreader] to turn it into a `BufRead`. | |
1154 | /// | |
1155 | /// For example, [`File`][file] implements `Read`, but not `BufRead`. | |
1156 | /// `BufReader` to the rescue! | |
85aaf69f | 1157 | /// |
c1a9b12d SL |
1158 | /// [bufreader]: struct.BufReader.html |
1159 | /// [file]: ../fs/struct.File.html | |
1160 | /// | |
1161 | /// ``` | |
1162 | /// use std::io::{self, BufReader}; | |
1163 | /// use std::io::prelude::*; | |
1164 | /// use std::fs::File; | |
1165 | /// | |
1166 | /// # fn foo() -> io::Result<()> { | |
1167 | /// let f = try!(File::open("foo.txt")); | |
1168 | /// let f = BufReader::new(f); | |
1169 | /// | |
1170 | /// for line in f.lines() { | |
1171 | /// println!("{}", line.unwrap()); | |
1172 | /// } | |
1173 | /// | |
1174 | /// # Ok(()) | |
1175 | /// # } | |
1176 | /// ``` | |
62682a34 | 1177 | /// |
c34b1796 | 1178 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1179 | pub trait BufRead: Read { |
1a4d82fc | 1180 | /// Fills the internal buffer of this object, returning the buffer contents. |
85aaf69f | 1181 | /// |
c1a9b12d SL |
1182 | /// This function is a lower-level call. It needs to be paired with the |
1183 | /// [`consume`][consume] method to function properly. When calling this | |
1184 | /// method, none of the contents will be "read" in the sense that later | |
1185 | /// calling `read` may return the same contents. As such, `consume` must be | |
1186 | /// called with the number of bytes that are consumed from this buffer to | |
1187 | /// ensure that the bytes are never returned twice. | |
1a4d82fc | 1188 | /// |
c1a9b12d | 1189 | /// [consume]: #tymethod.consume |
1a4d82fc | 1190 | /// |
85aaf69f SL |
1191 | /// An empty buffer returned indicates that the stream has reached EOF. |
1192 | /// | |
1193 | /// # Errors | |
1a4d82fc JJ |
1194 | /// |
1195 | /// This function will return an I/O error if the underlying reader was | |
85aaf69f | 1196 | /// read, but returned an error. |
c1a9b12d SL |
1197 | /// |
1198 | /// # Examples | |
1199 | /// | |
1200 | /// A locked standard input implements `BufRead`: | |
1201 | /// | |
1202 | /// ``` | |
1203 | /// use std::io; | |
1204 | /// use std::io::prelude::*; | |
1205 | /// | |
1206 | /// let stdin = io::stdin(); | |
1207 | /// let mut stdin = stdin.lock(); | |
1208 | /// | |
1209 | /// // we can't have two `&mut` references to `stdin`, so use a block | |
1210 | /// // to end the borrow early. | |
1211 | /// let length = { | |
1212 | /// let buffer = stdin.fill_buf().unwrap(); | |
1213 | /// | |
1214 | /// // work with buffer | |
1215 | /// println!("{:?}", buffer); | |
1216 | /// | |
1217 | /// buffer.len() | |
1218 | /// }; | |
1219 | /// | |
1220 | /// // ensure the bytes we worked with aren't returned again later | |
1221 | /// stdin.consume(length); | |
1222 | /// ``` | |
c34b1796 | 1223 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1224 | fn fill_buf(&mut self) -> Result<&[u8]>; |
1a4d82fc JJ |
1225 | |
1226 | /// Tells this buffer that `amt` bytes have been consumed from the buffer, | |
1227 | /// so they should no longer be returned in calls to `read`. | |
c34b1796 | 1228 | /// |
c1a9b12d SL |
1229 | /// This function is a lower-level call. It needs to be paired with the |
1230 | /// [`fill_buf`][fillbuf] method to function properly. This function does | |
1231 | /// not perform any I/O, it simply informs this object that some amount of | |
1232 | /// its buffer, returned from `fill_buf`, has been consumed and should no | |
1233 | /// longer be returned. As such, this function may do odd things if | |
1234 | /// `fill_buf` isn't called before calling it. | |
1235 | /// | |
1236 | /// [fillbuf]: #tymethod.fill_buff | |
1237 | /// | |
1238 | /// The `amt` must be `<=` the number of bytes in the buffer returned by | |
1239 | /// `fill_buf`. | |
c34b1796 | 1240 | /// |
c1a9b12d | 1241 | /// # Examples |
c34b1796 | 1242 | /// |
c1a9b12d SL |
1243 | /// Since `consume()` is meant to be used with [`fill_buf()`][fillbuf], |
1244 | /// that method's example includes an example of `consume()`. | |
c34b1796 | 1245 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1246 | fn consume(&mut self, amt: usize); |
1a4d82fc | 1247 | |
c1a9b12d | 1248 | /// Read all bytes into `buf` until the delimiter `byte` is reached. |
1a4d82fc | 1249 | /// |
c1a9b12d SL |
1250 | /// This function will read bytes from the underlying stream until the |
1251 | /// delimiter or EOF is found. Once found, all bytes up to, and including, | |
1252 | /// the delimiter (if found) will be appended to `buf`. | |
1a4d82fc | 1253 | /// |
c1a9b12d SL |
1254 | /// If this reader is currently at EOF then this function will not modify |
1255 | /// `buf` and will return `Ok(n)` where `n` is the number of bytes which | |
1256 | /// were read. | |
1a4d82fc | 1257 | /// |
85aaf69f | 1258 | /// # Errors |
1a4d82fc | 1259 | /// |
85aaf69f SL |
1260 | /// This function will ignore all instances of `ErrorKind::Interrupted` and |
1261 | /// will otherwise return any errors returned by `fill_buf`. | |
1a4d82fc | 1262 | /// |
85aaf69f SL |
1263 | /// If an I/O error is encountered then all bytes read so far will be |
1264 | /// present in `buf` and its length will have been adjusted appropriately. | |
c1a9b12d SL |
1265 | /// |
1266 | /// # Examples | |
1267 | /// | |
1268 | /// A locked standard input implements `BufRead`. In this example, we'll | |
1269 | /// read from standard input until we see an `a` byte. | |
1270 | /// | |
1271 | /// ``` | |
1272 | /// use std::io; | |
1273 | /// use std::io::prelude::*; | |
1274 | /// | |
1275 | /// fn foo() -> io::Result<()> { | |
1276 | /// let stdin = io::stdin(); | |
1277 | /// let mut stdin = stdin.lock(); | |
1278 | /// let mut buffer = Vec::new(); | |
1279 | /// | |
1280 | /// try!(stdin.read_until(b'a', &mut buffer)); | |
1281 | /// | |
1282 | /// println!("{:?}", buffer); | |
1283 | /// # Ok(()) | |
1284 | /// # } | |
1285 | /// ``` | |
c34b1796 AL |
1286 | #[stable(feature = "rust1", since = "1.0.0")] |
1287 | fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize> { | |
85aaf69f | 1288 | read_until(self, byte, buf) |
1a4d82fc JJ |
1289 | } |
1290 | ||
c1a9b12d SL |
1291 | /// Read all bytes until a newline (the 0xA byte) is reached, and append |
1292 | /// them to the provided buffer. | |
1a4d82fc | 1293 | /// |
c1a9b12d SL |
1294 | /// This function will read bytes from the underlying stream until the |
1295 | /// newline delimiter (the 0xA byte) or EOF is found. Once found, all bytes | |
1296 | /// up to, and including, the delimiter (if found) will be appended to | |
1297 | /// `buf`. | |
1a4d82fc | 1298 | /// |
85aaf69f | 1299 | /// If this reader is currently at EOF then this function will not modify |
c34b1796 AL |
1300 | /// `buf` and will return `Ok(n)` where `n` is the number of bytes which |
1301 | /// were read. | |
85aaf69f SL |
1302 | /// |
1303 | /// # Errors | |
1304 | /// | |
1305 | /// This function has the same error semantics as `read_until` and will also | |
1306 | /// return an error if the read bytes are not valid UTF-8. If an I/O error | |
1307 | /// is encountered then `buf` may contain some bytes already read in the | |
1308 | /// event that all data read so far was valid UTF-8. | |
c1a9b12d SL |
1309 | /// |
1310 | /// # Examples | |
1311 | /// | |
1312 | /// A locked standard input implements `BufRead`. In this example, we'll | |
1313 | /// read all of the lines from standard input. If we were to do this in | |
1314 | /// an actual project, the [`lines()`][lines] method would be easier, of | |
1315 | /// course. | |
1316 | /// | |
1317 | /// [lines]: #method.lines | |
1318 | /// | |
1319 | /// ``` | |
1320 | /// use std::io; | |
1321 | /// use std::io::prelude::*; | |
1322 | /// | |
1323 | /// let stdin = io::stdin(); | |
1324 | /// let mut stdin = stdin.lock(); | |
1325 | /// let mut buffer = String::new(); | |
1326 | /// | |
1327 | /// while stdin.read_line(&mut buffer).unwrap() > 0 { | |
1328 | /// // work with buffer | |
1329 | /// println!("{:?}", buffer); | |
1330 | /// | |
1331 | /// buffer.clear(); | |
1332 | /// } | |
1333 | /// ``` | |
c34b1796 AL |
1334 | #[stable(feature = "rust1", since = "1.0.0")] |
1335 | fn read_line(&mut self, buf: &mut String) -> Result<usize> { | |
85aaf69f SL |
1336 | // Note that we are not calling the `.read_until` method here, but |
1337 | // rather our hardcoded implementation. For more details as to why, see | |
1338 | // the comments in `read_to_end`. | |
1339 | append_to_string(buf, |b| read_until(self, b'\n', b)) | |
1a4d82fc | 1340 | } |
1a4d82fc | 1341 | |
85aaf69f SL |
1342 | /// Returns an iterator over the contents of this reader split on the byte |
1343 | /// `byte`. | |
1a4d82fc | 1344 | /// |
85aaf69f SL |
1345 | /// The iterator returned from this function will return instances of |
1346 | /// `io::Result<Vec<u8>>`. Each vector returned will *not* have the | |
1347 | /// delimiter byte at the end. | |
1a4d82fc | 1348 | /// |
85aaf69f SL |
1349 | /// This function will yield errors whenever `read_until` would have also |
1350 | /// yielded an error. | |
c1a9b12d SL |
1351 | /// |
1352 | /// # Examples | |
1353 | /// | |
1354 | /// A locked standard input implements `BufRead`. In this example, we'll | |
1355 | /// read some input from standard input, splitting on commas. | |
1356 | /// | |
1357 | /// ``` | |
1358 | /// use std::io; | |
1359 | /// use std::io::prelude::*; | |
1360 | /// | |
1361 | /// let stdin = io::stdin(); | |
1362 | /// | |
1363 | /// for content in stdin.lock().split(b',') { | |
1364 | /// println!("{:?}", content.unwrap()); | |
1365 | /// } | |
1366 | /// ``` | |
c34b1796 AL |
1367 | #[stable(feature = "rust1", since = "1.0.0")] |
1368 | fn split(self, byte: u8) -> Split<Self> where Self: Sized { | |
85aaf69f SL |
1369 | Split { buf: self, delim: byte } |
1370 | } | |
1a4d82fc | 1371 | |
85aaf69f | 1372 | /// Returns an iterator over the lines of this reader. |
1a4d82fc | 1373 | /// |
85aaf69f SL |
1374 | /// The iterator returned from this function will yield instances of |
1375 | /// `io::Result<String>`. Each string returned will *not* have a newline | |
1376 | /// byte (the 0xA byte) at the end. | |
c1a9b12d SL |
1377 | /// |
1378 | /// # Examples | |
1379 | /// | |
1380 | /// A locked standard input implements `BufRead`: | |
1381 | /// | |
1382 | /// ``` | |
1383 | /// use std::io; | |
1384 | /// use std::io::prelude::*; | |
1385 | /// | |
1386 | /// let stdin = io::stdin(); | |
1387 | /// | |
1388 | /// for line in stdin.lock().lines() { | |
1389 | /// println!("{}", line.unwrap()); | |
1390 | /// } | |
1391 | /// ``` | |
c34b1796 AL |
1392 | #[stable(feature = "rust1", since = "1.0.0")] |
1393 | fn lines(self) -> Lines<Self> where Self: Sized { | |
85aaf69f SL |
1394 | Lines { buf: self } |
1395 | } | |
1396 | } | |
1397 | ||
85aaf69f SL |
1398 | /// A `Write` adaptor which will write data to multiple locations. |
1399 | /// | |
c1a9b12d SL |
1400 | /// This struct is generally created by calling [`broadcast()`][broadcast] on a |
1401 | /// writer. Please see the documentation of `broadcast()` for more details. | |
1402 | /// | |
1403 | /// [broadcast]: trait.Write.html#method.broadcast | |
c34b1796 | 1404 | #[unstable(feature = "io", reason = "awaiting stability of Write::broadcast")] |
85aaf69f SL |
1405 | pub struct Broadcast<T, U> { |
1406 | first: T, | |
1407 | second: U, | |
1a4d82fc JJ |
1408 | } |
1409 | ||
c34b1796 | 1410 | #[unstable(feature = "io", reason = "awaiting stability of Write::broadcast")] |
85aaf69f SL |
1411 | impl<T: Write, U: Write> Write for Broadcast<T, U> { |
1412 | fn write(&mut self, data: &[u8]) -> Result<usize> { | |
1413 | let n = try!(self.first.write(data)); | |
1414 | // FIXME: what if the write fails? (we wrote something) | |
1415 | try!(self.second.write_all(&data[..n])); | |
1416 | Ok(n) | |
1a4d82fc JJ |
1417 | } |
1418 | ||
85aaf69f SL |
1419 | fn flush(&mut self) -> Result<()> { |
1420 | self.first.flush().and(self.second.flush()) | |
1a4d82fc JJ |
1421 | } |
1422 | } | |
1423 | ||
c1a9b12d SL |
1424 | /// Adaptor to chain together two readers. |
1425 | /// | |
1426 | /// This struct is generally created by calling [`chain()`][chain] on a reader. | |
1427 | /// Please see the documentation of `chain()` for more details. | |
85aaf69f | 1428 | /// |
c1a9b12d | 1429 | /// [chain]: trait.Read.html#method.chain |
c34b1796 | 1430 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1431 | pub struct Chain<T, U> { |
1432 | first: T, | |
1433 | second: U, | |
1434 | done_first: bool, | |
1a4d82fc JJ |
1435 | } |
1436 | ||
c34b1796 | 1437 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1438 | impl<T: Read, U: Read> Read for Chain<T, U> { |
1439 | fn read(&mut self, buf: &mut [u8]) -> Result<usize> { | |
1440 | if !self.done_first { | |
1441 | match try!(self.first.read(buf)) { | |
1442 | 0 => { self.done_first = true; } | |
1443 | n => return Ok(n), | |
1444 | } | |
1445 | } | |
1446 | self.second.read(buf) | |
1447 | } | |
1a4d82fc JJ |
1448 | } |
1449 | ||
85aaf69f | 1450 | /// Reader adaptor which limits the bytes read from an underlying reader. |
1a4d82fc | 1451 | /// |
c1a9b12d SL |
1452 | /// This struct is generally created by calling [`take()`][take] on a reader. |
1453 | /// Please see the documentation of `take()` for more details. | |
1454 | /// | |
1455 | /// [take]: trait.Read.html#method.take | |
c34b1796 | 1456 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1457 | pub struct Take<T> { |
1458 | inner: T, | |
1459 | limit: u64, | |
1a4d82fc JJ |
1460 | } |
1461 | ||
c34b1796 | 1462 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1463 | impl<T> Take<T> { |
1464 | /// Returns the number of bytes that can be read before this instance will | |
1465 | /// return EOF. | |
1a4d82fc | 1466 | /// |
85aaf69f | 1467 | /// # Note |
1a4d82fc | 1468 | /// |
85aaf69f SL |
1469 | /// This instance may reach EOF after reading fewer bytes than indicated by |
1470 | /// this method if the underlying `Read` instance reaches EOF. | |
c34b1796 | 1471 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1472 | pub fn limit(&self) -> u64 { self.limit } |
1473 | } | |
1a4d82fc | 1474 | |
c34b1796 | 1475 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1476 | impl<T: Read> Read for Take<T> { |
1477 | fn read(&mut self, buf: &mut [u8]) -> Result<usize> { | |
c34b1796 AL |
1478 | // Don't call into inner reader at all at EOF because it may still block |
1479 | if self.limit == 0 { | |
1480 | return Ok(0); | |
1481 | } | |
1482 | ||
85aaf69f SL |
1483 | let max = cmp::min(buf.len() as u64, self.limit) as usize; |
1484 | let n = try!(self.inner.read(&mut buf[..max])); | |
1485 | self.limit -= n as u64; | |
1486 | Ok(n) | |
1a4d82fc JJ |
1487 | } |
1488 | } | |
1489 | ||
c34b1796 AL |
1490 | #[stable(feature = "rust1", since = "1.0.0")] |
1491 | impl<T: BufRead> BufRead for Take<T> { | |
1492 | fn fill_buf(&mut self) -> Result<&[u8]> { | |
1493 | let buf = try!(self.inner.fill_buf()); | |
1494 | let cap = cmp::min(buf.len() as u64, self.limit) as usize; | |
1495 | Ok(&buf[..cap]) | |
1496 | } | |
1497 | ||
1498 | fn consume(&mut self, amt: usize) { | |
1499 | // Don't let callers reset the limit by passing an overlarge value | |
1500 | let amt = cmp::min(amt as u64, self.limit) as usize; | |
1501 | self.limit -= amt as u64; | |
1502 | self.inner.consume(amt); | |
1503 | } | |
1504 | } | |
1505 | ||
85aaf69f | 1506 | /// An adaptor which will emit all read data to a specified writer as well. |
1a4d82fc | 1507 | /// |
c1a9b12d SL |
1508 | /// This struct is generally created by calling [`tee()`][tee] on a reader. |
1509 | /// Please see the documentation of `tee()` for more details. | |
1510 | /// | |
1511 | /// [tee]: trait.Read.html#method.tee | |
c34b1796 | 1512 | #[unstable(feature = "io", reason = "awaiting stability of Read::tee")] |
85aaf69f SL |
1513 | pub struct Tee<R, W> { |
1514 | reader: R, | |
1515 | writer: W, | |
1a4d82fc JJ |
1516 | } |
1517 | ||
c34b1796 | 1518 | #[unstable(feature = "io", reason = "awaiting stability of Read::tee")] |
85aaf69f SL |
1519 | impl<R: Read, W: Write> Read for Tee<R, W> { |
1520 | fn read(&mut self, buf: &mut [u8]) -> Result<usize> { | |
1521 | let n = try!(self.reader.read(buf)); | |
1522 | // FIXME: what if the write fails? (we read something) | |
1523 | try!(self.writer.write_all(&buf[..n])); | |
1524 | Ok(n) | |
1a4d82fc JJ |
1525 | } |
1526 | } | |
1527 | ||
c1a9b12d SL |
1528 | /// An iterator over `u8` values of a reader. |
1529 | /// | |
1530 | /// This struct is generally created by calling [`bytes()`][bytes] on a reader. | |
1531 | /// Please see the documentation of `bytes()` for more details. | |
1a4d82fc | 1532 | /// |
c1a9b12d | 1533 | /// [bytes]: trait.Read.html#method.bytes |
c34b1796 | 1534 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1535 | pub struct Bytes<R> { |
1536 | inner: R, | |
1a4d82fc JJ |
1537 | } |
1538 | ||
c34b1796 | 1539 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1540 | impl<R: Read> Iterator for Bytes<R> { |
1541 | type Item = Result<u8>; | |
1a4d82fc | 1542 | |
85aaf69f SL |
1543 | fn next(&mut self) -> Option<Result<u8>> { |
1544 | let mut buf = [0]; | |
1545 | match self.inner.read(&mut buf) { | |
1546 | Ok(0) => None, | |
1547 | Ok(..) => Some(Ok(buf[0])), | |
1548 | Err(e) => Some(Err(e)), | |
1549 | } | |
1550 | } | |
1a4d82fc JJ |
1551 | } |
1552 | ||
c1a9b12d | 1553 | /// An iterator over the `char`s of a reader. |
1a4d82fc | 1554 | /// |
c1a9b12d SL |
1555 | /// This struct is generally created by calling [`chars()`][chars] on a reader. |
1556 | /// Please see the documentation of `chars()` for more details. | |
1557 | /// | |
1558 | /// [chars]: trait.Read.html#method.chars | |
c34b1796 | 1559 | #[unstable(feature = "io", reason = "awaiting stability of Read::chars")] |
85aaf69f SL |
1560 | pub struct Chars<R> { |
1561 | inner: R, | |
1a4d82fc JJ |
1562 | } |
1563 | ||
85aaf69f SL |
1564 | /// An enumeration of possible errors that can be generated from the `Chars` |
1565 | /// adapter. | |
c34b1796 AL |
1566 | #[derive(Debug)] |
1567 | #[unstable(feature = "io", reason = "awaiting stability of Read::chars")] | |
85aaf69f SL |
1568 | pub enum CharsError { |
1569 | /// Variant representing that the underlying stream was read successfully | |
1570 | /// but it did not contain valid utf8 data. | |
1571 | NotUtf8, | |
1a4d82fc | 1572 | |
85aaf69f SL |
1573 | /// Variant representing that an I/O error occurred. |
1574 | Other(Error), | |
1a4d82fc JJ |
1575 | } |
1576 | ||
c34b1796 | 1577 | #[unstable(feature = "io", reason = "awaiting stability of Read::chars")] |
85aaf69f SL |
1578 | impl<R: Read> Iterator for Chars<R> { |
1579 | type Item = result::Result<char, CharsError>; | |
1a4d82fc | 1580 | |
85aaf69f SL |
1581 | fn next(&mut self) -> Option<result::Result<char, CharsError>> { |
1582 | let mut buf = [0]; | |
1583 | let first_byte = match self.inner.read(&mut buf) { | |
1584 | Ok(0) => return None, | |
1585 | Ok(..) => buf[0], | |
1586 | Err(e) => return Some(Err(CharsError::Other(e))), | |
1587 | }; | |
1588 | let width = core_str::utf8_char_width(first_byte); | |
1589 | if width == 1 { return Some(Ok(first_byte as char)) } | |
1590 | if width == 0 { return Some(Err(CharsError::NotUtf8)) } | |
1591 | let mut buf = [first_byte, 0, 0, 0]; | |
1592 | { | |
1593 | let mut start = 1; | |
1594 | while start < width { | |
1595 | match self.inner.read(&mut buf[start..width]) { | |
1596 | Ok(0) => return Some(Err(CharsError::NotUtf8)), | |
1597 | Ok(n) => start += n, | |
1598 | Err(e) => return Some(Err(CharsError::Other(e))), | |
1599 | } | |
1600 | } | |
1601 | } | |
1602 | Some(match str::from_utf8(&buf[..width]).ok() { | |
1603 | Some(s) => Ok(s.char_at(0)), | |
1604 | None => Err(CharsError::NotUtf8), | |
1605 | }) | |
1606 | } | |
1a4d82fc JJ |
1607 | } |
1608 | ||
c34b1796 AL |
1609 | #[unstable(feature = "io", reason = "awaiting stability of Read::chars")] |
1610 | impl std_error::Error for CharsError { | |
85aaf69f SL |
1611 | fn description(&self) -> &str { |
1612 | match *self { | |
1613 | CharsError::NotUtf8 => "invalid utf8 encoding", | |
c34b1796 | 1614 | CharsError::Other(ref e) => std_error::Error::description(e), |
85aaf69f SL |
1615 | } |
1616 | } | |
c34b1796 | 1617 | fn cause(&self) -> Option<&std_error::Error> { |
85aaf69f SL |
1618 | match *self { |
1619 | CharsError::NotUtf8 => None, | |
1620 | CharsError::Other(ref e) => e.cause(), | |
1621 | } | |
1a4d82fc JJ |
1622 | } |
1623 | } | |
1624 | ||
c34b1796 | 1625 | #[unstable(feature = "io", reason = "awaiting stability of Read::chars")] |
85aaf69f | 1626 | impl fmt::Display for CharsError { |
1a4d82fc | 1627 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
85aaf69f SL |
1628 | match *self { |
1629 | CharsError::NotUtf8 => { | |
1630 | "byte stream did not contain valid utf8".fmt(f) | |
1631 | } | |
1632 | CharsError::Other(ref e) => e.fmt(f), | |
1633 | } | |
1a4d82fc JJ |
1634 | } |
1635 | } | |
1636 | ||
85aaf69f SL |
1637 | /// An iterator over the contents of an instance of `BufRead` split on a |
1638 | /// particular byte. | |
1639 | /// | |
c1a9b12d SL |
1640 | /// This struct is generally created by calling [`split()`][split] on a |
1641 | /// `BufRead`. Please see the documentation of `split()` for more details. | |
1642 | /// | |
1643 | /// [split]: trait.BufRead.html#method.split | |
c34b1796 | 1644 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1645 | pub struct Split<B> { |
1646 | buf: B, | |
1647 | delim: u8, | |
1648 | } | |
1a4d82fc | 1649 | |
c34b1796 | 1650 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1651 | impl<B: BufRead> Iterator for Split<B> { |
1652 | type Item = Result<Vec<u8>>; | |
1a4d82fc | 1653 | |
85aaf69f SL |
1654 | fn next(&mut self) -> Option<Result<Vec<u8>>> { |
1655 | let mut buf = Vec::new(); | |
1656 | match self.buf.read_until(self.delim, &mut buf) { | |
c34b1796 AL |
1657 | Ok(0) => None, |
1658 | Ok(_n) => { | |
85aaf69f SL |
1659 | if buf[buf.len() - 1] == self.delim { |
1660 | buf.pop(); | |
1661 | } | |
1662 | Some(Ok(buf)) | |
1663 | } | |
1664 | Err(e) => Some(Err(e)) | |
1a4d82fc JJ |
1665 | } |
1666 | } | |
85aaf69f SL |
1667 | } |
1668 | ||
c1a9b12d | 1669 | /// An iterator over the lines of an instance of `BufRead`. |
85aaf69f | 1670 | /// |
c1a9b12d SL |
1671 | /// This struct is generally created by calling [`lines()`][lines] on a |
1672 | /// `BufRead`. Please see the documentation of `lines()` for more details. | |
1673 | /// | |
1674 | /// [lines]: trait.BufRead.html#method.lines | |
c34b1796 | 1675 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1676 | pub struct Lines<B> { |
1677 | buf: B, | |
1678 | } | |
1679 | ||
c34b1796 | 1680 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f SL |
1681 | impl<B: BufRead> Iterator for Lines<B> { |
1682 | type Item = Result<String>; | |
1a4d82fc | 1683 | |
85aaf69f SL |
1684 | fn next(&mut self) -> Option<Result<String>> { |
1685 | let mut buf = String::new(); | |
1686 | match self.buf.read_line(&mut buf) { | |
c34b1796 AL |
1687 | Ok(0) => None, |
1688 | Ok(_n) => { | |
85aaf69f SL |
1689 | if buf.ends_with("\n") { |
1690 | buf.pop(); | |
1a4d82fc | 1691 | } |
85aaf69f | 1692 | Some(Ok(buf)) |
1a4d82fc | 1693 | } |
85aaf69f | 1694 | Err(e) => Some(Err(e)) |
1a4d82fc JJ |
1695 | } |
1696 | } | |
85aaf69f SL |
1697 | } |
1698 | ||
1699 | #[cfg(test)] | |
1700 | mod tests { | |
1701 | use prelude::v1::*; | |
1702 | use io::prelude::*; | |
c34b1796 | 1703 | use io; |
85aaf69f | 1704 | use super::Cursor; |
c1a9b12d SL |
1705 | use test; |
1706 | use super::repeat; | |
1a4d82fc JJ |
1707 | |
1708 | #[test] | |
85aaf69f | 1709 | fn read_until() { |
c34b1796 | 1710 | let mut buf = Cursor::new(&b"12"[..]); |
85aaf69f | 1711 | let mut v = Vec::new(); |
c34b1796 | 1712 | assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 2); |
85aaf69f SL |
1713 | assert_eq!(v, b"12"); |
1714 | ||
c34b1796 | 1715 | let mut buf = Cursor::new(&b"1233"[..]); |
85aaf69f | 1716 | let mut v = Vec::new(); |
c34b1796 | 1717 | assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 3); |
85aaf69f SL |
1718 | assert_eq!(v, b"123"); |
1719 | v.truncate(0); | |
c34b1796 | 1720 | assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 1); |
85aaf69f SL |
1721 | assert_eq!(v, b"3"); |
1722 | v.truncate(0); | |
c34b1796 | 1723 | assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 0); |
85aaf69f | 1724 | assert_eq!(v, []); |
1a4d82fc JJ |
1725 | } |
1726 | ||
1727 | #[test] | |
85aaf69f | 1728 | fn split() { |
c34b1796 | 1729 | let buf = Cursor::new(&b"12"[..]); |
85aaf69f | 1730 | let mut s = buf.split(b'3'); |
c34b1796 AL |
1731 | assert_eq!(s.next().unwrap().unwrap(), vec![b'1', b'2']); |
1732 | assert!(s.next().is_none()); | |
1a4d82fc | 1733 | |
c34b1796 | 1734 | let buf = Cursor::new(&b"1233"[..]); |
85aaf69f | 1735 | let mut s = buf.split(b'3'); |
c34b1796 AL |
1736 | assert_eq!(s.next().unwrap().unwrap(), vec![b'1', b'2']); |
1737 | assert_eq!(s.next().unwrap().unwrap(), vec![]); | |
1738 | assert!(s.next().is_none()); | |
85aaf69f | 1739 | } |
1a4d82fc | 1740 | |
85aaf69f SL |
1741 | #[test] |
1742 | fn read_line() { | |
c34b1796 | 1743 | let mut buf = Cursor::new(&b"12"[..]); |
85aaf69f | 1744 | let mut v = String::new(); |
c34b1796 | 1745 | assert_eq!(buf.read_line(&mut v).unwrap(), 2); |
85aaf69f SL |
1746 | assert_eq!(v, "12"); |
1747 | ||
c34b1796 | 1748 | let mut buf = Cursor::new(&b"12\n\n"[..]); |
85aaf69f | 1749 | let mut v = String::new(); |
c34b1796 | 1750 | assert_eq!(buf.read_line(&mut v).unwrap(), 3); |
85aaf69f SL |
1751 | assert_eq!(v, "12\n"); |
1752 | v.truncate(0); | |
c34b1796 | 1753 | assert_eq!(buf.read_line(&mut v).unwrap(), 1); |
85aaf69f SL |
1754 | assert_eq!(v, "\n"); |
1755 | v.truncate(0); | |
c34b1796 | 1756 | assert_eq!(buf.read_line(&mut v).unwrap(), 0); |
85aaf69f SL |
1757 | assert_eq!(v, ""); |
1758 | } | |
1a4d82fc | 1759 | |
85aaf69f SL |
1760 | #[test] |
1761 | fn lines() { | |
c34b1796 | 1762 | let buf = Cursor::new(&b"12"[..]); |
85aaf69f | 1763 | let mut s = buf.lines(); |
c34b1796 AL |
1764 | assert_eq!(s.next().unwrap().unwrap(), "12".to_string()); |
1765 | assert!(s.next().is_none()); | |
1a4d82fc | 1766 | |
c34b1796 | 1767 | let buf = Cursor::new(&b"12\n\n"[..]); |
85aaf69f | 1768 | let mut s = buf.lines(); |
c34b1796 AL |
1769 | assert_eq!(s.next().unwrap().unwrap(), "12".to_string()); |
1770 | assert_eq!(s.next().unwrap().unwrap(), "".to_string()); | |
1771 | assert!(s.next().is_none()); | |
1a4d82fc JJ |
1772 | } |
1773 | ||
1774 | #[test] | |
85aaf69f | 1775 | fn read_to_end() { |
c34b1796 | 1776 | let mut c = Cursor::new(&b""[..]); |
85aaf69f | 1777 | let mut v = Vec::new(); |
c34b1796 | 1778 | assert_eq!(c.read_to_end(&mut v).unwrap(), 0); |
85aaf69f SL |
1779 | assert_eq!(v, []); |
1780 | ||
c34b1796 | 1781 | let mut c = Cursor::new(&b"1"[..]); |
85aaf69f | 1782 | let mut v = Vec::new(); |
c34b1796 | 1783 | assert_eq!(c.read_to_end(&mut v).unwrap(), 1); |
85aaf69f | 1784 | assert_eq!(v, b"1"); |
c1a9b12d SL |
1785 | |
1786 | let cap = 1024 * 1024; | |
1787 | let data = (0..cap).map(|i| (i / 3) as u8).collect::<Vec<_>>(); | |
1788 | let mut v = Vec::new(); | |
1789 | let (a, b) = data.split_at(data.len() / 2); | |
1790 | assert_eq!(Cursor::new(a).read_to_end(&mut v).unwrap(), a.len()); | |
1791 | assert_eq!(Cursor::new(b).read_to_end(&mut v).unwrap(), b.len()); | |
1792 | assert_eq!(v, data); | |
1a4d82fc JJ |
1793 | } |
1794 | ||
85aaf69f SL |
1795 | #[test] |
1796 | fn read_to_string() { | |
c34b1796 | 1797 | let mut c = Cursor::new(&b""[..]); |
85aaf69f | 1798 | let mut v = String::new(); |
c34b1796 | 1799 | assert_eq!(c.read_to_string(&mut v).unwrap(), 0); |
85aaf69f SL |
1800 | assert_eq!(v, ""); |
1801 | ||
c34b1796 | 1802 | let mut c = Cursor::new(&b"1"[..]); |
85aaf69f | 1803 | let mut v = String::new(); |
c34b1796 | 1804 | assert_eq!(c.read_to_string(&mut v).unwrap(), 1); |
85aaf69f SL |
1805 | assert_eq!(v, "1"); |
1806 | ||
c34b1796 | 1807 | let mut c = Cursor::new(&b"\xff"[..]); |
85aaf69f SL |
1808 | let mut v = String::new(); |
1809 | assert!(c.read_to_string(&mut v).is_err()); | |
1a4d82fc | 1810 | } |
c34b1796 AL |
1811 | |
1812 | #[test] | |
1813 | fn take_eof() { | |
1814 | struct R; | |
1815 | ||
1816 | impl Read for R { | |
1817 | fn read(&mut self, _: &mut [u8]) -> io::Result<usize> { | |
1818 | Err(io::Error::new(io::ErrorKind::Other, "")) | |
1819 | } | |
1820 | } | |
1821 | ||
1822 | let mut buf = [0; 1]; | |
1823 | assert_eq!(0, R.take(0).read(&mut buf).unwrap()); | |
1824 | } | |
c1a9b12d SL |
1825 | |
1826 | #[bench] | |
1827 | fn bench_read_to_end(b: &mut test::Bencher) { | |
1828 | b.iter(|| { | |
1829 | let mut lr = repeat(1).take(10000000); | |
1830 | let mut vec = Vec::with_capacity(1024); | |
1831 | super::read_to_end(&mut lr, &mut vec); | |
1832 | }); | |
1833 | } | |
1a4d82fc | 1834 | } |