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diff --git a/ctr-std/src/io/mod.rs b/ctr-std/src/io/mod.rs new file mode 100644 index 0000000..1653790 --- /dev/null +++ b/ctr-std/src/io/mod.rs @@ -0,0 +1,1990 @@ +// Copyright 2015 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Traits, helpers, and type definitions for core I/O functionality. +//! +//! The `std::io` module contains a number of common things you'll need +//! when doing input and output. The most core part of this module is +//! the [`Read`] and [`Write`] traits, which provide the +//! most general interface for reading and writing input and output. +//! +//! # Read and Write +//! +//! Because they are traits, [`Read`] and [`Write`] are implemented by a number +//! of other types, and you can implement them for your types too. As such, +//! you'll see a few different types of I/O throughout the documentation in +//! this module: [`File`]s, [`TcpStream`]s, and sometimes even [`Vec<T>`]s. For +//! example, `Read` adds a `read()` method, which we can use on `File`s: +//! +//! ``` +//! use std::io; +//! use std::io::prelude::*; +//! use std::fs::File; +//! +//! # fn foo() -> io::Result<()> { +//! let mut f = try!(File::open("foo.txt")); +//! let mut buffer = [0; 10]; +//! +//! // read up to 10 bytes +//! try!(f.read(&mut buffer)); +//! +//! println!("The bytes: {:?}", buffer); +//! # Ok(()) +//! # } +//! ``` +//! +//! [`Read`] and [`Write`] are so important, implementors of the two traits have a +//! nickname: readers and writers. So you'll sometimes see 'a reader' instead +//! of 'a type that implements the [`Read`] trait'. Much easier! +//! +//! ## Seek and BufRead +//! +//! Beyond that, there are two important traits that are provided: [`Seek`] +//! and [`BufRead`]. Both of these build on top of a reader to control +//! how the reading happens. [`Seek`] lets you control where the next byte is +//! coming from: +//! +//! ``` +//! use std::io; +//! use std::io::prelude::*; +//! use std::io::SeekFrom; +//! use std::fs::File; +//! +//! # fn foo() -> io::Result<()> { +//! let mut f = try!(File::open("foo.txt")); +//! let mut buffer = [0; 10]; +//! +//! // skip to the last 10 bytes of the file +//! try!(f.seek(SeekFrom::End(-10))); +//! +//! // read up to 10 bytes +//! try!(f.read(&mut buffer)); +//! +//! println!("The bytes: {:?}", buffer); +//! # Ok(()) +//! # } +//! ``` +//! +//! [`BufRead`] uses an internal buffer to provide a number of other ways to read, but +//! to show it off, we'll need to talk about buffers in general. Keep reading! +//! +//! ## BufReader and BufWriter +//! +//! Byte-based interfaces are unwieldy and can be inefficient, as we'd need to be +//! making near-constant calls to the operating system. To help with this, +//! `std::io` comes with two structs, [`BufReader`] and [`BufWriter`], which wrap +//! readers and writers. The wrapper uses a buffer, reducing the number of +//! calls and providing nicer methods for accessing exactly what you want. +//! +//! For example, [`BufReader`] works with the [`BufRead`] trait to add extra +//! methods to any reader: +//! +//! ``` +//! use std::io; +//! use std::io::prelude::*; +//! use std::io::BufReader; +//! use std::fs::File; +//! +//! # fn foo() -> io::Result<()> { +//! let f = try!(File::open("foo.txt")); +//! let mut reader = BufReader::new(f); +//! let mut buffer = String::new(); +//! +//! // read a line into buffer +//! try!(reader.read_line(&mut buffer)); +//! +//! println!("{}", buffer); +//! # Ok(()) +//! # } +//! ``` +//! +//! [`BufWriter`] doesn't add any new ways of writing; it just buffers every call +//! to [`write()`]: +//! +//! ``` +//! use std::io; +//! use std::io::prelude::*; +//! use std::io::BufWriter; +//! use std::fs::File; +//! +//! # fn foo() -> io::Result<()> { +//! let f = try!(File::create("foo.txt")); +//! { +//! let mut writer = BufWriter::new(f); +//! +//! // write a byte to the buffer +//! try!(writer.write(&[42])); +//! +//! } // the buffer is flushed once writer goes out of scope +//! +//! # Ok(()) +//! # } +//! ``` +//! +//! ## Standard input and output +//! +//! A very common source of input is standard input: +//! +//! ``` +//! use std::io; +//! +//! # fn foo() -> io::Result<()> { +//! let mut input = String::new(); +//! +//! try!(io::stdin().read_line(&mut input)); +//! +//! println!("You typed: {}", input.trim()); +//! # Ok(()) +//! # } +//! ``` +//! +//! And a very common source of output is standard output: +//! +//! ``` +//! use std::io; +//! use std::io::prelude::*; +//! +//! # fn foo() -> io::Result<()> { +//! try!(io::stdout().write(&[42])); +//! # Ok(()) +//! # } +//! ``` +//! +//! Of course, using [`io::stdout()`] directly is less common than something like +//! [`println!`]. +//! +//! ## Iterator types +//! +//! A large number of the structures provided by `std::io` are for various +//! ways of iterating over I/O. For example, [`Lines`] is used to split over +//! lines: +//! +//! ``` +//! use std::io; +//! use std::io::prelude::*; +//! use std::io::BufReader; +//! use std::fs::File; +//! +//! # fn foo() -> io::Result<()> { +//! let f = try!(File::open("foo.txt")); +//! let reader = BufReader::new(f); +//! +//! for line in reader.lines() { +//! println!("{}", try!(line)); +//! } +//! +//! # Ok(()) +//! # } +//! ``` +//! +//! ## Functions +//! +//! There are a number of [functions][functions-list] that offer access to various +//! features. For example, we can use three of these functions to copy everything +//! from standard input to standard output: +//! +//! ``` +//! use std::io; +//! +//! # fn foo() -> io::Result<()> { +//! try!(io::copy(&mut io::stdin(), &mut io::stdout())); +//! # Ok(()) +//! # } +//! ``` +//! +//! [functions-list]: #functions-1 +//! +//! ## io::Result +//! +//! Last, but certainly not least, is [`io::Result`]. This type is used +//! as the return type of many `std::io` functions that can cause an error, and +//! can be returned from your own functions as well. Many of the examples in this +//! module use the [`try!`] macro: +//! +//! ``` +//! use std::io; +//! +//! fn read_input() -> io::Result<()> { +//! let mut input = String::new(); +//! +//! try!(io::stdin().read_line(&mut input)); +//! +//! println!("You typed: {}", input.trim()); +//! +//! Ok(()) +//! } +//! ``` +//! +//! The return type of `read_input()`, [`io::Result<()>`][`io::Result`], is a very +//! common type for functions which don't have a 'real' return value, but do want to +//! return errors if they happen. In this case, the only purpose of this function is +//! to read the line and print it, so we use `()`. +//! +//! ## Platform-specific behavior +//! +//! Many I/O functions throughout the standard library are documented to indicate +//! what various library or syscalls they are delegated to. This is done to help +//! applications both understand what's happening under the hood as well as investigate +//! any possibly unclear semantics. Note, however, that this is informative, not a binding +//! contract. The implementation of many of these functions are subject to change over +//! time and may call fewer or more syscalls/library functions. +//! +//! [`Read`]: trait.Read.html +//! [`Write`]: trait.Write.html +//! [`Seek`]: trait.Seek.html +//! [`BufRead`]: trait.BufRead.html +//! [`File`]: ../fs/struct.File.html +//! [`TcpStream`]: ../net/struct.TcpStream.html +//! [`Vec<T>`]: ../vec/struct.Vec.html +//! [`BufReader`]: struct.BufReader.html +//! [`BufWriter`]: struct.BufWriter.html +//! [`write()`]: trait.Write.html#tymethod.write +//! [`io::stdout()`]: fn.stdout.html +//! [`println!`]: ../macro.println.html +//! [`Lines`]: struct.Lines.html +//! [`io::Result`]: type.Result.html +//! [`try!`]: ../macro.try.html + +#![stable(feature = "rust1", since = "1.0.0")] + +use cmp; +use std_unicode::str as core_str; +use error as std_error; +use fmt; +use result; +use str; +use memchr; + +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::buffered::{BufReader, BufWriter, LineWriter}; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::buffered::IntoInnerError; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::cursor::Cursor; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::error::{Result, Error, ErrorKind}; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::util::{copy, sink, Sink, empty, Empty, repeat, Repeat}; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::print::{STDOUT, _print}; + + +pub mod prelude; +mod buffered; +mod cursor; +mod error; +mod impls; +mod util; +mod print; + +const DEFAULT_BUF_SIZE: usize = ::sys_common::io::DEFAULT_BUF_SIZE; + +// A few methods below (read_to_string, read_line) will append data into a +// `String` buffer, but we need to be pretty careful when doing this. The +// implementation will just call `.as_mut_vec()` and then delegate to a +// byte-oriented reading method, but we must ensure that when returning we never +// leave `buf` in a state such that it contains invalid UTF-8 in its bounds. +// +// To this end, we use an RAII guard (to protect against panics) which updates +// the length of the string when it is dropped. This guard initially truncates +// the string to the prior length and only after we've validated that the +// new contents are valid UTF-8 do we allow it to set a longer length. +// +// The unsafety in this function is twofold: +// +// 1. We're looking at the raw bytes of `buf`, so we take on the burden of UTF-8 +// checks. +// 2. We're passing a raw buffer to the function `f`, and it is expected that +// the function only *appends* bytes to the buffer. We'll get undefined +// behavior if existing bytes are overwritten to have non-UTF-8 data. +fn append_to_string<F>(buf: &mut String, f: F) -> Result<usize> + where F: FnOnce(&mut Vec<u8>) -> Result<usize> +{ + struct Guard<'a> { s: &'a mut Vec<u8>, len: usize } + impl<'a> Drop for Guard<'a> { + fn drop(&mut self) { + unsafe { self.s.set_len(self.len); } + } + } + + unsafe { + let mut g = Guard { len: buf.len(), s: buf.as_mut_vec() }; + let ret = f(g.s); + if str::from_utf8(&g.s[g.len..]).is_err() { + ret.and_then(|_| { + Err(Error::new(ErrorKind::InvalidData, + "stream did not contain valid UTF-8")) + }) + } else { + g.len = g.s.len(); + ret + } + } +} + +// This uses an adaptive system to extend the vector when it fills. We want to +// avoid paying to allocate and zero a huge chunk of memory if the reader only +// has 4 bytes while still making large reads if the reader does have a ton +// of data to return. Simply tacking on an extra DEFAULT_BUF_SIZE space every +// time is 4,500 times (!) slower than this if the reader has a very small +// amount of data to return. +fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize> { + let start_len = buf.len(); + let mut len = start_len; + let mut new_write_size = 16; + let ret; + loop { + if len == buf.len() { + if new_write_size < DEFAULT_BUF_SIZE { + new_write_size *= 2; + } + buf.resize(len + new_write_size, 0); + } + + match r.read(&mut buf[len..]) { + Ok(0) => { + ret = Ok(len - start_len); + break; + } + Ok(n) => len += n, + Err(ref e) if e.kind() == ErrorKind::Interrupted => {} + Err(e) => { + ret = Err(e); + break; + } + } + } + + buf.truncate(len); + ret +} + +/// The `Read` trait allows for reading bytes from a source. +/// +/// Implementors of the `Read` trait are sometimes called 'readers'. +/// +/// Readers are defined by one required method, `read()`. Each call to `read` +/// will attempt to pull bytes from this source into a provided buffer. A +/// number of other methods are implemented in terms of `read()`, giving +/// implementors a number of ways to read bytes while only needing to implement +/// a single method. +/// +/// Readers are intended to be composable with one another. Many implementors +/// throughout `std::io` take and provide types which implement the `Read` +/// trait. +/// +/// Please note that each call to `read` may involve a system call, and +/// therefore, using something that implements [`BufRead`][bufread], such as +/// [`BufReader`][bufreader], will be more efficient. +/// +/// [bufread]: trait.BufRead.html +/// [bufreader]: struct.BufReader.html +/// +/// # Examples +/// +/// [`File`][file]s implement `Read`: +/// +/// [file]: ../fs/struct.File.html +/// +/// ``` +/// use std::io; +/// use std::io::prelude::*; +/// use std::fs::File; +/// +/// # fn foo() -> io::Result<()> { +/// let mut f = try!(File::open("foo.txt")); +/// let mut buffer = [0; 10]; +/// +/// // read up to 10 bytes +/// try!(f.read(&mut buffer)); +/// +/// let mut buffer = vec![0; 10]; +/// // read the whole file +/// try!(f.read_to_end(&mut buffer)); +/// +/// // read into a String, so that you don't need to do the conversion. +/// let mut buffer = String::new(); +/// try!(f.read_to_string(&mut buffer)); +/// +/// // and more! See the other methods for more details. +/// # Ok(()) +/// # } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub trait Read { + /// Pull some bytes from this source into the specified buffer, returning + /// how many bytes were read. + /// + /// This function does not provide any guarantees about whether it blocks + /// waiting for data, but if an object needs to block for a read but cannot + /// it will typically signal this via an `Err` return value. + /// + /// If the return value of this method is `Ok(n)`, then it must be + /// guaranteed that `0 <= n <= buf.len()`. A nonzero `n` value indicates + /// that the buffer `buf` has been filled in with `n` bytes of data from this + /// source. If `n` is `0`, then it can indicate one of two scenarios: + /// + /// 1. This reader has reached its "end of file" and will likely no longer + /// be able to produce bytes. Note that this does not mean that the + /// reader will *always* no longer be able to produce bytes. + /// 2. The buffer specified was 0 bytes in length. + /// + /// No guarantees are provided about the contents of `buf` when this + /// function is called, implementations cannot rely on any property of the + /// contents of `buf` being true. It is recommended that implementations + /// only write data to `buf` instead of reading its contents. + /// + /// # Errors + /// + /// If this function encounters any form of I/O or other error, an error + /// variant will be returned. If an error is returned then it must be + /// guaranteed that no bytes were read. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// let mut buffer = [0; 10]; + /// + /// // read 10 bytes + /// try!(f.read(&mut buffer[..])); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn read(&mut self, buf: &mut [u8]) -> Result<usize>; + + /// Read all bytes until EOF in this source, placing them into `buf`. + /// + /// All bytes read from this source will be appended to the specified buffer + /// `buf`. This function will continuously call `read` to append more data to + /// `buf` until `read` returns either `Ok(0)` or an error of + /// non-`ErrorKind::Interrupted` kind. + /// + /// If successful, this function will return the total number of bytes read. + /// + /// # Errors + /// + /// If this function encounters an error of the kind + /// `ErrorKind::Interrupted` then the error is ignored and the operation + /// will continue. + /// + /// If any other read error is encountered then this function immediately + /// returns. Any bytes which have already been read will be appended to + /// `buf`. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// let mut buffer = Vec::new(); + /// + /// // read the whole file + /// try!(f.read_to_end(&mut buffer)); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize> { + read_to_end(self, buf) + } + + /// Read all bytes until EOF in this source, placing them into `buf`. + /// + /// If successful, this function returns the number of bytes which were read + /// and appended to `buf`. + /// + /// # Errors + /// + /// If the data in this stream is *not* valid UTF-8 then an error is + /// returned and `buf` is unchanged. + /// + /// See [`read_to_end()`][readtoend] for other error semantics. + /// + /// [readtoend]: #method.read_to_end + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// let mut buffer = String::new(); + /// + /// try!(f.read_to_string(&mut buffer)); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn read_to_string(&mut self, buf: &mut String) -> Result<usize> { + // Note that we do *not* call `.read_to_end()` here. We are passing + // `&mut Vec<u8>` (the raw contents of `buf`) into the `read_to_end` + // method to fill it up. An arbitrary implementation could overwrite the + // entire contents of the vector, not just append to it (which is what + // we are expecting). + // + // To prevent extraneously checking the UTF-8-ness of the entire buffer + // we pass it to our hardcoded `read_to_end` implementation which we + // know is guaranteed to only read data into the end of the buffer. + append_to_string(buf, |b| read_to_end(self, b)) + } + + /// Read the exact number of bytes required to fill `buf`. + /// + /// This function reads as many bytes as necessary to completely fill the + /// specified buffer `buf`. + /// + /// No guarantees are provided about the contents of `buf` when this + /// function is called, implementations cannot rely on any property of the + /// contents of `buf` being true. It is recommended that implementations + /// only write data to `buf` instead of reading its contents. + /// + /// # Errors + /// + /// If this function encounters an error of the kind + /// `ErrorKind::Interrupted` then the error is ignored and the operation + /// will continue. + /// + /// If this function encounters an "end of file" before completely filling + /// the buffer, it returns an error of the kind `ErrorKind::UnexpectedEof`. + /// The contents of `buf` are unspecified in this case. + /// + /// If any other read error is encountered then this function immediately + /// returns. The contents of `buf` are unspecified in this case. + /// + /// If this function returns an error, it is unspecified how many bytes it + /// has read, but it will never read more than would be necessary to + /// completely fill the buffer. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// let mut buffer = [0; 10]; + /// + /// // read exactly 10 bytes + /// try!(f.read_exact(&mut buffer)); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "read_exact", since = "1.6.0")] + fn read_exact(&mut self, mut buf: &mut [u8]) -> Result<()> { + while !buf.is_empty() { + match self.read(buf) { + Ok(0) => break, + Ok(n) => { let tmp = buf; buf = &mut tmp[n..]; } + Err(ref e) if e.kind() == ErrorKind::Interrupted => {} + Err(e) => return Err(e), + } + } + if !buf.is_empty() { + Err(Error::new(ErrorKind::UnexpectedEof, + "failed to fill whole buffer")) + } else { + Ok(()) + } + } + + /// Creates a "by reference" adaptor for this instance of `Read`. + /// + /// The returned adaptor also implements `Read` and will simply borrow this + /// current reader. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::Read; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// let mut buffer = Vec::new(); + /// let mut other_buffer = Vec::new(); + /// + /// { + /// let reference = f.by_ref(); + /// + /// // read at most 5 bytes + /// try!(reference.take(5).read_to_end(&mut buffer)); + /// + /// } // drop our &mut reference so we can use f again + /// + /// // original file still usable, read the rest + /// try!(f.read_to_end(&mut other_buffer)); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn by_ref(&mut self) -> &mut Self where Self: Sized { self } + + /// Transforms this `Read` instance to an `Iterator` over its bytes. + /// + /// The returned type implements `Iterator` where the `Item` is `Result<u8, + /// R::Err>`. The yielded item is `Ok` if a byte was successfully read and + /// `Err` otherwise for I/O errors. EOF is mapped to returning `None` from + /// this iterator. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// + /// for byte in f.bytes() { + /// println!("{}", byte.unwrap()); + /// } + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn bytes(self) -> Bytes<Self> where Self: Sized { + Bytes { inner: self } + } + + /// Transforms this `Read` instance to an `Iterator` over `char`s. + /// + /// This adaptor will attempt to interpret this reader as a UTF-8 encoded + /// sequence of characters. The returned iterator will return `None` once + /// EOF is reached for this reader. Otherwise each element yielded will be a + /// `Result<char, E>` where `E` may contain information about what I/O error + /// occurred or where decoding failed. + /// + /// Currently this adaptor will discard intermediate data read, and should + /// be avoided if this is not desired. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// #![feature(io)] + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// + /// for c in f.chars() { + /// println!("{}", c.unwrap()); + /// } + /// # Ok(()) + /// # } + /// ``` + #[unstable(feature = "io", reason = "the semantics of a partial read/write \ + of where errors happen is currently \ + unclear and may change", + issue = "27802")] + fn chars(self) -> Chars<Self> where Self: Sized { + Chars { inner: self } + } + + /// Creates an adaptor which will chain this stream with another. + /// + /// The returned `Read` instance will first read all bytes from this object + /// until EOF is encountered. Afterwards the output is equivalent to the + /// output of `next`. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f1 = try!(File::open("foo.txt")); + /// let mut f2 = try!(File::open("bar.txt")); + /// + /// let mut handle = f1.chain(f2); + /// let mut buffer = String::new(); + /// + /// // read the value into a String. We could use any Read method here, + /// // this is just one example. + /// try!(handle.read_to_string(&mut buffer)); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn chain<R: Read>(self, next: R) -> Chain<Self, R> where Self: Sized { + Chain { first: self, second: next, done_first: false } + } + + /// Creates an adaptor which will read at most `limit` bytes from it. + /// + /// This function returns a new instance of `Read` which will read at most + /// `limit` bytes, after which it will always return EOF (`Ok(0)`). Any + /// read errors will not count towards the number of bytes read and future + /// calls to `read` may succeed. + /// + /// # Examples + /// + /// [`File`][file]s implement `Read`: + /// + /// [file]: ../fs/struct.File.html + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut f = try!(File::open("foo.txt")); + /// let mut buffer = [0; 5]; + /// + /// // read at most five bytes + /// let mut handle = f.take(5); + /// + /// try!(handle.read(&mut buffer)); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn take(self, limit: u64) -> Take<Self> where Self: Sized { + Take { inner: self, limit: limit } + } +} + +/// A trait for objects which are byte-oriented sinks. +/// +/// Implementors of the `Write` trait are sometimes called 'writers'. +/// +/// Writers are defined by two required methods, `write()` and `flush()`: +/// +/// * The `write()` method will attempt to write some data into the object, +/// returning how many bytes were successfully written. +/// +/// * The `flush()` method is useful for adaptors and explicit buffers +/// themselves for ensuring that all buffered data has been pushed out to the +/// 'true sink'. +/// +/// Writers are intended to be composable with one another. Many implementors +/// throughout `std::io` take and provide types which implement the `Write` +/// trait. +/// +/// # Examples +/// +/// ``` +/// use std::io::prelude::*; +/// use std::fs::File; +/// +/// # fn foo() -> std::io::Result<()> { +/// let mut buffer = try!(File::create("foo.txt")); +/// +/// try!(buffer.write(b"some bytes")); +/// # Ok(()) +/// # } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub trait Write { + /// Write a buffer into this object, returning how many bytes were written. + /// + /// This function will attempt to write the entire contents of `buf`, but + /// the entire write may not succeed, or the write may also generate an + /// error. A call to `write` represents *at most one* attempt to write to + /// any wrapped object. + /// + /// Calls to `write` are not guaranteed to block waiting for data to be + /// written, and a write which would otherwise block can be indicated through + /// an `Err` variant. + /// + /// If the return value is `Ok(n)` then it must be guaranteed that + /// `0 <= n <= buf.len()`. A return value of `0` typically means that the + /// underlying object is no longer able to accept bytes and will likely not + /// be able to in the future as well, or that the buffer provided is empty. + /// + /// # Errors + /// + /// Each call to `write` may generate an I/O error indicating that the + /// operation could not be completed. If an error is returned then no bytes + /// in the buffer were written to this writer. + /// + /// It is **not** considered an error if the entire buffer could not be + /// written to this writer. + /// + /// # Examples + /// + /// ``` + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> std::io::Result<()> { + /// let mut buffer = try!(File::create("foo.txt")); + /// + /// try!(buffer.write(b"some bytes")); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn write(&mut self, buf: &[u8]) -> Result<usize>; + + /// Flush this output stream, ensuring that all intermediately buffered + /// contents reach their destination. + /// + /// # Errors + /// + /// It is considered an error if not all bytes could be written due to + /// I/O errors or EOF being reached. + /// + /// # Examples + /// + /// ``` + /// use std::io::prelude::*; + /// use std::io::BufWriter; + /// use std::fs::File; + /// + /// # fn foo() -> std::io::Result<()> { + /// let mut buffer = BufWriter::new(try!(File::create("foo.txt"))); + /// + /// try!(buffer.write(b"some bytes")); + /// try!(buffer.flush()); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn flush(&mut self) -> Result<()>; + + /// Attempts to write an entire buffer into this write. + /// + /// This method will continuously call `write` while there is more data to + /// write. This method will not return until the entire buffer has been + /// successfully written or an error occurs. The first error generated from + /// this method will be returned. + /// + /// # Errors + /// + /// This function will return the first error that `write` returns. + /// + /// # Examples + /// + /// ``` + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> std::io::Result<()> { + /// let mut buffer = try!(File::create("foo.txt")); + /// + /// try!(buffer.write_all(b"some bytes")); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn write_all(&mut self, mut buf: &[u8]) -> Result<()> { + while !buf.is_empty() { + match self.write(buf) { + Ok(0) => return Err(Error::new(ErrorKind::WriteZero, + "failed to write whole buffer")), + Ok(n) => buf = &buf[n..], + Err(ref e) if e.kind() == ErrorKind::Interrupted => {} + Err(e) => return Err(e), + } + } + Ok(()) + } + + /// Writes a formatted string into this writer, returning any error + /// encountered. + /// + /// This method is primarily used to interface with the + /// [`format_args!`][formatargs] macro, but it is rare that this should + /// explicitly be called. The [`write!`][write] macro should be favored to + /// invoke this method instead. + /// + /// [formatargs]: ../macro.format_args.html + /// [write]: ../macro.write.html + /// + /// This function internally uses the [`write_all`][writeall] method on + /// this trait and hence will continuously write data so long as no errors + /// are received. This also means that partial writes are not indicated in + /// this signature. + /// + /// [writeall]: #method.write_all + /// + /// # Errors + /// + /// This function will return any I/O error reported while formatting. + /// + /// # Examples + /// + /// ``` + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> std::io::Result<()> { + /// let mut buffer = try!(File::create("foo.txt")); + /// + /// // this call + /// try!(write!(buffer, "{:.*}", 2, 1.234567)); + /// // turns into this: + /// try!(buffer.write_fmt(format_args!("{:.*}", 2, 1.234567))); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn write_fmt(&mut self, fmt: fmt::Arguments) -> Result<()> { + // Create a shim which translates a Write to a fmt::Write and saves + // off I/O errors. instead of discarding them + struct Adaptor<'a, T: ?Sized + 'a> { + inner: &'a mut T, + error: Result<()>, + } + + impl<'a, T: Write + ?Sized> fmt::Write for Adaptor<'a, T> { + fn write_str(&mut self, s: &str) -> fmt::Result { + match self.inner.write_all(s.as_bytes()) { + Ok(()) => Ok(()), + Err(e) => { + self.error = Err(e); + Err(fmt::Error) + } + } + } + } + + let mut output = Adaptor { inner: self, error: Ok(()) }; + match fmt::write(&mut output, fmt) { + Ok(()) => Ok(()), + Err(..) => { + // check if the error came from the underlying `Write` or not + if output.error.is_err() { + output.error + } else { + Err(Error::new(ErrorKind::Other, "formatter error")) + } + } + } + } + + /// Creates a "by reference" adaptor for this instance of `Write`. + /// + /// The returned adaptor also implements `Write` and will simply borrow this + /// current writer. + /// + /// # Examples + /// + /// ``` + /// use std::io::Write; + /// use std::fs::File; + /// + /// # fn foo() -> std::io::Result<()> { + /// let mut buffer = try!(File::create("foo.txt")); + /// + /// let reference = buffer.by_ref(); + /// + /// // we can use reference just like our original buffer + /// try!(reference.write_all(b"some bytes")); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn by_ref(&mut self) -> &mut Self where Self: Sized { self } +} + +/// The `Seek` trait provides a cursor which can be moved within a stream of +/// bytes. +/// +/// The stream typically has a fixed size, allowing seeking relative to either +/// end or the current offset. +/// +/// # Examples +/// +/// [`File`][file]s implement `Seek`: +/// +/// [file]: ../fs/struct.File.html +/// +/// ``` +/// use std::io; +/// use std::io::prelude::*; +/// use std::fs::File; +/// use std::io::SeekFrom; +/// +/// # fn foo() -> io::Result<()> { +/// let mut f = try!(File::open("foo.txt")); +/// +/// // move the cursor 42 bytes from the start of the file +/// try!(f.seek(SeekFrom::Start(42))); +/// # Ok(()) +/// # } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub trait Seek { + /// Seek to an offset, in bytes, in a stream. + /// + /// A seek beyond the end of a stream is allowed, but implementation + /// defined. + /// + /// If the seek operation completed successfully, + /// this method returns the new position from the start of the stream. + /// That position can be used later with [`SeekFrom::Start`]. + /// + /// # Errors + /// + /// Seeking to a negative offset is considered an error. + /// + /// [`SeekFrom::Start`]: enum.SeekFrom.html#variant.Start + #[stable(feature = "rust1", since = "1.0.0")] + fn seek(&mut self, pos: SeekFrom) -> Result<u64>; +} + +/// Enumeration of possible methods to seek within an I/O object. +/// +/// It is used by the [`Seek`] trait. +/// +/// [`Seek`]: trait.Seek.html +#[derive(Copy, PartialEq, Eq, Clone, Debug)] +#[stable(feature = "rust1", since = "1.0.0")] +pub enum SeekFrom { + /// Set the offset to the provided number of bytes. + #[stable(feature = "rust1", since = "1.0.0")] + Start(#[stable(feature = "rust1", since = "1.0.0")] u64), + + /// Set the offset to the size of this object plus the specified number of + /// bytes. + /// + /// It is possible to seek beyond the end of an object, but it's an error to + /// seek before byte 0. + #[stable(feature = "rust1", since = "1.0.0")] + End(#[stable(feature = "rust1", since = "1.0.0")] i64), + + /// Set the offset to the current position plus the specified number of + /// bytes. + /// + /// It is possible to seek beyond the end of an object, but it's an error to + /// seek before byte 0. + #[stable(feature = "rust1", since = "1.0.0")] + Current(#[stable(feature = "rust1", since = "1.0.0")] i64), +} + +fn read_until<R: BufRead + ?Sized>(r: &mut R, delim: u8, buf: &mut Vec<u8>) + -> Result<usize> { + let mut read = 0; + loop { + let (done, used) = { + let available = match r.fill_buf() { + Ok(n) => n, + Err(ref e) if e.kind() == ErrorKind::Interrupted => continue, + Err(e) => return Err(e) + }; + match memchr::memchr(delim, available) { + Some(i) => { + buf.extend_from_slice(&available[..i + 1]); + (true, i + 1) + } + None => { + buf.extend_from_slice(available); + (false, available.len()) + } + } + }; + r.consume(used); + read += used; + if done || used == 0 { + return Ok(read); + } + } +} + +/// A `BufRead` is a type of `Read`er which has an internal buffer, allowing it +/// to perform extra ways of reading. +/// +/// For example, reading line-by-line is inefficient without using a buffer, so +/// if you want to read by line, you'll need `BufRead`, which includes a +/// [`read_line()`] method as well as a [`lines()`] iterator. +/// +/// # Examples +/// +/// A locked standard input implements `BufRead`: +/// +/// ``` +/// use std::io; +/// use std::io::prelude::*; +/// +/// let stdin = io::stdin(); +/// for line in stdin.lock().lines() { +/// println!("{}", line.unwrap()); +/// } +/// ``` +/// +/// If you have something that implements [`Read`], you can use the [`BufReader` +/// type][`BufReader`] to turn it into a `BufRead`. +/// +/// For example, [`File`] implements [`Read`], but not `BufRead`. +/// [`BufReader`] to the rescue! +/// +/// [`BufReader`]: struct.BufReader.html +/// [`File`]: ../fs/struct.File.html +/// [`read_line()`]: #method.read_line +/// [`lines()`]: #method.lines +/// [`Read`]: trait.Read.html +/// +/// ``` +/// use std::io::{self, BufReader}; +/// use std::io::prelude::*; +/// use std::fs::File; +/// +/// # fn foo() -> io::Result<()> { +/// let f = try!(File::open("foo.txt")); +/// let f = BufReader::new(f); +/// +/// for line in f.lines() { +/// println!("{}", line.unwrap()); +/// } +/// +/// # Ok(()) +/// # } +/// ``` +/// +#[stable(feature = "rust1", since = "1.0.0")] +pub trait BufRead: Read { + /// Fills the internal buffer of this object, returning the buffer contents. + /// + /// This function is a lower-level call. It needs to be paired with the + /// [`consume()`] method to function properly. When calling this + /// method, none of the contents will be "read" in the sense that later + /// calling `read` may return the same contents. As such, [`consume()`] must + /// be called with the number of bytes that are consumed from this buffer to + /// ensure that the bytes are never returned twice. + /// + /// [`consume()`]: #tymethod.consume + /// + /// An empty buffer returned indicates that the stream has reached EOF. + /// + /// # Errors + /// + /// This function will return an I/O error if the underlying reader was + /// read, but returned an error. + /// + /// # Examples + /// + /// A locked standard input implements `BufRead`: + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// + /// let stdin = io::stdin(); + /// let mut stdin = stdin.lock(); + /// + /// // we can't have two `&mut` references to `stdin`, so use a block + /// // to end the borrow early. + /// let length = { + /// let buffer = stdin.fill_buf().unwrap(); + /// + /// // work with buffer + /// println!("{:?}", buffer); + /// + /// buffer.len() + /// }; + /// + /// // ensure the bytes we worked with aren't returned again later + /// stdin.consume(length); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn fill_buf(&mut self) -> Result<&[u8]>; + + /// Tells this buffer that `amt` bytes have been consumed from the buffer, + /// so they should no longer be returned in calls to `read`. + /// + /// This function is a lower-level call. It needs to be paired with the + /// [`fill_buf()`] method to function properly. This function does + /// not perform any I/O, it simply informs this object that some amount of + /// its buffer, returned from [`fill_buf()`], has been consumed and should + /// no longer be returned. As such, this function may do odd things if + /// [`fill_buf()`] isn't called before calling it. + /// + /// The `amt` must be `<=` the number of bytes in the buffer returned by + /// [`fill_buf()`]. + /// + /// # Examples + /// + /// Since `consume()` is meant to be used with [`fill_buf()`], + /// that method's example includes an example of `consume()`. + /// + /// [`fill_buf()`]: #tymethod.fill_buf + #[stable(feature = "rust1", since = "1.0.0")] + fn consume(&mut self, amt: usize); + + /// Read all bytes into `buf` until the delimiter `byte` or EOF is reached. + /// + /// This function will read bytes from the underlying stream until the + /// delimiter or EOF is found. Once found, all bytes up to, and including, + /// the delimiter (if found) will be appended to `buf`. + /// + /// If successful, this function will return the total number of bytes read. + /// + /// # Errors + /// + /// This function will ignore all instances of [`ErrorKind::Interrupted`] and + /// will otherwise return any errors returned by [`fill_buf()`]. + /// + /// If an I/O error is encountered then all bytes read so far will be + /// present in `buf` and its length will have been adjusted appropriately. + /// + /// # Examples + /// + /// A locked standard input implements `BufRead`. In this example, we'll + /// read from standard input until we see an `a` byte. + /// + /// [`fill_buf()`]: #tymethod.fill_buf + /// [`ErrorKind::Interrupted`]: enum.ErrorKind.html#variant.Interrupted + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// + /// fn foo() -> io::Result<()> { + /// let stdin = io::stdin(); + /// let mut stdin = stdin.lock(); + /// let mut buffer = Vec::new(); + /// + /// try!(stdin.read_until(b'a', &mut buffer)); + /// + /// println!("{:?}", buffer); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize> { + read_until(self, byte, buf) + } + + /// Read all bytes until a newline (the 0xA byte) is reached, and append + /// them to the provided buffer. + /// + /// This function will read bytes from the underlying stream until the + /// newline delimiter (the 0xA byte) or EOF is found. Once found, all bytes + /// up to, and including, the delimiter (if found) will be appended to + /// `buf`. + /// + /// If successful, this function will return the total number of bytes read. + /// + /// # Errors + /// + /// This function has the same error semantics as [`read_until()`] and will + /// also return an error if the read bytes are not valid UTF-8. If an I/O + /// error is encountered then `buf` may contain some bytes already read in + /// the event that all data read so far was valid UTF-8. + /// + /// # Examples + /// + /// A locked standard input implements `BufRead`. In this example, we'll + /// read all of the lines from standard input. If we were to do this in + /// an actual project, the [`lines()`] method would be easier, of + /// course. + /// + /// [`lines()`]: #method.lines + /// [`read_until()`]: #method.read_until + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// + /// let stdin = io::stdin(); + /// let mut stdin = stdin.lock(); + /// let mut buffer = String::new(); + /// + /// while stdin.read_line(&mut buffer).unwrap() > 0 { + /// // work with buffer + /// println!("{:?}", buffer); + /// + /// buffer.clear(); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn read_line(&mut self, buf: &mut String) -> Result<usize> { + // Note that we are not calling the `.read_until` method here, but + // rather our hardcoded implementation. For more details as to why, see + // the comments in `read_to_end`. + append_to_string(buf, |b| read_until(self, b'\n', b)) + } + + /// Returns an iterator over the contents of this reader split on the byte + /// `byte`. + /// + /// The iterator returned from this function will return instances of + /// [`io::Result`]`<`[`Vec<u8>`]`>`. Each vector returned will *not* have + /// the delimiter byte at the end. + /// + /// This function will yield errors whenever [`read_until()`] would have + /// also yielded an error. + /// + /// # Examples + /// + /// A locked standard input implements `BufRead`. In this example, we'll + /// read some input from standard input, splitting on commas. + /// + /// [`io::Result`]: type.Result.html + /// [`Vec<u8>`]: ../vec/struct.Vec.html + /// [`read_until()`]: #method.read_until + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// + /// let stdin = io::stdin(); + /// + /// for content in stdin.lock().split(b',') { + /// println!("{:?}", content.unwrap()); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn split(self, byte: u8) -> Split<Self> where Self: Sized { + Split { buf: self, delim: byte } + } + + /// Returns an iterator over the lines of this reader. + /// + /// The iterator returned from this function will yield instances of + /// [`io::Result`]`<`[`String`]`>`. Each string returned will *not* have a newline + /// byte (the 0xA byte) or CRLF (0xD, 0xA bytes) at the end. + /// + /// [`io::Result`]: type.Result.html + /// [`String`]: ../string/struct.String.html + /// + /// # Examples + /// + /// A locked standard input implements `BufRead`: + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// + /// let stdin = io::stdin(); + /// + /// for line in stdin.lock().lines() { + /// println!("{}", line.unwrap()); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + fn lines(self) -> Lines<Self> where Self: Sized { + Lines { buf: self } + } +} + +/// Adaptor to chain together two readers. +/// +/// This struct is generally created by calling [`chain()`] on a reader. +/// Please see the documentation of [`chain()`] for more details. +/// +/// [`chain()`]: trait.Read.html#method.chain +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Chain<T, U> { + first: T, + second: U, + done_first: bool, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: Read, U: Read> Read for Chain<T, U> { + fn read(&mut self, buf: &mut [u8]) -> Result<usize> { + if !self.done_first { + match self.first.read(buf)? { + 0 if buf.len() != 0 => { self.done_first = true; } + n => return Ok(n), + } + } + self.second.read(buf) + } +} + +#[stable(feature = "chain_bufread", since = "1.9.0")] +impl<T: BufRead, U: BufRead> BufRead for Chain<T, U> { + fn fill_buf(&mut self) -> Result<&[u8]> { + if !self.done_first { + match self.first.fill_buf()? { + buf if buf.len() == 0 => { self.done_first = true; } + buf => return Ok(buf), + } + } + self.second.fill_buf() + } + + fn consume(&mut self, amt: usize) { + if !self.done_first { + self.first.consume(amt) + } else { + self.second.consume(amt) + } + } +} + +/// Reader adaptor which limits the bytes read from an underlying reader. +/// +/// This struct is generally created by calling [`take()`][take] on a reader. +/// Please see the documentation of `take()` for more details. +/// +/// [take]: trait.Read.html#method.take +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Take<T> { + inner: T, + limit: u64, +} + +impl<T> Take<T> { + /// Returns the number of bytes that can be read before this instance will + /// return EOF. + /// + /// # Note + /// + /// This instance may reach EOF after reading fewer bytes than indicated by + /// this method if the underlying `Read` instance reaches EOF. + /// + /// # Examples + /// + /// ``` + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let f = try!(File::open("foo.txt")); + /// + /// // read at most five bytes + /// let handle = f.take(5); + /// + /// println!("limit: {}", handle.limit()); + /// # Ok(()) + /// # } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn limit(&self) -> u64 { self.limit } + + /// Consumes the `Take`, returning the wrapped reader. + /// + /// # Examples + /// + /// ``` + /// #![feature(io_take_into_inner)] + /// + /// use std::io; + /// use std::io::prelude::*; + /// use std::fs::File; + /// + /// # fn foo() -> io::Result<()> { + /// let mut file = try!(File::open("foo.txt")); + /// + /// let mut buffer = [0; 5]; + /// let mut handle = file.take(5); + /// try!(handle.read(&mut buffer)); + /// + /// let file = handle.into_inner(); + /// # Ok(()) + /// # } + /// ``` + #[unstable(feature = "io_take_into_inner", issue = "23755")] + pub fn into_inner(self) -> T { + self.inner + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: Read> Read for Take<T> { + fn read(&mut self, buf: &mut [u8]) -> Result<usize> { + // Don't call into inner reader at all at EOF because it may still block + if self.limit == 0 { + return Ok(0); + } + + let max = cmp::min(buf.len() as u64, self.limit) as usize; + let n = self.inner.read(&mut buf[..max])?; + self.limit -= n as u64; + Ok(n) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: BufRead> BufRead for Take<T> { + fn fill_buf(&mut self) -> Result<&[u8]> { + // Don't call into inner reader at all at EOF because it may still block + if self.limit == 0 { + return Ok(&[]); + } + + let buf = self.inner.fill_buf()?; + let cap = cmp::min(buf.len() as u64, self.limit) as usize; + Ok(&buf[..cap]) + } + + fn consume(&mut self, amt: usize) { + // Don't let callers reset the limit by passing an overlarge value + let amt = cmp::min(amt as u64, self.limit) as usize; + self.limit -= amt as u64; + self.inner.consume(amt); + } +} + +fn read_one_byte(reader: &mut Read) -> Option<Result<u8>> { + let mut buf = [0]; + loop { + return match reader.read(&mut buf) { + Ok(0) => None, + Ok(..) => Some(Ok(buf[0])), + Err(ref e) if e.kind() == ErrorKind::Interrupted => continue, + Err(e) => Some(Err(e)), + }; + } +} + +/// An iterator over `u8` values of a reader. +/// +/// This struct is generally created by calling [`bytes()`] on a reader. +/// Please see the documentation of [`bytes()`] for more details. +/// +/// [`bytes()`]: trait.Read.html#method.bytes +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Bytes<R> { + inner: R, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<R: Read> Iterator for Bytes<R> { + type Item = Result<u8>; + + fn next(&mut self) -> Option<Result<u8>> { + read_one_byte(&mut self.inner) + } +} + +/// An iterator over the `char`s of a reader. +/// +/// This struct is generally created by calling [`chars()`][chars] on a reader. +/// Please see the documentation of `chars()` for more details. +/// +/// [chars]: trait.Read.html#method.chars +#[unstable(feature = "io", reason = "awaiting stability of Read::chars", + issue = "27802")] +pub struct Chars<R> { + inner: R, +} + +/// An enumeration of possible errors that can be generated from the `Chars` +/// adapter. +#[derive(Debug)] +#[unstable(feature = "io", reason = "awaiting stability of Read::chars", + issue = "27802")] +pub enum CharsError { + /// Variant representing that the underlying stream was read successfully + /// but it did not contain valid utf8 data. + NotUtf8, + + /// Variant representing that an I/O error occurred. + Other(Error), +} + +#[unstable(feature = "io", reason = "awaiting stability of Read::chars", + issue = "27802")] +impl<R: Read> Iterator for Chars<R> { + type Item = result::Result<char, CharsError>; + + fn next(&mut self) -> Option<result::Result<char, CharsError>> { + let first_byte = match read_one_byte(&mut self.inner) { + None => return None, + Some(Ok(b)) => b, + Some(Err(e)) => return Some(Err(CharsError::Other(e))), + }; + let width = core_str::utf8_char_width(first_byte); + if width == 1 { return Some(Ok(first_byte as char)) } + if width == 0 { return Some(Err(CharsError::NotUtf8)) } + let mut buf = [first_byte, 0, 0, 0]; + { + let mut start = 1; + while start < width { + match self.inner.read(&mut buf[start..width]) { + Ok(0) => return Some(Err(CharsError::NotUtf8)), + Ok(n) => start += n, + Err(ref e) if e.kind() == ErrorKind::Interrupted => continue, + Err(e) => return Some(Err(CharsError::Other(e))), + } + } + } + Some(match str::from_utf8(&buf[..width]).ok() { + Some(s) => Ok(s.chars().next().unwrap()), + None => Err(CharsError::NotUtf8), + }) + } +} + +#[unstable(feature = "io", reason = "awaiting stability of Read::chars", + issue = "27802")] +impl std_error::Error for CharsError { + fn description(&self) -> &str { + match *self { + CharsError::NotUtf8 => "invalid utf8 encoding", + CharsError::Other(ref e) => std_error::Error::description(e), + } + } + fn cause(&self) -> Option<&std_error::Error> { + match *self { + CharsError::NotUtf8 => None, + CharsError::Other(ref e) => e.cause(), + } + } +} + +#[unstable(feature = "io", reason = "awaiting stability of Read::chars", + issue = "27802")] +impl fmt::Display for CharsError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + CharsError::NotUtf8 => { + "byte stream did not contain valid utf8".fmt(f) + } + CharsError::Other(ref e) => e.fmt(f), + } + } +} + +/// An iterator over the contents of an instance of `BufRead` split on a +/// particular byte. +/// +/// This struct is generally created by calling [`split()`][split] on a +/// `BufRead`. Please see the documentation of `split()` for more details. +/// +/// [split]: trait.BufRead.html#method.split +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Split<B> { + buf: B, + delim: u8, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<B: BufRead> Iterator for Split<B> { + type Item = Result<Vec<u8>>; + + fn next(&mut self) -> Option<Result<Vec<u8>>> { + let mut buf = Vec::new(); + match self.buf.read_until(self.delim, &mut buf) { + Ok(0) => None, + Ok(_n) => { + if buf[buf.len() - 1] == self.delim { + buf.pop(); + } + Some(Ok(buf)) + } + Err(e) => Some(Err(e)) + } + } +} + +/// An iterator over the lines of an instance of `BufRead`. +/// +/// This struct is generally created by calling [`lines()`][lines] on a +/// `BufRead`. Please see the documentation of `lines()` for more details. +/// +/// [lines]: trait.BufRead.html#method.lines +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Lines<B> { + buf: B, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<B: BufRead> Iterator for Lines<B> { + type Item = Result<String>; + + fn next(&mut self) -> Option<Result<String>> { + let mut buf = String::new(); + match self.buf.read_line(&mut buf) { + Ok(0) => None, + Ok(_n) => { + if buf.ends_with("\n") { + buf.pop(); + if buf.ends_with("\r") { + buf.pop(); + } + } + Some(Ok(buf)) + } + Err(e) => Some(Err(e)) + } + } +} + +#[cfg(test)] +mod tests { + use io::prelude::*; + use io; + use super::Cursor; + use test; + use super::repeat; + + #[test] + #[cfg_attr(target_os = "emscripten", ignore)] + fn read_until() { + let mut buf = Cursor::new(&b"12"[..]); + let mut v = Vec::new(); + assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 2); + assert_eq!(v, b"12"); + + let mut buf = Cursor::new(&b"1233"[..]); + let mut v = Vec::new(); + assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 3); + assert_eq!(v, b"123"); + v.truncate(0); + assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 1); + assert_eq!(v, b"3"); + v.truncate(0); + assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 0); + assert_eq!(v, []); + } + + #[test] + fn split() { + let buf = Cursor::new(&b"12"[..]); + let mut s = buf.split(b'3'); + assert_eq!(s.next().unwrap().unwrap(), vec![b'1', b'2']); + assert!(s.next().is_none()); + + let buf = Cursor::new(&b"1233"[..]); + let mut s = buf.split(b'3'); + assert_eq!(s.next().unwrap().unwrap(), vec![b'1', b'2']); + assert_eq!(s.next().unwrap().unwrap(), vec![]); + assert!(s.next().is_none()); + } + + #[test] + fn read_line() { + let mut buf = Cursor::new(&b"12"[..]); + let mut v = String::new(); + assert_eq!(buf.read_line(&mut v).unwrap(), 2); + assert_eq!(v, "12"); + + let mut buf = Cursor::new(&b"12\n\n"[..]); + let mut v = String::new(); + assert_eq!(buf.read_line(&mut v).unwrap(), 3); + assert_eq!(v, "12\n"); + v.truncate(0); + assert_eq!(buf.read_line(&mut v).unwrap(), 1); + assert_eq!(v, "\n"); + v.truncate(0); + assert_eq!(buf.read_line(&mut v).unwrap(), 0); + assert_eq!(v, ""); + } + + #[test] + fn lines() { + let buf = Cursor::new(&b"12\r"[..]); + let mut s = buf.lines(); + assert_eq!(s.next().unwrap().unwrap(), "12\r".to_string()); + assert!(s.next().is_none()); + + let buf = Cursor::new(&b"12\r\n\n"[..]); + let mut s = buf.lines(); + assert_eq!(s.next().unwrap().unwrap(), "12".to_string()); + assert_eq!(s.next().unwrap().unwrap(), "".to_string()); + assert!(s.next().is_none()); + } + + #[test] + fn read_to_end() { + let mut c = Cursor::new(&b""[..]); + let mut v = Vec::new(); + assert_eq!(c.read_to_end(&mut v).unwrap(), 0); + assert_eq!(v, []); + + let mut c = Cursor::new(&b"1"[..]); + let mut v = Vec::new(); + assert_eq!(c.read_to_end(&mut v).unwrap(), 1); + assert_eq!(v, b"1"); + + let cap = 1024 * 1024; + let data = (0..cap).map(|i| (i / 3) as u8).collect::<Vec<_>>(); + let mut v = Vec::new(); + let (a, b) = data.split_at(data.len() / 2); + assert_eq!(Cursor::new(a).read_to_end(&mut v).unwrap(), a.len()); + assert_eq!(Cursor::new(b).read_to_end(&mut v).unwrap(), b.len()); + assert_eq!(v, data); + } + + #[test] + fn read_to_string() { + let mut c = Cursor::new(&b""[..]); + let mut v = String::new(); + assert_eq!(c.read_to_string(&mut v).unwrap(), 0); + assert_eq!(v, ""); + + let mut c = Cursor::new(&b"1"[..]); + let mut v = String::new(); + assert_eq!(c.read_to_string(&mut v).unwrap(), 1); + assert_eq!(v, "1"); + + let mut c = Cursor::new(&b"\xff"[..]); + let mut v = String::new(); + assert!(c.read_to_string(&mut v).is_err()); + } + + #[test] + fn read_exact() { + let mut buf = [0; 4]; + + let mut c = Cursor::new(&b""[..]); + assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), + io::ErrorKind::UnexpectedEof); + + let mut c = Cursor::new(&b"123"[..]).chain(Cursor::new(&b"456789"[..])); + c.read_exact(&mut buf).unwrap(); + assert_eq!(&buf, b"1234"); + c.read_exact(&mut buf).unwrap(); + assert_eq!(&buf, b"5678"); + assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), + io::ErrorKind::UnexpectedEof); + } + + #[test] + fn read_exact_slice() { + let mut buf = [0; 4]; + + let mut c = &b""[..]; + assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), + io::ErrorKind::UnexpectedEof); + + let mut c = &b"123"[..]; + assert_eq!(c.read_exact(&mut buf).unwrap_err().kind(), + io::ErrorKind::UnexpectedEof); + // make sure the optimized (early returning) method is being used + assert_eq!(&buf, &[0; 4]); + + let mut c = &b"1234"[..]; + c.read_exact(&mut buf).unwrap(); + assert_eq!(&buf, b"1234"); + + let mut c = &b"56789"[..]; + c.read_exact(&mut buf).unwrap(); + assert_eq!(&buf, b"5678"); + assert_eq!(c, b"9"); + } + + #[test] + fn take_eof() { + struct R; + + impl Read for R { + fn read(&mut self, _: &mut [u8]) -> io::Result<usize> { + Err(io::Error::new(io::ErrorKind::Other, "")) + } + } + impl BufRead for R { + fn fill_buf(&mut self) -> io::Result<&[u8]> { + Err(io::Error::new(io::ErrorKind::Other, "")) + } + fn consume(&mut self, _amt: usize) { } + } + + let mut buf = [0; 1]; + assert_eq!(0, R.take(0).read(&mut buf).unwrap()); + assert_eq!(b"", R.take(0).fill_buf().unwrap()); + } + + fn cmp_bufread<Br1: BufRead, Br2: BufRead>(mut br1: Br1, mut br2: Br2, exp: &[u8]) { + let mut cat = Vec::new(); + loop { + let consume = { + let buf1 = br1.fill_buf().unwrap(); + let buf2 = br2.fill_buf().unwrap(); + let minlen = if buf1.len() < buf2.len() { buf1.len() } else { buf2.len() }; + assert_eq!(buf1[..minlen], buf2[..minlen]); + cat.extend_from_slice(&buf1[..minlen]); + minlen + }; + if consume == 0 { + break; + } + br1.consume(consume); + br2.consume(consume); + } + assert_eq!(br1.fill_buf().unwrap().len(), 0); + assert_eq!(br2.fill_buf().unwrap().len(), 0); + assert_eq!(&cat[..], &exp[..]) + } + + #[test] + fn chain_bufread() { + let testdata = b"ABCDEFGHIJKL"; + let chain1 = (&testdata[..3]).chain(&testdata[3..6]) + .chain(&testdata[6..9]) + .chain(&testdata[9..]); + let chain2 = (&testdata[..4]).chain(&testdata[4..8]) + .chain(&testdata[8..]); + cmp_bufread(chain1, chain2, &testdata[..]); + } + + #[test] + fn chain_zero_length_read_is_not_eof() { + let a = b"A"; + let b = b"B"; + let mut s = String::new(); + let mut chain = (&a[..]).chain(&b[..]); + chain.read(&mut []).unwrap(); + chain.read_to_string(&mut s).unwrap(); + assert_eq!("AB", s); + } + + #[bench] + #[cfg_attr(target_os = "emscripten", ignore)] + fn bench_read_to_end(b: &mut test::Bencher) { + b.iter(|| { + let mut lr = repeat(1).take(10000000); + let mut vec = Vec::with_capacity(1024); + super::read_to_end(&mut lr, &mut vec) + }); + } +} |