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/*! Utilities for working with I/O using byte strings. This module currently only exports a single trait, `BufReadExt`, which provides facilities for conveniently and efficiently working with lines as byte strings. More APIs may be added in the future. */ use std::io; use ext_slice::ByteSlice; use ext_vec::ByteVec; /// An extention trait for /// [`std::io::BufRead`](https://doc.rust-lang.org/std/io/trait.BufRead.html) /// which provides convenience APIs for dealing with byte strings. pub trait BufReadExt: io::BufRead { /// Returns an iterator over the lines of this reader, where each line /// is represented as a byte string. /// /// Each item yielded by this iterator is a `io::Result<Vec<u8>>`, where /// an error is yielded if there was a problem reading from the underlying /// reader. /// /// On success, the next line in the iterator is returned. The line does /// *not* contain a trailing `\n` or `\r\n`. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::io; /// /// use bstr::io::BufReadExt; /// /// # fn example() -> Result<(), io::Error> { /// let cursor = io::Cursor::new(b"lorem\nipsum\r\ndolor"); /// /// let mut lines = vec![]; /// for result in cursor.byte_lines() { /// let line = result?; /// lines.push(line); /// } /// assert_eq!(lines.len(), 3); /// assert_eq!(lines[0], "lorem".as_bytes()); /// assert_eq!(lines[1], "ipsum".as_bytes()); /// assert_eq!(lines[2], "dolor".as_bytes()); /// # Ok(()) }; example().unwrap() /// ``` fn byte_lines(self) -> ByteLines<Self> where Self: Sized, { ByteLines { buf: self } } /// Executes the given closure on each line in the underlying reader. /// /// If the closure returns an error (or if the underlying reader returns an /// error), then iteration is stopped and the error is returned. If false /// is returned, then iteration is stopped and no error is returned. /// /// The closure given is called on exactly the same values as yielded by /// the [`byte_lines`](trait.BufReadExt.html#method.byte_lines) /// iterator. Namely, lines do _not_ contain trailing `\n` or `\r\n` bytes. /// /// This routine is useful for iterating over lines as quickly as /// possible. Namely, a single allocation is reused for each line. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::io; /// /// use bstr::io::BufReadExt; /// /// # fn example() -> Result<(), io::Error> { /// let cursor = io::Cursor::new(b"lorem\nipsum\r\ndolor"); /// /// let mut lines = vec![]; /// cursor.for_byte_line(|line| { /// lines.push(line.to_vec()); /// Ok(true) /// })?; /// assert_eq!(lines.len(), 3); /// assert_eq!(lines[0], "lorem".as_bytes()); /// assert_eq!(lines[1], "ipsum".as_bytes()); /// assert_eq!(lines[2], "dolor".as_bytes()); /// # Ok(()) }; example().unwrap() /// ``` fn for_byte_line<F>(mut self, mut for_each_line: F) -> io::Result<()> where Self: Sized, F: FnMut(&[u8]) -> io::Result<bool>, { let mut bytes = vec![]; while self.read_until(b'\n', &mut bytes)? > 0 { trim_line(&mut bytes); if !for_each_line(&bytes)? { break; } bytes.clear(); } Ok(()) } /// Executes the given closure on each line in the underlying reader. /// /// If the closure returns an error (or if the underlying reader returns an /// error), then iteration is stopped and the error is returned. If false /// is returned, then iteration is stopped and no error is returned. /// /// Unlike /// [`for_byte_line`](trait.BufReadExt.html#method.for_byte_line), /// the lines given to the closure *do* include the line terminator, if one /// exists. /// /// This routine is useful for iterating over lines as quickly as /// possible. Namely, a single allocation is reused for each line. /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::io; /// /// use bstr::io::BufReadExt; /// /// # fn example() -> Result<(), io::Error> { /// let cursor = io::Cursor::new(b"lorem\nipsum\r\ndolor"); /// /// let mut lines = vec![]; /// cursor.for_byte_line_with_terminator(|line| { /// lines.push(line.to_vec()); /// Ok(true) /// })?; /// assert_eq!(lines.len(), 3); /// assert_eq!(lines[0], "lorem\n".as_bytes()); /// assert_eq!(lines[1], "ipsum\r\n".as_bytes()); /// assert_eq!(lines[2], "dolor".as_bytes()); /// # Ok(()) }; example().unwrap() /// ``` fn for_byte_line_with_terminator<F>( mut self, mut for_each_line: F, ) -> io::Result<()> where Self: Sized, F: FnMut(&[u8]) -> io::Result<bool>, { let mut bytes = vec![]; while self.read_until(b'\n', &mut bytes)? > 0 { if !for_each_line(&bytes)? { break; } bytes.clear(); } Ok(()) } } impl<B: io::BufRead> BufReadExt for B {} /// An iterator over lines from an instance of /// [`std::io::BufRead`](https://doc.rust-lang.org/std/io/trait.BufRead.html). /// /// This iterator is generally created by calling the /// [`byte_lines`](trait.BufReadExt.html#method.byte_lines) /// method on the /// [`BufReadExt`](trait.BufReadExt.html) /// trait. #[derive(Debug)] pub struct ByteLines<B> { buf: B, } impl<B: io::BufRead> Iterator for ByteLines<B> { type Item = io::Result<Vec<u8>>; fn next(&mut self) -> Option<io::Result<Vec<u8>>> { let mut bytes = vec![]; match self.buf.read_until(b'\n', &mut bytes) { Err(e) => Some(Err(e)), Ok(0) => None, Ok(_) => { trim_line(&mut bytes); Some(Ok(bytes)) } } } } fn trim_line(line: &mut Vec<u8>) { if line.last_byte() == Some(b'\n') { line.pop_byte(); if line.last_byte() == Some(b'\r') { line.pop_byte(); } } }