1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515
/*!
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 alloc::{vec, vec::Vec};
use std::io;
use crate::{ext_slice::ByteSlice, ext_vec::ByteVec};
/// An extension 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 mut 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 }
}
/// Returns an iterator over byte-terminated records of this reader, where
/// each record 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 record in the iterator is returned. The record
/// does *not* contain its trailing terminator.
///
/// Note that calling `byte_records(b'\n')` differs from `byte_lines()` in
/// that it has no special handling for `\r`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::io;
///
/// use bstr::io::BufReadExt;
///
/// # fn example() -> Result<(), io::Error> {
/// let mut cursor = io::Cursor::new(b"lorem\x00ipsum\x00dolor");
///
/// let mut records = vec![];
/// for result in cursor.byte_records(b'\x00') {
/// let record = result?;
/// records.push(record);
/// }
/// assert_eq!(records.len(), 3);
/// assert_eq!(records[0], "lorem".as_bytes());
/// assert_eq!(records[1], "ipsum".as_bytes());
/// assert_eq!(records[2], "dolor".as_bytes());
/// # Ok(()) }; example().unwrap()
/// ```
fn byte_records(self, terminator: u8) -> ByteRecords<Self>
where
Self: Sized,
{
ByteRecords { terminator, 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 mut 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>,
{
self.for_byte_line_with_terminator(|line| {
for_each_line(&trim_line_slice(&line))
})
}
/// Executes the given closure on each byte-terminated record 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_records`](trait.BufReadExt.html#method.byte_records)
/// iterator. Namely, records do _not_ contain a trailing terminator byte.
///
/// This routine is useful for iterating over records as quickly as
/// possible. Namely, a single allocation is reused for each record.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::io;
///
/// use bstr::io::BufReadExt;
///
/// # fn example() -> Result<(), io::Error> {
/// let mut cursor = io::Cursor::new(b"lorem\x00ipsum\x00dolor");
///
/// let mut records = vec![];
/// cursor.for_byte_record(b'\x00', |record| {
/// records.push(record.to_vec());
/// Ok(true)
/// })?;
/// assert_eq!(records.len(), 3);
/// assert_eq!(records[0], "lorem".as_bytes());
/// assert_eq!(records[1], "ipsum".as_bytes());
/// assert_eq!(records[2], "dolor".as_bytes());
/// # Ok(()) }; example().unwrap()
/// ```
fn for_byte_record<F>(
&mut self,
terminator: u8,
mut for_each_record: F,
) -> io::Result<()>
where
Self: Sized,
F: FnMut(&[u8]) -> io::Result<bool>,
{
self.for_byte_record_with_terminator(terminator, |chunk| {
for_each_record(&trim_record_slice(&chunk, terminator))
})
}
/// 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.
///
/// This is identical to `for_byte_record_with_terminator` with a
/// terminator of `\n`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::io;
///
/// use bstr::io::BufReadExt;
///
/// # fn example() -> Result<(), io::Error> {
/// let mut 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,
for_each_line: F,
) -> io::Result<()>
where
Self: Sized,
F: FnMut(&[u8]) -> io::Result<bool>,
{
self.for_byte_record_with_terminator(b'\n', for_each_line)
}
/// Executes the given closure on each byte-terminated record 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_record`](trait.BufReadExt.html#method.for_byte_record),
/// the lines given to the closure *do* include the record terminator, if
/// one exists.
///
/// This routine is useful for iterating over records as quickly as
/// possible. Namely, a single allocation is reused for each record.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::io;
///
/// use bstr::{io::BufReadExt, B};
///
/// # fn example() -> Result<(), io::Error> {
/// let mut cursor = io::Cursor::new(b"lorem\x00ipsum\x00dolor");
///
/// let mut records = vec![];
/// cursor.for_byte_record_with_terminator(b'\x00', |record| {
/// records.push(record.to_vec());
/// Ok(true)
/// })?;
/// assert_eq!(records.len(), 3);
/// assert_eq!(records[0], B(b"lorem\x00"));
/// assert_eq!(records[1], B("ipsum\x00"));
/// assert_eq!(records[2], B("dolor"));
/// # Ok(()) }; example().unwrap()
/// ```
fn for_byte_record_with_terminator<F>(
&mut self,
terminator: u8,
mut for_each_record: F,
) -> io::Result<()>
where
Self: Sized,
F: FnMut(&[u8]) -> io::Result<bool>,
{
let mut bytes = vec![];
let mut res = Ok(());
let mut consumed = 0;
'outer: loop {
// Lend out complete record slices from our buffer
{
let mut buf = self.fill_buf()?;
while let Some(index) = buf.find_byte(terminator) {
let (record, rest) = buf.split_at(index + 1);
buf = rest;
consumed += record.len();
match for_each_record(&record) {
Ok(false) => break 'outer,
Err(err) => {
res = Err(err);
break 'outer;
}
_ => (),
}
}
// Copy the final record fragment to our local buffer. This
// saves read_until() from re-scanning a buffer we know
// contains no remaining terminators.
bytes.extend_from_slice(&buf);
consumed += buf.len();
}
self.consume(consumed);
consumed = 0;
// N.B. read_until uses a different version of memchr that may
// be slower than the memchr crate that bstr uses. However, this
// should only run for a fairly small number of records, assuming a
// decent buffer size.
self.read_until(terminator, &mut bytes)?;
if bytes.is_empty() || !for_each_record(&bytes)? {
break;
}
bytes.clear();
}
self.consume(consumed);
res
}
}
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,
}
/// An iterator over records from an instance of
/// [`std::io::BufRead`](https://doc.rust-lang.org/std/io/trait.BufRead.html).
///
/// A byte record is any sequence of bytes terminated by a particular byte
/// chosen by the caller. For example, NUL separated byte strings are said to
/// be NUL-terminated byte records.
///
/// This iterator is generally created by calling the
/// [`byte_records`](trait.BufReadExt.html#method.byte_records)
/// method on the
/// [`BufReadExt`](trait.BufReadExt.html)
/// trait.
#[derive(Debug)]
pub struct ByteRecords<B> {
buf: B,
terminator: u8,
}
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))
}
}
}
}
impl<B: io::BufRead> Iterator for ByteRecords<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(self.terminator, &mut bytes) {
Err(e) => Some(Err(e)),
Ok(0) => None,
Ok(_) => {
trim_record(&mut bytes, self.terminator);
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();
}
}
}
fn trim_line_slice(mut line: &[u8]) -> &[u8] {
if line.last_byte() == Some(b'\n') {
line = &line[..line.len() - 1];
if line.last_byte() == Some(b'\r') {
line = &line[..line.len() - 1];
}
}
line
}
fn trim_record(record: &mut Vec<u8>, terminator: u8) {
if record.last_byte() == Some(terminator) {
record.pop_byte();
}
}
fn trim_record_slice(mut record: &[u8], terminator: u8) -> &[u8] {
if record.last_byte() == Some(terminator) {
record = &record[..record.len() - 1];
}
record
}
#[cfg(all(test, feature = "std"))]
mod tests {
use crate::bstring::BString;
use super::BufReadExt;
fn collect_lines<B: AsRef<[u8]>>(slice: B) -> Vec<BString> {
let mut lines = vec![];
slice
.as_ref()
.for_byte_line(|line| {
lines.push(BString::from(line.to_vec()));
Ok(true)
})
.unwrap();
lines
}
fn collect_lines_term<B: AsRef<[u8]>>(slice: B) -> Vec<BString> {
let mut lines = vec![];
slice
.as_ref()
.for_byte_line_with_terminator(|line| {
lines.push(BString::from(line.to_vec()));
Ok(true)
})
.unwrap();
lines
}
#[test]
fn lines_without_terminator() {
assert_eq!(collect_lines(""), Vec::<BString>::new());
assert_eq!(collect_lines("\n"), vec![""]);
assert_eq!(collect_lines("\n\n"), vec!["", ""]);
assert_eq!(collect_lines("a\nb\n"), vec!["a", "b"]);
assert_eq!(collect_lines("a\nb"), vec!["a", "b"]);
assert_eq!(collect_lines("abc\nxyz\n"), vec!["abc", "xyz"]);
assert_eq!(collect_lines("abc\nxyz"), vec!["abc", "xyz"]);
assert_eq!(collect_lines("\r\n"), vec![""]);
assert_eq!(collect_lines("\r\n\r\n"), vec!["", ""]);
assert_eq!(collect_lines("a\r\nb\r\n"), vec!["a", "b"]);
assert_eq!(collect_lines("a\r\nb"), vec!["a", "b"]);
assert_eq!(collect_lines("abc\r\nxyz\r\n"), vec!["abc", "xyz"]);
assert_eq!(collect_lines("abc\r\nxyz"), vec!["abc", "xyz"]);
assert_eq!(collect_lines("abc\rxyz"), vec!["abc\rxyz"]);
}
#[test]
fn lines_with_terminator() {
assert_eq!(collect_lines_term(""), Vec::<BString>::new());
assert_eq!(collect_lines_term("\n"), vec!["\n"]);
assert_eq!(collect_lines_term("\n\n"), vec!["\n", "\n"]);
assert_eq!(collect_lines_term("a\nb\n"), vec!["a\n", "b\n"]);
assert_eq!(collect_lines_term("a\nb"), vec!["a\n", "b"]);
assert_eq!(collect_lines_term("abc\nxyz\n"), vec!["abc\n", "xyz\n"]);
assert_eq!(collect_lines_term("abc\nxyz"), vec!["abc\n", "xyz"]);
assert_eq!(collect_lines_term("\r\n"), vec!["\r\n"]);
assert_eq!(collect_lines_term("\r\n\r\n"), vec!["\r\n", "\r\n"]);
assert_eq!(collect_lines_term("a\r\nb\r\n"), vec!["a\r\n", "b\r\n"]);
assert_eq!(collect_lines_term("a\r\nb"), vec!["a\r\n", "b"]);
assert_eq!(
collect_lines_term("abc\r\nxyz\r\n"),
vec!["abc\r\n", "xyz\r\n"]
);
assert_eq!(collect_lines_term("abc\r\nxyz"), vec!["abc\r\n", "xyz"]);
assert_eq!(collect_lines_term("abc\rxyz"), vec!["abc\rxyz"]);
}
}