quick_xml/reader/buffered_reader.rs
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
//! This is an implementation of [`Reader`] for reading from a [`BufRead`] as
//! underlying byte stream.
use std::fs::File;
use std::io::{self, BufRead, BufReader};
use std::path::Path;
use crate::errors::{Error, Result};
use crate::events::Event;
use crate::name::QName;
use crate::parser::Parser;
use crate::reader::{BangType, ReadTextResult, Reader, Span, XmlSource};
use crate::utils::is_whitespace;
macro_rules! impl_buffered_source {
($($lf:lifetime, $reader:tt, $async:ident, $await:ident)?) => {
#[cfg(not(feature = "encoding"))]
#[inline]
$($async)? fn remove_utf8_bom(&mut self) -> io::Result<()> {
use crate::encoding::UTF8_BOM;
loop {
break match self $(.$reader)? .fill_buf() $(.$await)? {
Ok(n) => {
if n.starts_with(UTF8_BOM) {
self $(.$reader)? .consume(UTF8_BOM.len());
}
Ok(())
},
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => Err(e),
};
}
}
#[cfg(feature = "encoding")]
#[inline]
$($async)? fn detect_encoding(&mut self) -> io::Result<Option<&'static encoding_rs::Encoding>> {
loop {
break match self $(.$reader)? .fill_buf() $(.$await)? {
Ok(n) => if let Some((enc, bom_len)) = crate::encoding::detect_encoding(n) {
self $(.$reader)? .consume(bom_len);
Ok(Some(enc))
} else {
Ok(None)
},
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => Err(e),
};
}
}
#[inline]
$($async)? fn read_text $(<$lf>)? (
&mut self,
buf: &'b mut Vec<u8>,
position: &mut u64,
) -> ReadTextResult<'b, &'b mut Vec<u8>> {
let mut read = 0;
let start = buf.len();
loop {
let available = match self $(.$reader)? .fill_buf() $(.$await)? {
Ok(n) if n.is_empty() => break,
Ok(n) => n,
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => {
*position += read;
return ReadTextResult::Err(e);
}
};
match memchr::memchr(b'<', available) {
// Special handling is needed only on the first iteration.
// On next iterations we already read something and should emit Text event
Some(0) if read == 0 => {
self $(.$reader)? .consume(1);
*position += 1;
return ReadTextResult::Markup(buf);
}
Some(i) => {
buf.extend_from_slice(&available[..i]);
let used = i + 1;
self $(.$reader)? .consume(used);
read += used as u64;
*position += read;
return ReadTextResult::UpToMarkup(&buf[start..]);
}
None => {
buf.extend_from_slice(available);
let used = available.len();
self $(.$reader)? .consume(used);
read += used as u64;
}
}
}
*position += read;
ReadTextResult::UpToEof(&buf[start..])
}
#[inline]
$($async)? fn read_with<$($lf,)? P: Parser>(
&mut self,
mut parser: P,
buf: &'b mut Vec<u8>,
position: &mut u64,
) -> Result<&'b [u8]> {
let mut read = 0;
let start = buf.len();
loop {
let available = match self $(.$reader)? .fill_buf() $(.$await)? {
Ok(n) if n.is_empty() => break,
Ok(n) => n,
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => {
*position += read;
return Err(Error::Io(e.into()));
}
};
if let Some(i) = parser.feed(available) {
buf.extend_from_slice(&available[..i]);
// +1 for `>` which we do not include
self $(.$reader)? .consume(i + 1);
read += i as u64 + 1;
*position += read;
return Ok(&buf[start..]);
}
// The `>` symbol not yet found, continue reading
buf.extend_from_slice(available);
let used = available.len();
self $(.$reader)? .consume(used);
read += used as u64;
}
*position += read;
Err(Error::Syntax(P::eof_error()))
}
#[inline]
$($async)? fn read_bang_element $(<$lf>)? (
&mut self,
buf: &'b mut Vec<u8>,
position: &mut u64,
) -> Result<(BangType, &'b [u8])> {
// Peeked one bang ('!') before being called, so it's guaranteed to
// start with it.
let start = buf.len();
let mut read = 1;
buf.push(b'!');
self $(.$reader)? .consume(1);
let mut bang_type = BangType::new(self.peek_one() $(.$await)? ?)?;
loop {
match self $(.$reader)? .fill_buf() $(.$await)? {
// Note: Do not update position, so the error points to
// somewhere sane rather than at the EOF
Ok(n) if n.is_empty() => break,
Ok(available) => {
// We only parse from start because we don't want to consider
// whatever is in the buffer before the bang element
if let Some((consumed, used)) = bang_type.parse(&buf[start..], available) {
buf.extend_from_slice(consumed);
self $(.$reader)? .consume(used);
read += used as u64;
*position += read;
return Ok((bang_type, &buf[start..]));
} else {
buf.extend_from_slice(available);
let used = available.len();
self $(.$reader)? .consume(used);
read += used as u64;
}
}
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => {
*position += read;
return Err(Error::Io(e.into()));
}
}
}
*position += read;
Err(bang_type.to_err().into())
}
#[inline]
$($async)? fn skip_whitespace(&mut self, position: &mut u64) -> io::Result<()> {
loop {
break match self $(.$reader)? .fill_buf() $(.$await)? {
Ok(n) => {
let count = n.iter().position(|b| !is_whitespace(*b)).unwrap_or(n.len());
if count > 0 {
self $(.$reader)? .consume(count);
*position += count as u64;
continue;
} else {
Ok(())
}
}
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => Err(e),
};
}
}
#[inline]
$($async)? fn peek_one(&mut self) -> io::Result<Option<u8>> {
loop {
break match self $(.$reader)? .fill_buf() $(.$await)? {
Ok(n) => Ok(n.first().cloned()),
Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
Err(e) => Err(e),
};
}
}
};
}
// Make it public for use in async implementations.
// New rustc reports
// > warning: the item `impl_buffered_source` is imported redundantly
// so make it public only when async feature is enabled
#[cfg(feature = "async-tokio")]
pub(super) use impl_buffered_source;
/// Implementation of `XmlSource` for any `BufRead` reader using a user-given
/// `Vec<u8>` as buffer that will be borrowed by events.
impl<'b, R: BufRead> XmlSource<'b, &'b mut Vec<u8>> for R {
impl_buffered_source!();
}
////////////////////////////////////////////////////////////////////////////////////////////////////
/// This is an implementation for reading from a [`BufRead`] as underlying byte stream.
impl<R: BufRead> Reader<R> {
/// Reads the next `Event`.
///
/// This is the main entry point for reading XML `Event`s.
///
/// `Event`s borrow `buf` and can be converted to own their data if needed (uses `Cow`
/// internally).
///
/// Having the possibility to control the internal buffers gives you some additional benefits
/// such as:
///
/// - Reduce the number of allocations by reusing the same buffer. For constrained systems,
/// you can call `buf.clear()` once you are done with processing the event (typically at the
/// end of your loop).
/// - Reserve the buffer length if you know the file size (using `Vec::with_capacity`).
///
/// # Examples
///
/// ```
/// # use pretty_assertions::assert_eq;
/// use quick_xml::events::Event;
/// use quick_xml::reader::Reader;
///
/// let xml = r#"<tag1 att1 = "test">
/// <tag2><!--Test comment-->Test</tag2>
/// <tag2>Test 2</tag2>
/// </tag1>"#;
/// let mut reader = Reader::from_str(xml);
/// reader.config_mut().trim_text(true);
/// let mut count = 0;
/// let mut buf = Vec::new();
/// let mut txt = Vec::new();
/// loop {
/// match reader.read_event_into(&mut buf) {
/// Ok(Event::Start(_)) => count += 1,
/// Ok(Event::Text(e)) => txt.push(e.unescape().unwrap().into_owned()),
/// Err(e) => panic!("Error at position {}: {:?}", reader.error_position(), e),
/// Ok(Event::Eof) => break,
/// _ => (),
/// }
/// buf.clear();
/// }
/// assert_eq!(count, 3);
/// assert_eq!(txt, vec!["Test".to_string(), "Test 2".to_string()]);
/// ```
#[inline]
pub fn read_event_into<'b>(&mut self, buf: &'b mut Vec<u8>) -> Result<Event<'b>> {
self.read_event_impl(buf)
}
/// Reads until end element is found using provided buffer as intermediate
/// storage for events content. This function is supposed to be called after
/// you already read a [`Start`] event.
///
/// Returns a span that cover content between `>` of an opening tag and `<` of
/// a closing tag or an empty slice, if [`expand_empty_elements`] is set and
/// this method was called after reading expanded [`Start`] event.
///
/// Manages nested cases where parent and child elements have the _literally_
/// same name.
///
/// If a corresponding [`End`] event is not found, an error of type [`Error::IllFormed`]
/// will be returned. In particularly, that error will be returned if you call
/// this method without consuming the corresponding [`Start`] event first.
///
/// If your reader created from a string slice or byte array slice, it is
/// better to use [`read_to_end()`] method, because it will not copy bytes
/// into intermediate buffer.
///
/// The provided `buf` buffer will be filled only by one event content at time.
/// Before reading of each event the buffer will be cleared. If you know an
/// appropriate size of each event, you can preallocate the buffer to reduce
/// number of reallocations.
///
/// The `end` parameter should contain name of the end element _in the reader
/// encoding_. It is good practice to always get that parameter using
/// [`BytesStart::to_end()`] method.
///
/// The correctness of the skipped events does not checked, if you disabled
/// the [`check_end_names`] option.
///
/// # Namespaces
///
/// While the `Reader` does not support namespace resolution, namespaces
/// does not change the algorithm for comparing names. Although the names
/// `a:name` and `b:name` where both prefixes `a` and `b` resolves to the
/// same namespace, are semantically equivalent, `</b:name>` cannot close
/// `<a:name>`, because according to [the specification]
///
/// > The end of every element that begins with a **start-tag** MUST be marked
/// > by an **end-tag** containing a name that echoes the element's type as
/// > given in the **start-tag**
///
/// # Examples
///
/// This example shows, how you can skip XML content after you read the
/// start event.
///
/// ```
/// # use pretty_assertions::assert_eq;
/// use quick_xml::events::{BytesStart, Event};
/// use quick_xml::reader::Reader;
///
/// let mut reader = Reader::from_str(r#"
/// <outer>
/// <inner>
/// <inner></inner>
/// <inner/>
/// <outer></outer>
/// <outer/>
/// </inner>
/// </outer>
/// "#);
/// reader.config_mut().trim_text(true);
/// let mut buf = Vec::new();
///
/// let start = BytesStart::new("outer");
/// let end = start.to_end().into_owned();
///
/// // First, we read a start event...
/// assert_eq!(reader.read_event_into(&mut buf).unwrap(), Event::Start(start));
///
/// // ...then, we could skip all events to the corresponding end event.
/// // This call will correctly handle nested <outer> elements.
/// // Note, however, that this method does not handle namespaces.
/// reader.read_to_end_into(end.name(), &mut buf).unwrap();
///
/// // At the end we should get an Eof event, because we ate the whole XML
/// assert_eq!(reader.read_event_into(&mut buf).unwrap(), Event::Eof);
/// ```
///
/// [`Start`]: Event::Start
/// [`End`]: Event::End
/// [`BytesStart::to_end()`]: crate::events::BytesStart::to_end
/// [`read_to_end()`]: Self::read_to_end
/// [`expand_empty_elements`]: crate::reader::Config::expand_empty_elements
/// [`check_end_names`]: crate::reader::Config::check_end_names
/// [the specification]: https://www.w3.org/TR/xml11/#dt-etag
pub fn read_to_end_into(&mut self, end: QName, buf: &mut Vec<u8>) -> Result<Span> {
Ok(read_to_end!(self, end, buf, read_event_impl, {
buf.clear();
}))
}
}
impl Reader<BufReader<File>> {
/// Creates an XML reader from a file path.
pub fn from_file<P: AsRef<Path>>(path: P) -> Result<Self> {
let file = File::open(path)?;
let reader = BufReader::new(file);
Ok(Self::from_reader(reader))
}
}
#[cfg(test)]
mod test {
use crate::reader::test::check;
use crate::reader::XmlSource;
/// Default buffer constructor just pass the byte array from the test
fn identity<T>(input: T) -> T {
input
}
check!(
#[test]
read_event_impl,
read_until_close,
identity,
&mut Vec::new()
);
}