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//! This is an implementation of [`Reader`] for reading from a [`AsyncBufRead`]
//! as underlying byte stream. This reader fully implements async/await so reading
//! can use non-blocking I/O.
use std::future::Future;
use std::pin::Pin;
use tokio::io::{self, AsyncBufRead, AsyncBufReadExt};
use crate::events::Event;
use crate::name::{QName, ResolveResult};
use crate::reader::buffered_reader::impl_buffered_source;
use crate::reader::{
is_whitespace, BangType, NsReader, ParseState, ReadElementState, Reader, Span,
};
use crate::{Error, Result};
/// A struct for read XML asynchronously from an [`AsyncBufRead`].
///
/// Having own struct allows us to implement anything without risk of name conflicts
/// and does not suffer from the impossibility of having `async` in traits.
struct TokioAdapter<'a, R>(&'a mut R);
impl<'a, R: AsyncBufRead + Unpin> TokioAdapter<'a, R> {
impl_buffered_source!('b, 0, async, await);
}
////////////////////////////////////////////////////////////////////////////////////////////////////
impl<R: AsyncBufRead + Unpin> Reader<R> {
/// An asynchronous version of [`read_event_into()`]. Reads the next event into
/// given buffer.
///
/// > This function should be defined as
/// > ```ignore
/// > pub async fn read_event_into_async<'b>(
/// > &mut self,
/// > buf: &'b mut Vec<u8>
/// > ) -> Result<Event<'b>>;
/// > ```
/// > but Rust does not allow to write that for recursive asynchronous function
///
/// This is the main entry point for reading XML `Event`s when using an async reader.
///
/// See the documentation of [`read_event_into()`] for more information.
///
/// # Examples
///
/// ```
/// # tokio_test::block_on(async {
/// # use pretty_assertions::assert_eq;
/// use quick_xml::events::Event;
/// use quick_xml::reader::Reader;
///
/// // This explicitly uses `from_reader("...".as_bytes())` to use a buffered
/// // reader instead of relying on the zero-copy optimizations for reading
/// // from byte slices, which is provides the sync interface anyway.
/// let mut reader = Reader::from_reader(r#"
/// <tag1 att1 = "test">
/// <tag2><!--Test comment-->Test</tag2>
/// <tag2>Test 2</tag2>
/// </tag1>
/// "#.as_bytes());
/// reader.trim_text(true);
///
/// let mut count = 0;
/// let mut buf = Vec::new();
/// let mut txt = Vec::new();
/// loop {
/// match reader.read_event_into_async(&mut buf).await {
/// Ok(Event::Start(_)) => count += 1,
/// Ok(Event::Text(e)) => txt.push(e.unescape().unwrap().into_owned()),
/// Err(e) => panic!("Error at position {}: {:?}", reader.buffer_position(), e),
/// Ok(Event::Eof) => break,
/// _ => (),
/// }
/// buf.clear();
/// }
/// assert_eq!(count, 3);
/// assert_eq!(txt, vec!["Test".to_string(), "Test 2".to_string()]);
/// # }) // tokio_test::block_on
/// ```
///
/// [`read_event_into()`]: Reader::read_event_into
pub fn read_event_into_async<'reader, 'b: 'reader>(
&'reader mut self,
buf: &'b mut Vec<u8>,
) -> Pin<Box<dyn Future<Output = Result<Event<'b>>> + 'reader>> {
Box::pin(async move {
read_event_impl!(
self, buf,
TokioAdapter(&mut self.reader),
read_until_open_async,
read_until_close_async,
await
)
})
}
/// An asynchronous version of [`read_to_end_into()`].
/// Reads asynchronously 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.
///
/// See the documentation of [`read_to_end_into()`] for more information.
///
/// # Examples
///
/// This example shows, how you can skip XML content after you read the
/// start event.
///
/// ```
/// # tokio_test::block_on(async {
/// # use pretty_assertions::assert_eq;
/// use quick_xml::events::{BytesStart, Event};
/// use quick_xml::reader::Reader;
///
/// let mut reader = Reader::from_reader(r#"
/// <outer>
/// <inner>
/// <inner></inner>
/// <inner/>
/// <outer></outer>
/// <outer/>
/// </inner>
/// </outer>
/// "#.as_bytes());
/// reader.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_async(&mut buf).await.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_async(end.name(), &mut buf).await.unwrap();
///
/// // At the end we should get an Eof event, because we ate the whole XML
/// assert_eq!(reader.read_event_into_async(&mut buf).await.unwrap(), Event::Eof);
/// # }) // tokio_test::block_on
/// ```
///
/// [`read_to_end_into()`]: Self::read_to_end_into
/// [`Start`]: Event::Start
pub async fn read_to_end_into_async<'n>(
&mut self,
// We should name that lifetime due to https://github.com/rust-lang/rust/issues/63033`
end: QName<'n>,
buf: &mut Vec<u8>,
) -> Result<Span> {
Ok(read_to_end!(self, end, buf, read_event_into_async, { buf.clear(); }, await))
}
/// Read until '<' is found, moves reader to an `OpenedTag` state and returns a `Text` event.
async fn read_until_open_async<'b>(&mut self, buf: &'b mut Vec<u8>) -> Result<Event<'b>> {
read_until_open!(self, buf, TokioAdapter(&mut self.reader), read_event_into_async, await)
}
/// Private function to read until `>` is found. This function expects that
/// it was called just after encounter a `<` symbol.
async fn read_until_close_async<'b>(&mut self, buf: &'b mut Vec<u8>) -> Result<Event<'b>> {
read_until_close!(self, buf, TokioAdapter(&mut self.reader), await)
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////
impl<R: AsyncBufRead + Unpin> NsReader<R> {
/// An asynchronous version of [`read_event_into()`]. Reads the next event into
/// given buffer.
///
/// This method manages namespaces but doesn't resolve them automatically.
/// You should call [`resolve_element()`] if you want to get a namespace.
///
/// You also can use [`read_resolved_event_into_async()`] instead if you want
/// to resolve namespace as soon as you get an event.
///
/// # Examples
///
/// ```
/// # tokio_test::block_on(async {
/// # use pretty_assertions::assert_eq;
/// use quick_xml::events::Event;
/// use quick_xml::name::{Namespace, ResolveResult::*};
/// use quick_xml::reader::NsReader;
///
/// let mut reader = NsReader::from_reader(r#"
/// <x:tag1 xmlns:x="www.xxxx" xmlns:y="www.yyyy" att1 = "test">
/// <y:tag2><!--Test comment-->Test</y:tag2>
/// <y:tag2>Test 2</y:tag2>
/// </x:tag1>
/// "#.as_bytes());
/// reader.trim_text(true);
///
/// let mut count = 0;
/// let mut buf = Vec::new();
/// let mut txt = Vec::new();
/// loop {
/// match reader.read_event_into_async(&mut buf).await.unwrap() {
/// Event::Start(e) => {
/// count += 1;
/// let (ns, local) = reader.resolve_element(e.name());
/// match local.as_ref() {
/// b"tag1" => assert_eq!(ns, Bound(Namespace(b"www.xxxx"))),
/// b"tag2" => assert_eq!(ns, Bound(Namespace(b"www.yyyy"))),
/// _ => unreachable!(),
/// }
/// }
/// Event::Text(e) => {
/// txt.push(e.unescape().unwrap().into_owned())
/// }
/// Event::Eof => break,
/// _ => (),
/// }
/// buf.clear();
/// }
/// assert_eq!(count, 3);
/// assert_eq!(txt, vec!["Test".to_string(), "Test 2".to_string()]);
/// # }) // tokio_test::block_on
/// ```
///
/// [`read_event_into()`]: NsReader::read_event_into
/// [`resolve_element()`]: Self::resolve_element
/// [`read_resolved_event_into_async()`]: Self::read_resolved_event_into_async
pub async fn read_event_into_async<'b>(&mut self, buf: &'b mut Vec<u8>) -> Result<Event<'b>> {
self.pop();
let event = self.reader.read_event_into_async(buf).await;
self.process_event(event)
}
/// An asynchronous version of [`read_to_end_into()`].
/// Reads asynchronously 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.
///
/// See the documentation of [`read_to_end_into()`] for more information.
///
/// # Examples
///
/// This example shows, how you can skip XML content after you read the
/// start event.
///
/// ```
/// # tokio_test::block_on(async {
/// # use pretty_assertions::assert_eq;
/// use quick_xml::name::{Namespace, ResolveResult};
/// use quick_xml::events::{BytesStart, Event};
/// use quick_xml::reader::NsReader;
///
/// let mut reader = NsReader::from_reader(r#"
/// <outer xmlns="namespace 1">
/// <inner xmlns="namespace 2">
/// <outer></outer>
/// </inner>
/// <inner>
/// <inner></inner>
/// <inner/>
/// <outer></outer>
/// <p:outer xmlns:p="ns"></p:outer>
/// <outer/>
/// </inner>
/// </outer>
/// "#.as_bytes());
/// reader.trim_text(true);
/// let mut buf = Vec::new();
///
/// let ns = Namespace(b"namespace 1");
/// let start = BytesStart::from_content(r#"outer xmlns="namespace 1""#, 5);
/// let end = start.to_end().into_owned();
///
/// // First, we read a start event...
/// assert_eq!(
/// reader.read_resolved_event_into_async(&mut buf).await.unwrap(),
/// (ResolveResult::Bound(ns), 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_async(end.name(), &mut buf).await.unwrap();
///
/// // At the end we should get an Eof event, because we ate the whole XML
/// assert_eq!(
/// reader.read_resolved_event_into_async(&mut buf).await.unwrap(),
/// (ResolveResult::Unbound, Event::Eof)
/// );
/// # }) // tokio_test::block_on
/// ```
///
/// [`read_to_end_into()`]: Self::read_to_end_into
/// [`Start`]: Event::Start
pub async fn read_to_end_into_async<'n>(
&mut self,
// We should name that lifetime due to https://github.com/rust-lang/rust/issues/63033`
end: QName<'n>,
buf: &mut Vec<u8>,
) -> Result<Span> {
// According to the https://www.w3.org/TR/xml11/#dt-etag, end name should
// match literally the start name. See `Reader::check_end_names` documentation
self.reader.read_to_end_into_async(end, buf).await
}
/// An asynchronous version of [`read_resolved_event_into()`]. Reads the next
/// event into given buffer asynchronously and resolves its namespace (if applicable).
///
/// Namespace is resolved only for [`Start`], [`Empty`] and [`End`] events.
/// For all other events the concept of namespace is not defined, so
/// a [`ResolveResult::Unbound`] is returned.
///
/// If you are not interested in namespaces, you can use [`read_event_into_async()`]
/// which will not automatically resolve namespaces for you.
///
/// # Examples
///
/// ```
/// # tokio_test::block_on(async {
/// # use pretty_assertions::assert_eq;
/// use quick_xml::events::Event;
/// use quick_xml::name::{Namespace, QName, ResolveResult::*};
/// use quick_xml::reader::NsReader;
///
/// let mut reader = NsReader::from_reader(r#"
/// <x:tag1 xmlns:x="www.xxxx" xmlns:y="www.yyyy" att1 = "test">
/// <y:tag2><!--Test comment-->Test</y:tag2>
/// <y:tag2>Test 2</y:tag2>
/// </x:tag1>
/// "#.as_bytes());
/// reader.trim_text(true);
///
/// let mut count = 0;
/// let mut buf = Vec::new();
/// let mut txt = Vec::new();
/// loop {
/// match reader.read_resolved_event_into_async(&mut buf).await.unwrap() {
/// (Bound(Namespace(b"www.xxxx")), Event::Start(e)) => {
/// count += 1;
/// assert_eq!(e.local_name(), QName(b"tag1").into());
/// }
/// (Bound(Namespace(b"www.yyyy")), Event::Start(e)) => {
/// count += 1;
/// assert_eq!(e.local_name(), QName(b"tag2").into());
/// }
/// (_, Event::Start(_)) => unreachable!(),
///
/// (_, Event::Text(e)) => {
/// txt.push(e.unescape().unwrap().into_owned())
/// }
/// (_, Event::Eof) => break,
/// _ => (),
/// }
/// buf.clear();
/// }
/// assert_eq!(count, 3);
/// assert_eq!(txt, vec!["Test".to_string(), "Test 2".to_string()]);
/// # }) // tokio_test::block_on
/// ```
///
/// [`read_resolved_event_into()`]: NsReader::read_resolved_event_into
/// [`Start`]: Event::Start
/// [`Empty`]: Event::Empty
/// [`End`]: Event::End
/// [`read_event_into_async()`]: Self::read_event_into_async
pub async fn read_resolved_event_into_async<'ns, 'b>(
// Name 'ns lifetime, because otherwise we get an error
// "implicit elided lifetime not allowed here" on ResolveResult
&'ns mut self,
buf: &'b mut Vec<u8>,
) -> Result<(ResolveResult<'ns>, Event<'b>)> {
let event = self.read_event_into_async(buf).await;
self.resolve_event(event)
}
}
#[cfg(test)]
mod test {
use super::TokioAdapter;
use crate::reader::test::{check, small_buffers};
check!(
#[tokio::test]
read_event_into_async,
read_until_close_async,
TokioAdapter,
&mut Vec::new(),
async, await
);
small_buffers!(
#[tokio::test]
read_event_into_async: tokio::io::BufReader<_>,
async, await
);
}