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use crate::io::util::fill_buf::{fill_buf, FillBuf};
use crate::io::util::lines::{lines, Lines};
use crate::io::util::read_line::{read_line, ReadLine};
use crate::io::util::read_until::{read_until, ReadUntil};
use crate::io::util::split::{split, Split};
use crate::io::AsyncBufRead;
cfg_io_util! {
/// An extension trait which adds utility methods to [`AsyncBufRead`] types.
///
/// [`AsyncBufRead`]: crate::io::AsyncBufRead
pub trait AsyncBufReadExt: AsyncBufRead {
/// Reads all bytes into `buf` until the delimiter `byte` or EOF is reached.
///
/// Equivalent to:
///
/// ```ignore
/// async fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize>;
/// ```
///
/// 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.
///
/// If this function returns `Ok(0)`, the stream has reached EOF.
///
/// # 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.
///
/// [`fill_buf`]: AsyncBufRead::poll_fill_buf
/// [`ErrorKind::Interrupted`]: std::io::ErrorKind::Interrupted
///
/// # Cancel safety
///
/// If the method is used as the event in a
/// [`tokio::select!`](crate::select) statement and some other branch
/// completes first, then some data may have been partially read. Any
/// partially read bytes are appended to `buf`, and the method can be
/// called again to continue reading until `byte`.
///
/// This method returns the total number of bytes read. If you cancel
/// the call to `read_until` and then call it again to continue reading,
/// the counter is reset.
///
/// # Examples
///
/// [`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
/// this example, we use [`Cursor`] to read all the bytes in a byte slice
/// in hyphen delimited segments:
///
/// [`Cursor`]: std::io::Cursor
///
/// ```
/// use tokio::io::AsyncBufReadExt;
///
/// use std::io::Cursor;
///
/// #[tokio::main]
/// async fn main() {
/// let mut cursor = Cursor::new(b"lorem-ipsum");
/// let mut buf = vec![];
///
/// // cursor is at 'l'
/// let num_bytes = cursor.read_until(b'-', &mut buf)
/// .await
/// .expect("reading from cursor won't fail");
///
/// assert_eq!(num_bytes, 6);
/// assert_eq!(buf, b"lorem-");
/// buf.clear();
///
/// // cursor is at 'i'
/// let num_bytes = cursor.read_until(b'-', &mut buf)
/// .await
/// .expect("reading from cursor won't fail");
///
/// assert_eq!(num_bytes, 5);
/// assert_eq!(buf, b"ipsum");
/// buf.clear();
///
/// // cursor is at EOF
/// let num_bytes = cursor.read_until(b'-', &mut buf)
/// .await
/// .expect("reading from cursor won't fail");
/// assert_eq!(num_bytes, 0);
/// assert_eq!(buf, b"");
/// }
/// ```
fn read_until<'a>(&'a mut self, byte: u8, buf: &'a mut Vec<u8>) -> ReadUntil<'a, Self>
where
Self: Unpin,
{
read_until(self, byte, buf)
}
/// Reads all bytes until a newline (the 0xA byte) is reached, and append
/// them to the provided buffer.
///
/// Equivalent to:
///
/// ```ignore
/// async fn read_line(&mut self, buf: &mut String) -> io::Result<usize>;
/// ```
///
/// 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.
///
/// If this function returns `Ok(0)`, the stream has reached EOF.
///
/// # 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.
///
/// [`read_until`]: AsyncBufReadExt::read_until
///
/// # Cancel safety
///
/// This method is not cancellation safe. If the method is used as the
/// event in a [`tokio::select!`](crate::select) statement and some
/// other branch completes first, then some data may have been partially
/// read, and this data is lost. There are no guarantees regarding the
/// contents of `buf` when the call is cancelled. The current
/// implementation replaces `buf` with the empty string, but this may
/// change in the future.
///
/// This function does not behave like [`read_until`] because of the
/// requirement that a string contains only valid utf-8. If you need a
/// cancellation safe `read_line`, there are three options:
///
/// * Call [`read_until`] with a newline character and manually perform the utf-8 check.
/// * The stream returned by [`lines`] has a cancellation safe
/// [`next_line`] method.
/// * Use [`tokio_util::codec::LinesCodec`][LinesCodec].
///
/// [`read_until`]: Self::read_until
/// [`lines`]: Self::lines
/// [`next_line`]: crate::io::Lines::next_line
///
/// # Examples
///
/// [`std::io::Cursor`][`Cursor`] is a type that implements
/// `AsyncBufRead`. In this example, we use [`Cursor`] to read all the
/// lines in a byte slice:
///
/// [`Cursor`]: std::io::Cursor
///
/// ```
/// use tokio::io::AsyncBufReadExt;
///
/// use std::io::Cursor;
///
/// #[tokio::main]
/// async fn main() {
/// let mut cursor = Cursor::new(b"foo\nbar");
/// let mut buf = String::new();
///
/// // cursor is at 'f'
/// let num_bytes = cursor.read_line(&mut buf)
/// .await
/// .expect("reading from cursor won't fail");
///
/// assert_eq!(num_bytes, 4);
/// assert_eq!(buf, "foo\n");
/// buf.clear();
///
/// // cursor is at 'b'
/// let num_bytes = cursor.read_line(&mut buf)
/// .await
/// .expect("reading from cursor won't fail");
///
/// assert_eq!(num_bytes, 3);
/// assert_eq!(buf, "bar");
/// buf.clear();
///
/// // cursor is at EOF
/// let num_bytes = cursor.read_line(&mut buf)
/// .await
/// .expect("reading from cursor won't fail");
///
/// assert_eq!(num_bytes, 0);
/// assert_eq!(buf, "");
/// }
/// ```
fn read_line<'a>(&'a mut self, buf: &'a mut String) -> ReadLine<'a, Self>
where
Self: Unpin,
{
read_line(self, buf)
}
/// Returns a stream of the contents of this reader split on the byte
/// `byte`.
///
/// This method is the asynchronous equivalent to
/// [`BufRead::split`](std::io::BufRead::split).
///
/// The stream returned from this function will yield instances of
/// [`io::Result`]`<`[`Option`]`<`[`Vec<u8>`]`>>`. Each vector returned will *not* have
/// the delimiter byte at the end.
///
/// [`io::Result`]: std::io::Result
/// [`Option`]: core::option::Option
/// [`Vec<u8>`]: std::vec::Vec
///
/// # Errors
///
/// Each item of the stream has the same error semantics as
/// [`AsyncBufReadExt::read_until`](AsyncBufReadExt::read_until).
///
/// # Examples
///
/// ```
/// # use tokio::io::AsyncBufRead;
/// use tokio::io::AsyncBufReadExt;
///
/// # async fn dox(my_buf_read: impl AsyncBufRead + Unpin) -> std::io::Result<()> {
/// let mut segments = my_buf_read.split(b'f');
///
/// while let Some(segment) = segments.next_segment().await? {
/// println!("length = {}", segment.len())
/// }
/// # Ok(())
/// # }
/// ```
fn split(self, byte: u8) -> Split<Self>
where
Self: Sized + Unpin,
{
split(self, byte)
}
/// Returns the contents of the internal buffer, filling it with more
/// data from the inner reader if it is empty.
///
/// 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.
///
/// An empty buffer returned indicates that the stream has reached EOF.
///
/// Equivalent to:
///
/// ```ignore
/// async fn fill_buf(&mut self) -> io::Result<&[u8]>;
/// ```
///
/// # Errors
///
/// This function will return an I/O error if the underlying reader was
/// read, but returned an error.
///
/// [`consume`]: crate::io::AsyncBufReadExt::consume
fn fill_buf(&mut self) -> FillBuf<'_, Self>
where
Self: Unpin,
{
fill_buf(self)
}
/// 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 less than the number of bytes in the buffer
/// returned by [`fill_buf`].
///
/// [`read`]: crate::io::AsyncReadExt::read
/// [`fill_buf`]: crate::io::AsyncBufReadExt::fill_buf
fn consume(&mut self, amt: usize)
where
Self: Unpin,
{
std::pin::Pin::new(self).consume(amt)
}
/// Returns a stream over the lines of this reader.
/// This method is the async equivalent to [`BufRead::lines`](std::io::BufRead::lines).
///
/// The stream returned from this function will yield instances of
/// [`io::Result`]`<`[`Option`]`<`[`String`]`>>`. Each string returned will *not* have a newline
/// byte (the 0xA byte) or CRLF (0xD, 0xA bytes) at the end.
///
/// [`io::Result`]: std::io::Result
/// [`Option`]: core::option::Option
/// [`String`]: String
///
/// # Errors
///
/// Each line of the stream has the same error semantics as [`AsyncBufReadExt::read_line`].
///
/// # Examples
///
/// [`std::io::Cursor`][`Cursor`] is a type that implements `BufRead`. In
/// this example, we use [`Cursor`] to iterate over all the lines in a byte
/// slice.
///
/// [`Cursor`]: std::io::Cursor
///
/// ```
/// use tokio::io::AsyncBufReadExt;
///
/// use std::io::Cursor;
///
/// #[tokio::main]
/// async fn main() {
/// let cursor = Cursor::new(b"lorem\nipsum\r\ndolor");
///
/// let mut lines = cursor.lines();
///
/// assert_eq!(lines.next_line().await.unwrap(), Some(String::from("lorem")));
/// assert_eq!(lines.next_line().await.unwrap(), Some(String::from("ipsum")));
/// assert_eq!(lines.next_line().await.unwrap(), Some(String::from("dolor")));
/// assert_eq!(lines.next_line().await.unwrap(), None);
/// }
/// ```
///
/// [`AsyncBufReadExt::read_line`]: AsyncBufReadExt::read_line
fn lines(self) -> Lines<Self>
where
Self: Sized,
{
lines(self)
}
}
}
impl<R: AsyncBufRead + ?Sized> AsyncBufReadExt for R {}