Struct Empty

1.0.0 · Source
#[non_exhaustive]
pub struct Empty;
Expand description

Empty ignores any data written via Write, and will always be empty (returning zero bytes) when read via Read.

This struct is generally created by calling empty(). Please see the documentation of empty() for more details.

Trait Implementations§

1.0.0 · Source§

impl BufRead for Empty

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fn fill_buf(&mut self) -> Result<&[u8], Error>

Returns the contents of the internal buffer, filling it with more data, via Read methods, if empty. Read more
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fn consume(&mut self, _n: usize)

Marks the given amount of additional bytes from the internal buffer as having been read. Subsequent calls to read only return bytes that have not been marked as read. Read more
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fn has_data_left(&mut self) -> Result<bool, Error>

🔬This is a nightly-only experimental API. (buf_read_has_data_left)
Checks if there is any data left to be read. Read more
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fn read_until(&mut self, _byte: u8, _buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes into buf until the delimiter byte or EOF is reached. Read more
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fn skip_until(&mut self, _byte: u8) -> Result<usize, Error>

Skips all bytes until the delimiter byte or EOF is reached. Read more
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fn read_line(&mut self, _buf: &mut String) -> Result<usize, Error>

Reads all bytes until a newline (the 0xA byte) is reached, and append them to the provided String buffer. Read more
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fn split(self, byte: u8) -> Split<Self>
where Self: Sized,

Returns an iterator over the contents of this reader split on the byte byte. Read more
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fn lines(self) -> Lines<Self>
where Self: Sized,

Returns an iterator over the lines of this reader. Read more
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impl Clone for Empty

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fn clone(&self) -> Empty

Returns a duplicate of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Empty

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Default for Empty

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fn default() -> Empty

Returns the “default value” for a type. Read more
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impl Read for Empty

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fn read(&mut self, _buf: &mut [u8]) -> Result<usize, Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
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fn read_buf(&mut self, _cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)
Pull some bytes from this source into the specified buffer. Read more
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fn read_vectored( &mut self, _bufs: &mut [IoSliceMut<'_>], ) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers. Read more
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fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)
Determines if this Reader has an efficient read_vectored implementation. Read more
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fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf. Read more
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fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)
Reads the exact number of bytes required to fill cursor. Read more
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fn read_to_end(&mut self, _buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes until EOF in this source, placing them into buf. Read more
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fn read_to_string(&mut self, _buf: &mut String) -> Result<usize, Error>

Reads all bytes until EOF in this source, appending them to buf. Read more
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fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adaptor for this instance of Read. Read more
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fn bytes(self) -> Bytes<Self>
where Self: Sized,

Transforms this Read instance to an Iterator over its bytes. Read more
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fn chain<R>(self, next: R) -> Chain<Self, R>
where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another. Read more
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fn take(self, limit: u64) -> Take<Self>
where Self: Sized,

Creates an adapter which will read at most limit bytes from it. Read more
1.51.0 · Source§

impl Seek for Empty

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fn seek(&mut self, _pos: SeekFrom) -> Result<u64, Error>

Seek to an offset, in bytes, in a stream. Read more
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fn stream_len(&mut self) -> Result<u64, Error>

🔬This is a nightly-only experimental API. (seek_stream_len)
Returns the length of this stream (in bytes). Read more
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fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream. Read more
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fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream. Read more
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fn seek_relative(&mut self, offset: i64) -> Result<(), Error>

Seeks relative to the current position. Read more
1.73.0 · Source§

impl Write for &Empty

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fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written. Read more
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fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers. Read more
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fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)
Determines if this Writer has an efficient write_vectored implementation. Read more
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fn write_all(&mut self, _buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer. Read more
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fn write_all_vectored(&mut self, _bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)
Attempts to write multiple buffers into this writer. Read more
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fn write_fmt(&mut self, _args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered. Read more
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fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
1.0.0 · Source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of Write. Read more
1.73.0 · Source§

impl Write for Empty

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fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written. Read more
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fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers. Read more
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fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)
Determines if this Writer has an efficient write_vectored implementation. Read more
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fn write_all(&mut self, _buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer. Read more
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fn write_all_vectored(&mut self, _bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)
Attempts to write multiple buffers into this writer. Read more
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fn write_fmt(&mut self, _args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered. Read more
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fn flush(&mut self) -> Result<(), Error>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
1.0.0 · Source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of Write. Read more
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impl Copy for Empty

Auto Trait Implementations§

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impl Freeze for Empty

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impl RefUnwindSafe for Empty

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impl Send for Empty

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impl Sync for Empty

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impl Unpin for Empty

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impl UnwindSafe for Empty

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<T> ExecutableCommand for T
where T: Write + ?Sized,

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fn execute(&mut self, command: impl Command) -> Result<&mut T, Error>

Executes the given command directly.

The given command its ANSI escape code will be written and flushed onto Self.

§Arguments
  • Command

    The command that you want to execute directly.

§Example
use std::io;
use crossterm::{ExecutableCommand, style::Print};

fn main() -> io::Result<()> {
     // will be executed directly
      io::stdout()
        .execute(Print("sum:\n".to_string()))?
        .execute(Print(format!("1 + 1= {} ", 1 + 1)))?;

      Ok(())

     // ==== Output ====
     // sum:
     // 1 + 1 = 2
}

Have a look over at the Command API for more details.

§Notes
  • In the case of UNIX and Windows 10, ANSI codes are written to the given ‘writer’.
  • In case of Windows versions lower than 10, a direct WinAPI call will be made. The reason for this is that Windows versions lower than 10 do not support ANSI codes, and can therefore not be written to the given writer. Therefore, there is no difference between execute and queue for those old Windows versions.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T> QueueableCommand for T
where T: Write + ?Sized,

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fn queue(&mut self, command: impl Command) -> Result<&mut T, Error>

Queues the given command for further execution.

Queued commands will be executed in the following cases:

  • When flush is called manually on the given type implementing io::Write.
  • The terminal will flush automatically if the buffer is full.
  • Each line is flushed in case of stdout, because it is line buffered.
§Arguments
  • Command

    The command that you want to queue for later execution.

§Examples
use std::io::{self, Write};
use crossterm::{QueueableCommand, style::Print};

 fn main() -> io::Result<()> {
    let mut stdout = io::stdout();

    // `Print` will executed executed when `flush` is called.
    stdout
        .queue(Print("foo 1\n".to_string()))?
        .queue(Print("foo 2".to_string()))?;

    // some other code (no execution happening here) ...

    // when calling `flush` on `stdout`, all commands will be written to the stdout and therefore executed.
    stdout.flush()?;

    Ok(())

    // ==== Output ====
    // foo 1
    // foo 2
}

Have a look over at the Command API for more details.

§Notes
  • In the case of UNIX and Windows 10, ANSI codes are written to the given ‘writer’.
  • In case of Windows versions lower than 10, a direct WinAPI call will be made. The reason for this is that Windows versions lower than 10 do not support ANSI codes, and can therefore not be written to the given writer. Therefore, there is no difference between execute and queue for those old Windows versions.
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<W> SynchronizedUpdate for W
where W: Write + ?Sized,

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fn sync_update<T>( &mut self, operations: impl FnOnce(&mut W) -> T, ) -> Result<T, Error>

Performs a set of actions within a synchronous update.

Updates will be suspended in the terminal, the function will be executed against self, updates will be resumed, and a flush will be performed.

§Arguments
  • Function

    A function that performs the operations that must execute in a synchronized update.

§Examples
use std::io;
use crossterm::{ExecutableCommand, SynchronizedUpdate, style::Print};

fn main() -> io::Result<()> {
    let mut stdout = io::stdout();

    stdout.sync_update(|stdout| {
        stdout.execute(Print("foo 1\n".to_string()))?;
        stdout.execute(Print("foo 2".to_string()))?;
        // The effects of the print command will not be present in the terminal
        // buffer, but not visible in the terminal.
        std::io::Result::Ok(())
    })?;

    // The effects of the commands will be visible.

    Ok(())

    // ==== Output ====
    // foo 1
    // foo 2
}
§Notes

This command is performed only using ANSI codes, and will do nothing on terminals that do not support ANSI codes, or this specific extension.

When rendering the screen of the terminal, the Emulator usually iterates through each visible grid cell and renders its current state. With applications updating the screen a at higher frequency this can cause tearing.

This mode attempts to mitigate that.

When the synchronization mode is enabled following render calls will keep rendering the last rendered state. The terminal Emulator keeps processing incoming text and sequences. When the synchronized update mode is disabled again the renderer may fetch the latest screen buffer state again, effectively avoiding the tearing effect by unintentionally rendering in the middle a of an application screen update.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.