Struct rhit::io::Cursor 1.0.0[−][src]
A Cursor
wraps an in-memory buffer and provides it with a
Seek
implementation.
Cursor
s are used with in-memory buffers, anything implementing
AsRef
<[u8]>
, to allow them to implement Read
and/or Write
,
allowing these buffers to be used anywhere you might use a reader or writer
that does actual I/O.
The standard library implements some I/O traits on various types which
are commonly used as a buffer, like Cursor<
Vec
<u8>>
and
Cursor<
&[u8]
>
.
Examples
We may want to write bytes to a File
in our production
code, but use an in-memory buffer in our tests. We can do this with
Cursor
:
use std::io::prelude::*; use std::io::{self, SeekFrom}; use std::fs::File; // a library function we've written fn write_ten_bytes_at_end<W: Write + Seek>(writer: &mut W) -> io::Result<()> { writer.seek(SeekFrom::End(-10))?; for i in 0..10 { writer.write(&[i])?; } // all went well Ok(()) } // Here's some code that uses this library function. // // We might want to use a BufReader here for efficiency, but let's // keep this example focused. let mut file = File::create("foo.txt")?; write_ten_bytes_at_end(&mut file)?; // now let's write a test #[test] fn test_writes_bytes() { // setting up a real File is much slower than an in-memory buffer, // let's use a cursor instead use std::io::Cursor; let mut buff = Cursor::new(vec![0; 15]); write_ten_bytes_at_end(&mut buff).unwrap(); assert_eq!(&buff.get_ref()[5..15], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); }
Implementations
impl<T> Cursor<T>
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pub const fn new(inner: T) -> Cursor<T>ⓘ
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Creates a new cursor wrapping the provided underlying in-memory buffer.
Cursor initial position is 0
even if underlying buffer (e.g., Vec
)
is not empty. So writing to cursor starts with overwriting Vec
content, not with appending to it.
Examples
use std::io::Cursor; let buff = Cursor::new(Vec::new());
pub fn into_inner(self) -> T
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Consumes this cursor, returning the underlying value.
Examples
use std::io::Cursor; let buff = Cursor::new(Vec::new()); let vec = buff.into_inner();
pub const fn get_ref(&self) -> &Tⓘ
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Gets a reference to the underlying value in this cursor.
Examples
use std::io::Cursor; let buff = Cursor::new(Vec::new()); let reference = buff.get_ref();
pub fn get_mut(&mut self) -> &mut Tⓘ
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Gets a mutable reference to the underlying value in this cursor.
Care should be taken to avoid modifying the internal I/O state of the underlying value as it may corrupt this cursor's position.
Examples
use std::io::Cursor; let mut buff = Cursor::new(Vec::new()); let reference = buff.get_mut();
pub const fn position(&self) -> u64
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Returns the current position of this cursor.
Examples
use std::io::Cursor; use std::io::prelude::*; use std::io::SeekFrom; let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]); assert_eq!(buff.position(), 0); buff.seek(SeekFrom::Current(2)).unwrap(); assert_eq!(buff.position(), 2); buff.seek(SeekFrom::Current(-1)).unwrap(); assert_eq!(buff.position(), 1);
pub fn set_position(&mut self, pos: u64)
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Sets the position of this cursor.
Examples
use std::io::Cursor; let mut buff = Cursor::new(vec![1, 2, 3, 4, 5]); assert_eq!(buff.position(), 0); buff.set_position(2); assert_eq!(buff.position(), 2); buff.set_position(4); assert_eq!(buff.position(), 4);
Trait Implementations
impl<T> BufRead for Cursor<T> where
T: AsRef<[u8]>,
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T: AsRef<[u8]>,
pub fn fill_buf(&mut self) -> Result<&[u8], Error>
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pub fn consume(&mut self, amt: usize)
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pub fn read_until(
&mut self,
byte: u8,
buf: &mut Vec<u8, Global>
) -> Result<usize, Error>
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&mut self,
byte: u8,
buf: &mut Vec<u8, Global>
) -> Result<usize, Error>
pub fn read_line(&mut self, buf: &mut String) -> Result<usize, Error>
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pub fn split(self, byte: u8) -> Split<Self>ⓘ
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pub fn lines(self) -> Lines<Self>ⓘ
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impl<T> Clone for Cursor<T> where
T: Clone,
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T: Clone,
impl<T> Debug for Cursor<T> where
T: Debug,
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T: Debug,
impl<T> Default for Cursor<T> where
T: Default,
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T: Default,
impl<T> Eq for Cursor<T> where
T: Eq,
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T: Eq,
impl<T> PartialEq<Cursor<T>> for Cursor<T> where
T: PartialEq<T>,
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T: PartialEq<T>,
impl<T> Read for Cursor<T> where
T: AsRef<[u8]>,
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T: AsRef<[u8]>,
pub fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>
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pub fn read_vectored(
&mut self,
bufs: &mut [IoSliceMut<'_>]
) -> Result<usize, Error>
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&mut self,
bufs: &mut [IoSliceMut<'_>]
) -> Result<usize, Error>
pub fn is_read_vectored(&self) -> bool
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pub fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>
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pub unsafe fn initializer(&self) -> Initializer
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pub fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>
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pub fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>
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pub fn by_ref(&mut self) -> &mut Selfⓘ
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pub fn bytes(self) -> Bytes<Self>ⓘ
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pub fn chain<R>(self, next: R) -> Chain<Self, R>ⓘ where
R: Read,
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R: Read,
pub fn take(self, limit: u64) -> Take<Self>ⓘ
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impl<T> Seek for Cursor<T> where
T: AsRef<[u8]>,
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T: AsRef<[u8]>,
pub fn seek(&mut self, style: SeekFrom) -> Result<u64, Error>
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pub fn stream_len(&mut self) -> Result<u64, Error>
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pub fn stream_position(&mut self) -> Result<u64, Error>
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impl<T> StructuralEq for Cursor<T>
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impl<T> StructuralPartialEq for Cursor<T>
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impl Write for Cursor<Box<[u8], Global>>
1.5.0[src]
pub fn write(&mut self, buf: &[u8]) -> Result<usize, Error>
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pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>
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pub fn is_write_vectored(&self) -> bool
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pub fn flush(&mut self) -> Result<(), Error>
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pub fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
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pub fn write_all_vectored(
&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
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&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>
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pub fn by_ref(&mut self) -> &mut Selfⓘ
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impl Write for Cursor<Vec<u8, Global>>
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pub fn write(&mut self, buf: &[u8]) -> Result<usize, Error>
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pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>
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pub fn is_write_vectored(&self) -> bool
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pub fn flush(&mut self) -> Result<(), Error>
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pub fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
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pub fn write_all_vectored(
&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
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&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>
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pub fn by_ref(&mut self) -> &mut Selfⓘ
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impl<'_> Write for Cursor<&'_ mut Vec<u8, Global>>
1.25.0[src]
pub fn write(&mut self, buf: &[u8]) -> Result<usize, Error>
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pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>
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pub fn is_write_vectored(&self) -> bool
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pub fn flush(&mut self) -> Result<(), Error>
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pub fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
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pub fn write_all_vectored(
&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
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&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>
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pub fn by_ref(&mut self) -> &mut Selfⓘ
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impl<'_> Write for Cursor<&'_ mut [u8]>
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pub fn write(&mut self, buf: &[u8]) -> Result<usize, Error>
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pub fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>
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pub fn is_write_vectored(&self) -> bool
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pub fn flush(&mut self) -> Result<(), Error>
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pub fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
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pub fn write_all_vectored(
&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
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&mut self,
bufs: &mut [IoSlice<'_>]
) -> Result<(), Error>
pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>
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pub fn by_ref(&mut self) -> &mut Selfⓘ
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Auto Trait Implementations
impl<T> RefUnwindSafe for Cursor<T> where
T: RefUnwindSafe,
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T: RefUnwindSafe,
impl<T> Send for Cursor<T> where
T: Send,
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T: Send,
impl<T> Sync for Cursor<T> where
T: Sync,
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T: Sync,
impl<T> Unpin for Cursor<T> where
T: Unpin,
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T: Unpin,
impl<T> UnwindSafe for Cursor<T> where
T: UnwindSafe,
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T: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut Tⓘ
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impl<T, A> ExecutableCommand<A> for T where
T: Write,
A: Display,
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T: Write,
A: Display,
pub fn execute(
&mut self,
command: impl Command<AnsiType = A>
) -> Result<&mut T, ErrorKind>
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&mut self,
command: impl Command<AnsiType = A>
) -> Result<&mut T, ErrorKind>
Executes the given command directly.
The given command its ANSI escape code will be written and flushed onto Self
.
Arguments
-
The command that you want to execute directly.
Example
use std::io::{Write, stdout}; use crossterm::{Result, ExecutableCommand, style::Print}; fn main() -> Result<()> { // will be executed directly 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.
impl<T> From<T> for T
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impl<T> Fun for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> Pointable for T
pub const ALIGN: usize
type Init = T
The type for initializers.
pub unsafe fn init(init: <T as Pointable>::Init) -> usize
pub unsafe fn deref<'a>(ptr: usize) -> &'a Tⓘ
pub unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut Tⓘ
pub unsafe fn drop(ptr: usize)
impl<T, A> QueueableCommand<A> for T where
T: Write,
A: Display,
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T: Write,
A: Display,
pub fn queue(
&mut self,
command: impl Command<AnsiType = A>
) -> Result<&mut T, ErrorKind>
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&mut self,
command: impl Command<AnsiType = A>
) -> Result<&mut T, ErrorKind>
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 implementingio::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
-
The command that you want to queue for later execution.
Examples
use std::io::{Write, stdout}; use crossterm::{Result, QueueableCommand, style::Print}; fn main() -> Result<()> { let mut stdout = 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.
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,