Struct otter_api_tests::io::LineWriter 1.0.0[−][src]
pub struct LineWriter<W> where
W: Write, { /* fields omitted */ }
Expand description
Wraps a writer and buffers output to it, flushing whenever a newline
(0x0a
, '\n'
) is detected.
The BufWriter
struct wraps a writer and buffers its output.
But it only does this batched write when it goes out of scope, or when the
internal buffer is full. Sometimes, you’d prefer to write each line as it’s
completed, rather than the entire buffer at once. Enter LineWriter
. It
does exactly that.
Like BufWriter
, a LineWriter
’s buffer will also be flushed when the
LineWriter
goes out of scope or when its internal buffer is full.
If there’s still a partial line in the buffer when the LineWriter
is
dropped, it will flush those contents.
Examples
We can use LineWriter
to write one line at a time, significantly
reducing the number of actual writes to the file.
use std::fs::{self, File}; use std::io::prelude::*; use std::io::LineWriter; fn main() -> std::io::Result<()> { let road_not_taken = b"I shall be telling this with a sigh Somewhere ages and ages hence: Two roads diverged in a wood, and I - I took the one less traveled by, And that has made all the difference."; let file = File::create("poem.txt")?; let mut file = LineWriter::new(file); file.write_all(b"I shall be telling this with a sigh")?; // No bytes are written until a newline is encountered (or // the internal buffer is filled). assert_eq!(fs::read_to_string("poem.txt")?, ""); file.write_all(b"\n")?; assert_eq!( fs::read_to_string("poem.txt")?, "I shall be telling this with a sigh\n", ); // Write the rest of the poem. file.write_all(b"Somewhere ages and ages hence: Two roads diverged in a wood, and I - I took the one less traveled by, And that has made all the difference.")?; // The last line of the poem doesn't end in a newline, so // we have to flush or drop the `LineWriter` to finish // writing. file.flush()?; // Confirm the whole poem was written. assert_eq!(fs::read("poem.txt")?, &road_not_taken[..]); Ok(()) }
Implementations
pub fn new(inner: W) -> LineWriter<W>ⓘNotable traits for LineWriter<W>
impl<W> Write for LineWriter<W> where
W: Write,
[src]
pub fn new(inner: W) -> LineWriter<W>ⓘNotable traits for LineWriter<W>
impl<W> Write for LineWriter<W> where
W: Write,
[src]Creates a new LineWriter
.
Examples
use std::fs::File; use std::io::LineWriter; fn main() -> std::io::Result<()> { let file = File::create("poem.txt")?; let file = LineWriter::new(file); Ok(()) }
pub fn with_capacity(capacity: usize, inner: W) -> LineWriter<W>ⓘNotable traits for LineWriter<W>
impl<W> Write for LineWriter<W> where
W: Write,
[src]
pub fn with_capacity(capacity: usize, inner: W) -> LineWriter<W>ⓘNotable traits for LineWriter<W>
impl<W> Write for LineWriter<W> where
W: Write,
[src]Creates a new LineWriter
with a specified capacity for the internal
buffer.
Examples
use std::fs::File; use std::io::LineWriter; fn main() -> std::io::Result<()> { let file = File::create("poem.txt")?; let file = LineWriter::with_capacity(100, file); Ok(()) }
Gets a reference to the underlying writer.
Examples
use std::fs::File; use std::io::LineWriter; fn main() -> std::io::Result<()> { let file = File::create("poem.txt")?; let file = LineWriter::new(file); let reference = file.get_ref(); Ok(()) }
Gets a mutable reference to the underlying writer.
Caution must be taken when calling methods on the mutable reference returned as extra writes could corrupt the output stream.
Examples
use std::fs::File; use std::io::LineWriter; fn main() -> std::io::Result<()> { let file = File::create("poem.txt")?; let mut file = LineWriter::new(file); // we can use reference just like file let reference = file.get_mut(); Ok(()) }
Unwraps this LineWriter
, returning the underlying writer.
The internal buffer is written out before returning the writer.
Errors
An Err
will be returned if an error occurs while flushing the buffer.
Examples
use std::fs::File; use std::io::LineWriter; fn main() -> std::io::Result<()> { let file = File::create("poem.txt")?; let writer: LineWriter<File> = LineWriter::new(file); let file: File = writer.into_inner()?; Ok(()) }
Trait Implementations
Write a buffer into this writer, returning how many bytes were written. Read more
Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
can_vector
)Determines if this Write
r has an efficient write_vectored
implementation. Read more
Attempts to write an entire buffer into this writer. Read more
write_all_vectored
)Attempts to write multiple buffers into this writer. Read more
Writes a formatted string into this writer, returning any error encountered. Read more
Auto Trait Implementations
impl<W> RefUnwindSafe for LineWriter<W> where
W: RefUnwindSafe,
impl<W> Send for LineWriter<W> where
W: Send,
impl<W> Sync for LineWriter<W> where
W: Sync,
impl<W> Unpin for LineWriter<W> where
W: Unpin,
impl<W> UnwindSafe for LineWriter<W> where
W: UnwindSafe,
Blanket Implementations
Mutably borrows from an owned value. Read more
pub fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<R, Global>
impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<I, A> Iterator for Box<I, A> where
A: Allocator,
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
A: Allocator + 'static,
F: Future + Unpin + ?Sized, type Output = <F as Future>::Output;
pub fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<R, Global>
impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<I, A> Iterator for Box<I, A> where
A: Allocator,
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<F, A> Future for Box<F, A> where
A: Allocator + 'static,
F: Future + Unpin + ?Sized, type Output = <F as Future>::Output;
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
pub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
pub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
pub fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
pub fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
impl<A> DynCastExt for A
impl<A> DynCastExt for A
pub fn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
T: ?Sized,
A: DynCastExtHelper<T>,
pub fn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
T: ?Sized,
A: DynCastExtHelper<T>,
Use this to cast from one trait object type to another. Read more
pub fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
T: ?Sized,
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
pub fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
T: ?Sized,
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
Use this to upcast a trait to one of its supertraits. Read more
pub fn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
T: ?Sized,
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
pub fn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
T: ?Sized,
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
pub fn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
pub fn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
Use this to cast from one trait object type to another. With this method the type parameter is a config type that uniquely specifies which cast should be preformed. Read more
fn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
[src]
fn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
[src]Instruments this type with the provided Span
, returning an
Instrumented
wrapper. Read more
fn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
[src]
fn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
[src]pub fn vzip(self) -> V
impl<W> WriteBytesExt for W where
W: Write + ?Sized,
impl<W> WriteBytesExt for W where
W: Write + ?Sized,
Writes an unsigned 8 bit integer to the underlying writer. Read more
Writes a signed 8 bit integer to the underlying writer. Read more
Writes an unsigned 16 bit integer to the underlying writer. Read more
Writes a signed 16 bit integer to the underlying writer. Read more
Writes an unsigned 24 bit integer to the underlying writer. Read more
Writes a signed 24 bit integer to the underlying writer. Read more
Writes an unsigned 32 bit integer to the underlying writer. Read more
Writes a signed 32 bit integer to the underlying writer. Read more
Writes an unsigned 48 bit integer to the underlying writer. Read more
Writes a signed 48 bit integer to the underlying writer. Read more
Writes an unsigned 64 bit integer to the underlying writer. Read more
Writes a signed 64 bit integer to the underlying writer. Read more
fn write_u128<T>(&mut self, n: u128) -> Result<(), Error> where
T: ByteOrder,
fn write_u128<T>(&mut self, n: u128) -> Result<(), Error> where
T: ByteOrder,
Writes an unsigned 128 bit integer to the underlying writer.
fn write_i128<T>(&mut self, n: i128) -> Result<(), Error> where
T: ByteOrder,
fn write_i128<T>(&mut self, n: i128) -> Result<(), Error> where
T: ByteOrder,
Writes a signed 128 bit integer to the underlying writer.
Writes an unsigned n-bytes integer to the underlying writer. Read more
Writes a signed n-bytes integer to the underlying writer. Read more
Writes an unsigned n-bytes integer to the underlying writer. Read more
Writes a signed n-bytes integer to the underlying writer. Read more
Writes a IEEE754 single-precision (4 bytes) floating point number to the underlying writer. Read more