1.0.0[][src]Trait nom::lib::std::convert::From

pub trait From<T> {
    fn from(T) -> Self;
}

Simple and safe type conversions in to Self. It is the reciprocal of Into.

This trait is useful when performing error handling as described by the book and is closely related to the ? operator.

When constructing a function that is capable of failing the return type will generally be of the form Result<T, E>.

The From trait allows for simplification of error handling by providing a means of returning a single error type that encapsulates numerous possible erroneous situations.

This trait is not limited to error handling, rather the general case for this trait would be in any type conversions to have an explicit definition of how they are performed.

Note: this trait must not fail. If the conversion can fail, use TryFrom or a dedicated method which returns an Option<T> or a Result<T, E>.

Generic Implementations

Examples

String implements From<&str>:

let string = "hello".to_string();
let other_string = String::from("hello");

assert_eq!(string, other_string);

An example usage for error handling:

use std::io::{self, Read};
use std::num;

enum CliError {
    IoError(io::Error),
    ParseError(num::ParseIntError),
}

impl From<io::Error> for CliError {
    fn from(error: io::Error) -> Self {
        CliError::IoError(error)
    }
}

impl From<num::ParseIntError> for CliError {
    fn from(error: num::ParseIntError) -> Self {
        CliError::ParseError(error)
    }
}

fn open_and_parse_file(file_name: &str) -> Result<i32, CliError> {
    let mut file = std::fs::File::open("test")?;
    let mut contents = String::new();
    file.read_to_string(&mut contents)?;
    let num: i32 = contents.trim().parse()?;
    Ok(num)
}

Required Methods

Performs the conversion.

Implementations on Foreign Types

impl<'a> From<Cow<'a, CStr>> for CString
[src]

impl<'a> From<&'a PathBuf> for Cow<'a, Path>
[src]

impl From<OsString> for Arc<OsStr>
[src]

Converts a OsString into a Arc<OsStr> without copying or allocating.

impl From<OsString> for PathBuf
[src]

impl<'a> From<&'a Path> for Rc<Path>
[src]

impl<'a> From<&'a OsStr> for Arc<OsStr>
[src]

impl From<PathBuf> for Arc<Path>
[src]

impl<'a> From<&'a Path> for Cow<'a, Path>
[src]

impl From<RecvError> for RecvTimeoutError
[src]

impl<'a> From<&'a CString> for Cow<'a, CStr>
[src]

impl From<ErrorKind> for Error
[src]

Intended for use for errors not exposed to the user, where allocating onto the heap (for normal construction via Error::new) is too costly.

impl<'a> From<&'a CStr> for CString
[src]

impl From<SocketAddrV4> for SocketAddr
[src]

Converts a [SocketAddrV4] into a [SocketAddr::V4].

impl From<Box<Path>> for PathBuf
[src]

impl<'a> From<&'a CStr> for Arc<CStr>
[src]

impl<'a> From<&'a OsStr> for Rc<OsStr>
[src]

impl From<CString> for Arc<CStr>
[src]

Converts a CString into a Arc<CStr> without copying or allocating.

impl<T> From<T> for Mutex<T>
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Creates a new mutex in an unlocked state ready for use. This is equivalent to [Mutex::new].

impl<W> From<IntoInnerError<W>> for Error
[src]

impl From<SocketAddrV6> for SocketAddr
[src]

Converts a [SocketAddrV6] into a [SocketAddr::V6].

impl From<Ipv6Addr> for IpAddr
[src]

impl<'a, T> From<&'a T> for PathBuf where
    T: AsRef<OsStr> + ?Sized
[src]

impl<'a> From<CString> for Cow<'a, CStr>
[src]

impl From<[u16; 8]> for Ipv6Addr
[src]

impl From<RecvError> for TryRecvError
[src]

impl From<Ipv4Addr> for u32
[src]

Convert an Ipv4Addr into a host byte order u32.

Examples

use std::net::Ipv4Addr;

let addr = Ipv4Addr::new(13, 12, 11, 10);
assert_eq!(0x0d0c0b0au32, u32::from(addr));

impl From<PathBuf> for OsString
[src]

impl<'a> From<OsString> for Cow<'a, OsStr>
[src]

impl From<Box<OsStr>> for OsString
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Converts a Box<OsStr> into a OsString without copying or allocating.

impl From<[u8; 16]> for IpAddr
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Create an IpAddr::V6 from a sixteen element byte array.

Examples

use std::net::{IpAddr, Ipv6Addr};

let addr = IpAddr::from([
    25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8,
    17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8,
]);
assert_eq!(
    IpAddr::V6(Ipv6Addr::new(
        0x1918, 0x1716,
        0x1514, 0x1312,
        0x1110, 0x0f0e,
        0x0d0c, 0x0b0a
    )),
    addr
);

impl From<ChildStdout> for Stdio
[src]

impl From<Box<CStr>> for CString
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Converts a Box<CStr> into a CString without copying or allocating.

impl From<u128> for Ipv6Addr
[src]

impl From<String> for OsString
[src]

Converts a String into a [OsString].

The conversion copies the data, and includes an allocation on the heap.

impl<'a> From<&'a CStr> for Rc<CStr>
[src]

impl From<u32> for Ipv4Addr
[src]

Convert a host byte order u32 into an Ipv4Addr.

Examples

use std::net::Ipv4Addr;

let addr = Ipv4Addr::from(0x0d0c0b0au32);
assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);

impl<'a> From<&'a Path> for Arc<Path>
[src]

impl<'a, T> From<&'a T> for OsString where
    T: AsRef<OsStr> + ?Sized
[src]

impl From<[u8; 4]> for IpAddr
[src]

Create an IpAddr::V4 from a four element byte array.

Examples

use std::net::{IpAddr, Ipv4Addr};

let addr = IpAddr::from([13u8, 12u8, 11u8, 10u8]);
assert_eq!(IpAddr::V4(Ipv4Addr::new(13, 12, 11, 10)), addr);

impl From<Ipv4Addr> for IpAddr
[src]

impl From<CString> for Rc<CStr>
[src]

Converts a CString into a Rc<CStr> without copying or allocating.

impl From<ChildStderr> for Stdio
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impl From<PathBuf> for Rc<Path>
[src]

impl From<DefaultEnvKey> for OsString
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impl From<File> for Stdio
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impl<T> From<SendError<T>> for TrySendError<T>
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impl<'a> From<PathBuf> for Cow<'a, Path>
[src]

impl<'a> From<&'a OsStr> for Cow<'a, OsStr>
[src]

impl From<NulError> for Error
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Converts a NulError into a io::Error.

impl From<[u8; 16]> for Ipv6Addr
[src]

impl From<OsString> for Rc<OsStr>
[src]

Converts a OsString into a Rc<OsStr> without copying or allocating.

impl From<[u16; 8]> for IpAddr
[src]

Create an IpAddr::V6 from an eight element 16-bit array.

Examples

use std::net::{IpAddr, Ipv6Addr};

let addr = IpAddr::from([
    525u16, 524u16, 523u16, 522u16,
    521u16, 520u16, 519u16, 518u16,
]);
assert_eq!(
    IpAddr::V6(Ipv6Addr::new(
        0x20d, 0x20c,
        0x20b, 0x20a,
        0x209, 0x208,
        0x207, 0x206
    )),
    addr
);

impl<T> From<PoisonError<T>> for TryLockError<T>
[src]

impl From<Ipv6Addr> for u128
[src]

impl From<[u8; 4]> for Ipv4Addr
[src]

Examples

use std::net::Ipv4Addr;

let addr = Ipv4Addr::from([13u8, 12u8, 11u8, 10u8]);
assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);

impl<'a> From<&'a OsString> for Cow<'a, OsStr>
[src]

impl<I> From<(I, u16)> for SocketAddr where
    I: Into<IpAddr>, 
[src]

Converts a tuple struct (Into<[IpAddr]>, u16) into a [SocketAddr].

This conversion creates a [SocketAddr::V4] for a [IpAddr::V4] and creates a [SocketAddr::V6] for a [IpAddr::V6].

u16 is treated as port of the newly created [SocketAddr].

impl From<String> for PathBuf
[src]

impl<'a> From<&'a CStr> for Cow<'a, CStr>
[src]

impl<'a> From<Cow<'a, Path>> for PathBuf
[src]

impl From<ChildStdin> for Stdio
[src]

impl<T> From<T> for RwLock<T>
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Creates a new instance of an RwLock<T> which is unlocked. This is equivalent to [RwLock::new].

impl<'a> From<Cow<'a, OsStr>> for OsString
[src]

impl From<u32> for u64
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Converts u32 to u64 losslessly.

impl From<i32> for i64
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Converts i32 to i64 losslessly.

impl From<u8> for f64
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Converts u8 to f64 losslessly.

impl From<bool> for i32
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Converts a bool to a i32. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(i32::from(true), 1);
assert_eq!(i32::from(false), 0);

impl From<u8> for isize
[src]

Converts u8 to isize losslessly.

impl From<NonZeroU16> for u16
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impl From<bool> for i8
[src]

Converts a bool to a i8. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(i8::from(true), 1);
assert_eq!(i8::from(false), 0);

impl From<bool> for u128
[src]

Converts a bool to a u128. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(u128::from(true), 1);
assert_eq!(u128::from(false), 0);

impl From<u8> for AtomicU8
[src]

impl From<bool> for u8
[src]

Converts a bool to a u8. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(u8::from(true), 1);
assert_eq!(u8::from(false), 0);

impl From<u32> for AtomicU32
[src]

impl From<u32> for u128
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Converts u32 to u128 losslessly.

impl From<u16> for usize
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Converts u16 to usize losslessly.

impl From<bool> for u32
[src]

Converts a bool to a u32. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(u32::from(true), 1);
assert_eq!(u32::from(false), 0);

impl From<i16> for i64
[src]

Converts i16 to i64 losslessly.

impl From<u16> for AtomicU16
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impl From<bool> for i16
[src]

Converts a bool to a i16. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(i16::from(true), 1);
assert_eq!(i16::from(false), 0);

impl From<bool> for AtomicBool
[src]

impl From<u16> for i128
[src]

Converts u16 to i128 losslessly.

impl From<u8> for u32
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Converts u8 to u32 losslessly.

impl From<u32> for i128
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Converts u32 to i128 losslessly.

impl From<LocalWaker> for Waker
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impl From<u64> for i128
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Converts u64 to i128 losslessly.

impl From<u8> for usize
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Converts u8 to usize losslessly.

impl From<usize> for AtomicUsize
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impl From<i64> for i128
[src]

Converts i64 to i128 losslessly.

impl From<bool> for i64
[src]

Converts a bool to a i64. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(i64::from(true), 1);
assert_eq!(i64::from(false), 0);

impl From<i8> for i128
[src]

Converts i8 to i128 losslessly.

impl<T> From<T> for Cell<T>
[src]

impl From<i64> for AtomicI64
[src]

impl From<u8> for i64
[src]

Converts u8 to i64 losslessly.

impl From<i16> for AtomicI16
[src]

impl From<i32> for AtomicI32
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impl From<u8> for i128
[src]

Converts u8 to i128 losslessly.

impl From<NonZeroU64> for u64
[src]

impl From<i8> for AtomicI8
[src]

impl From<u32> for i64
[src]

Converts u32 to i64 losslessly.

impl From<u32> for f64
[src]

Converts u32 to f64 losslessly.

impl From<u16> for f32
[src]

Converts u16 to f32 losslessly.

impl From<bool> for usize
[src]

Converts a bool to a usize. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(usize::from(true), 1);
assert_eq!(usize::from(false), 0);

impl<'a, T> From<&'a T> for NonNull<T> where
    T: ?Sized
[src]

impl<'a, T> From<&'a mut T> for NonNull<T> where
    T: ?Sized
[src]

impl From<u8> for u128
[src]

Converts u8 to u128 losslessly.

impl From<i16> for i32
[src]

Converts i16 to i32 losslessly.

impl From<bool> for u16
[src]

Converts a bool to a u16. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(u16::from(true), 1);
assert_eq!(u16::from(false), 0);

impl<T> From<T> for RefCell<T>
[src]

impl From<bool> for isize
[src]

Converts a bool to a isize. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(isize::from(true), 1);
assert_eq!(isize::from(false), 0);

impl From<i16> for i128
[src]

Converts i16 to i128 losslessly.

impl From<i16> for isize
[src]

Converts i16 to isize losslessly.

impl From<NonZeroU8> for u8
[src]

impl From<i16> for f32
[src]

Converts i16 to f32 losslessly.

impl From<NonZeroU128> for u128
[src]

impl From<u16> for i64
[src]

Converts u16 to i64 losslessly.

impl From<f32> for f64
[src]

Converts f32 to f64 losslessly.

impl From<i8> for isize
[src]

Converts i8 to isize losslessly.

impl From<bool> for u64
[src]

Converts a bool to a u64. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(u64::from(true), 1);
assert_eq!(u64::from(false), 0);

impl From<u8> for i32
[src]

Converts u8 to i32 losslessly.

impl<T> From<*mut T> for AtomicPtr<T>
[src]

impl From<i32> for i128
[src]

Converts i32 to i128 losslessly.

impl From<u16> for u64
[src]

Converts u16 to u64 losslessly.

impl From<u16> for f64
[src]

Converts u16 to f64 losslessly.

impl From<i8> for i32
[src]

Converts i8 to i32 losslessly.

impl From<u16> for u128
[src]

Converts u16 to u128 losslessly.

impl<T> From<T> for UnsafeCell<T>
[src]

impl From<i8> for f32
[src]

Converts i8 to f32 losslessly.

impl From<u16> for i32
[src]

Converts u16 to i32 losslessly.

impl From<isize> for AtomicIsize
[src]

impl From<u8> for u64
[src]

Converts u8 to u64 losslessly.

impl From<i8> for i64
[src]

Converts i8 to i64 losslessly.

impl From<NonZeroUsize> for usize
[src]

impl From<char> for u32
[src]

Converts a [char] into a [u32].

Examples

use std::mem;

fn main() {
    let c = 'c';
    let u = u32::from(c);
    assert!(4 == mem::size_of_val(&u))
}

impl From<bool> for i128
[src]

Converts a bool to a i128. The resulting value is 0 for false and 1 for true values.

Examples

assert_eq!(i128::from(true), 1);
assert_eq!(i128::from(false), 0);

impl From<u64> for u128
[src]

Converts u64 to u128 losslessly.

impl From<NonZeroU32> for u32
[src]

impl From<u8> for u16
[src]

Converts u8 to u16 losslessly.

impl From<i16> for f64
[src]

Converts i16 to f64 losslessly.

impl From<u64> for AtomicU64
[src]

impl From<i8> for i16
[src]

Converts i8 to i16 losslessly.

impl From<i8> for f64
[src]

Converts i8 to f64 losslessly.

impl From<u8> for char
[src]

Maps a byte in 0x00...0xFF to a char whose code point has the same value, in U+0000 to U+00FF.

Unicode is designed such that this effectively decodes bytes with the character encoding that IANA calls ISO-8859-1. This encoding is compatible with ASCII.

Note that this is different from ISO/IEC 8859-1 a.k.a. ISO 8859-1 (with one less hyphen), which leaves some "blanks", byte values that are not assigned to any character. ISO-8859-1 (the IANA one) assigns them to the C0 and C1 control codes.

Note that this is also different from Windows-1252 a.k.a. code page 1252, which is a superset ISO/IEC 8859-1 that assigns some (not all!) blanks to punctuation and various Latin characters.

To confuse things further, on the Web ascii, iso-8859-1, and windows-1252 are all aliases for a superset of Windows-1252 that fills the remaining blanks with corresponding C0 and C1 control codes.

Converts a u8 into a [char].

Examples

use std::mem;

fn main() {
    let u = 32 as u8;
    let c = char::from(u);
    assert!(4 == mem::size_of_val(&c))
}

impl From<!> for TryFromIntError
[src]

impl From<u8> for f32
[src]

Converts u8 to f32 losslessly.

impl<T> From<Unique<T>> for NonNull<T> where
    T: ?Sized
[src]

impl From<u16> for u32
[src]

Converts u16 to u32 losslessly.

impl From<u8> for i16
[src]

Converts u8 to i16 losslessly.

impl<T> From<T> for Poll<T>
[src]

impl From<i32> for f64
[src]

Converts i32 to f64 losslessly.

impl<'a> From<&'a String> for Cow<'a, str>
[src]

impl<T> From<Box<T>> for Pin<Box<T>>
[src]

impl<T> From<Box<T>> for Arc<T> where
    T: ?Sized
[src]

impl<'a, T> From<Vec<T>> for Cow<'a, [T]> where
    T: Clone
[src]

impl<'a, T> From<&'a [T]> for Cow<'a, [T]> where
    T: Clone
[src]

impl<'a, T> From<&'a Vec<T>> for Cow<'a, [T]> where
    T: Clone
[src]

impl<'a> From<&'a str> for Rc<str>
[src]

impl<'a> From<&'a str> for Cow<'a, str>
[src]

impl<'a, T> From<&'a [T]> for Rc<[T]> where
    T: Clone
[src]

impl<T> From<Arc<T>> for Waker where
    T: Wake + 'static, 
[src]

impl From<String> for Arc<str>
[src]

impl<T> From<Vec<T>> for Arc<[T]>
[src]

impl<'a> From<&'a str> for Arc<str>
[src]

impl<T> From<T> for Arc<T>
[src]

impl<T> From<Vec<T>> for Rc<[T]>
[src]

impl From<String> for Rc<str>
[src]

impl<T> From<T> for Rc<T>
[src]

impl<T> From<Box<T>> for Rc<T> where
    T: ?Sized
[src]

impl<'a, T> From<&'a [T]> for Arc<[T]> where
    T: Clone
[src]

impl<'a> From<String> for Cow<'a, str>
[src]

Implementors

impl From<AllocErr> for CollectionAllocErr
[src]

impl From<LayoutErr> for CollectionAllocErr
[src]

impl From<Box<str>> for Box<[u8]>
[src]

Important traits for Box<W>

impl From<Box<str>> for String
[src]

impl From<String> for Box<Error + 'static>
[src]

Important traits for Box<W>

impl From<String> for Box<str>
[src]

Important traits for Box<W>

impl From<String> for Box<Error + 'static + Send + Sync>
[src]

Important traits for Box<W>

impl From<String> for Vec<u8>
[src]

Important traits for Vec<u8>

impl From<CString> for Box<CStr>
[src]

Important traits for Box<W>

Converts a CString into a Box<CStr> without copying or allocating.

impl From<CString> for Vec<u8>
[src]

Important traits for Vec<u8>

Converts a CString into a Vec<u8>.

The conversion consumes the CString, and removes the terminating NUL byte.

impl From<OsString> for Box<OsStr>
[src]

Important traits for Box<W>

Converts a OsString into a Box<OsStr> without copying or allocating.

impl From<PathBuf> for Box<Path>
[src]

Important traits for Box<W>

impl<'a> From<&'a str> for CompleteStr<'a>
[src]

impl<'a> From<&'a str> for Box<Error + 'static>
[src]

Important traits for Box<W>

impl<'a> From<&'a str> for Box<str>
[src]

Important traits for Box<W>

impl<'a> From<&'a str> for String
[src]

impl<'a> From<&'a str> for Vec<u8>
[src]

Important traits for Vec<u8>

impl<'a> From<&'a CStr> for Box<CStr>
[src]

Important traits for Box<W>

impl<'a> From<&'a OsStr> for Box<OsStr>
[src]

Important traits for Box<W>

impl<'a> From<&'a Path> for Box<Path>
[src]

Important traits for Box<W>

impl<'a> From<Cow<'a, str>> for Box<Error + 'static>
[src]

Important traits for Box<W>

impl<'a> From<Cow<'a, str>> for String
[src]

impl<'a> From<&'a [u8]> for CompleteByteSlice<'a>
[src]

impl<'a, 'b> From<&'b &'a str> for CompleteStr<'a>
[src]

impl<'a, 'b> From<&'b &'a [u8]> for CompleteByteSlice<'a>
[src]

impl<'a, 'b> From<&'b str> for Box<Error + 'a + Send + Sync>
[src]

Important traits for Box<W>

impl<'a, 'b> From<Cow<'b, str>> for Box<Error + 'a + Send + Sync>
[src]

Important traits for Box<W>

impl<'a, E> From<E> for Box<Error + 'a> where
    E: 'a + Error
[src]

Important traits for Box<W>

impl<'a, E> From<E> for Box<Error + 'a + Send + Sync> where
    E: 'a + Error + Send + Sync
[src]

Important traits for Box<W>

impl<'a, T> From<&'a Option<T>> for Option<&'a T>
[src]

impl<'a, T> From<&'a mut Option<T>> for Option<&'a mut T>
[src]

impl<'a, T> From<Cow<'a, [T]>> for Vec<T> where
    [T]: ToOwned,
    <[T] as ToOwned>::Owned == Vec<T>, 
[src]

Important traits for Vec<u8>

impl<'a, T> From<&'a [T]> for Box<[T]> where
    T: Copy
[src]

Important traits for Box<W>

impl<'a, T> From<&'a [T]> for Vec<T> where
    T: Clone
[src]

Important traits for Vec<u8>

impl<'a, T> From<&'a mut [T]> for Vec<T> where
    T: Clone
[src]

Important traits for Vec<u8>

impl<T> From<T> for T
[src]

impl<T> From<BinaryHeap<T>> for Vec<T>
[src]

Important traits for Vec<u8>

impl<T> From<VecDeque<T>> for Vec<T>
[src]

Important traits for Vec<u8>

impl<T> From<Box<[T]>> for Vec<T>
[src]

Important traits for Vec<u8>

impl<T> From<Vec<T>> for VecDeque<T>
[src]

impl<T> From<Vec<T>> for BinaryHeap<T> where
    T: Ord
[src]

impl<T> From<Vec<T>> for Box<[T]>
[src]

Important traits for Box<W>

impl<T> From<T> for Option<T>
[src]

impl<T> From<T> for Box<T>
[src]

Important traits for Box<W>