Trait concordium_std::convert::From1.0.0[−][src]

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

Used to do value-to-value conversions while consuming the input value. It is the reciprocal of Into.

One should always prefer implementing From over Into because implementing From automatically provides one with an implementation of Into thanks to the blanket implementation in the standard library.

Only implement Into when targeting a version prior to Rust 1.41 and converting to a type outside the current crate. From was not able to do these types of conversions in earlier versions because of Rust’s orphaning rules. See Into for more details.

Prefer using Into over using From when specifying trait bounds on a generic function. This way, types that directly implement Into can be used as arguments as well.

The From is also very useful when performing error handling. When constructing a function that is capable of failing, the return type will generally be of the form Result<T, E>. The From trait simplifies error handling by allowing a function to return a single error type that encapsulate multiple error types. See the “Examples” section and the book for more details.

Note: This trait must not fail. If the conversion can fail, use TryFrom.

Generic Implementations

  • From<T> for U implies Into<U> for T
  • From is reflexive, which means that From<T> for T is implemented

Examples

String implements From<&str>:

An explicit conversion from a &str to a String is done as follows:

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

assert_eq!(string, other_string);

While performing error handling it is often useful to implement From for your own error type. By converting underlying error types to our own custom error type that encapsulates the underlying error type, we can return a single error type without losing information on the underlying cause. The ‘?’ operator automatically converts the underlying error type to our custom error type by calling Into<CliError>::into which is automatically provided when implementing From. The compiler then infers which implementation of Into should be used.

use std::fs;
use std::io;
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 contents = fs::read_to_string(&file_name)?;
    let num: i32 = contents.trim().parse()?;
    Ok(num)
}

Required methods

Performs the conversion.

Implementations on Foreign Types

Creates a clone-on-write pointer from an owned instance of PathBuf.

This conversion does not clone or allocate.

Converts a Box<Path> into a PathBuf

This conversion does not allocate or copy memory.

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

Creates 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
);

Converts a CStr into a borrowed Cow without copying or allocating.

Creates an Ipv4Addr from a four element byte array.

Examples
use std::net::Ipv4Addr;

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

Converts a String into a PathBuf

This conversion does not allocate or copy memory.

Converts a Path into an Arc by copying the Path data into a new Arc buffer.

Converts a ChildStdin into a Stdio

Examples

ChildStdin will be converted to Stdio using Stdio::from under the hood.

use std::process::{Command, Stdio};

let reverse = Command::new("rev")
    .stdin(Stdio::piped())
    .spawn()
    .expect("failed reverse command");

let _echo = Command::new("echo")
    .arg("Hello, world!")
    .stdout(reverse.stdin.unwrap()) // Converted into a Stdio here
    .output()
    .expect("failed echo command");

// "!dlrow ,olleH" echoed to console

Converts a SocketAddrV6 into a SocketAddr::V6.

Converts a Path into an Rc by copying the Path data into a new Rc buffer.

Converts a borrowed OsStr to a PathBuf.

Allocates a PathBuf and copies the data into it.

Creates a boxed Path from a clone-on-write pointer.

Converting from a Cow::Owned does not clone or allocate.

Converts a Cow into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::mem;
use std::borrow::Cow;

let a_cow_str_error = Cow::from("a str error");
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))

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

Creates an Ipv6Addr from a sixteen element byte array.

Examples
use std::net::Ipv6Addr;

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

Converts a RecvError into a RecvTimeoutError.

This conversion always returns RecvTimeoutError::Disconnected.

No data is allocated on the heap.

Convert a host byte order u128 into an Ipv6Addr.

Examples
use std::net::Ipv6Addr;

let addr = Ipv6Addr::from(0x102030405060708090A0B0C0D0E0F00D_u128);
assert_eq!(
    Ipv6Addr::new(
        0x1020, 0x3040, 0x5060, 0x7080,
        0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
    ),
    addr);

Converts a str into a box of dyn Error.

Examples
use std::error::Error;
use std::mem;

let a_str_error = "a str error";
let a_boxed_error = Box::<dyn Error>::from(a_str_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))

Converts a PathBuf into an OsString

This conversion does not allocate or copy memory.

Converts an OsString into a PathBuf

This conversion does not allocate or copy memory.

Copies this address to a new IpAddr::V4.

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

let addr = Ipv4Addr::new(127, 0, 0, 1);

assert_eq!(
    IpAddr::V4(addr),
    IpAddr::from(addr)
)

Converts a &CString into a borrowed Cow without copying or allocating.

Converts a type of Error into a box of dyn Error.

Examples
use std::error::Error;
use std::fmt;
use std::mem;

#[derive(Debug)]
struct AnError;

impl fmt::Display for AnError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "An error")
    }
}

impl Error for AnError {}

let an_error = AnError;
assert!(0 == mem::size_of_val(&an_error));
let a_boxed_error = Box::<dyn Error>::from(an_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))

Converts a String into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::mem;

let a_string_error = "a string error".to_string();
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))

Converts a NulError into a io::Error.

Converts a ChildStdout into a Stdio

Examples

ChildStdout will be converted to Stdio using Stdio::from under the hood.

use std::process::{Command, Stdio};

let hello = Command::new("echo")
    .arg("Hello, world!")
    .stdout(Stdio::piped())
    .spawn()
    .expect("failed echo command");

let reverse = Command::new("rev")
    .stdin(hello.stdout.unwrap())  // Converted into a Stdio here
    .output()
    .expect("failed reverse command");

assert_eq!(reverse.stdout, b"!dlrow ,olleH\n");

Creates a clone-on-write pointer from a reference to Path.

This conversion does not clone or allocate.

Converts a Cow into a box of dyn Error.

Examples
use std::error::Error;
use std::mem;
use std::borrow::Cow;

let a_cow_str_error = Cow::from("a str error");
let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))

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

Creates 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);

Convert an Ipv6Addr into a host byte order u128.

Examples
use std::net::Ipv6Addr;

let addr = Ipv6Addr::new(
    0x1020, 0x3040, 0x5060, 0x7080,
    0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
);
assert_eq!(0x102030405060708090A0B0C0D0E0F00D_u128, u128::from(addr));

Converts a String into a box of dyn Error.

Examples
use std::error::Error;
use std::mem;

let a_string_error = "a string error".to_string();
let a_boxed_error = Box::<dyn Error>::from(a_string_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))

Converts a host byte order u32 into an Ipv4Addr.

Examples
use std::net::Ipv4Addr;

let addr = Ipv4Addr::from(0x12345678);
assert_eq!(Ipv4Addr::new(0x12, 0x34, 0x56, 0x78), addr);

Converts a File into a Stdio

Examples

File will be converted to Stdio using Stdio::from under the hood.

use std::fs::File;
use std::process::Command;

// With the `foo.txt` file containing `Hello, world!"
let file = File::open("foo.txt").unwrap();

let reverse = Command::new("rev")
    .stdin(file)  // Implicit File conversion into a Stdio
    .output()
    .expect("failed reverse command");

assert_eq!(reverse.stdout, b"!dlrow ,olleH");

Converts a SendError<T> into a TrySendError<T>.

This conversion always returns a TrySendError::Disconnected containing the data in the SendError<T>.

No data is allocated on the heap.

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

Converts a Vec<NonZeroU8> into a CString without copying nor checking for inner null bytes.

Copies this address to a new IpAddr::V6.

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

let addr = Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff);

assert_eq!(
    IpAddr::V6(addr),
    IpAddr::from(addr)
);

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

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

u16 is treated as port of the newly created SocketAddr.

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

Converts a CString into an owned Cow without copying or allocating.

Creates a new instance of an RwLock<T> which is unlocked. This is equivalent to RwLock::new.

Creates a boxed Path from a reference.

This will allocate and clone path to it.

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

Converts a PathBuf into an Arc by moving the PathBuf data into a new Arc buffer.

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

Converts a PathBuf into an Rc by moving the PathBuf data into a new Rc buffer.

Converts a SocketAddrV4 into a SocketAddr::V4.

Creates 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
);

Converts a RecvError into a TryRecvError.

This conversion always returns TryRecvError::Disconnected.

No data is allocated on the heap.

Creates an Ipv6Addr from an eight element 16-bit array.

Examples
use std::net::Ipv6Addr;

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

Converts an Ipv4Addr into a host byte order u32.

Examples
use std::net::Ipv4Addr;

let addr = Ipv4Addr::new(0x12, 0x34, 0x56, 0x78);
assert_eq!(0x12345678, u32::from(addr));

Converts a ChildStderr into a Stdio

Examples
use std::process::{Command, Stdio};

let reverse = Command::new("rev")
    .arg("non_existing_file.txt")
    .stderr(Stdio::piped())
    .spawn()
    .expect("failed reverse command");

let cat = Command::new("cat")
    .arg("-")
    .stdin(reverse.stderr.unwrap()) // Converted into a Stdio here
    .output()
    .expect("failed echo command");

assert_eq!(
    String::from_utf8_lossy(&cat.stdout),
    "rev: cannot open non_existing_file.txt: No such file or directory\n"
);

Converts a clone-on-write pointer to an owned path.

Converting from a Cow::Owned does not clone or allocate.

Converts a PathBuf into a Box<Path>

This conversion currently should not allocate memory, but this behavior is not guaranteed on all platforms or in all future versions.

Converts a String into an OsString.

This conversion does not allocate or copy memory.

Creates a new mutex in an unlocked state ready for use. This is equivalent to Mutex::new.

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

Converts an ErrorKind into an Error.

This conversion allocates a new error with a simple representation of error kind.

Examples
use std::io::{Error, ErrorKind};

let not_found = ErrorKind::NotFound;
let error = Error::from(not_found);
assert_eq!("entity not found", format!("{}", error));

Converts a str into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::mem;

let a_str_error = "a str error";
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))

Converts a type of Error + Send + Sync into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::fmt;
use std::mem;

#[derive(Debug)]
struct AnError;

impl fmt::Display for AnError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "An error")
    }
}

impl Error for AnError {}

unsafe impl Send for AnError {}

unsafe impl Sync for AnError {}

let an_error = AnError;
assert!(0 == mem::size_of_val(&an_error));
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(an_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))

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

Create a new cell with its contents set to value.

Example
#![feature(once_cell)]

use std::lazy::SyncOnceCell;

let a = SyncOnceCell::from(3);
let b = SyncOnceCell::new();
b.set(3)?;
assert_eq!(a, b);
Ok(())

Creates a clone-on-write pointer from a reference to PathBuf.

This conversion does not clone or allocate.

Converts i32 to i64 losslessly.

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impl From<Simd<u8, 64_usize>> for __m512i

Converts u32 to i128 losslessly.

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impl From<__m512i> for Simd<u32, 16_usize>

Converts a NonZeroU32 into an u32

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impl From<__m512i> for Simd<i16, 32_usize>

Converts i8 to i16 losslessly.

Converts a char into a u32.

Examples
use std::mem;

let c = 'c';
let u = u32::from(c);
assert!(4 == mem::size_of_val(&u))
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impl From<__m512i> for Simd<u64, 8_usize>

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impl From<__m128i> for Simd<i64, 2_usize>

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impl From<Simd<i64, 4_usize>> for __m256i

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impl From<__m512i> for Simd<i64, 8_usize>

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impl From<__m256i> for Simd<i8, 32_usize>

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impl From<Simd<u32, 4_usize>> for __m128i

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impl From<Simd<i64, 2_usize>> for __m128i

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impl From<Simd<u8, 32_usize>> for __m256i

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impl From<Simd<u16, 8_usize>> for __m128i

Converts a NonZeroUsize into an usize

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impl From<Simd<u64, 4_usize>> for __m256i

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impl From<__m128i> for Simd<u64, 2_usize>

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impl From<__m512> for Simd<f32, 16_usize>

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impl From<__m256i> for Simd<i32, 8_usize>

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impl From<__m512i> for Simd<u8, 64_usize>

Converts u8 to usize losslessly.

Converts an i16 into an AtomicI16.

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);
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impl From<__m128i> for Simd<usize, 4_usize>

Converts i16 to f32 losslessly.

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impl From<Simd<i32, 16_usize>> for __m512i

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impl From<Simd<isize, 4_usize>> for __m128i

Converts u8 to u16 losslessly.

Converts u64 to i128 losslessly.

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impl From<Simd<i8, 32_usize>> for __m256i

Converts a NonZeroU128 into an u128

Converts u16 to usize losslessly.

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impl From<__m128i> for Simd<u16, 8_usize>

Converts i8 to f32 losslessly.

Converts a NonZeroI32 into an i32

Converts a bool into an AtomicBool.

Examples
use std::sync::atomic::AtomicBool;
let atomic_bool = AtomicBool::from(true);
assert_eq!(format!("{:?}", atomic_bool), "true")

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);
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impl From<Simd<u32, 16_usize>> for __m512i

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impl From<__m512i> for Simd<i32, 16_usize>

Converts u32 to i64 losslessly.

Converts u16 to u32 losslessly.

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);

Converts u8 to isize losslessly.

Converts a NonZeroI64 into an i64

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);

Converts i64 to i128 losslessly.

Converts a NonZeroU64 into an u64

Converts an usize into an AtomicUsize.

Converts i8 to i64 losslessly.

Converts a NonZeroI128 into an i128

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impl From<__m256i> for Simd<u16, 16_usize>

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);
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impl From<Simd<u32, 8_usize>> for __m256i

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impl From<Simd<u64, 2_usize>> for __m128i

Converts u16 to f32 losslessly.

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impl From<__m128i> for Simd<i32, 4_usize>

Converts f32 to f64 losslessly.

Converts u16 to f64 losslessly.

Converts i8 to i32 losslessly.

Converts i32 to f64 losslessly.

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impl From<Simd<u16, 16_usize>> for __m256i

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impl From<__m256i> for Simd<isize, 8_usize>

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impl From<Simd<f32, 8_usize>> for __m256

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impl From<Simd<i32, 8_usize>> for __m256i

Converts an u64 into an AtomicU64.

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impl From<__m256i> for Simd<u64, 4_usize>

Converts i16 to isize losslessly.

Converts an u8 into an AtomicU8.

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impl From<__m512i> for Simd<usize, 16_usize>

Converts u16 to u64 losslessly.

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impl From<__m256i> for Simd<i64, 4_usize>

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);

Converts a NonZeroU8 into an u8

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impl From<Simd<isize, 8_usize>> for __m256i

Converts a NonZeroU16 into an u16

Converts u16 to i32 losslessly.

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);
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impl From<Simd<i8, 64_usize>> for __m512i

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impl From<Simd<i16, 32_usize>> for __m512i

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impl From<__m256i> for Simd<usize, 8_usize>

Converts a NonZeroI8 into an i8

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impl From<__m256i> for Simd<u32, 8_usize>

Converts i32 to i128 losslessly.

Converts an u32 into an AtomicU32.

Converts u32 to u64 losslessly.

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impl From<Simd<f64, 8_usize>> for __m512d

Converts u16 to u128 losslessly.

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impl From<__m512d> for Simd<f64, 8_usize>

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impl From<__m512i> for Simd<isize, 16_usize>

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impl From<__m256> for Simd<f32, 8_usize>

Converts i8 to i128 losslessly.

Converts u32 to f64 losslessly.

Moves val into a new Some.

Examples
let o: Option<u8> = Option::from(67);

assert_eq!(Some(67), o);

Converts i16 to f64 losslessly.

Converts u8 to u32 losslessly.

Converts an i64 into an AtomicI64.

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);
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impl From<__m128i> for Simd<u8, 16_usize>

Converts u32 to u128 losslessly.

Converts from &Option<T> to Option<&T>.

Examples

Converts an Option<String> into an Option<usize>, preserving the original. The map method takes the self argument by value, consuming the original, so this technique uses from to first take an Option to a reference to the value inside the original.

let s: Option<String> = Some(String::from("Hello, Rustaceans!"));
let o: Option<usize> = Option::from(&s).map(|ss: &String| ss.len());

println!("Can still print s: {:?}", s);

assert_eq!(o, Some(18));

Converts i16 to i128 losslessly.

Converts u8 to i128 losslessly.

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impl From<Simd<i16, 16_usize>> for __m256i

Converts from &mut Option<T> to Option<&mut T>

Examples
let mut s = Some(String::from("Hello"));
let o: Option<&mut String> = Option::from(&mut s);

match o {
    Some(t) => *t = String::from("Hello, Rustaceans!"),
    None => (),
}

assert_eq!(s, Some(String::from("Hello, Rustaceans!")));

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);
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impl From<__m128> for Simd<f32, 4_usize>

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impl From<Simd<usize, 8_usize>> for __m256i

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impl From<Simd<isize, 16_usize>> for __m512i

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);

Converts u16 to i128 losslessly.

Converts i8 to isize losslessly.

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impl From<__m256i> for Simd<u8, 32_usize>

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);
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impl From<Simd<u8, 16_usize>> for __m128i

Converts an isize into an AtomicIsize.

Converts u8 to f32 losslessly.

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impl From<__m128d> for Simd<f64, 2_usize>

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impl From<__m128i> for Simd<i16, 8_usize>

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impl From<__m512i> for Simd<u16, 32_usize>

Converts u8 to i64 losslessly.

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);

Converts a char into a u64.

Examples
use std::mem;

let c = '👤';
let u = u64::from(c);
assert!(8 == mem::size_of_val(&u))

Converts an i8 into an AtomicI8.

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impl From<Simd<i64, 8_usize>> for __m512i

Converts u8 to u64 losslessly.

Converts u8 to f64 losslessly.

Converts u64 to u128 losslessly.

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impl From<Simd<i32, 4_usize>> for __m128i

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

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

Converts u8 to u128 losslessly.

Converts a char into a u128.

Examples
use std::mem;

let c = '⚙';
let u = u128::from(c);
assert!(16 == mem::size_of_val(&u))
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impl From<__m512i> for Simd<i8, 64_usize>

Converts i16 to i32 losslessly.

Converts a NonZeroIsize into an isize

Convert to a Ready variant.

Example
assert_eq!(Poll::from(true), Poll::Ready(true));
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impl From<__m256i> for Simd<i16, 16_usize>

Converts u8 to i32 losslessly.

Converts u16 to i64 losslessly.

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impl From<Simd<f64, 2_usize>> for __m128d

Converts i16 to i64 losslessly.

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impl From<__m128i> for Simd<isize, 4_usize>

Converts an i32 into an AtomicI32.

Converts u8 to i16 losslessly.

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impl From<Simd<f32, 4_usize>> for __m128

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impl From<Simd<usize, 4_usize>> for __m128i

Converts an u16 into an AtomicU16.

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impl From<__m256d> for Simd<f64, 4_usize>

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impl From<Simd<i8, 16_usize>> for __m128i

Converts i8 to f64 losslessly.

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impl From<Simd<i16, 8_usize>> for __m128i

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impl From<Simd<f32, 16_usize>> for __m512

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impl From<__m128i> for Simd<i8, 16_usize>

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impl From<Simd<u64, 8_usize>> for __m512i

Converts a NonZeroI16 into an i16

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impl From<Simd<f64, 4_usize>> for __m256d

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impl From<__m128i> for Simd<u32, 4_usize>

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impl From<Simd<u16, 32_usize>> for __m512i

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impl From<Simd<usize, 16_usize>> for __m512i

Converts a String reference into a Borrowed variant. No heap allocation is performed, and the string is not copied.

Example
let s = "eggplant".to_string();
assert_eq!(Cow::from(&s), Cow::Borrowed("eggplant"));

Converts a Cow<'_, str> into a Box<str>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying str. Otherwise, it will try to reuse the owned String’s allocation.

Examples
use std::borrow::Cow;

let unboxed = Cow::Borrowed("hello");
let boxed: Box<str> = Box::from(unboxed);
println!("{}", boxed);
let unboxed = Cow::Owned("hello".to_string());
let boxed: Box<str> = Box::from(unboxed);
println!("{}", boxed);

Converts a String into an Owned variant. No heap allocation is performed, and the string is not copied.

Example
let s = "eggplant".to_string();
let s2 = "eggplant".to_string();
assert_eq!(Cow::from(s), Cow::<'static, str>::Owned(s2));

Create a reference-counted pointer from a clone-on-write pointer by copying its content.

Example
let cow: Cow<str> = Cow::Borrowed("eggplant");
let shared: Rc<str> = Rc::from(cow);
assert_eq!("eggplant", &shared[..]);

Converts a &[T] into a Box<[T]>

This conversion allocates on the heap and performs a copy of slice.

Examples
// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice: Box<[u8]> = Box::from(slice);

println!("{:?}", boxed_slice);

Create an atomically reference-counted pointer from a clone-on-write pointer by copying its content.

Example
let cow: Cow<str> = Cow::Borrowed("eggplant");
let shared: Arc<str> = Arc::from(cow);
assert_eq!("eggplant", &shared[..]);

Move a boxed object to a new, reference-counted allocation.

Example
let unique: Box<str> = Box::from("eggplant");
let shared: Arc<str> = Arc::from(unique);
assert_eq!("eggplant", &shared[..]);

Move a boxed object to a new, reference counted, allocation.

Example
let original: Box<i32> = Box::new(1);
let shared: Rc<i32> = Rc::from(original);
assert_eq!(1, *shared);

Allocate a reference-counted slice and fill it by cloning v’s items.

Example
let original: &[i32] = &[1, 2, 3];
let shared: Rc<[i32]> = Rc::from(original);
assert_eq!(&[1, 2, 3], &shared[..]);

Use a Wake-able type as a Waker.

No heap allocations or atomic operations are used for this conversion.

Converts a [T; N] into a Box<[T]>

This conversion moves the array to newly heap-allocated memory.

Examples
let boxed: Box<[u8]> = Box::from([4, 2]);
println!("{:?}", boxed);

Converts a generic type T into an Rc<T>

The conversion allocates on the heap and moves t from the stack into it.

Example
let x = 5;
let rc = Rc::new(5);

assert_eq!(Rc::from(x), rc);

Creates a Borrowed variant of Cow from a slice.

This conversion does not allocate or clone the data.

Creates a Borrowed variant of Cow from a reference to Vec.

This conversion does not allocate or clone the data.

Converts a Cow<'_, [T]> into a Box<[T]>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying slice. Otherwise, it will try to reuse the owned Vec’s allocation.

Converts a T into an Arc<T>

The conversion moves the value into a newly allocated Arc. It is equivalent to calling Arc::new(t).

Example
let x = 5;
let arc = Arc::new(5);

assert_eq!(Arc::from(x), arc);

Use a Wake-able type as a RawWaker.

No heap allocations or atomic operations are used for this conversion.

Converts a T into a Box<T>

The conversion allocates on the heap and moves t from the stack into it.

Examples
let x = 5;
let boxed = Box::new(5);

assert_eq!(Box::from(x), boxed);

Convert a vector into a boxed slice.

If v has excess capacity, its items will be moved into a newly-allocated buffer with exactly the right capacity.

Examples
assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice());

Converts a Box<str> into a Box<[u8]>

This conversion does not allocate on the heap and happens in place.

Examples
// create a Box<str> which will be used to create a Box<[u8]>
let boxed: Box<str> = Box::from("hello");
let boxed_str: Box<[u8]> = Box::from(boxed);

// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice = Box::from(slice);

assert_eq!(boxed_slice, boxed_str);

Converts a string slice into a Borrowed variant. No heap allocation is performed, and the string is not copied.

Example
assert_eq!(Cow::from("eggplant"), Cow::Borrowed("eggplant"));

Allocate a reference-counted slice and move v’s items into it.

Example
let unique: Vec<i32> = vec![1, 2, 3];
let shared: Arc<[i32]> = Arc::from(unique);
assert_eq!(&[1, 2, 3], &shared[..]);

Converts a Box<T> into a Pin<Box<T>>

This conversion does not allocate on the heap and happens in place.

Allocate a reference-counted string slice and copy v into it.

Example
let shared: Rc<str> = Rc::from("statue");
assert_eq!("statue", &shared[..]);

Allocate a reference-counted string slice and copy v into it.

Example
let original: String = "statue".to_owned();
let shared: Rc<str> = Rc::from(original);
assert_eq!("statue", &shared[..]);

Allocate a reference-counted str and copy v into it.

Example
let unique: String = "eggplant".to_owned();
let shared: Arc<str> = Arc::from(unique);
assert_eq!("eggplant", &shared[..]);

Allocate a reference-counted str and copy v into it.

Example
let shared: Arc<str> = Arc::from("eggplant");
assert_eq!("eggplant", &shared[..]);

Creates an Owned variant of Cow from an owned instance of Vec.

This conversion does not allocate or clone the data.

Allocate a reference-counted slice and fill it by cloning v’s items.

Example
let original: &[i32] = &[1, 2, 3];
let shared: Arc<[i32]> = Arc::from(original);
assert_eq!(&[1, 2, 3], &shared[..]);

Allocate a reference-counted slice and move v’s items into it.

Example
let original: Box<Vec<i32>> = Box::new(vec![1, 2, 3]);
let shared: Rc<Vec<i32>> = Rc::from(original);
assert_eq!(vec![1, 2, 3], *shared);

Converts a &str into a Box<str>

This conversion allocates on the heap and performs a copy of s.

Examples
let boxed: Box<str> = Box::from("hello");
println!("{}", boxed);

Converts the given String to a boxed str slice that is owned.

Examples

Basic usage:

let s1: String = String::from("hello world");
let s2: Box<str> = Box::from(s1);
let s3: String = String::from(s2);

assert_eq!("hello world", s3)

Implementors

Full is mapped to i32::MIN+3, Malformed is mapped to i32::MIN+4.

MissingInitPrefix is mapped to i32::MIN + 5, TooLong to i32::MIN + 6, ContainsDot to i32::MIN + 9, and InvalidCharacters to i32::MIN + 10.

MissingDotSeparator is mapped to i32::MIN + 7, TooLong to i32::MIN + 8, and InvalidCharacters to i32::MIN + 11.

The error code is i32::MIN + 12

Stability note: This impl does not yet exist, but we are “reserving space” to add it in the future. See rust-lang/rust#64715 for details.