跳到主要内容

Chain

搜索

结构体 Chain 

Source
pub struct Chain<T, U> { /* private fields */ }
展开描述

Chain 将两个缓冲区串联起来。

Chain 是一个适配器,它将两个底层缓冲区链接起来,并提供一个跨越两者的连续视图。它可以将不可变缓冲区(Buf 值)或可变缓冲区(BufMut 值)串联起来。

此结构体通常通过调用 Buf::chain 创建。详情请参阅该函数的文档。

§示例

use bytes::{Bytes, Buf};

let mut buf = (&b"hello "[..])
    .chain(&b"world"[..]);

let full: Bytes = buf.copy_to_bytes(11);
assert_eq!(full[..], b"hello world"[..]);

实现§

Source§

impl<T, U> Chain<T, U>

Source

pub fn first_ref(&self) -> &T

获取对第一个底层 Buf 的引用。

§示例
use bytes::Buf;

let buf = (&b"hello"[..])
    .chain(&b"world"[..]);

assert_eq!(buf.first_ref()[..], b"hello"[..]);
Source

pub fn first_mut(&mut self) -> &mut T

获取对第一个底层 Buf 的可变引用。

§示例
use bytes::Buf;

let mut buf = (&b"hello"[..])
    .chain(&b"world"[..]);

buf.first_mut().advance(1);

let full = buf.copy_to_bytes(9);
assert_eq!(full, b"elloworld"[..]);
Source

pub fn last_ref(&self) -> &U

获取对最后一个底层 Buf 的引用。

§示例
use bytes::Buf;

let buf = (&b"hello"[..])
    .chain(&b"world"[..]);

assert_eq!(buf.last_ref()[..], b"world"[..]);
Source

pub fn last_mut(&mut self) -> &mut U

获取对最后一个底层 Buf 的可变引用。

§示例
use bytes::Buf;

let mut buf = (&b"hello "[..])
    .chain(&b"world"[..]);

buf.last_mut().advance(1);

let full = buf.copy_to_bytes(10);
assert_eq!(full, b"hello orld"[..]);
Source

pub fn into_inner(self) -> (T, U)

消耗此 Chain,返回底层的值。

§示例
use bytes::Buf;

let chain = (&b"hello"[..])
    .chain(&b"world"[..]);

let (first, last) = chain.into_inner();
assert_eq!(first[..], b"hello"[..]);
assert_eq!(last[..], b"world"[..]);

Trait 实现§

Source§

impl<T, U> Buf for Chain<T, U>
where T: Buf, U: Buf,

Source§

fn remaining(&self) -> usize

Returns the number of bytes between the current position and the end of the buffer. 更多信息
Source§

fn chunk(&self) -> &[u8]

Returns a slice starting at the current position and of length between 0 and Buf::remaining(). Note that this can return a shorter slice (this allows non-continuous internal representation). 更多信息
Source§

fn advance(&mut self, cnt: usize)

Advance the internal cursor of the Buf 更多信息
Source§

fn chunks_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize

Fills dst with potentially multiple slices starting at self’s current position. 更多信息
Source§

fn copy_to_bytes(&mut self, len: usize) -> Bytes

Consumes len bytes inside self and returns new instance of Bytes with this data. 更多信息
Source§

fn has_remaining(&self) -> bool

Returns true if there are any more bytes to consume 更多信息
Source§

fn copy_to_slice(&mut self, dst: &mut [u8])

Copies bytes from self into dst. 更多信息
Source§

fn get_u8(&mut self) -> u8

Gets an unsigned 8 bit integer from self. 更多信息
Source§

fn get_i8(&mut self) -> i8

Gets a signed 8 bit integer from self. 更多信息
Source§

fn get_u16(&mut self) -> u16

Gets an unsigned 16 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_u16_le(&mut self) -> u16

Gets an unsigned 16 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_u16_ne(&mut self) -> u16

Gets an unsigned 16 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_i16(&mut self) -> i16

Gets a signed 16 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_i16_le(&mut self) -> i16

Gets a signed 16 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_i16_ne(&mut self) -> i16

Gets a signed 16 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_u32(&mut self) -> u32

Gets an unsigned 32 bit integer from self in the big-endian byte order. 更多信息
Source§

fn get_u32_le(&mut self) -> u32

Gets an unsigned 32 bit integer from self in the little-endian byte order. 更多信息
Source§

fn get_u32_ne(&mut self) -> u32

Gets an unsigned 32 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_i32(&mut self) -> i32

Gets a signed 32 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_i32_le(&mut self) -> i32

Gets a signed 32 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_i32_ne(&mut self) -> i32

Gets a signed 32 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_u64(&mut self) -> u64

Gets an unsigned 64 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_u64_le(&mut self) -> u64

Gets an unsigned 64 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_u64_ne(&mut self) -> u64

Gets an unsigned 64 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_i64(&mut self) -> i64

Gets a signed 64 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_i64_le(&mut self) -> i64

Gets a signed 64 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_i64_ne(&mut self) -> i64

Gets a signed 64 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_u128(&mut self) -> u128

Gets an unsigned 128 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_u128_le(&mut self) -> u128

Gets an unsigned 128 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_u128_ne(&mut self) -> u128

Gets an unsigned 128 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_i128(&mut self) -> i128

Gets a signed 128 bit integer from self in big-endian byte order. 更多信息
Source§

fn get_i128_le(&mut self) -> i128

Gets a signed 128 bit integer from self in little-endian byte order. 更多信息
Source§

fn get_i128_ne(&mut self) -> i128

Gets a signed 128 bit integer from self in native-endian byte order. 更多信息
Source§

fn get_uint(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in big-endian byte order. 更多信息
Source§

fn get_uint_le(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in little-endian byte order. 更多信息
Source§

fn get_uint_ne(&mut self, nbytes: usize) -> u64

Gets an unsigned n-byte integer from self in native-endian byte order. 更多信息
Source§

fn get_int(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in big-endian byte order. 更多信息
Source§

fn get_int_le(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in little-endian byte order. 更多信息
Source§

fn get_int_ne(&mut self, nbytes: usize) -> i64

Gets a signed n-byte integer from self in native-endian byte order. 更多信息
Source§

fn get_f32(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in big-endian byte order. 更多信息
Source§

fn get_f32_le(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in little-endian byte order. 更多信息
Source§

fn get_f32_ne(&mut self) -> f32

Gets an IEEE754 single-precision (4 bytes) floating point number from self in native-endian byte order. 更多信息
Source§

fn get_f64(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in big-endian byte order. 更多信息
Source§

fn get_f64_le(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in little-endian byte order. 更多信息
Source§

fn get_f64_ne(&mut self) -> f64

Gets an IEEE754 double-precision (8 bytes) floating point number from self in native-endian byte order. 更多信息
Source§

fn try_copy_to_slice(&mut self, dst: &mut [u8]) -> Result<(), TryGetError>

Copies bytes from self into dst. 更多信息
Source§

fn try_get_u8(&mut self) -> Result<u8, TryGetError>

Gets an unsigned 8 bit integer from self. 更多信息
Source§

fn try_get_i8(&mut self) -> Result<i8, TryGetError>

Gets a signed 8 bit integer from self. 更多信息
Source§

fn try_get_u16(&mut self) -> Result<u16, TryGetError>

Gets an unsigned 16 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_u16_le(&mut self) -> Result<u16, TryGetError>

Gets an unsigned 16 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_u16_ne(&mut self) -> Result<u16, TryGetError>

Gets an unsigned 16 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_i16(&mut self) -> Result<i16, TryGetError>

Gets a signed 16 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_i16_le(&mut self) -> Result<i16, TryGetError>

Gets an signed 16 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_i16_ne(&mut self) -> Result<i16, TryGetError>

Gets a signed 16 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_u32(&mut self) -> Result<u32, TryGetError>

Gets an unsigned 32 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_u32_le(&mut self) -> Result<u32, TryGetError>

Gets an unsigned 32 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_u32_ne(&mut self) -> Result<u32, TryGetError>

Gets an unsigned 32 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_i32(&mut self) -> Result<i32, TryGetError>

Gets a signed 32 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_i32_le(&mut self) -> Result<i32, TryGetError>

Gets a signed 32 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_i32_ne(&mut self) -> Result<i32, TryGetError>

Gets a signed 32 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_u64(&mut self) -> Result<u64, TryGetError>

Gets an unsigned 64 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_u64_le(&mut self) -> Result<u64, TryGetError>

Gets an unsigned 64 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_u64_ne(&mut self) -> Result<u64, TryGetError>

Gets an unsigned 64 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_i64(&mut self) -> Result<i64, TryGetError>

Gets a signed 64 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_i64_le(&mut self) -> Result<i64, TryGetError>

Gets a signed 64 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_i64_ne(&mut self) -> Result<i64, TryGetError>

Gets a signed 64 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_u128(&mut self) -> Result<u128, TryGetError>

Gets an unsigned 128 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_u128_le(&mut self) -> Result<u128, TryGetError>

Gets an unsigned 128 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_u128_ne(&mut self) -> Result<u128, TryGetError>

Gets an unsigned 128 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_i128(&mut self) -> Result<i128, TryGetError>

Gets a signed 128 bit integer from self in big-endian byte order. 更多信息
Source§

fn try_get_i128_le(&mut self) -> Result<i128, TryGetError>

Gets a signed 128 bit integer from self in little-endian byte order. 更多信息
Source§

fn try_get_i128_ne(&mut self) -> Result<i128, TryGetError>

Gets a signed 128 bit integer from self in native-endian byte order. 更多信息
Source§

fn try_get_uint(&mut self, nbytes: usize) -> Result<u64, TryGetError>

Gets an unsigned n-byte integer from self in big-endian byte order. 更多信息
Source§

fn try_get_uint_le(&mut self, nbytes: usize) -> Result<u64, TryGetError>

Gets an unsigned n-byte integer from self in little-endian byte order. 更多信息
Source§

fn try_get_uint_ne(&mut self, nbytes: usize) -> Result<u64, TryGetError>

Gets an unsigned n-byte integer from self in native-endian byte order. 更多信息
Source§

fn try_get_int(&mut self, nbytes: usize) -> Result<i64, TryGetError>

Gets a signed n-byte integer from self in big-endian byte order. 更多信息
Source§

fn try_get_int_le(&mut self, nbytes: usize) -> Result<i64, TryGetError>

Gets a signed n-byte integer from self in little-endian byte order. 更多信息
Source§

fn try_get_int_ne(&mut self, nbytes: usize) -> Result<i64, TryGetError>

Gets a signed n-byte integer from self in native-endian byte order. 更多信息
Source§

fn try_get_f32(&mut self) -> Result<f32, TryGetError>

Gets an IEEE754 single-precision (4 bytes) floating point number from self in big-endian byte order. 更多信息
Source§

fn try_get_f32_le(&mut self) -> Result<f32, TryGetError>

Gets an IEEE754 single-precision (4 bytes) floating point number from self in little-endian byte order. 更多信息
Source§

fn try_get_f32_ne(&mut self) -> Result<f32, TryGetError>

Gets an IEEE754 single-precision (4 bytes) floating point number from self in native-endian byte order. 更多信息
Source§

fn try_get_f64(&mut self) -> Result<f64, TryGetError>

Gets an IEEE754 double-precision (8 bytes) floating point number from self in big-endian byte order. 更多信息
Source§

fn try_get_f64_le(&mut self) -> Result<f64, TryGetError>

Gets an IEEE754 double-precision (8 bytes) floating point number from self in little-endian byte order. 更多信息
Source§

fn try_get_f64_ne(&mut self) -> Result<f64, TryGetError>

Gets an IEEE754 double-precision (8 bytes) floating point number from self in native-endian byte order. 更多信息
Source§

fn take(self, limit: usize) -> Take<Self>
where Self: Sized,

Creates an adaptor which will read at most limit bytes from self. 更多信息
Source§

fn chain<U: Buf>(self, next: U) -> Chain<Self, U>
where Self: Sized,

Creates an adaptor which will chain this buffer with another. 更多信息
Source§

fn reader(self) -> Reader<Self>
where Self: Sized,

Creates an adaptor which implements the Read trait for self. 更多信息
Source§

impl<T, U> BufMut for Chain<T, U>
where T: BufMut, U: BufMut,

Source§

fn remaining_mut(&self) -> usize

Returns the number of bytes that can be written from the current position until the end of the buffer is reached. 更多信息
Source§

fn chunk_mut(&mut self) -> &mut UninitSlice

Returns a mutable slice starting at the current BufMut position and of length between 0 and BufMut::remaining_mut(). Note that this can be shorter than the whole remainder of the buffer (this allows non-continuous implementation). 更多信息
Source§

unsafe fn advance_mut(&mut self, cnt: usize)

Advance the internal cursor of the BufMut 更多信息
Source§

fn has_remaining_mut(&self) -> bool

Returns true if there is space in self for more bytes. 更多信息
Source§

fn put<T: Buf>(&mut self, src: T)
where Self: Sized,

Transfer bytes into self from src and advance the cursor by the number of bytes written. 更多信息
Source§

fn put_slice(&mut self, src: &[u8])

Transfer bytes into self from src and advance the cursor by the number of bytes written. 更多信息
Source§

fn put_bytes(&mut self, val: u8, cnt: usize)

Put cnt bytes val into self. 更多信息
Source§

fn put_u8(&mut self, n: u8)

Writes an unsigned 8 bit integer to self. 更多信息
Source§

fn put_i8(&mut self, n: i8)

Writes a signed 8 bit integer to self. 更多信息
Source§

fn put_u16(&mut self, n: u16)

Writes an unsigned 16 bit integer to self in big-endian byte order. 更多信息
Source§

fn put_u16_le(&mut self, n: u16)

Writes an unsigned 16 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_u16_ne(&mut self, n: u16)

Writes an unsigned 16 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_i16(&mut self, n: i16)

Writes a signed 16 bit integer to self in big-endian byte order. 更多信息
Source§

fn put_i16_le(&mut self, n: i16)

Writes a signed 16 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_i16_ne(&mut self, n: i16)

Writes a signed 16 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_u32(&mut self, n: u32)

Writes an unsigned 32 bit integer to self in big-endian byte order. 更多信息
Source§

fn put_u32_le(&mut self, n: u32)

Writes an unsigned 32 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_u32_ne(&mut self, n: u32)

Writes an unsigned 32 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_i32(&mut self, n: i32)

Writes a signed 32 bit integer to self in big-endian byte order. 更多信息
Source§

fn put_i32_le(&mut self, n: i32)

Writes a signed 32 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_i32_ne(&mut self, n: i32)

Writes a signed 32 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_u64(&mut self, n: u64)

Writes an unsigned 64 bit integer to self in the big-endian byte order. 更多信息
Source§

fn put_u64_le(&mut self, n: u64)

Writes an unsigned 64 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_u64_ne(&mut self, n: u64)

Writes an unsigned 64 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_i64(&mut self, n: i64)

Writes a signed 64 bit integer to self in the big-endian byte order. 更多信息
Source§

fn put_i64_le(&mut self, n: i64)

Writes a signed 64 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_i64_ne(&mut self, n: i64)

Writes a signed 64 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_u128(&mut self, n: u128)

Writes an unsigned 128 bit integer to self in the big-endian byte order. 更多信息
Source§

fn put_u128_le(&mut self, n: u128)

Writes an unsigned 128 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_u128_ne(&mut self, n: u128)

Writes an unsigned 128 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_i128(&mut self, n: i128)

Writes a signed 128 bit integer to self in the big-endian byte order. 更多信息
Source§

fn put_i128_le(&mut self, n: i128)

Writes a signed 128 bit integer to self in little-endian byte order. 更多信息
Source§

fn put_i128_ne(&mut self, n: i128)

Writes a signed 128 bit integer to self in native-endian byte order. 更多信息
Source§

fn put_uint(&mut self, n: u64, nbytes: usize)

Writes an unsigned n-byte integer to self in big-endian byte order. 更多信息
Source§

fn put_uint_le(&mut self, n: u64, nbytes: usize)

Writes an unsigned n-byte integer to self in the little-endian byte order. 更多信息
Source§

fn put_uint_ne(&mut self, n: u64, nbytes: usize)

Writes an unsigned n-byte integer to self in the native-endian byte order. 更多信息
Source§

fn put_int(&mut self, n: i64, nbytes: usize)

Writes low nbytes of a signed integer to self in big-endian byte order. 更多信息
Source§

fn put_int_le(&mut self, n: i64, nbytes: usize)

Writes low nbytes of a signed integer to self in little-endian byte order. 更多信息
Source§

fn put_int_ne(&mut self, n: i64, nbytes: usize)

Writes low nbytes of a signed integer to self in native-endian byte order. 更多信息
Source§

fn put_f32(&mut self, n: f32)

Writes an IEEE754 single-precision (4 bytes) floating point number to self in big-endian byte order. 更多信息
Source§

fn put_f32_le(&mut self, n: f32)

Writes an IEEE754 single-precision (4 bytes) floating point number to self in little-endian byte order. 更多信息
Source§

fn put_f32_ne(&mut self, n: f32)

Writes an IEEE754 single-precision (4 bytes) floating point number to self in native-endian byte order. 更多信息
Source§

fn put_f64(&mut self, n: f64)

Writes an IEEE754 double-precision (8 bytes) floating point number to self in big-endian byte order. 更多信息
Source§

fn put_f64_le(&mut self, n: f64)

Writes an IEEE754 double-precision (8 bytes) floating point number to self in little-endian byte order. 更多信息
Source§

fn put_f64_ne(&mut self, n: f64)

Writes an IEEE754 double-precision (8 bytes) floating point number to self in native-endian byte order. 更多信息
Source§

fn limit(self, limit: usize) -> Limit<Self>
where Self: Sized,

Creates an adaptor which can write at most limit bytes to self. 更多信息
Source§

fn writer(self) -> Writer<Self>
where Self: Sized,

Creates an adaptor which implements the Write trait for self. 更多信息
Source§

fn chain_mut<U: BufMut>(self, next: U) -> Chain<Self, U>
where Self: Sized,

Creates an adapter which will chain this buffer with another. 更多信息
Source§

impl<T: Debug, U: Debug> Debug for Chain<T, U>

Source§

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

使用给定的格式化器格式化此值。 更多信息
Source§

impl<T, U> IntoIterator for Chain<T, U>
where T: Buf, U: Buf,

Source§

type Item = u8

被迭代元素的类型。
Source§

type IntoIter = IntoIter<Chain<T, U>>

Which kind of iterator are we turning this into?
Source§

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value. 更多信息

自动 Trait 实现§

§

impl<T, U> Freeze for Chain<T, U>
where T: Freeze, U: Freeze,

§

impl<T, U> RefUnwindSafe for Chain<T, U>

§

impl<T, U> Send for Chain<T, U>
where T: Send, U: Send,

§

impl<T, U> Sync for Chain<T, U>
where T: Sync, U: Sync,

§

impl<T, U> Unpin for Chain<T, U>
where T: Unpin, U: Unpin,

§

impl<T, U> UnsafeUnpin for Chain<T, U>
where T: UnsafeUnpin, U: UnsafeUnpin,

§

impl<T, U> UnwindSafe for Chain<T, U>
where T: UnwindSafe, U: UnwindSafe,

Blanket 实现§

Source§

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

Source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. 更多信息
Source§

impl<T> Borrow<T> for T
where T: ?Sized,

Source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. 更多信息
Source§

impl<T> BorrowMut<T> for T
where T: ?Sized,

Source§

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

Mutably borrows from an owned value. 更多信息
Source§

impl<T> From<T> for T

Source§

fn from(t: T) -> T

原样返回传入的参数。

Source§

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

Source§

fn into(self) -> U

调用 U::from(self)

That is, this conversion is whatever the implementation of From<T> for U 的实现方式。

Source§

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

Source§

type Error = Infallible

转换出错时返回的类型。
Source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

执行转换。
Source§

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

Source§

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

转换出错时返回的类型。
Source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

执行转换。