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1.0.0[][src]Struct std::str::Utf8Error

pub struct Utf8Error { /* fields omitted */ }

Errors which can occur when attempting to interpret a sequence of u8 as a string.

As such, the from_utf8 family of functions and methods for both Strings and &strs make use of this error, for example.

Examples

This error type’s methods can be used to create functionality similar to String::from_utf8_lossy without allocating heap memory:

fn from_utf8_lossy<F>(mut input: &[u8], mut push: F) where F: FnMut(&str) {
    loop {
        match ::std::str::from_utf8(input) {
            Ok(valid) => {
                push(valid);
                break
            }
            Err(error) => {
                let (valid, after_valid) = input.split_at(error.valid_up_to());
                unsafe {
                    push(::std::str::from_utf8_unchecked(valid))
                }
                push("\u{FFFD}");

                if let Some(invalid_sequence_length) = error.error_len() {
                    input = &after_valid[invalid_sequence_length..]
                } else {
                    break
                }
            }
        }
    }
}Run

Methods

impl Utf8Error[src]

pub fn valid_up_to(&self) -> usize
1.5.0
[src]

Returns the index in the given string up to which valid UTF-8 was verified.

It is the maximum index such that from_utf8(&input[..index]) would return Ok(_).

Examples

Basic usage:

use std::str;

// some invalid bytes, in a vector
let sparkle_heart = vec![0, 159, 146, 150];

// std::str::from_utf8 returns a Utf8Error
let error = str::from_utf8(&sparkle_heart).unwrap_err();

// the second byte is invalid here
assert_eq!(1, error.valid_up_to());Run

pub fn error_len(&self) -> Option<usize>
1.20.0
[src]

Provides more information about the failure:

  • None: the end of the input was reached unexpectedly. self.valid_up_to() is 1 to 3 bytes from the end of the input. If a byte stream (such as a file or a network socket) is being decoded incrementally, this could be a valid char whose UTF-8 byte sequence is spanning multiple chunks.

  • Some(len): an unexpected byte was encountered. The length provided is that of the invalid byte sequence that starts at the index given by valid_up_to(). Decoding should resume after that sequence (after inserting a U+FFFD REPLACEMENT CHARACTER) in case of lossy decoding.

Trait Implementations

impl Display for Utf8Error[src]

impl Clone for Utf8Error[src]

fn clone_from(&mut self, source: &Self)[src]

Performs copy-assignment from source. Read more

impl Eq for Utf8Error[src]

impl Debug for Utf8Error[src]

impl PartialEq<Utf8Error> for Utf8Error[src]

impl Copy for Utf8Error[src]

impl Error for Utf8Error[src]

fn cause(&self) -> Option<&dyn Error>[src]

Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

The lower-level cause of this error, if any. Read more

fn source(&self) -> Option<&(dyn Error + 'static)>
1.30.0
[src]

The lower-level source of this error, if any. Read more

fn type_id(&self) -> TypeId where
    Self: 'static, 
1.34.0
[src]

Gets the TypeId of self

Auto Trait Implementations

impl Send for Utf8Error

impl Sync for Utf8Error

Blanket Implementations

impl<T> From for T[src]

impl<T, U> TryFrom for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto for T where
    U: TryFrom<T>, 
[src]

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

The type returned in the event of a conversion error.

impl<T, U> Into for T where
    U: From<T>, 
[src]

impl<T> Borrow for T where
    T: ?Sized
[src]

impl<T> BorrowMut for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

impl<T> ToString for T where
    T: Display + ?Sized
[src]