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) -> usize1.5.0[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 Eq for Utf8Error[src]

impl Display for Utf8Error[src]

impl PartialEq<Utf8Error> for Utf8Error[src]

impl Debug for Utf8Error[src]

impl Clone for Utf8Error[src]

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

Performs copy-assignment from source. Read more

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

Auto Trait Implementations

impl UnwindSafe for Utf8Error

impl RefUnwindSafe for Utf8Error

impl Unpin for Utf8Error

impl Sync for Utf8Error

impl Send for Utf8Error

Blanket Implementations

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

type Error = Infallible

The type returned in the event of a conversion error.

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

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

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

impl<T> BorrowMut<T> 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

The resulting type after obtaining ownership.

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