pub struct Utf8Error { /* private fields */ }
Expand description
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 String
s
and &str
s 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
}
}
}
}
}
RunImplementations
sourceimpl Utf8Error
impl Utf8Error
1.5.0 (const: unstable) · sourcepub fn valid_up_to(&self) -> usize
pub fn valid_up_to(&self) -> usize
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());
Run1.20.0 (const: unstable) · sourcepub fn error_len(&self) -> Option<usize>
pub fn error_len(&self) -> Option<usize>
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 validchar
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 byvalid_up_to()
. Decoding should resume after that sequence (after inserting aU+FFFD REPLACEMENT CHARACTER
) in case of lossy decoding.
Trait Implementations
sourceimpl Error for Utf8Error
impl Error for Utf8Error
sourcefn description(&self) -> &str
fn description(&self) -> &str
use the Display impl or to_string()
1.30.0 · sourcefn source(&self) -> Option<&(dyn Error + 'static)>
fn source(&self) -> Option<&(dyn Error + 'static)>
The lower-level source of this error, if any. Read more
impl Copy for Utf8Error
impl Eq for Utf8Error
impl StructuralEq for Utf8Error
impl StructuralPartialEq for Utf8Error
Auto Trait Implementations
impl RefUnwindSafe for Utf8Error
impl Send for Utf8Error
impl Sync for Utf8Error
impl Unpin for Utf8Error
impl UnwindSafe for Utf8Error
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
Uses borrowed data to replace owned data, usually by cloning. Read more