| //! Defines utf8 error type. |
| |
| use crate::fmt; |
| |
| /// 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. |
| /// |
| /// [`String`]: ../../std/string/struct.String.html#method.from_utf8 |
| /// [`&str`]: super::from_utf8 |
| /// |
| /// # 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 |
| /// } |
| /// } |
| /// } |
| /// } |
| /// } |
| /// ``` |
| #[derive(Copy, Eq, PartialEq, Clone, Debug)] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct Utf8Error { |
| pub(super) valid_up_to: usize, |
| pub(super) error_len: Option<u8>, |
| } |
| |
| impl Utf8Error { |
| /// 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()); |
| /// ``` |
| #[stable(feature = "utf8_error", since = "1.5.0")] |
| #[inline] |
| pub fn valid_up_to(&self) -> usize { |
| self.valid_up_to |
| } |
| |
| /// 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`][U+FFFD]) in case of |
| /// lossy decoding. |
| /// |
| /// [U+FFFD]: ../../std/char/constant.REPLACEMENT_CHARACTER.html |
| #[stable(feature = "utf8_error_error_len", since = "1.20.0")] |
| #[inline] |
| pub fn error_len(&self) -> Option<usize> { |
| self.error_len.map(|len| len as usize) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl fmt::Display for Utf8Error { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| if let Some(error_len) = self.error_len { |
| write!( |
| f, |
| "invalid utf-8 sequence of {} bytes from index {}", |
| error_len, self.valid_up_to |
| ) |
| } else { |
| write!(f, "incomplete utf-8 byte sequence from index {}", self.valid_up_to) |
| } |
| } |
| } |
| |
| /// An error returned when parsing a `bool` using [`from_str`] fails |
| /// |
| /// [`from_str`]: super::FromStr::from_str |
| #[derive(Debug, Clone, PartialEq, Eq)] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct ParseBoolError { |
| pub(super) _priv: (), |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl fmt::Display for ParseBoolError { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| "provided string was not `true` or `false`".fmt(f) |
| } |
| } |