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use crate::std::fmt;
/// A general error that can occur when working with UUIDs.
#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub struct Error(pub(crate) ErrorKind);
#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub(crate) enum ErrorKind {
/// Invalid character in the [`Uuid`] string.
///
/// [`Uuid`]: ../struct.Uuid.html
Char { character: char, index: usize },
/// A simple [`Uuid`] didn't contain 32 characters.
///
/// [`Uuid`]: ../struct.Uuid.html
SimpleLength { len: usize },
/// A byte array didn't contain 16 bytes
ByteLength { len: usize },
/// A hyphenated [`Uuid`] didn't contain 5 groups
///
/// [`Uuid`]: ../struct.Uuid.html
GroupCount { count: usize },
/// A hyphenated [`Uuid`] had a group that wasn't the right length
///
/// [`Uuid`]: ../struct.Uuid.html
GroupLength {
group: usize,
len: usize,
index: usize,
},
/// The input was not a valid UTF8 string
InvalidUTF8,
/// Some other error occurred.
Other,
}
/// A string that is guaranteed to fail to parse to a [`Uuid`].
///
/// This type acts as a lightweight error indicator, suggesting
/// that the string cannot be parsed but offering no error
/// details. To get details, use `InvalidUuid::into_err`.
///
/// [`Uuid`]: ../struct.Uuid.html
#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub struct InvalidUuid<'a>(pub(crate) &'a [u8]);
impl<'a> InvalidUuid<'a> {
/// Converts the lightweight error type into detailed diagnostics.
pub fn into_err(self) -> Error {
// Check whether or not the input was ever actually a valid UTF8 string
let input_str = match std::str::from_utf8(self.0) {
Ok(s) => s,
Err(_) => return Error(ErrorKind::InvalidUTF8),
};
let (uuid_str, offset, simple) = match input_str.as_bytes() {
[b'{', s @ .., b'}'] => (s, 1, false),
[b'u', b'r', b'n', b':', b'u', b'u', b'i', b'd', b':', s @ ..] => {
(s, "urn:uuid:".len(), false)
}
s => (s, 0, true),
};
let mut hyphen_count = 0;
let mut group_bounds = [0; 4];
// SAFETY: the byte array came from a valid utf8 string,
// and is aligned along char boundaries.
let uuid_str = unsafe { std::str::from_utf8_unchecked(uuid_str) };
for (index, character) in uuid_str.char_indices() {
let byte = character as u8;
if character as u32 - byte as u32 > 0 {
// Multibyte char
return Error(ErrorKind::Char {
character,
index: index + offset + 1,
});
} else if byte == b'-' {
// While we search, also count group breaks
if hyphen_count < 4 {
group_bounds[hyphen_count] = index;
}
hyphen_count += 1;
} else if !matches!(byte, b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F') {
// Non-hex char
return Error(ErrorKind::Char {
character: byte as char,
index: index + offset + 1,
});
}
}
if hyphen_count == 0 && simple {
// This means that we tried and failed to parse a simple uuid.
// Since we verified that all the characters are valid, this means
// that it MUST have an invalid length.
Error(ErrorKind::SimpleLength {
len: input_str.len(),
})
} else if hyphen_count != 4 {
// We tried to parse a hyphenated variant, but there weren't
// 5 groups (4 hyphen splits).
Error(ErrorKind::GroupCount {
count: hyphen_count + 1,
})
} else {
// There are 5 groups, one of them has an incorrect length
const BLOCK_STARTS: [usize; 5] = [0, 9, 14, 19, 24];
for i in 0..4 {
if group_bounds[i] != BLOCK_STARTS[i + 1] - 1 {
return Error(ErrorKind::GroupLength {
group: i,
len: group_bounds[i] - BLOCK_STARTS[i],
index: offset + BLOCK_STARTS[i] + 1,
});
}
}
// The last group must be too long
Error(ErrorKind::GroupLength {
group: 4,
len: input_str.len() - BLOCK_STARTS[4],
index: offset + BLOCK_STARTS[4] + 1,
})
}
}
}
// NOTE: This impl is part of the public API. Breaking changes to it should be carefully considered
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self.0 {
ErrorKind::Char {
character, index, ..
} => {
write!(f, "invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-zA-Z], found `{}` at {}", character, index)
}
ErrorKind::SimpleLength { len } => {
write!(
f,
"invalid length: expected length 32 for simple format, found {}",
len
)
}
ErrorKind::ByteLength { len } => {
write!(f, "invalid length: expected 16 bytes, found {}", len)
}
ErrorKind::GroupCount { count } => {
write!(f, "invalid group count: expected 5, found {}", count)
}
ErrorKind::GroupLength { group, len, .. } => {
let expected = [8, 4, 4, 4, 12][group];
write!(
f,
"invalid group length in group {}: expected {}, found {}",
group, expected, len
)
}
ErrorKind::InvalidUTF8 => write!(f, "non-UTF8 input"),
ErrorKind::Other => write!(f, "failed to parse a UUID"),
}
}
}
#[cfg(feature = "std")]
mod std_support {
use super::*;
use crate::std::error;
impl error::Error for Error {}
}