| use std::error; |
| use std::fmt; |
| use std::str; |
| use std::string::FromUtf8Error; |
| |
| use raw::FstType; |
| |
| /// An error that occurred while using a finite state transducer. |
| pub enum Error { |
| /// A version mismatch occurred while reading a finite state transducer. |
| /// |
| /// This occurs when the API version (of the crate) does not match the |
| /// version encoded in the finite state transducer. |
| /// |
| /// When this error is encountered, there are only two ways to fix it: |
| /// |
| /// 1. Change the version of the library to one that is compatible with |
| /// the given finite state transducer. |
| /// 2. Rebuild the finite state transducer. |
| Version { |
| /// The expected version, which is hard-coded into the current version |
| /// of this crate. |
| expected: u64, |
| /// The version read from the finite state transducer. |
| got: u64, |
| }, |
| /// An unexpected error occurred while reading a finite state transducer. |
| /// Usually this occurs because the data is corrupted or is not actually |
| /// a finite state transducer serialized by this library. |
| Format, |
| /// A duplicate key was inserted into a finite state transducer, which is |
| /// not allowed. |
| DuplicateKey { |
| /// The duplicate key. |
| got: Vec<u8>, |
| }, |
| /// A key was inserted out of order into a finite state transducer. |
| /// |
| /// Keys must always be inserted in lexicographic order. |
| OutOfOrder { |
| /// The last key successfully inserted. |
| previous: Vec<u8>, |
| /// The key that caused this error to occur. |
| got: Vec<u8>, |
| }, |
| /// A finite state transducer with an unexpected type was found. |
| /// |
| /// This is not currently used in this crate, but callers may wish to |
| /// employ its use for alternative data structures implemented on top of |
| /// finite state transducers. |
| WrongType { |
| /// The expected finite state transducer type. |
| expected: FstType, |
| /// The type read from a finite state transducer. |
| got: FstType, |
| }, |
| /// An error that occurred when trying to decode a UTF-8 byte key. |
| FromUtf8(FromUtf8Error), |
| } |
| |
| impl fmt::Display for Error { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| use self::Error::*; |
| match *self { |
| FromUtf8(ref err) => err.fmt(f), |
| Version { expected, got } => { |
| write!(f, "\ |
| Error opening FST: expected API version {}, got API version {}. |
| It looks like the FST you're trying to open is either not an FST file or it |
| was generated with a different version of the 'fst' crate. You'll either need |
| to change the version of the 'fst' crate you're using, or re-generate the |
| FST.", expected, got) |
| } |
| Format => write!(f, "\ |
| Error opening FST: An unknown error occurred. This usually means you're trying |
| to read data that isn't actually an encoded FST."), |
| DuplicateKey { ref got } => write!(f, "\ |
| Error inserting duplicate key: {}.", format_bytes(&*got)), |
| OutOfOrder { ref previous, ref got } => write!(f, "\ |
| Error inserting out-of-order key: {}. (Previous key was {}.) Keys must be |
| inserted in lexicographic order.", |
| format_bytes(&*got), format_bytes(&*previous)), |
| WrongType { expected, got } => write!(f, "\ |
| Error opening FST: expected type {}, got type {}.", expected, got), |
| } |
| } |
| } |
| |
| impl fmt::Debug for Error { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| fmt::Display::fmt(self, f) |
| } |
| } |
| |
| impl error::Error for Error { |
| fn description(&self) -> &str { |
| use self::Error::*; |
| match *self { |
| FromUtf8(ref err) => err.description(), |
| Version { .. } => "incompatible version found when opening FST", |
| Format => "unknown invalid format found when opening FST", |
| DuplicateKey { .. } => "duplicate key insertion", |
| OutOfOrder { .. } => "out-of-order key insertion", |
| WrongType { .. } => "incompatible type found when opening FST", |
| } |
| } |
| |
| fn cause(&self) -> Option<&error::Error> { |
| match *self { |
| Error::FromUtf8(ref err) => Some(err), |
| _ => None, |
| } |
| } |
| } |
| |
| impl From<FromUtf8Error> for Error { |
| fn from(err: FromUtf8Error) -> Self { |
| Error::FromUtf8(err) |
| } |
| } |
| |
| /// Attempt to convert an arbitrary byte string to a more convenient display |
| /// form. |
| /// |
| /// Essentially, try to decode the bytes as UTF-8 and show that. Failing that, |
| /// just show the sequence of bytes. |
| fn format_bytes(bytes: &[u8]) -> String { |
| match str::from_utf8(bytes) { |
| Ok(s) => s.to_owned(), |
| Err(_) => format!("{:?}", bytes), |
| } |
| } |