fpe 0.6.1

Format-preserving encryption
Documentation 
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use core::fmt;

/// Error indicating that a radix was not in the supported range of values for FF1.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct InvalidRadix(pub(super) u32);

impl fmt::Display for InvalidRadix {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "The radix {} is not in the range 2..=(1 << 16)", self.0)
    }
}

#[cfg(feature = "std")]
impl std::error::Error for InvalidRadix {}

/// Errors that can occur while using FF1 for encryption or decryption.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum NumeralStringError {
    /// The numeral string was not compatible with the configured radix.
    InvalidForRadix(u32),
    /// The numeral string was longer than the maximum allowed length for FF1.
    TooLong {
        /// The length of the numeral string.
        ns_len: usize,
        /// The maximum length allowed (in numerals) for a numeral string of its radix.
        max_len: usize,
    },
    /// The numeral string was shorter than the minimum allowed length for FF1.
    TooShort {
        /// The length of the numeral string.
        ns_len: usize,
        /// The minimum length allowed (in numerals) for a numeral string of its radix.
        min_len: usize,
    },
}

impl fmt::Display for NumeralStringError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            NumeralStringError::InvalidForRadix(radix) => {
                write!(f, "The given numeral string is invalid for radix {}", radix)
            }
            NumeralStringError::TooLong { ns_len, max_len } => write!(
                f,
                "The given numeral string is too long for FF1 ({} > {})",
                ns_len, max_len,
            ),
            NumeralStringError::TooShort { ns_len, min_len } => write!(
                f,
                "The given numeral string is too short for FF1 ({} < {})",
                ns_len, min_len,
            ),
        }
    }
}

#[cfg(feature = "std")]
impl std::error::Error for NumeralStringError {}