| //! Hex binary-to-text encoding |
| |
| pub use self::FromHexError::*; |
| |
| use std::fmt; |
| use std::error; |
| |
| /// A trait for converting a value to hexadecimal encoding |
| pub trait ToHex { |
| /// Converts the value of `self` to a hex value, returning the owned |
| /// string. |
| fn to_hex(&self) -> String; |
| } |
| |
| const CHARS: &[u8] = b"0123456789abcdef"; |
| |
| impl ToHex for [u8] { |
| /// Turn a vector of `u8` bytes into a hexadecimal string. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(rustc_private)] |
| /// |
| /// extern crate serialize; |
| /// use serialize::hex::ToHex; |
| /// |
| /// fn main () { |
| /// let str = [52,32].to_hex(); |
| /// println!("{}", str); |
| /// } |
| /// ``` |
| fn to_hex(&self) -> String { |
| let mut v = Vec::with_capacity(self.len() * 2); |
| for &byte in self { |
| v.push(CHARS[(byte >> 4) as usize]); |
| v.push(CHARS[(byte & 0xf) as usize]); |
| } |
| |
| unsafe { |
| String::from_utf8_unchecked(v) |
| } |
| } |
| } |
| |
| /// A trait for converting hexadecimal encoded values |
| pub trait FromHex { |
| /// Converts the value of `self`, interpreted as hexadecimal encoded data, |
| /// into an owned vector of bytes, returning the vector. |
| fn from_hex(&self) -> Result<Vec<u8>, FromHexError>; |
| } |
| |
| /// Errors that can occur when decoding a hex encoded string |
| #[derive(Copy, Clone, Debug)] |
| pub enum FromHexError { |
| /// The input contained a character not part of the hex format |
| InvalidHexCharacter(char, usize), |
| /// The input had an invalid length |
| InvalidHexLength, |
| } |
| |
| impl fmt::Display for FromHexError { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| match *self { |
| InvalidHexCharacter(ch, idx) => |
| write!(f, "Invalid character '{}' at position {}", ch, idx), |
| InvalidHexLength => write!(f, "Invalid input length"), |
| } |
| } |
| } |
| |
| impl error::Error for FromHexError { |
| fn description(&self) -> &str { |
| match *self { |
| InvalidHexCharacter(..) => "invalid character", |
| InvalidHexLength => "invalid length", |
| } |
| } |
| } |
| |
| |
| impl FromHex for str { |
| /// Converts any hexadecimal encoded string (literal, `@`, `&`, or `~`) |
| /// to the byte values it encodes. |
| /// |
| /// You can use the `String::from_utf8` function to turn a |
| /// `Vec<u8>` into a string with characters corresponding to those values. |
| /// |
| /// # Examples |
| /// |
| /// This converts a string literal to hexadecimal and back. |
| /// |
| /// ``` |
| /// #![feature(rustc_private)] |
| /// |
| /// extern crate serialize; |
| /// use serialize::hex::{FromHex, ToHex}; |
| /// |
| /// fn main () { |
| /// let hello_str = "Hello, World".as_bytes().to_hex(); |
| /// println!("{}", hello_str); |
| /// let bytes = hello_str.from_hex().unwrap(); |
| /// println!("{:?}", bytes); |
| /// let result_str = String::from_utf8(bytes).unwrap(); |
| /// println!("{}", result_str); |
| /// } |
| /// ``` |
| fn from_hex(&self) -> Result<Vec<u8>, FromHexError> { |
| // This may be an overestimate if there is any whitespace |
| let mut b = Vec::with_capacity(self.len() / 2); |
| let mut modulus = 0; |
| let mut buf = 0; |
| |
| for (idx, byte) in self.bytes().enumerate() { |
| buf <<= 4; |
| |
| match byte { |
| b'A'..=b'F' => buf |= byte - b'A' + 10, |
| b'a'..=b'f' => buf |= byte - b'a' + 10, |
| b'0'..=b'9' => buf |= byte - b'0', |
| b' '|b'\r'|b'\n'|b'\t' => { |
| buf >>= 4; |
| continue |
| } |
| _ => { |
| let ch = self[idx..].chars().next().unwrap(); |
| return Err(InvalidHexCharacter(ch, idx)) |
| } |
| } |
| |
| modulus += 1; |
| if modulus == 2 { |
| modulus = 0; |
| b.push(buf); |
| } |
| } |
| |
| match modulus { |
| 0 => Ok(b), |
| _ => Err(InvalidHexLength), |
| } |
| } |
| } |
| |
| #[cfg(test)] |
| mod tests; |