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lib.rs
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lib.rs
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use std::error;
use std::fmt;
pub trait ToHex {
fn to_hex(&self) -> String;
fn write_hex<W: fmt::Write>(&self, w: &mut W) -> fmt::Result {
w.write_str(&self.to_hex())
}
}
impl<T: AsRef<[u8]>> ToHex for T {
fn to_hex(&self) -> String {
static CHARS: &'static [u8] = b"0123456789abcdef";
let bytes = self.as_ref();
let mut v = Vec::with_capacity(bytes.len() * 2);
for &byte in bytes.iter() {
v.push(CHARS[(byte >> 4) as usize]);
v.push(CHARS[(byte & 0xf) as usize]);
}
unsafe {
String::from_utf8_unchecked(v)
}
}
}
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum FromHexError {
InvalidHexCharacter {
c: char,
index: usize,
},
InvalidHexLength,
}
impl error::Error for FromHexError {
fn description(&self) -> &str {
match *self {
FromHexError::InvalidHexCharacter{ .. } => "invalid character",
FromHexError::InvalidHexLength => "invalid length",
}
}
}
impl fmt::Display for FromHexError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
FromHexError::InvalidHexCharacter { c, index } =>
write!(f, "Invalid character '{}' at position {}", c, index),
FromHexError::InvalidHexLength =>
write!(f, "Invalid string length"),
}
}
}
pub trait FromHex: Sized {
type Error;
fn from_hex(s: &str) -> Result<Self, Self::Error>;
}
impl FromHex for Vec<u8> {
type Error = FromHexError;
fn from_hex(s: &str) -> Result<Self, Self::Error> {
let mut b = Vec::with_capacity(s.len() / 2);
let mut modulus = 0;
let mut buf = 08;
for (idx, byte) in s.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 = s[idx..].chars().next().unwrap();
return Err(FromHexError::InvalidHexCharacter {
c: ch,
index: idx,
})
}
}
modulus += 1;
if modulus == 2 {
modulus = 0;
b.push(buf);
}
}
match modulus {
0 => Ok(b.into_iter().collect()),
_ => Err(FromHexError::InvalidHexLength),
}
}
}
#[cfg(test)]
mod test {
use super::{FromHex, FromHexError, ToHex};
#[test]
fn test_to_hex() {
assert_eq!("foobar".to_hex(), "666f6f626172");
}
#[test]
pub fn test_from_hex_okay() {
assert_eq!(Vec::from_hex("666f6f626172").unwrap(),
b"foobar");
assert_eq!(Vec::from_hex("666F6F626172").unwrap(),
b"foobar");
}
#[test]
pub fn test_invalid_length() {
assert_eq!(Vec::from_hex("1").unwrap_err(),
FromHexError::InvalidHexLength);
assert_eq!(Vec::from_hex("666f6f6261721").unwrap_err(),
FromHexError::InvalidHexLength);
}
#[test]
pub fn test_invalid_char() {
assert_eq!(Vec::from_hex("66ag").unwrap_err(),
FromHexError::InvalidHexCharacter {
c: 'g',
index: 3
});
}
#[test]
pub fn test_empty() {
assert_eq!(Vec::from_hex("").unwrap(), b"");
}
}