53 lines
1.3 KiB
Rust
53 lines
1.3 KiB
Rust
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use std::fmt::Write;
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#[derive(Debug)]
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pub enum DecodeError {
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InvalidCharacter(u8),
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InvalidCharacterCount(usize),
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}
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impl std::fmt::Display for DecodeError {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match self {
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Self::InvalidCharacter(c) => {
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write!(f, "Invalid character: {c} not in [0123456789ABCDEF]")
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}
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Self::InvalidCharacterCount(n) => {
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write!(f, "Invalid character count: {n} % 2 != 0")
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}
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}
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}
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}
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impl std::error::Error for DecodeError {}
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pub fn encode(input: &[u8]) -> String {
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let mut s = String::new();
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for byte in input {
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write!(s, "{byte:02x}").unwrap();
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}
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s
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}
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fn val(c: u8) -> Result<u8, DecodeError> {
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match c {
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b'A'..=b'F' => Ok(c - b'A' + 10),
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b'a'..=b'f' => Ok(c - b'a' + 10),
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b'0'..=b'9' => Ok(c - b'0'),
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_ => Err(DecodeError::InvalidCharacter(c)),
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}
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}
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pub fn decode(input: &str) -> Result<Vec<u8>, DecodeError> {
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let len = input.len();
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if len % 2 != 0 {
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return Err(DecodeError::InvalidCharacterCount(len));
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}
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input
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.as_bytes()
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.chunks_exact(2)
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.map(|pair| Ok(val(pair[0])? << 4 | val(pair[1])?))
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.collect()
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}
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