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mod internal;
#[derive(Debug, Copy, Clone)]
pub enum DecodeError {
InvalidByte(usize, u8),
InvalidChunk(usize),
InvalidLength,
InvalidTail,
}
impl DecodeError {
fn add_offset(&self, chunk_count: usize) -> Self {
let offset = chunk_count * 5;
use DecodeError::*;
match self {
InvalidByte(index, byte) => InvalidByte(index + offset, *byte),
InvalidChunk(index) => InvalidChunk(index + offset),
_ => *self,
}
}
}
pub fn encode<T: AsRef<[u8]>>(input: T) -> String {
let input = input.as_ref();
let length = input.len();
if length == 0 {
return String::with_capacity(0);
}
let tail_size = length % 4;
let chunked_size = length - tail_size;
let mut out = Vec::with_capacity(length / 4 * 5 + 5);
for chunk in input[..chunked_size].chunks(4) {
let z85_chunk = internal::encode_chunk(chunk);
out.extend_from_slice(&z85_chunk);
}
if tail_size > 0 {
let bintail = &input[chunked_size..];
let tail = internal::encode_tail(bintail);
out.extend_from_slice(&tail);
}
unsafe { String::from_utf8_unchecked(out) }
}
pub fn decode<T: AsRef<[u8]>>(input: T) -> Result<Vec<u8>, DecodeError> {
let input = input.as_ref();
let length = input.len();
if length == 0 {
return Ok(Vec::with_capacity(0));
}
if length % 5 != 0 {
return Err(DecodeError::InvalidLength);
}
let has_tail = input[length - 5] == b'#';
let chunked_size = if has_tail { length - 5 } else { length };
let mut out = Vec::with_capacity(length / 5 * 4);
for (chunk_count, chunk) in input[..chunked_size].chunks(5).enumerate() {
match internal::decode_chunk(chunk) {
Err(decode_error) => return Err(decode_error.add_offset(chunk_count)),
Ok(binchunk) => out.extend_from_slice(&binchunk),
}
}
if has_tail {
let last_chunk = &input[chunked_size..];
match internal::decode_tail(last_chunk) {
Err(decode_error) => return Err(decode_error.add_offset(length - 5)),
Ok(bintail) => bintail.append_to_vec(&mut out),
}
}
Ok(out)
}