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use crate::{
Any, ByteSlice, Encodable, Encoder, Error, ErrorKind, Header, Length, Result, Tag, Tagged,
};
use core::convert::TryFrom;
#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
pub struct BitString<'a> {
inner: ByteSlice<'a>,
}
impl<'a> BitString<'a> {
pub fn new(slice: &'a [u8]) -> Result<Self> {
ByteSlice::new(slice)
.map(|inner| Self { inner })
.map_err(|_| ErrorKind::Length { tag: Self::TAG }.into())
}
pub fn as_bytes(&self) -> &'a [u8] {
self.inner.as_bytes()
}
pub fn len(&self) -> Length {
self.inner.len()
}
pub fn is_empty(&self) -> bool {
self.inner.is_empty()
}
}
impl AsRef<[u8]> for BitString<'_> {
fn as_ref(&self) -> &[u8] {
self.as_bytes()
}
}
impl<'a> From<&BitString<'a>> for BitString<'a> {
fn from(value: &BitString<'a>) -> BitString<'a> {
*value
}
}
impl<'a> TryFrom<Any<'a>> for BitString<'a> {
type Error = Error;
fn try_from(any: Any<'a>) -> Result<BitString<'a>> {
any.tag().assert_eq(Tag::BitString)?;
if let Some(bs) = any.as_bytes().get(1..) {
if any.as_bytes()[0] == 0 {
return ByteSlice::new(bs)
.map(|inner| Self { inner })
.map_err(|_| ErrorKind::Length { tag: Self::TAG }.into());
}
}
Err(ErrorKind::Length { tag: Self::TAG }.into())
}
}
impl<'a> From<BitString<'a>> for Any<'a> {
fn from(bit_string: BitString<'a>) -> Any<'a> {
Any {
tag: Tag::BitString,
value: bit_string.inner,
}
}
}
impl<'a> From<BitString<'a>> for &'a [u8] {
fn from(bit_string: BitString<'a>) -> &'a [u8] {
bit_string.as_bytes()
}
}
impl<'a> Encodable for BitString<'a> {
fn encoded_len(&self) -> Result<Length> {
(Length::one() + self.inner.len())?.for_tlv()
}
fn encode(&self, encoder: &mut Encoder<'_>) -> Result<()> {
Header::new(Self::TAG, (Length::one() + self.inner.len())?)?.encode(encoder)?;
encoder.byte(0)?;
encoder.bytes(self.as_bytes())
}
}
impl<'a> Tagged for BitString<'a> {
const TAG: Tag = Tag::BitString;
}
#[cfg(test)]
mod tests {
use super::{Any, BitString, ErrorKind, Result, Tag};
use core::convert::TryInto;
fn parse_bitstring_from_any(bytes: &[u8]) -> Result<BitString<'_>> {
Any::new(Tag::BitString, bytes)?.try_into()
}
#[test]
fn reject_non_prefixed_bitstring() {
let err = parse_bitstring_from_any(&[]).err().unwrap();
assert_eq!(
err.kind(),
ErrorKind::Length {
tag: Tag::BitString
}
);
}
#[test]
fn reject_non_zero_prefix() {
let err = parse_bitstring_from_any(&[1, 1, 2, 3]).err().unwrap();
assert_eq!(
err.kind(),
ErrorKind::Length {
tag: Tag::BitString
}
);
}
#[test]
fn decode_empty_bitstring() {
let bs = parse_bitstring_from_any(&[0]).unwrap();
assert_eq!(bs.as_ref(), &[]);
}
#[test]
fn decode_non_empty_bitstring() {
let bs = parse_bitstring_from_any(&[0, 1, 2, 3]).unwrap();
assert_eq!(bs.as_ref(), &[1, 2, 3]);
}
}