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use std::io::Read;
use crate::error::Error;
use super::read_u8;
#[derive(Debug, Copy, Clone, PartialEq)]
#[allow(clippy::large_enum_variant)]
pub enum BooleanRun {
Run(u8, u16),
Literals([u8; 255]),
}
pub struct BooleanRleRunIter<R: Read> {
reader: R,
}
impl<R: Read> BooleanRleRunIter<R> {
pub fn new(reader: R) -> Self {
Self { reader }
}
pub fn into_inner(self) -> R {
self.reader
}
}
fn read_literals<R: Read>(reader: &mut R, header: i8) -> Result<[u8; 255], Error> {
let length = (-header) as usize;
let mut literals = [0u8; 255];
reader
.take(length as u64)
.read_exact(&mut literals[..length])?;
Ok(literals)
}
impl<R: Read> Iterator for BooleanRleRunIter<R> {
type Item = Result<BooleanRun, Error>;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
let header = read_u8(&mut self.reader);
let header = match header {
Ok(header) => header as i8,
Err(e) => return Some(Err(e.into())),
};
if header < 0 {
Some(read_literals(&mut self.reader, header).map(BooleanRun::Literals))
} else {
let length = header as u16 + 3;
let value = read_u8(&mut self.reader);
let value = match value {
Ok(value) => value,
Err(e) => return Some(Err(e.into())),
};
Some(Ok(BooleanRun::Run(value, length)))
}
}
}
pub struct BooleanIter<R: Read> {
iter: BooleanRleRunIter<R>,
current: Option<BooleanRun>,
position: u8,
byte_position: usize,
remaining: usize,
}
impl<'a, R: Read> BooleanIter<R> {
pub fn new(reader: R, length: usize) -> Self {
Self {
iter: BooleanRleRunIter::new(reader),
current: None,
position: 0,
byte_position: 0,
remaining: length,
}
}
pub fn into_inner(self) -> R {
self.iter.into_inner()
}
}
impl<R: Read> Iterator for BooleanIter<R> {
type Item = Result<bool, Error>;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
if let Some(run) = &self.current {
match run {
BooleanRun::Run(value, repetitions) => {
let repetitions = *repetitions;
let mask = 128u8 >> self.position;
let result = value & mask == mask;
self.position += 1;
if self.remaining == 0 {
self.current = None;
return None;
} else {
self.remaining -= 1;
}
if self.position == 8 {
if repetitions == 0 {
self.current = None;
} else {
self.current = Some(BooleanRun::Run(*value, repetitions - 1));
}
self.position = 0;
}
Some(Ok(result))
}
BooleanRun::Literals(bytes) => {
let mask = 128u8 >> self.position;
let result = bytes[self.byte_position] & mask == mask;
self.position += 1;
if self.remaining == 0 {
self.current = None;
return None;
} else {
self.remaining -= 1;
}
if self.position == 8 {
if bytes.len() == 1 {
self.current = None;
self.byte_position = 0;
} else {
self.byte_position += 1;
}
self.position = 0;
}
Some(Ok(result))
}
}
} else if self.remaining > 0 {
match self.iter.next()? {
Ok(run) => {
self.current = Some(run);
self.next()
}
Err(e) => {
self.remaining = 0;
Some(Err(e))
}
}
} else {
None
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.remaining, Some(self.remaining))
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn basic() {
let data = [0x61u8, 0x00];
let data = &mut data.as_ref();
let iter = BooleanIter::new(data, 100)
.collect::<Result<Vec<_>, Error>>()
.unwrap();
assert_eq!(iter, vec![false; 100])
}
#[test]
fn literals() {
let data = [0xfeu8, 0b01000100, 0b01000101];
let data = &mut data.as_ref();
let iter = BooleanIter::new(data, 16)
.collect::<Result<Vec<_>, Error>>()
.unwrap();
assert_eq!(
iter,
vec![
false, true, false, false, false, true, false, false,
false, true, false, false, false, true, false, true,
]
)
}
#[test]
fn another() {
let data = [0xff, 0x80];
let data = &mut data.as_ref();
let iter = BooleanIter::new(data, 8)
.collect::<Result<Vec<_>, Error>>()
.unwrap();
assert_eq!(
iter,
vec![true, false, false, false, false, false, false, false,]
)
}
}