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use crate::error::{ErrorKind, ParseError};
use crate::internal::{Err, IResult};
use crate::lib::std::ops::{AddAssign, RangeFrom, Shl, Shr, Div};
use crate::traits::{InputIter, InputLength, Slice, ToUsize};
pub fn take<I, O, C, E: ParseError<(I, usize)>>(count: C) -> impl Fn((I, usize)) -> IResult<(I, usize), O, E>
where
I: Slice<RangeFrom<usize>> + InputIter<Item = u8> + InputLength,
C: ToUsize,
O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O>,
{
let count = count.to_usize();
move |(input, bit_offset): (I, usize)| {
if count == 0 {
Ok(((input, bit_offset), 0u8.into()))
} else {
let cnt = (count + bit_offset).div(8);
if input.input_len() * 8 < count + bit_offset {
Err(Err::Error(E::from_error_kind((input, bit_offset), ErrorKind::Eof)))
} else {
let mut acc:O = (0 as u8).into();
let mut offset: usize = bit_offset;
let mut remaining: usize = count;
let mut end_offset: usize = 0;
for byte in input.iter_elements().take(cnt + 1) {
if remaining == 0 {
break;
}
let val: O = if offset == 0 {
byte.into()
} else {
((byte << offset) as u8 >> offset).into()
};
if remaining < 8 - offset {
acc += val >> (8 - offset - remaining);
end_offset = remaining + offset;
break;
} else {
acc += val << (remaining - (8 - offset));
remaining -= 8 - offset;
offset = 0;
}
}
Ok(( (input.slice(cnt..), end_offset) , acc))
}
}
}
}
pub fn tag<I, O, C, E: ParseError<(I, usize)>>(pattern: O, count: C) -> impl Fn((I, usize)) -> IResult<(I, usize), O, E>
where
I: Slice<RangeFrom<usize>> + InputIter<Item = u8> + InputLength + Clone,
C: ToUsize,
O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O> + PartialEq,
{
let count = count.to_usize();
move |input: (I, usize)| {
let inp = input.clone();
take(count)(input).and_then(|(i, o)| {
if pattern == o {
Ok((i, o))
} else {
Err(Err::Error(error_position!(inp, ErrorKind::TagBits)))
}
})
}
}