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Merge common parts of parsers

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Bert Peters
2021-12-16 19:26:10 +01:00
parent 3e2a3f5206
commit 0f6167e90f
1 changed files with 20 additions and 34 deletions
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54
2021/src/day16.rs
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@@ -98,46 +98,32 @@ fn parse_operator_len(input: Input) -> IResult<Input, Vec<Packet>> {
fn parse_operator_count(input: Input) -> IResult<Input, Vec<Packet>> { fn parse_operator_count(input: Input) -> IResult<Input, Vec<Packet>> {
const SIZE_LEN: usize = 11; const SIZE_LEN: usize = 11;
let (input, to_read) = take::<_, usize, _, _>(SIZE_LEN)(input)?; let (input, to_read) = take(SIZE_LEN)(input)?;
count(parse_packet, to_read)(input) count(parse_packet, to_read)(input)
} }
fn parse_packet(input: Input) -> IResult<Input, Packet> { fn parse_packet(input: Input) -> IResult<Input, Packet> {
let parse_literal_packet = map( let parse_literal_packet = preceded(tag(4u8, 3usize), parse_literal);
tuple((take(3usize), preceded(tag(4u8, 3usize), parse_literal))),
let parse_operator_packet = map(
tuple((
take(3usize),
alt((
preceded(tag(0u8, 1usize), parse_operator_len),
preceded(tag(1u8, 1usize), parse_operator_count),
)),
)),
|(operator, contents)| Contents::Operator(operator, contents),
);
map(
tuple((
take(3usize),
alt((parse_literal_packet, parse_operator_packet)),
)),
|(version, contents)| Packet { version, contents }, |(version, contents)| Packet { version, contents },
); )(input)
let parse_operator_len_packet = map(
tuple((
take(3usize),
take(3usize),
preceded(tag(0u8, 1usize), parse_operator_len),
)),
|(version, operator, contents)| Packet {
version,
contents: Contents::Operator(operator, contents),
},
);
let parse_operator_count_packet = map(
tuple((
take(3usize),
take(3usize),
preceded(tag(1u8, 1usize), parse_operator_count),
)),
|(version, operator, contents)| Packet {
version,
contents: Contents::Operator(operator, contents),
},
);
alt((
parse_literal_packet,
parse_operator_len_packet,
parse_operator_count_packet,
))(input)
} }
fn convert_hex(hex: &[u8]) -> Vec<u8> { fn convert_hex(hex: &[u8]) -> Vec<u8> {