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use super::{Context, Error, Parse, Parser};
use crate::{NumberBuf, SMALL_STRING_CAPACITY};
use decoded_char::DecodedChar;
use locspan::{Meta, Span};
use smallvec::SmallVec;
impl<M> Parse<M> for NumberBuf {
fn parse_spanned<C, F, E>(
parser: &mut Parser<C, F, E>,
context: Context,
) -> Result<Meta<Self, Span>, Meta<Error<M, E>, M>>
where
C: Iterator<Item = Result<DecodedChar, E>>,
F: FnMut(Span) -> M,
{
let mut buffer: SmallVec<[u8; SMALL_STRING_CAPACITY]> = SmallVec::new();
enum State {
Init,
FirstDigit,
Zero,
NonZero,
FractionalFirst,
FractionalRest,
ExponentSign,
ExponentFirst,
ExponentRest,
}
let mut state = State::Init;
while let Some(c) = parser.peek_char()? {
match state {
State::Init => match c {
'-' => state = State::FirstDigit,
'0' => state = State::Zero,
'1'..='9' => state = State::NonZero,
_ => return Err(Meta(Error::unexpected(Some(c)), parser.position.last())),
},
State::FirstDigit => match c {
'0' => state = State::Zero,
'1'..='9' => state = State::NonZero,
_ => return Err(Meta(Error::unexpected(Some(c)), parser.position.last())),
},
State::Zero => match c {
'.' => state = State::FractionalFirst,
'e' | 'E' => state = State::ExponentSign,
_ => {
if context.follows(c) {
break;
} else {
return Err(Meta(Error::unexpected(Some(c)), parser.position.last()));
}
}
},
State::NonZero => match c {
'0'..='9' => state = State::NonZero,
'.' => state = State::FractionalFirst,
'e' | 'E' => state = State::ExponentSign,
_ => {
if context.follows(c) {
break;
} else {
return Err(Meta(Error::unexpected(Some(c)), parser.position.last()));
}
}
},
State::FractionalFirst => match c {
'0'..='9' => state = State::FractionalRest,
_ => return Err(Meta(Error::unexpected(Some(c)), parser.position.last())),
},
State::FractionalRest => match c {
'0'..='9' => state = State::FractionalRest,
'e' | 'E' => state = State::ExponentSign,
_ => {
if context.follows(c) {
break;
} else {
return Err(Meta(Error::unexpected(Some(c)), parser.position.last()));
}
}
},
State::ExponentSign => match c {
'+' | '-' => state = State::ExponentFirst,
'0'..='9' => state = State::ExponentRest,
_ => return Err(Meta(Error::unexpected(Some(c)), parser.position.last())),
},
State::ExponentFirst => match c {
'0'..='9' => state = State::ExponentRest,
_ => return Err(Meta(Error::unexpected(Some(c)), parser.position.last())),
},
State::ExponentRest => match c {
'0'..='9' => state = State::ExponentRest,
_ => {
if context.follows(c) {
break;
} else {
return Err(Meta(Error::unexpected(Some(c)), parser.position.last()));
}
}
},
}
buffer.push(c as u8);
parser.next_char()?;
}
if matches!(
state,
State::Zero | State::NonZero | State::FractionalRest | State::ExponentRest
) {
Ok(Meta(
unsafe { NumberBuf::new_unchecked(buffer) },
parser.position.current_span(),
))
} else {
Err(Meta(Error::unexpected(None), parser.position.last()))
}
}
}