use core::marker::PhantomData;
use core::mem;
use crate::Context;
use crate::de::{Decoder, SequenceDecoder, SizeHint};
use crate::json::parser::{Parser, Token};
use super::JsonDecoder;
#[must_use = "Must call skip_sequence_remaining"]
pub(crate) struct JsonSequenceDecoder<P, C, M> {
cx: C,
len: Option<usize>,
first: bool,
parser: P,
finalized: bool,
_marker: PhantomData<M>,
}
impl<'de, P, C, M> JsonSequenceDecoder<P, C, M>
where
P: Parser<'de>,
C: Context,
M: 'static,
{
#[inline]
pub(super) fn new(cx: C, len: Option<usize>, mut parser: P) -> Result<Self, C::Error> {
let actual = parser.lex(cx);
if !matches!(actual, Token::OpenBracket) {
return Err(cx.message(format_args!("Expected opening bracket, was {actual}")));
}
parser.skip(cx, 1)?;
Ok(Self {
cx,
len,
first: true,
parser,
finalized: false,
_marker: PhantomData,
})
}
fn parse_next_value(&mut self) -> Result<bool, C::Error> {
let first = mem::take(&mut self.first);
loop {
let token = self.parser.lex(self.cx);
if token.is_value() {
return Ok(true);
}
match token {
Token::Comma if !first => {
self.parser.skip(self.cx, 1)?;
}
Token::CloseBracket => {
return Ok(false);
}
_ => {
return Err(self.cx.message(format_args!(
"Expected value or closing bracket `]`, but found {token}"
)));
}
}
}
}
#[inline]
pub(super) fn skip_sequence_remaining(mut self) -> Result<(), C::Error> {
if self.finalized {
return Ok(());
}
while let Some(decoder) = SequenceDecoder::try_decode_next(&mut self)? {
decoder.skip()?;
}
let actual = self.parser.lex(self.cx);
if !matches!(actual, Token::CloseBracket) {
return Err(self
.cx
.message(format_args!("Expected closing bracket, was {actual}")));
}
self.parser.skip(self.cx, 1)?;
self.finalized = true;
Ok(())
}
}
impl<'de, P, C, M> SequenceDecoder<'de> for JsonSequenceDecoder<P, C, M>
where
P: Parser<'de>,
C: Context,
M: 'static,
{
type Cx = C;
type Error = C::Error;
type Allocator = C::Allocator;
type Mode = M;
type DecodeNext<'this>
= JsonDecoder<P::Mut<'this>, C, M>
where
Self: 'this;
#[inline]
fn cx(&self) -> Self::Cx {
self.cx
}
#[inline]
fn size_hint(&self) -> SizeHint {
SizeHint::from(self.len)
}
#[inline]
fn try_decode_next(&mut self) -> Result<Option<Self::DecodeNext<'_>>, C::Error> {
if !self.parse_next_value()? {
return Ok(None);
}
Ok(Some(JsonDecoder::new(self.cx, self.parser.borrow_mut())))
}
#[inline]
fn decode_next(&mut self) -> Result<Self::DecodeNext<'_>, C::Error> {
if !self.parse_next_value()? {
return Err(self.cx.message(format_args!("Encountered short array")));
}
Ok(JsonDecoder::new(self.cx, self.parser.borrow_mut()))
}
}