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use std::iter;
use super::{lexer, unused, Error, Location, Spanned, SpannedValue, Unused};
pub(super) enum Item<'a> {
Literal(Spanned<&'a [u8]>),
EscapedBracket {
_first: Unused<Location>,
_second: Unused<Location>,
},
Component {
_opening_bracket: Unused<Location>,
_leading_whitespace: Unused<Option<Spanned<&'a [u8]>>>,
name: Spanned<&'a [u8]>,
modifiers: Box<[Modifier<'a>]>,
_trailing_whitespace: Unused<Option<Spanned<&'a [u8]>>>,
_closing_bracket: Unused<Location>,
},
Optional {
opening_bracket: Location,
_leading_whitespace: Unused<Option<Spanned<&'a [u8]>>>,
_optional_kw: Unused<Spanned<&'a [u8]>>,
_whitespace: Unused<Spanned<&'a [u8]>>,
nested_format_description: NestedFormatDescription<'a>,
closing_bracket: Location,
},
First {
opening_bracket: Location,
_leading_whitespace: Unused<Option<Spanned<&'a [u8]>>>,
_first_kw: Unused<Spanned<&'a [u8]>>,
_whitespace: Unused<Spanned<&'a [u8]>>,
nested_format_descriptions: Box<[NestedFormatDescription<'a>]>,
closing_bracket: Location,
},
}
pub(super) struct NestedFormatDescription<'a> {
pub(super) _opening_bracket: Unused<Location>,
pub(super) items: Box<[Item<'a>]>,
pub(super) _closing_bracket: Unused<Location>,
pub(super) _trailing_whitespace: Unused<Option<Spanned<&'a [u8]>>>,
}
pub(super) struct Modifier<'a> {
pub(super) _leading_whitespace: Unused<Spanned<&'a [u8]>>,
pub(super) key: Spanned<&'a [u8]>,
pub(super) _colon: Unused<Location>,
pub(super) value: Spanned<&'a [u8]>,
}
pub(super) fn parse<
'item: 'iter,
'iter,
I: Iterator<Item = Result<lexer::Token<'item>, Error>>,
const VERSION: u8,
>(
tokens: &'iter mut lexer::Lexed<I>,
) -> impl Iterator<Item = Result<Item<'item>, Error>> + 'iter {
assert!(version!(1..=2));
parse_inner::<_, false, VERSION>(tokens)
}
fn parse_inner<
'item,
I: Iterator<Item = Result<lexer::Token<'item>, Error>>,
const NESTED: bool,
const VERSION: u8,
>(
tokens: &mut lexer::Lexed<I>,
) -> impl Iterator<Item = Result<Item<'item>, Error>> + '_ {
iter::from_fn(move || {
if NESTED && tokens.peek_closing_bracket().is_some() {
return None;
}
let next = match tokens.next()? {
Ok(token) => token,
Err(err) => return Some(Err(err)),
};
Some(match next {
lexer::Token::Literal(Spanned { value: _, span: _ }) if NESTED => {
bug!("literal should not be present in nested description")
}
lexer::Token::Literal(value) => Ok(Item::Literal(value)),
lexer::Token::Bracket {
kind: lexer::BracketKind::Opening,
location,
} => {
if version!(..=1) {
if let Some(second_location) = tokens.next_if_opening_bracket() {
Ok(Item::EscapedBracket {
_first: unused(location),
_second: unused(second_location),
})
} else {
parse_component::<_, VERSION>(location, tokens)
}
} else {
parse_component::<_, VERSION>(location, tokens)
}
}
lexer::Token::Bracket {
kind: lexer::BracketKind::Closing,
location: _,
} if NESTED => {
bug!("closing bracket should be caught by the `if` statement")
}
lexer::Token::Bracket {
kind: lexer::BracketKind::Closing,
location: _,
} => {
bug!("closing bracket should have been consumed by `parse_component`")
}
lexer::Token::ComponentPart { kind: _, value } if NESTED => Ok(Item::Literal(value)),
lexer::Token::ComponentPart { kind: _, value: _ } => {
bug!("component part should have been consumed by `parse_component`")
}
})
})
}
fn parse_component<'a, I: Iterator<Item = Result<lexer::Token<'a>, Error>>, const VERSION: u8>(
opening_bracket: Location,
tokens: &mut lexer::Lexed<I>,
) -> Result<Item<'a>, Error> {
let leading_whitespace = tokens.next_if_whitespace();
let Some(name) = tokens.next_if_not_whitespace() else {
let span = match leading_whitespace {
Some(Spanned { value: _, span }) => span,
None => opening_bracket.to(opening_bracket),
};
return Err(span.error("expected component name"));
};
if *name == b"optional" {
let Some(whitespace) = tokens.next_if_whitespace() else {
return Err(name.span.error("expected whitespace after `optional`"));
};
let nested = parse_nested::<_, VERSION>(whitespace.span.end, tokens)?;
let Some(closing_bracket) = tokens.next_if_closing_bracket() else {
return Err(opening_bracket.error("unclosed bracket"));
};
return Ok(Item::Optional {
opening_bracket,
_leading_whitespace: unused(leading_whitespace),
_optional_kw: unused(name),
_whitespace: unused(whitespace),
nested_format_description: nested,
closing_bracket,
});
}
if *name == b"first" {
let Some(whitespace) = tokens.next_if_whitespace() else {
return Err(name.span.error("expected whitespace after `first`"));
};
let mut nested_format_descriptions = Vec::new();
while let Ok(description) = parse_nested::<_, VERSION>(whitespace.span.end, tokens) {
nested_format_descriptions.push(description);
}
let Some(closing_bracket) = tokens.next_if_closing_bracket() else {
return Err(opening_bracket.error("unclosed bracket"));
};
return Ok(Item::First {
opening_bracket,
_leading_whitespace: unused(leading_whitespace),
_first_kw: unused(name),
_whitespace: unused(whitespace),
nested_format_descriptions: nested_format_descriptions.into_boxed_slice(),
closing_bracket,
});
}
let mut modifiers = Vec::new();
let trailing_whitespace = loop {
let Some(whitespace) = tokens.next_if_whitespace() else {
break None;
};
if let Some(location) = tokens.next_if_opening_bracket() {
return Err(location
.to(location)
.error("modifier must be of the form `key:value`"));
}
let Some(Spanned { value, span }) = tokens.next_if_not_whitespace() else {
break Some(whitespace);
};
let Some(colon_index) = value.iter().position(|&b| b == b':') else {
return Err(span.error("modifier must be of the form `key:value`"));
};
let key = &value[..colon_index];
let value = &value[colon_index + 1..];
if key.is_empty() {
return Err(span.shrink_to_start().error("expected modifier key"));
}
if value.is_empty() {
return Err(span.shrink_to_end().error("expected modifier value"));
}
modifiers.push(Modifier {
_leading_whitespace: unused(whitespace),
key: key.spanned(span.shrink_to_before(colon_index as _)),
_colon: unused(span.start.offset(colon_index as _)),
value: value.spanned(span.shrink_to_after(colon_index as _)),
});
};
let Some(closing_bracket) = tokens.next_if_closing_bracket() else {
return Err(opening_bracket.error("unclosed bracket"));
};
Ok(Item::Component {
_opening_bracket: unused(opening_bracket),
_leading_whitespace: unused(leading_whitespace),
name,
modifiers: modifiers.into_boxed_slice(),
_trailing_whitespace: unused(trailing_whitespace),
_closing_bracket: unused(closing_bracket),
})
}
fn parse_nested<'a, I: Iterator<Item = Result<lexer::Token<'a>, Error>>, const VERSION: u8>(
last_location: Location,
tokens: &mut lexer::Lexed<I>,
) -> Result<NestedFormatDescription<'a>, Error> {
let Some(opening_bracket) = tokens.next_if_opening_bracket() else {
return Err(last_location.error("expected opening bracket"));
};
let items = parse_inner::<_, true, VERSION>(tokens).collect::<Result<_, _>>()?;
let Some(closing_bracket) = tokens.next_if_closing_bracket() else {
return Err(opening_bracket.error("unclosed bracket"));
};
let trailing_whitespace = tokens.next_if_whitespace();
Ok(NestedFormatDescription {
_opening_bracket: unused(opening_bracket),
items,
_closing_bracket: unused(closing_bracket),
_trailing_whitespace: unused(trailing_whitespace),
})
}