diff options
Diffstat (limited to 'vendor/time/src/format_description/parse/ast.rs')
| -rw-r--r-- | vendor/time/src/format_description/parse/ast.rs | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/vendor/time/src/format_description/parse/ast.rs b/vendor/time/src/format_description/parse/ast.rs new file mode 100644 index 00000000..cf13de89 --- /dev/null +++ b/vendor/time/src/format_description/parse/ast.rs @@ -0,0 +1,384 @@ +//! AST for parsing format descriptions. + +use alloc::boxed::Box; +use alloc::string::String; +use alloc::vec::Vec; +use core::iter; + +use super::{lexer, unused, Error, Location, Spanned, SpannedValue, Unused}; +use crate::internal_macros::bug; + +/// One part of a complete format description. +pub(super) enum Item<'a> { + /// A literal string, formatted and parsed as-is. + /// + /// This should never be present inside a nested format description. + Literal(Spanned<&'a [u8]>), + /// A sequence of brackets. The first acts as the escape character. + /// + /// This should never be present if the lexer has `BACKSLASH_ESCAPE` set to `true`. + EscapedBracket { + /// The first bracket. + _first: Unused<Location>, + /// The second bracket. + _second: Unused<Location>, + }, + /// Part of a type, along with its modifiers. + Component { + /// Where the opening bracket was in the format string. + _opening_bracket: Unused<Location>, + /// Whitespace between the opening bracket and name. + _leading_whitespace: Unused<Option<Spanned<&'a [u8]>>>, + /// The name of the component. + name: Spanned<&'a [u8]>, + /// The modifiers for the component. + modifiers: Box<[Modifier<'a>]>, + /// Whitespace between the modifiers and closing bracket. + _trailing_whitespace: Unused<Option<Spanned<&'a [u8]>>>, + /// Where the closing bracket was in the format string. + _closing_bracket: Unused<Location>, + }, + /// An optional sequence of items. + Optional { + /// Where the opening bracket was in the format string. + opening_bracket: Location, + /// Whitespace between the opening bracket and "optional". + _leading_whitespace: Unused<Option<Spanned<&'a [u8]>>>, + /// The "optional" keyword. + _optional_kw: Unused<Spanned<&'a [u8]>>, + /// Whitespace between the "optional" keyword and the opening bracket. + _whitespace: Unused<Spanned<&'a [u8]>>, + /// The items within the optional sequence. + nested_format_description: NestedFormatDescription<'a>, + /// Where the closing bracket was in the format string. + closing_bracket: Location, + }, + /// The first matching parse of a sequence of items. + First { + /// Where the opening bracket was in the format string. + opening_bracket: Location, + /// Whitespace between the opening bracket and "first". + _leading_whitespace: Unused<Option<Spanned<&'a [u8]>>>, + /// The "first" keyword. + _first_kw: Unused<Spanned<&'a [u8]>>, + /// Whitespace between the "first" keyword and the opening bracket. + _whitespace: Unused<Spanned<&'a [u8]>>, + /// The sequences of items to try. + nested_format_descriptions: Box<[NestedFormatDescription<'a>]>, + /// Where the closing bracket was in the format string. + closing_bracket: Location, + }, +} + +/// A format description that is nested within another format description. +pub(super) struct NestedFormatDescription<'a> { + /// Where the opening bracket was in the format string. + pub(super) _opening_bracket: Unused<Location>, + /// The items within the nested format description. + pub(super) items: Box<[Item<'a>]>, + /// Where the closing bracket was in the format string. + pub(super) _closing_bracket: Unused<Location>, + /// Whitespace between the closing bracket and the next item. + pub(super) _trailing_whitespace: Unused<Option<Spanned<&'a [u8]>>>, +} + +/// A modifier for a component. +pub(super) struct Modifier<'a> { + /// Whitespace preceding the modifier. + pub(super) _leading_whitespace: Unused<Spanned<&'a [u8]>>, + /// The key of the modifier. + pub(super) key: Spanned<&'a [u8]>, + /// Where the colon of the modifier was in the format string. + pub(super) _colon: Unused<Location>, + /// The value of the modifier. + pub(super) value: Spanned<&'a [u8]>, +} + +/// Parse the provided tokens into an AST. +pub(super) fn parse< + 'item: 'iter, + 'iter, + I: Iterator<Item = Result<lexer::Token<'item>, Error>>, + const VERSION: usize, +>( + tokens: &'iter mut lexer::Lexed<I>, +) -> impl Iterator<Item = Result<Item<'item>, Error>> + 'iter { + validate_version!(VERSION); + parse_inner::<_, false, VERSION>(tokens) +} + +/// Parse the provided tokens into an AST. The const generic indicates whether the resulting +/// [`Item`] will be used directly or as part of a [`NestedFormatDescription`]. +fn parse_inner< + 'item, + I: Iterator<Item = Result<lexer::Token<'item>, Error>>, + const NESTED: bool, + const VERSION: usize, +>( + tokens: &mut lexer::Lexed<I>, +) -> impl Iterator<Item = Result<Item<'item>, Error>> + '_ { + validate_version!(VERSION); + 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: _, // whitespace is significant in nested components + value, + } if NESTED => Ok(Item::Literal(value)), + lexer::Token::ComponentPart { kind: _, value: _ } => { + bug!("component part should have been consumed by `parse_component`") + } + }) + }) +} + +/// Parse a component. This assumes that the opening bracket has already been consumed. +fn parse_component< + 'a, + I: Iterator<Item = Result<lexer::Token<'a>, Error>>, + const VERSION: usize, +>( + opening_bracket: Location, + tokens: &mut lexer::Lexed<I>, +) -> Result<Item<'a>, Error> { + validate_version!(VERSION); + 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_self(), + }; + return Err(Error { + _inner: unused(span.error("expected component name")), + public: crate::error::InvalidFormatDescription::MissingComponentName { + index: span.start.byte as usize, + }, + }); + }; + + if *name == b"optional" { + let Some(whitespace) = tokens.next_if_whitespace() else { + return Err(Error { + _inner: unused(name.span.error("expected whitespace after `optional`")), + public: crate::error::InvalidFormatDescription::Expected { + what: "whitespace after `optional`", + index: name.span.end.byte as usize, + }, + }); + }; + + let nested = parse_nested::<_, VERSION>(whitespace.span.end, tokens)?; + + let Some(closing_bracket) = tokens.next_if_closing_bracket() else { + return Err(Error { + _inner: unused(opening_bracket.error("unclosed bracket")), + public: crate::error::InvalidFormatDescription::UnclosedOpeningBracket { + index: opening_bracket.byte as usize, + }, + }); + }; + + 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(Error { + _inner: unused(name.span.error("expected whitespace after `first`")), + public: crate::error::InvalidFormatDescription::Expected { + what: "whitespace after `first`", + index: name.span.end.byte as usize, + }, + }); + }; + + 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(Error { + _inner: unused(opening_bracket.error("unclosed bracket")), + public: crate::error::InvalidFormatDescription::UnclosedOpeningBracket { + index: opening_bracket.byte as usize, + }, + }); + }; + + 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; + }; + + // This is not necessary for proper parsing, but provides a much better error when a nested + // description is used where it's not allowed. + if let Some(location) = tokens.next_if_opening_bracket() { + return Err(Error { + _inner: unused( + location + .to_self() + .error("modifier must be of the form `key:value`"), + ), + public: crate::error::InvalidFormatDescription::InvalidModifier { + value: String::from("["), + index: location.byte as usize, + }, + }); + } + + 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(Error { + _inner: unused(span.error("modifier must be of the form `key:value`")), + public: crate::error::InvalidFormatDescription::InvalidModifier { + value: String::from_utf8_lossy(value).into_owned(), + index: span.start.byte as usize, + }, + }); + }; + let key = &value[..colon_index]; + let value = &value[colon_index + 1..]; + + if key.is_empty() { + return Err(Error { + _inner: unused(span.shrink_to_start().error("expected modifier key")), + public: crate::error::InvalidFormatDescription::InvalidModifier { + value: String::new(), + index: span.start.byte as usize, + }, + }); + } + if value.is_empty() { + return Err(Error { + _inner: unused(span.shrink_to_end().error("expected modifier value")), + public: crate::error::InvalidFormatDescription::InvalidModifier { + value: String::new(), + index: span.shrink_to_end().start.byte as usize, + }, + }); + } + + modifiers.push(Modifier { + _leading_whitespace: unused(whitespace), + key: key.spanned(span.shrink_to_before(colon_index as u32)), + _colon: unused(span.start.offset(colon_index as u32)), + value: value.spanned(span.shrink_to_after(colon_index as u32)), + }); + }; + + let Some(closing_bracket) = tokens.next_if_closing_bracket() else { + return Err(Error { + _inner: unused(opening_bracket.error("unclosed bracket")), + public: crate::error::InvalidFormatDescription::UnclosedOpeningBracket { + index: opening_bracket.byte as usize, + }, + }); + }; + + 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), + }) +} + +/// Parse a nested format description. The location provided is the the most recent one consumed. +fn parse_nested<'a, I: Iterator<Item = Result<lexer::Token<'a>, Error>>, const VERSION: usize>( + last_location: Location, + tokens: &mut lexer::Lexed<I>, +) -> Result<NestedFormatDescription<'a>, Error> { + validate_version!(VERSION); + let Some(opening_bracket) = tokens.next_if_opening_bracket() else { + return Err(Error { + _inner: unused(last_location.error("expected opening bracket")), + public: crate::error::InvalidFormatDescription::Expected { + what: "opening bracket", + index: last_location.byte as usize, + }, + }); + }; + let items = parse_inner::<_, true, VERSION>(tokens).collect::<Result<_, _>>()?; + let Some(closing_bracket) = tokens.next_if_closing_bracket() else { + return Err(Error { + _inner: unused(opening_bracket.error("unclosed bracket")), + public: crate::error::InvalidFormatDescription::UnclosedOpeningBracket { + index: opening_bracket.byte as usize, + }, + }); + }; + 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), + }) +} |