Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 738 insertions, 0 deletions

diff --git a/vendor/time-macros/src/format_description/component.rs b/vendor/time-macros/src/format_description/component.rs
new file mode 100644
index 000000000..850da91d2
--- /dev/null
+++ b/vendor/time-macros/src/format_description/component.rs
@@ -0,0 +1,168 @@
+use proc_macro::{Ident, Span, TokenStream};
+
+use crate::format_description::error::InvalidFormatDescription;
+use crate::format_description::modifier;
+use crate::format_description::modifier::Modifiers;
+use crate::to_tokens::ToTokenStream;
+
+pub(crate) enum Component {
+    Day(modifier::Day),
+    Month(modifier::Month),
+    Ordinal(modifier::Ordinal),
+    Weekday(modifier::Weekday),
+    WeekNumber(modifier::WeekNumber),
+    Year(modifier::Year),
+    Hour(modifier::Hour),
+    Minute(modifier::Minute),
+    Period(modifier::Period),
+    Second(modifier::Second),
+    Subsecond(modifier::Subsecond),
+    OffsetHour(modifier::OffsetHour),
+    OffsetMinute(modifier::OffsetMinute),
+    OffsetSecond(modifier::OffsetSecond),
+}
+
+impl ToTokenStream for Component {
+    fn append_to(self, ts: &mut TokenStream) {
+        let mut mts = TokenStream::new();
+
+        macro_rules! component_name_and_append {
+            ($($name:ident)*) => {
+                match self {
+                    $(Self::$name(modifier) => {
+                        modifier.append_to(&mut mts);
+                        stringify!($name)
+                    })*
+                }
+            };
+        }
+
+        let component = component_name_and_append![
+            Day
+            Month
+            Ordinal
+            Weekday
+            WeekNumber
+            Year
+            Hour
+            Minute
+            Period
+            Second
+            Subsecond
+            OffsetHour
+            OffsetMinute
+            OffsetSecond
+        ];
+        let component = Ident::new(component, Span::mixed_site());
+
+        quote_append! { ts
+            ::time::format_description::Component::#(component)(#S(mts))
+        }
+    }
+}
+
+pub(crate) enum NakedComponent {
+    Day,
+    Month,
+    Ordinal,
+    Weekday,
+    WeekNumber,
+    Year,
+    Hour,
+    Minute,
+    Period,
+    Second,
+    Subsecond,
+    OffsetHour,
+    OffsetMinute,
+    OffsetSecond,
+}
+
+impl NakedComponent {
+    pub(crate) fn parse(
+        component_name: &[u8],
+        component_index: usize,
+    ) -> Result<Self, InvalidFormatDescription> {
+        match component_name {
+            b"day" => Ok(Self::Day),
+            b"month" => Ok(Self::Month),
+            b"ordinal" => Ok(Self::Ordinal),
+            b"weekday" => Ok(Self::Weekday),
+            b"week_number" => Ok(Self::WeekNumber),
+            b"year" => Ok(Self::Year),
+            b"hour" => Ok(Self::Hour),
+            b"minute" => Ok(Self::Minute),
+            b"period" => Ok(Self::Period),
+            b"second" => Ok(Self::Second),
+            b"subsecond" => Ok(Self::Subsecond),
+            b"offset_hour" => Ok(Self::OffsetHour),
+            b"offset_minute" => Ok(Self::OffsetMinute),
+            b"offset_second" => Ok(Self::OffsetSecond),
+            b"" => Err(InvalidFormatDescription::MissingComponentName {
+                index: component_index,
+            }),
+            _ => Err(InvalidFormatDescription::InvalidComponentName {
+                name: String::from_utf8_lossy(component_name).into_owned(),
+                index: component_index,
+            }),
+        }
+    }
+
+    pub(crate) fn attach_modifiers(self, modifiers: Modifiers) -> Component {
+        match self {
+            Self::Day => Component::Day(modifier::Day {
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+            Self::Month => Component::Month(modifier::Month {
+                padding: modifiers.padding.unwrap_or_default(),
+                repr: modifiers.month_repr.unwrap_or_default(),
+                case_sensitive: modifiers.case_sensitive.unwrap_or(true),
+            }),
+            Self::Ordinal => Component::Ordinal(modifier::Ordinal {
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+            Self::Weekday => Component::Weekday(modifier::Weekday {
+                repr: modifiers.weekday_repr.unwrap_or_default(),
+                one_indexed: modifiers.weekday_is_one_indexed.unwrap_or(true),
+                case_sensitive: modifiers.case_sensitive.unwrap_or(true),
+            }),
+            Self::WeekNumber => Component::WeekNumber(modifier::WeekNumber {
+                padding: modifiers.padding.unwrap_or_default(),
+                repr: modifiers.week_number_repr.unwrap_or_default(),
+            }),
+            Self::Year => Component::Year(modifier::Year {
+                padding: modifiers.padding.unwrap_or_default(),
+                repr: modifiers.year_repr.unwrap_or_default(),
+                iso_week_based: modifiers.year_is_iso_week_based.unwrap_or_default(),
+                sign_is_mandatory: modifiers.sign_is_mandatory.unwrap_or_default(),
+            }),
+            Self::Hour => Component::Hour(modifier::Hour {
+                padding: modifiers.padding.unwrap_or_default(),
+                is_12_hour_clock: modifiers.hour_is_12_hour_clock.unwrap_or_default(),
+            }),
+            Self::Minute => Component::Minute(modifier::Minute {
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+            Self::Period => Component::Period(modifier::Period {
+                is_uppercase: modifiers.period_is_uppercase.unwrap_or(true),
+                case_sensitive: modifiers.case_sensitive.unwrap_or(true),
+            }),
+            Self::Second => Component::Second(modifier::Second {
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+            Self::Subsecond => Component::Subsecond(modifier::Subsecond {
+                digits: modifiers.subsecond_digits.unwrap_or_default(),
+            }),
+            Self::OffsetHour => Component::OffsetHour(modifier::OffsetHour {
+                sign_is_mandatory: modifiers.sign_is_mandatory.unwrap_or_default(),
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+            Self::OffsetMinute => Component::OffsetMinute(modifier::OffsetMinute {
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+            Self::OffsetSecond => Component::OffsetSecond(modifier::OffsetSecond {
+                padding: modifiers.padding.unwrap_or_default(),
+            }),
+        }
+    }
+}
diff --git a/vendor/time-macros/src/format_description/error.rs b/vendor/time-macros/src/format_description/error.rs
new file mode 100644
index 000000000..9aacd7dc9
--- /dev/null
+++ b/vendor/time-macros/src/format_description/error.rs
@@ -0,0 +1,29 @@
+use std::fmt;
+
+pub(crate) enum InvalidFormatDescription {
+    UnclosedOpeningBracket { index: usize },
+    InvalidComponentName { name: String, index: usize },
+    InvalidModifier { value: String, index: usize },
+    MissingComponentName { index: usize },
+}
+
+impl fmt::Display for InvalidFormatDescription {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        #[allow(clippy::enum_glob_use)]
+        use InvalidFormatDescription::*;
+        match self {
+            UnclosedOpeningBracket { index } => {
+                write!(f, "unclosed opening bracket at byte index {index}")
+            }
+            InvalidComponentName { name, index } => {
+                write!(f, "invalid component name `{name}` at byte index {index}",)
+            }
+            InvalidModifier { value, index } => {
+                write!(f, "invalid modifier `{value}` at byte index {index}")
+            }
+            MissingComponentName { index } => {
+                write!(f, "missing component name at byte index {index}")
+            }
+        }
+    }
+}
diff --git a/vendor/time-macros/src/format_description/mod.rs b/vendor/time-macros/src/format_description/mod.rs
new file mode 100644
index 000000000..dd32db74d
--- /dev/null
+++ b/vendor/time-macros/src/format_description/mod.rs
@@ -0,0 +1,40 @@
+mod component;
+pub(crate) mod error;
+pub(crate) mod modifier;
+pub(crate) mod parse;
+
+use proc_macro::{Literal, TokenStream};
+
+pub(crate) use self::component::Component;
+pub(crate) use self::parse::parse;
+use crate::to_tokens::ToTokenStream;
+
+mod helper {
+    #[must_use = "This does not modify the original slice."]
+    pub(crate) fn consume_whitespace<'a>(bytes: &'a [u8], index: &mut usize) -> &'a [u8] {
+        let first_non_whitespace = bytes
+            .iter()
+            .position(|c| !c.is_ascii_whitespace())
+            .unwrap_or(bytes.len());
+        *index += first_non_whitespace;
+        &bytes[first_non_whitespace..]
+    }
+}
+
+#[allow(single_use_lifetimes)] // false positive
+#[allow(variant_size_differences)]
+pub(crate) enum FormatItem<'a> {
+    Literal(&'a [u8]),
+    Component(Component),
+}
+
+impl ToTokenStream for FormatItem<'_> {
+    fn append_to(self, ts: &mut TokenStream) {
+        quote_append! { ts
+            ::time::format_description::FormatItem::#S(match self {
+                FormatItem::Literal(bytes) => quote! { Literal(#(Literal::byte_string(bytes))) },
+                FormatItem::Component(component) => quote! { Component(#S(component)) },
+            })
+        }
+    }
+}
diff --git a/vendor/time-macros/src/format_description/modifier.rs b/vendor/time-macros/src/format_description/modifier.rs
new file mode 100644
index 000000000..f4e641a7b
--- /dev/null
+++ b/vendor/time-macros/src/format_description/modifier.rs
@@ -0,0 +1,417 @@
+use core::mem;
+
+use proc_macro::{Ident, Span, TokenStream, TokenTree};
+
+use crate::format_description::error::InvalidFormatDescription;
+use crate::format_description::helper;
+use crate::to_tokens::{ToTokenStream, ToTokenTree};
+
+macro_rules! to_tokens {
+    (
+        $(#[$struct_attr:meta])*
+        $struct_vis:vis struct $struct_name:ident {$(
+            $(#[$field_attr:meta])*
+            $field_vis:vis $field_name:ident : $field_ty:ty
+        ),+ $(,)?}
+    ) => {
+        $(#[$struct_attr])*
+        $struct_vis struct $struct_name {$(
+            $(#[$field_attr])*
+            $field_vis $field_name: $field_ty
+        ),+}
+
+        impl ToTokenTree for $struct_name {
+            fn into_token_tree(self) -> TokenTree {
+                let mut tokens = TokenStream::new();
+                let Self {$($field_name),+} = self;
+
+                quote_append! { tokens
+                    let mut value = ::time::format_description::modifier::$struct_name::default();
+                };
+                $(
+                    quote_append!(tokens value.$field_name =);
+                    $field_name.append_to(&mut tokens);
+                    quote_append!(tokens ;);
+                )+
+                quote_append!(tokens value);
+
+                proc_macro::TokenTree::Group(proc_macro::Group::new(
+                    proc_macro::Delimiter::Brace,
+                    tokens,
+                ))
+            }
+        }
+    };
+
+    (
+        $(#[$enum_attr:meta])*
+        $enum_vis:vis enum $enum_name:ident {$(
+            $(#[$variant_attr:meta])*
+            $variant_name:ident
+        ),+ $(,)?}
+    ) => {
+        $(#[$enum_attr])*
+        $enum_vis enum $enum_name {$(
+            $(#[$variant_attr])*
+            $variant_name
+        ),+}
+
+        impl ToTokenStream for $enum_name {
+            fn append_to(self, ts: &mut TokenStream) {
+                quote_append! { ts
+                    ::time::format_description::modifier::$enum_name::
+                };
+                let name = match self {
+                    $(Self::$variant_name => stringify!($variant_name)),+
+                };
+                ts.extend([TokenTree::Ident(Ident::new(name, Span::mixed_site()))]);
+            }
+        }
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Day {
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) enum MonthRepr {
+        Numerical,
+        Long,
+        Short,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Month {
+        pub(crate) padding: Padding,
+        pub(crate) repr: MonthRepr,
+        pub(crate) case_sensitive: bool,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Ordinal {
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) enum WeekdayRepr {
+        Short,
+        Long,
+        Sunday,
+        Monday,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Weekday {
+        pub(crate) repr: WeekdayRepr,
+        pub(crate) one_indexed: bool,
+        pub(crate) case_sensitive: bool,
+    }
+}
+
+to_tokens! {
+    pub(crate) enum WeekNumberRepr {
+        Iso,
+        Sunday,
+        Monday,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct WeekNumber {
+        pub(crate) padding: Padding,
+        pub(crate) repr: WeekNumberRepr,
+    }
+}
+
+to_tokens! {
+    pub(crate) enum YearRepr {
+        Full,
+        LastTwo,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Year {
+        pub(crate) padding: Padding,
+        pub(crate) repr: YearRepr,
+        pub(crate) iso_week_based: bool,
+        pub(crate) sign_is_mandatory: bool,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Hour {
+        pub(crate) padding: Padding,
+        pub(crate) is_12_hour_clock: bool,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Minute {
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Period {
+        pub(crate) is_uppercase: bool,
+        pub(crate) case_sensitive: bool,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Second {
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) enum SubsecondDigits {
+        One,
+        Two,
+        Three,
+        Four,
+        Five,
+        Six,
+        Seven,
+        Eight,
+        Nine,
+        OneOrMore,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct Subsecond {
+        pub(crate) digits: SubsecondDigits,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct OffsetHour {
+        pub(crate) sign_is_mandatory: bool,
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct OffsetMinute {
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) struct OffsetSecond {
+        pub(crate) padding: Padding,
+    }
+}
+
+to_tokens! {
+    pub(crate) enum Padding {
+        Space,
+        Zero,
+        None,
+    }
+}
+
+macro_rules! impl_default {
+    ($($type:ty => $default:expr;)*) => {$(
+        impl Default for $type {
+            fn default() -> Self {
+                $default
+            }
+        }
+    )*};
+}
+
+impl_default! {
+    Day => Self { padding: Padding::default() };
+    MonthRepr => Self::Numerical;
+    Month => Self {
+        padding: Padding::default(),
+        repr: MonthRepr::default(),
+        case_sensitive: true,
+    };
+    Ordinal => Self { padding: Padding::default() };
+    WeekdayRepr => Self::Long;
+    Weekday => Self {
+        repr: WeekdayRepr::default(),
+        one_indexed: true,
+        case_sensitive: true,
+    };
+    WeekNumberRepr => Self::Iso;
+    WeekNumber => Self {
+        padding: Padding::default(),
+        repr: WeekNumberRepr::default(),
+    };
+    YearRepr => Self::Full;
+    Year => Self {
+        padding: Padding::default(),
+        repr: YearRepr::default(),
+        iso_week_based: false,
+        sign_is_mandatory: false,
+    };
+    Hour => Self {
+        padding: Padding::default(),
+        is_12_hour_clock: false,
+    };
+    Minute => Self { padding: Padding::default() };
+    Period => Self { is_uppercase: true, case_sensitive: true };
+    Second => Self { padding: Padding::default() };
+    SubsecondDigits => Self::OneOrMore;
+    Subsecond => Self { digits: SubsecondDigits::default() };
+    OffsetHour => Self {
+        sign_is_mandatory: true,
+        padding: Padding::default(),
+    };
+    OffsetMinute => Self { padding: Padding::default() };
+    OffsetSecond => Self { padding: Padding::default() };
+    Padding => Self::Zero;
+}
+
+#[derive(Default)]
+pub(crate) struct Modifiers {
+    pub(crate) padding: Option<Padding>,
+    pub(crate) hour_is_12_hour_clock: Option<bool>,
+    pub(crate) period_is_uppercase: Option<bool>,
+    pub(crate) month_repr: Option<MonthRepr>,
+    pub(crate) subsecond_digits: Option<SubsecondDigits>,
+    pub(crate) weekday_repr: Option<WeekdayRepr>,
+    pub(crate) weekday_is_one_indexed: Option<bool>,
+    pub(crate) week_number_repr: Option<WeekNumberRepr>,
+    pub(crate) year_repr: Option<YearRepr>,
+    pub(crate) year_is_iso_week_based: Option<bool>,
+    pub(crate) sign_is_mandatory: Option<bool>,
+    pub(crate) case_sensitive: Option<bool>,
+}
+
+impl Modifiers {
+    #[allow(clippy::too_many_lines)]
+    pub(crate) fn parse(
+        component_name: &[u8],
+        mut bytes: &[u8],
+        index: &mut usize,
+    ) -> Result<Self, InvalidFormatDescription> {
+        let mut modifiers = Self::default();
+
+        while !bytes.is_empty() {
+            // Trim any whitespace between modifiers.
+            bytes = helper::consume_whitespace(bytes, index);
+
+            let modifier;
+            if let Some(whitespace_loc) = bytes.iter().position(u8::is_ascii_whitespace) {
+                *index += whitespace_loc;
+                modifier = &bytes[..whitespace_loc];
+                bytes = &bytes[whitespace_loc..];
+            } else {
+                modifier = mem::take(&mut bytes);
+            }
+
+            if modifier.is_empty() {
+                break;
+            }
+
+            match (component_name, modifier) {
+                (
+                    b"day" | b"hour" | b"minute" | b"month" | b"offset_hour" | b"offset_minute"
+                    | b"offset_second" | b"ordinal" | b"second" | b"week_number" | b"year",
+                    b"padding:space",
+                ) => modifiers.padding = Some(Padding::Space),
+                (
+                    b"day" | b"hour" | b"minute" | b"month" | b"offset_hour" | b"offset_minute"
+                    | b"offset_second" | b"ordinal" | b"second" | b"week_number" | b"year",
+                    b"padding:zero",
+                ) => modifiers.padding = Some(Padding::Zero),
+                (
+                    b"day" | b"hour" | b"minute" | b"month" | b"offset_hour" | b"offset_minute"
+                    | b"offset_second" | b"ordinal" | b"second" | b"week_number" | b"year",
+                    b"padding:none",
+                ) => modifiers.padding = Some(Padding::None),
+                (b"hour", b"repr:24") => modifiers.hour_is_12_hour_clock = Some(false),
+                (b"hour", b"repr:12") => modifiers.hour_is_12_hour_clock = Some(true),
+                (b"month" | b"period" | b"weekday", b"case_sensitive:true") => {
+                    modifiers.case_sensitive = Some(true)
+                }
+                (b"month" | b"period" | b"weekday", b"case_sensitive:false") => {
+                    modifiers.case_sensitive = Some(false)
+                }
+                (b"month", b"repr:numerical") => modifiers.month_repr = Some(MonthRepr::Numerical),
+                (b"month", b"repr:long") => modifiers.month_repr = Some(MonthRepr::Long),
+                (b"month", b"repr:short") => modifiers.month_repr = Some(MonthRepr::Short),
+                (b"offset_hour" | b"year", b"sign:automatic") => {
+                    modifiers.sign_is_mandatory = Some(false);
+                }
+                (b"offset_hour" | b"year", b"sign:mandatory") => {
+                    modifiers.sign_is_mandatory = Some(true);
+                }
+                (b"period", b"case:upper") => modifiers.period_is_uppercase = Some(true),
+                (b"period", b"case:lower") => modifiers.period_is_uppercase = Some(false),
+                (b"subsecond", b"digits:1") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::One);
+                }
+                (b"subsecond", b"digits:2") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Two);
+                }
+                (b"subsecond", b"digits:3") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Three);
+                }
+                (b"subsecond", b"digits:4") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Four);
+                }
+                (b"subsecond", b"digits:5") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Five);
+                }
+                (b"subsecond", b"digits:6") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Six);
+                }
+                (b"subsecond", b"digits:7") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Seven);
+                }
+                (b"subsecond", b"digits:8") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Eight);
+                }
+                (b"subsecond", b"digits:9") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::Nine);
+                }
+                (b"subsecond", b"digits:1+") => {
+                    modifiers.subsecond_digits = Some(SubsecondDigits::OneOrMore);
+                }
+                (b"weekday", b"repr:short") => modifiers.weekday_repr = Some(WeekdayRepr::Short),
+                (b"weekday", b"repr:long") => modifiers.weekday_repr = Some(WeekdayRepr::Long),
+                (b"weekday", b"repr:sunday") => modifiers.weekday_repr = Some(WeekdayRepr::Sunday),
+                (b"weekday", b"repr:monday") => modifiers.weekday_repr = Some(WeekdayRepr::Monday),
+                (b"weekday", b"one_indexed:true") => modifiers.weekday_is_one_indexed = Some(true),
+                (b"weekday", b"one_indexed:false") => {
+                    modifiers.weekday_is_one_indexed = Some(false);
+                }
+                (b"week_number", b"repr:iso") => {
+                    modifiers.week_number_repr = Some(WeekNumberRepr::Iso);
+                }
+                (b"week_number", b"repr:sunday") => {
+                    modifiers.week_number_repr = Some(WeekNumberRepr::Sunday);
+                }
+                (b"week_number", b"repr:monday") => {
+                    modifiers.week_number_repr = Some(WeekNumberRepr::Monday);
+                }
+                (b"year", b"repr:full") => modifiers.year_repr = Some(YearRepr::Full),
+                (b"year", b"repr:last_two") => modifiers.year_repr = Some(YearRepr::LastTwo),
+                (b"year", b"base:calendar") => modifiers.year_is_iso_week_based = Some(false),
+                (b"year", b"base:iso_week") => modifiers.year_is_iso_week_based = Some(true),
+                _ => {
+                    return Err(InvalidFormatDescription::InvalidModifier {
+                        value: String::from_utf8_lossy(modifier).into_owned(),
+                        index: *index,
+                    });
+                }
+            }
+        }
+
+        Ok(modifiers)
+    }
+}
diff --git a/vendor/time-macros/src/format_description/parse.rs b/vendor/time-macros/src/format_description/parse.rs
new file mode 100644
index 000000000..19c7bf608
--- /dev/null
+++ b/vendor/time-macros/src/format_description/parse.rs
@@ -0,0 +1,84 @@
+use proc_macro::Span;
+
+use crate::format_description::component::{Component, NakedComponent};
+use crate::format_description::error::InvalidFormatDescription;
+use crate::format_description::{helper, modifier, FormatItem};
+use crate::Error;
+
+struct ParsedItem<'a> {
+    item: FormatItem<'a>,
+    remaining: &'a [u8],
+}
+
+fn parse_component(mut s: &[u8], index: &mut usize) -> Result<Component, InvalidFormatDescription> {
+    s = helper::consume_whitespace(s, index);
+
+    let component_index = *index;
+    let whitespace_loc = s
+        .iter()
+        .position(u8::is_ascii_whitespace)
+        .unwrap_or(s.len());
+    *index += whitespace_loc;
+    let component_name = &s[..whitespace_loc];
+    s = &s[whitespace_loc..];
+    s = helper::consume_whitespace(s, index);
+
+    Ok(NakedComponent::parse(component_name, component_index)?
+        .attach_modifiers(modifier::Modifiers::parse(component_name, s, index)?))
+}
+
+fn parse_literal<'a>(s: &'a [u8], index: &mut usize) -> ParsedItem<'a> {
+    let loc = s.iter().position(|&c| c == b'[').unwrap_or(s.len());
+    *index += loc;
+    ParsedItem {
+        item: FormatItem::Literal(&s[..loc]),
+        remaining: &s[loc..],
+    }
+}
+
+fn parse_item<'a>(
+    s: &'a [u8],
+    index: &mut usize,
+) -> Result<ParsedItem<'a>, InvalidFormatDescription> {
+    if let [b'[', b'[', remaining @ ..] = s {
+        *index += 2;
+        return Ok(ParsedItem {
+            item: FormatItem::Literal(b"["),
+            remaining,
+        });
+    };
+
+    if s.starts_with(b"[") {
+        if let Some(bracket_index) = s.iter().position(|&c| c == b']') {
+            *index += 1; // opening bracket
+            let ret_val = ParsedItem {
+                item: FormatItem::Component(parse_component(&s[1..bracket_index], index)?),
+                remaining: &s[bracket_index + 1..],
+            };
+            *index += 1; // closing bracket
+            Ok(ret_val)
+        } else {
+            Err(InvalidFormatDescription::UnclosedOpeningBracket { index: *index })
+        }
+    } else {
+        Ok(parse_literal(s, index))
+    }
+}
+
+pub(crate) fn parse(mut s: &[u8], span: Span) -> Result<Vec<FormatItem<'_>>, Error> {
+    let mut compound = Vec::new();
+    let mut loc = 0;
+
+    while !s.is_empty() {
+        let ParsedItem { item, remaining } =
+            parse_item(s, &mut loc).map_err(|error| Error::InvalidFormatDescription {
+                error,
+                span_start: Some(span),
+                span_end: Some(span),
+            })?;
+        s = remaining;
+        compound.push(item);
+    }
+
+    Ok(compound)
+}