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//! Typed, validated representation of a parsed format description.
use alloc::boxed::Box;
use alloc::string::String;
use core::num::NonZeroU16;
use core::str::{self, FromStr};
use super::{ast, unused, Error, Span, Spanned};
use crate::internal_macros::bug;
/// Parse an AST iterator into a sequence of format items.
pub(super) fn parse<'a>(
ast_items: impl Iterator<Item = Result<ast::Item<'a>, Error>>,
) -> impl Iterator<Item = Result<Item<'a>, Error>> {
ast_items.map(|ast_item| ast_item.and_then(Item::from_ast))
}
/// A description of how to format and parse one part of a type.
pub(super) enum Item<'a> {
/// A literal string.
Literal(&'a [u8]),
/// Part of a type, along with its modifiers.
Component(Component),
/// A sequence of optional items.
Optional {
/// The items themselves.
value: Box<[Self]>,
/// The span of the full sequence.
span: Span,
},
/// The first matching parse of a sequence of format descriptions.
First {
/// The sequence of format descriptions.
value: Box<[Box<[Self]>]>,
/// The span of the full sequence.
span: Span,
},
}
impl Item<'_> {
/// Parse an AST item into a format item.
pub(super) fn from_ast(ast_item: ast::Item<'_>) -> Result<Item<'_>, Error> {
Ok(match ast_item {
ast::Item::Component {
_opening_bracket: _,
_leading_whitespace: _,
name,
modifiers,
_trailing_whitespace: _,
_closing_bracket: _,
} => Item::Component(component_from_ast(&name, &modifiers)?),
ast::Item::Literal(Spanned { value, span: _ }) => Item::Literal(value),
ast::Item::EscapedBracket {
_first: _,
_second: _,
} => Item::Literal(b"["),
ast::Item::Optional {
opening_bracket,
_leading_whitespace: _,
_optional_kw: _,
_whitespace: _,
nested_format_description,
closing_bracket,
} => {
let items = nested_format_description
.items
.into_vec()
.into_iter()
.map(Item::from_ast)
.collect::<Result<_, _>>()?;
Item::Optional {
value: items,
span: opening_bracket.to(closing_bracket),
}
}
ast::Item::First {
opening_bracket,
_leading_whitespace: _,
_first_kw: _,
_whitespace: _,
nested_format_descriptions,
closing_bracket,
} => {
let items = nested_format_descriptions
.into_vec()
.into_iter()
.map(|nested_format_description| {
nested_format_description
.items
.into_vec()
.into_iter()
.map(Item::from_ast)
.collect()
})
.collect::<Result<_, _>>()?;
Item::First {
value: items,
span: opening_bracket.to(closing_bracket),
}
}
})
}
}
impl<'a> TryFrom<Item<'a>> for crate::format_description::BorrowedFormatItem<'a> {
type Error = Error;
fn try_from(item: Item<'a>) -> Result<Self, Self::Error> {
match item {
Item::Literal(literal) => Ok(Self::Literal(literal)),
Item::Component(component) => Ok(Self::Component(component.into())),
Item::Optional { value: _, span } => Err(Error {
_inner: unused(span.error(
"optional items are not supported in runtime-parsed format descriptions",
)),
public: crate::error::InvalidFormatDescription::NotSupported {
what: "optional item",
context: "runtime-parsed format descriptions",
index: span.start.byte as _,
},
}),
Item::First { value: _, span } => Err(Error {
_inner: unused(span.error(
"'first' items are not supported in runtime-parsed format descriptions",
)),
public: crate::error::InvalidFormatDescription::NotSupported {
what: "'first' item",
context: "runtime-parsed format descriptions",
index: span.start.byte as _,
},
}),
}
}
}
impl From<Item<'_>> for crate::format_description::OwnedFormatItem {
fn from(item: Item<'_>) -> Self {
match item {
Item::Literal(literal) => Self::Literal(literal.to_vec().into_boxed_slice()),
Item::Component(component) => Self::Component(component.into()),
Item::Optional { value, span: _ } => Self::Optional(Box::new(value.into())),
Item::First { value, span: _ } => {
Self::First(value.into_vec().into_iter().map(Into::into).collect())
}
}
}
}
impl<'a> From<Box<[Item<'a>]>> for crate::format_description::OwnedFormatItem {
fn from(items: Box<[Item<'a>]>) -> Self {
let items = items.into_vec();
match <[_; 1]>::try_from(items) {
Ok([item]) => item.into(),
Err(vec) => Self::Compound(vec.into_iter().map(Into::into).collect()),
}
}
}
/// Declare the `Component` struct.
macro_rules! component_definition {
(@if_required required then { $($then:tt)* } $(else { $($else:tt)* })?) => { $($then)* };
(@if_required then { $($then:tt)* } $(else { $($else:tt)* })?) => { $($($else)*)? };
(@if_from_str from_str then { $($then:tt)* } $(else { $($else:tt)* })?) => { $($then)* };
(@if_from_str then { $($then:tt)* } $(else { $($else:tt)* })?) => { $($($else)*)? };
($vis:vis enum $name:ident {
$($variant:ident = $parse_variant:literal {$(
$(#[$required:tt])?
$field:ident = $parse_field:literal:
Option<$(#[$from_str:tt])? $field_type:ty>
=> $target_field:ident
),* $(,)?}),* $(,)?
}) => {
$vis enum $name {
$($variant($variant),)*
}
$($vis struct $variant {
$($field: Option<$field_type>),*
})*
$(impl $variant {
/// Parse the component from the AST, given its modifiers.
fn with_modifiers(
modifiers: &[ast::Modifier<'_>],
_component_span: Span,
) -> Result<Self, Error>
{
// rustc will complain if the modifier is empty.
#[allow(unused_mut)]
let mut this = Self {
$($field: None),*
};
for modifier in modifiers {
$(#[allow(clippy::string_lit_as_bytes)]
if modifier.key.eq_ignore_ascii_case($parse_field.as_bytes()) {
this.$field = component_definition!(@if_from_str $($from_str)?
then {
parse_from_modifier_value::<$field_type>(&modifier.value)?
} else {
<$field_type>::from_modifier_value(&modifier.value)?
});
continue;
})*
return Err(Error {
_inner: unused(modifier.key.span.error("invalid modifier key")),
public: crate::error::InvalidFormatDescription::InvalidModifier {
value: String::from_utf8_lossy(*modifier.key).into_owned(),
index: modifier.key.span.start.byte as _,
}
});
}
$(component_definition! { @if_required $($required)? then {
if this.$field.is_none() {
return Err(Error {
_inner: unused(_component_span.error("missing required modifier")),
public:
crate::error::InvalidFormatDescription::MissingRequiredModifier {
name: $parse_field,
index: _component_span.start.byte as _,
}
});
}
}})*
Ok(this)
}
})*
impl From<$name> for crate::format_description::Component {
fn from(component: $name) -> Self {
match component {$(
$name::$variant($variant { $($field),* }) => {
$crate::format_description::component::Component::$variant(
$crate::format_description::modifier::$variant {$(
$target_field: component_definition! { @if_required $($required)?
then {
match $field {
Some(value) => value.into(),
None => bug!("required modifier was not set"),
}
} else {
$field.unwrap_or_default().into()
}
}
),*}
)
}
)*}
}
}
/// Parse a component from the AST, given its name and modifiers.
fn component_from_ast(
name: &Spanned<&[u8]>,
modifiers: &[ast::Modifier<'_>],
) -> Result<Component, Error> {
$(#[allow(clippy::string_lit_as_bytes)]
if name.eq_ignore_ascii_case($parse_variant.as_bytes()) {
return Ok(Component::$variant($variant::with_modifiers(&modifiers, name.span)?,));
})*
Err(Error {
_inner: unused(name.span.error("invalid component")),
public: crate::error::InvalidFormatDescription::InvalidComponentName {
name: String::from_utf8_lossy(name).into_owned(),
index: name.span.start.byte as _,
},
})
}
}
}
// Keep in alphabetical order.
component_definition! {
pub(super) enum Component {
Day = "day" {
padding = "padding": Option<Padding> => padding,
},
End = "end" {},
Hour = "hour" {
padding = "padding": Option<Padding> => padding,
base = "repr": Option<HourBase> => is_12_hour_clock,
},
Ignore = "ignore" {
#[required]
count = "count": Option<#[from_str] NonZeroU16> => count,
},
Minute = "minute" {
padding = "padding": Option<Padding> => padding,
},
Month = "month" {
padding = "padding": Option<Padding> => padding,
repr = "repr": Option<MonthRepr> => repr,
case_sensitive = "case_sensitive": Option<MonthCaseSensitive> => case_sensitive,
},
OffsetHour = "offset_hour" {
sign_behavior = "sign": Option<SignBehavior> => sign_is_mandatory,
padding = "padding": Option<Padding> => padding,
},
OffsetMinute = "offset_minute" {
padding = "padding": Option<Padding> => padding,
},
OffsetSecond = "offset_second" {
padding = "padding": Option<Padding> => padding,
},
Ordinal = "ordinal" {
padding = "padding": Option<Padding> => padding,
},
Period = "period" {
case = "case": Option<PeriodCase> => is_uppercase,
case_sensitive = "case_sensitive": Option<PeriodCaseSensitive> => case_sensitive,
},
Second = "second" {
padding = "padding": Option<Padding> => padding,
},
Subsecond = "subsecond" {
digits = "digits": Option<SubsecondDigits> => digits,
},
UnixTimestamp = "unix_timestamp" {
precision = "precision": Option<UnixTimestampPrecision> => precision,
sign_behavior = "sign": Option<SignBehavior> => sign_is_mandatory,
},
Weekday = "weekday" {
repr = "repr": Option<WeekdayRepr> => repr,
one_indexed = "one_indexed": Option<WeekdayOneIndexed> => one_indexed,
case_sensitive = "case_sensitive": Option<WeekdayCaseSensitive> => case_sensitive,
},
WeekNumber = "week_number" {
padding = "padding": Option<Padding> => padding,
repr = "repr": Option<WeekNumberRepr> => repr,
},
Year = "year" {
padding = "padding": Option<Padding> => padding,
repr = "repr": Option<YearRepr> => repr,
base = "base": Option<YearBase> => iso_week_based,
sign_behavior = "sign": Option<SignBehavior> => sign_is_mandatory,
},
}
}
/// Get the target type for a given enum.
macro_rules! target_ty {
($name:ident $type:ty) => {
$type
};
($name:ident) => {
$crate::format_description::modifier::$name
};
}
/// Get the target value for a given enum.
macro_rules! target_value {
($name:ident $variant:ident $value:expr) => {
$value
};
($name:ident $variant:ident) => {
$crate::format_description::modifier::$name::$variant
};
}
/// Declare the various modifiers.
///
/// For the general case, ordinary syntax can be used. Note that you _must_ declare a default
/// variant. The only significant change is that the string representation of the variant must be
/// provided after the variant name. For example, `Numerical = b"numerical"` declares a variant
/// named `Numerical` with the string representation `b"numerical"`. This is the value that will be
/// used when parsing the modifier. The value is not case sensitive.
///
/// If the type in the public API does not have the same name as the type in the internal
/// representation, then the former must be specified in parenthesis after the internal name. For
/// example, `HourBase(bool)` has an internal name "HourBase", but is represented as a boolean in
/// the public API.
///
/// By default, the internal variant name is assumed to be the same as the public variant name. If
/// this is not the case, the qualified path to the variant must be specified in parenthesis after
/// the internal variant name. For example, `Twelve(true)` has an internal variant name "Twelve",
/// but is represented as `true` in the public API.
macro_rules! modifier {
($(
enum $name:ident $(($target_ty:ty))? {
$(
$(#[$attr:meta])?
$variant:ident $(($target_value:expr))? = $parse_variant:literal
),* $(,)?
}
)+) => {$(
#[derive(Default)]
enum $name {
$($(#[$attr])? $variant),*
}
impl $name {
/// Parse the modifier from its string representation.
fn from_modifier_value(value: &Spanned<&[u8]>) -> Result<Option<Self>, Error> {
$(if value.eq_ignore_ascii_case($parse_variant) {
return Ok(Some(Self::$variant));
})*
Err(Error {
_inner: unused(value.span.error("invalid modifier value")),
public: crate::error::InvalidFormatDescription::InvalidModifier {
value: String::from_utf8_lossy(value).into_owned(),
index: value.span.start.byte as _,
},
})
}
}
impl From<$name> for target_ty!($name $($target_ty)?) {
fn from(modifier: $name) -> Self {
match modifier {
$($name::$variant => target_value!($name $variant $($target_value)?)),*
}
}
}
)+};
}
// Keep in alphabetical order.
modifier! {
enum HourBase(bool) {
Twelve(true) = b"12",
#[default]
TwentyFour(false) = b"24",
}
enum MonthCaseSensitive(bool) {
False(false) = b"false",
#[default]
True(true) = b"true",
}
enum MonthRepr {
#[default]
Numerical = b"numerical",
Long = b"long",
Short = b"short",
}
enum Padding {
Space = b"space",
#[default]
Zero = b"zero",
None = b"none",
}
enum PeriodCase(bool) {
Lower(false) = b"lower",
#[default]
Upper(true) = b"upper",
}
enum PeriodCaseSensitive(bool) {
False(false) = b"false",
#[default]
True(true) = b"true",
}
enum SignBehavior(bool) {
#[default]
Automatic(false) = b"automatic",
Mandatory(true) = b"mandatory",
}
enum SubsecondDigits {
One = b"1",
Two = b"2",
Three = b"3",
Four = b"4",
Five = b"5",
Six = b"6",
Seven = b"7",
Eight = b"8",
Nine = b"9",
#[default]
OneOrMore = b"1+",
}
enum UnixTimestampPrecision {
#[default]
Second = b"second",
Millisecond = b"millisecond",
Microsecond = b"microsecond",
Nanosecond = b"nanosecond",
}
enum WeekNumberRepr {
#[default]
Iso = b"iso",
Sunday = b"sunday",
Monday = b"monday",
}
enum WeekdayCaseSensitive(bool) {
False(false) = b"false",
#[default]
True(true) = b"true",
}
enum WeekdayOneIndexed(bool) {
False(false) = b"false",
#[default]
True(true) = b"true",
}
enum WeekdayRepr {
Short = b"short",
#[default]
Long = b"long",
Sunday = b"sunday",
Monday = b"monday",
}
enum YearBase(bool) {
#[default]
Calendar(false) = b"calendar",
IsoWeek(true) = b"iso_week",
}
enum YearRepr {
#[default]
Full = b"full",
LastTwo = b"last_two",
}
}
/// Parse a modifier value using `FromStr`. Requires the modifier value to be valid UTF-8.
fn parse_from_modifier_value<T: FromStr>(value: &Spanned<&[u8]>) -> Result<Option<T>, Error> {
str::from_utf8(value)
.ok()
.and_then(|val| val.parse::<T>().ok())
.map(|val| Some(val))
.ok_or_else(|| Error {
_inner: unused(value.span.error("invalid modifier value")),
public: crate::error::InvalidFormatDescription::InvalidModifier {
value: String::from_utf8_lossy(value).into_owned(),
index: value.span.start.byte as _,
},
})
}