//! Parsing of [Rust `fmt` syntax][0].
//!
//! [0]: std::fmt#syntax
use std::{convert::identity, iter};
use unicode_xid::UnicodeXID as XID;
/// Output of the [`format_string`] parser.
#[derive(Debug, Clone, Eq, PartialEq)]
pub(crate) struct FormatString<'a> {
pub(crate) formats: Vec<Format<'a>>,
}
/// Output of the [`format`] parser.
///
/// [`format`]: fn@format
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) struct Format<'a> {
pub(crate) arg: Option<Argument<'a>>,
pub(crate) spec: Option<FormatSpec<'a>>,
}
/// Output of the [`format_spec`] parser.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) struct FormatSpec<'a> {
pub(crate) width: Option<Width<'a>>,
pub(crate) precision: Option<Precision<'a>>,
pub(crate) ty: Type,
}
/// Output of the [`argument`] parser.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) enum Argument<'a> {
Integer(usize),
Identifier(&'a str),
}
/// Output of the [`precision`] parser.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) enum Precision<'a> {
Count(Count<'a>),
Star,
}
/// Output of the [`count`] parser.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) enum Count<'a> {
Integer(usize),
Parameter(Parameter<'a>),
}
/// Output of the [`type_`] parser. See [formatting traits][1] for more info.
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#formatting-traits
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub(crate) enum Type {
Display,
Debug,
LowerDebug,
UpperDebug,
Octal,
LowerHex,
UpperHex,
Pointer,
Binary,
LowerExp,
UpperExp,
}
impl Type {
/// Returns trait name of this [`Type`].
pub(crate) fn trait_name(&self) -> &'static str {
match self {
Type::Display => "Display",
Type::Debug | Type::LowerDebug | Type::UpperDebug => "Debug",
Type::Octal => "Octal",
Type::LowerHex => "LowerHex",
Type::UpperHex => "UpperHex",
Type::Pointer => "Pointer",
Type::Binary => "Binary",
Type::LowerExp => "LowerExp",
Type::UpperExp => "UpperExp",
}
}
}
/// Type alias for the [`FormatSpec::width`].
type Width<'a> = Count<'a>;
/// Output of the [`maybe_format`] parser.
type MaybeFormat<'a> = Option<Format<'a>>;
/// Output of the [`identifier`] parser.
type Identifier<'a> = &'a str;
/// Output of the [`parameter`] parser.
type Parameter<'a> = Argument<'a>;
/// [`str`] left to parse.
///
/// [`str`]: prim@str
type LeftToParse<'a> = &'a str;
/// Parses a `format_string` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`format_string`]` := `[`text`]` [`[`maybe_format text`]`] *`
///
/// # Example
///
/// ```text
/// Hello
/// Hello, {}!
/// {:?}
/// Hello {people}!
/// {} {}
/// {:04}
/// {par:-^#.0$?}
/// ```
///
/// # Return value
///
/// - [`Some`] in case of successful parse.
/// - [`None`] otherwise (not all characters are consumed by underlying
/// parsers).
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
pub(crate) fn format_string(input: &str) -> Option<FormatString<'_>> {
let (mut input, _) = optional_result(text)(input);
let formats = iter::repeat(())
.scan(&mut input, |input, _| {
let (curr, format) =
alt(&mut [&mut maybe_format, &mut map(text, |(i, _)| (i, None))])(
input,
)?;
**input = curr;
Some(format)
})
.flatten()
.collect();
// Should consume all tokens for a successful parse.
input.is_empty().then_some(FormatString { formats })
}
/// Parses a `maybe_format` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`maybe_format`]` := '{' '{' | '}' '}' | `[`format`]
///
/// # Example
///
/// ```text
/// {{
/// }}
/// {:04}
/// {:#?}
/// {par:-^#.0$?}
/// ```
///
/// [`format`]: fn@format
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn maybe_format(input: &str) -> Option<(LeftToParse<'_>, MaybeFormat<'_>)> {
alt(&mut [
&mut map(str("{{"), |i| (i, None)),
&mut map(str("}}"), |i| (i, None)),
&mut map(format, |(i, format)| (i, Some(format))),
])(input)
}
/// Parses a `format` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`format`]` := '{' [`[`argument`]`] [':' `[`format_spec`]`] '}'`
///
/// # Example
///
/// ```text
/// {par}
/// {:#?}
/// {par:-^#.0$?}
/// ```
///
/// [`format`]: fn@format
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn format(input: &str) -> Option<(LeftToParse<'_>, Format<'_>)> {
let input = char('{')(input)?;
let (input, arg) = optional_result(argument)(input);
let (input, spec) = map_or_else(
char(':'),
|i| Some((i, None)),
map(format_spec, |(i, s)| (i, Some(s))),
)(input)?;
let input = char('}')(input)?;
Some((input, Format { arg, spec }))
}
/// Parses an `argument` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`argument`]` := `[`integer`]` | `[`identifier`]
///
/// # Example
///
/// ```text
/// 0
/// ident
/// Минск
/// ```
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn argument(input: &str) -> Option<(LeftToParse<'_>, Argument)> {
alt(&mut [
&mut map(identifier, |(i, ident)| (i, Argument::Identifier(ident))),
&mut map(integer, |(i, int)| (i, Argument::Integer(int))),
])(input)
}
/// Parses a `format_spec` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`format_spec`]` := [[fill]align][sign]['#']['0'][width]`
/// `['.' `[`precision`]`]`[`type`]
///
/// # Example
///
/// ```text
/// ^
/// <^
/// ->+#0width$.precision$x?
/// ```
///
/// [`type`]: type_
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn format_spec(input: &str) -> Option<(LeftToParse<'_>, FormatSpec<'_>)> {
let input = unwrap_or_else(
alt(&mut [
&mut try_seq(&mut [&mut any_char, &mut one_of("<^>")]),
&mut one_of("<^>"),
]),
identity,
)(input);
let input = seq(&mut [
&mut optional(one_of("+-")),
&mut optional(char('#')),
&mut optional(try_seq(&mut [
&mut char('0'),
&mut lookahead(check_char(|c| !matches!(c, '$'))),
])),
])(input);
let (input, width) = optional_result(count)(input);
let (input, precision) = map_or_else(
char('.'),
|i| Some((i, None)),
map(precision, |(i, p)| (i, Some(p))),
)(input)?;
let (input, ty) = type_(input)?;
Some((
input,
FormatSpec {
width,
precision,
ty,
},
))
}
/// Parses a `precision` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`precision`]` := `[`count`]` | '*'`
///
/// # Example
///
/// ```text
/// 0
/// 42$
/// par$
/// *
/// ```
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn precision(input: &str) -> Option<(LeftToParse<'_>, Precision<'_>)> {
alt(&mut [
&mut map(count, |(i, c)| (i, Precision::Count(c))),
&mut map(char('*'), |i| (i, Precision::Star)),
])(input)
}
/// Parses a `type` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`type`]` := '' | '?' | 'x?' | 'X?' | identifier`
///
/// # Example
///
/// All possible [`Type`]s.
///
/// ```text
/// ?
/// x?
/// X?
/// o
/// x
/// X
/// p
/// b
/// e
/// E
/// ```
///
/// [`type`]: type_
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn type_(input: &str) -> Option<(&str, Type)> {
alt(&mut [
&mut map(str("x?"), |i| (i, Type::LowerDebug)),
&mut map(str("X?"), |i| (i, Type::UpperDebug)),
&mut map(char('?'), |i| (i, Type::Debug)),
&mut map(char('o'), |i| (i, Type::Octal)),
&mut map(char('x'), |i| (i, Type::LowerHex)),
&mut map(char('X'), |i| (i, Type::UpperHex)),
&mut map(char('p'), |i| (i, Type::Pointer)),
&mut map(char('b'), |i| (i, Type::Binary)),
&mut map(char('e'), |i| (i, Type::LowerExp)),
&mut map(char('E'), |i| (i, Type::UpperExp)),
&mut map(lookahead(char('}')), |i| (i, Type::Display)),
])(input)
}
/// Parses a `count` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`count`]` := `[`parameter`]` | `[`integer`]
///
/// # Example
///
/// ```text
/// 0
/// 42$
/// par$
/// ```
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn count(input: &str) -> Option<(LeftToParse<'_>, Count<'_>)> {
alt(&mut [
&mut map(parameter, |(i, p)| (i, Count::Parameter(p))),
&mut map(integer, |(i, int)| (i, Count::Integer(int))),
])(input)
}
/// Parses a `parameter` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// [`parameter`]` := `[`argument`]` '$'`
///
/// # Example
///
/// ```text
/// 42$
/// par$
/// ```
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn parameter(input: &str) -> Option<(LeftToParse<'_>, Parameter<'_>)> {
and_then(argument, |(i, arg)| map(char('$'), |i| (i, arg))(i))(input)
}
/// Parses an `identifier` as defined in the [grammar spec][1].
///
/// # Grammar
///
/// `IDENTIFIER_OR_KEYWORD : XID_Start XID_Continue* | _ XID_Continue+`
///
/// See [rust reference][2] for more info.
///
/// # Example
///
/// ```text
/// identifier
/// Минск
/// ```
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
/// [2]:
https://doc.rust-lang.org/reference/identifiers.html
fn identifier(input: &str) -> Option<(LeftToParse<'_>, Identifier<'_>)> {
map(
alt(&mut [
&mut map(
check_char(XID::is_xid_start),
take_while0(check_char(XID::is_xid_continue)),
),
&mut and_then(char('_'), take_while1(check_char(XID::is_xid_continue))),
]),
|(i, _)| (i, &input[..(input.as_bytes().len() - i.as_bytes().len())]),
)(input)
}
/// Parses an `integer` as defined in the [grammar spec][1].
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn integer(input: &str) -> Option<(LeftToParse<'_>, usize)> {
and_then(
take_while1(check_char(|c| c.is_ascii_digit())),
|(i, int)| int.parse().ok().map(|int| (i, int)),
)(input)
}
/// Parses a `text` as defined in the [grammar spec][1].
///
/// [1]:
https://doc.rust-lang.org/stable/std/fmt/index.html#syntax
fn text(input: &str) -> Option<(LeftToParse<'_>, &str)> {
take_until1(any_char, one_of("{}"))(input)
}
type Parser<'p> = &'p mut dyn FnMut(&str) -> &str;
/// Applies non-failing parsers in sequence.
fn seq<'p>(parsers: &'p mut [Parser<'p>]) -> impl FnMut(&str) -> LeftToParse<'_> + 'p {
move |input| parsers.iter_mut().fold(input, |i, p| (**p)(i))
}
type FallibleParser<'p> = &'p mut dyn FnMut(&str) -> Option<&str>;
/// Tries to apply parsers in sequence. Returns [`None`] in case one of them
/// returned [`None`].
fn try_seq<'p>(
parsers: &'p mut [FallibleParser<'p>],
) -> impl FnMut(&str) -> Option<LeftToParse<'_>> + 'p {
move |input| parsers.iter_mut().try_fold(input, |i, p| (**p)(i))
}
/// Returns first successful parser or [`None`] in case all of them returned
/// [`None`].
fn alt<'p, 'i, T: 'i>(
parsers: &'p mut [&'p mut dyn FnMut(&'i str) -> Option<T>],
) -> impl FnMut(&'i str) -> Option<T> + 'p {
move |input| parsers.iter_mut().find_map(|p| (**p)(input))
}
/// Maps output of the parser in case it returned [`Some`].
fn map<'i, I: 'i, O: 'i>(
mut parser: impl FnMut(&'i str) -> Option<I>,
mut f: impl FnMut(I) -> O,
) -> impl FnMut(&'i str) -> Option<O> {
move |input| parser(input).map(&mut f)
}
/// Maps output of the parser in case it returned [`Some`] or uses `default`.
fn map_or_else<'i, I: 'i, O: 'i>(
mut parser: impl FnMut(&'i str) -> Option<I>,
mut default: impl FnMut(&'i str) -> O,
mut f: impl FnMut(I) -> O,
) -> impl FnMut(&'i str) -> O {
move |input| parser(input).map_or_else(|| default(input), &mut f)
}
/// Returns the contained [`Some`] value or computes it from a closure.
fn unwrap_or_else<'i, O: 'i>(
mut parser: impl FnMut(&'i str) -> Option<O>,
mut f: impl FnMut(&'i str) -> O,
) -> impl FnMut(&'i str) -> O {
move |input| parser(input).unwrap_or_else(|| f(input))
}
/// Returns [`None`] if the parser returned is [`None`], otherwise calls `f`
/// with the wrapped value and returns the result.
fn and_then<'i, I: 'i, O: 'i>(
mut parser: impl FnMut(&'i str) -> Option<I>,
mut f: impl FnMut(I) -> Option<O>,
) -> impl FnMut(&'i str) -> Option<O> {
move |input| parser(input).and_then(&mut f)
}
/// Checks whether `parser` is successful while not advancing the original
/// `input`.
fn lookahead(
mut parser: impl FnMut(&str) -> Option<&str>,
) -> impl FnMut(&str) -> Option<LeftToParse<'_>> {
move |input| map(&mut parser, |_| input)(input)
}
/// Makes underlying `parser` optional by returning the original `input` in case
/// it returned [`None`].
fn optional(
mut parser: impl FnMut(&str) -> Option<&str>,
) -> impl FnMut(&str) -> LeftToParse<'_> {
move |input: &str| parser(input).unwrap_or(input)
}
/// Makes underlying `parser` optional by returning the original `input` and
/// [`None`] in case it returned [`None`].
fn optional_result<'i, T: 'i>(
mut parser: impl FnMut(&'i str) -> Option<(&'i str, T)>,
) -> impl FnMut(&'i str) -> (LeftToParse<'i>, Option<T>) {
move |input: &str| {
map_or_else(&mut parser, |i| (i, None), |(i, c)| (i, Some(c)))(input)
}
}
/// Parses while `parser` is successful. Never fails.
fn take_while0(
mut parser: impl FnMut(&str) -> Option<&str>,
) -> impl FnMut(&str) -> (LeftToParse<'_>, &str) {
move |input| {
let mut cur = input;
while let Some(step) = parser(cur) {
cur = step;
}
(
cur,
&input[..(input.as_bytes().len() - cur.as_bytes().len())],
)
}
}
/// Parses while `parser` is successful. Returns [`None`] in case `parser` never
/// succeeded.
fn take_while1(
mut parser: impl FnMut(&str) -> Option<&str>,
) -> impl FnMut(&str) -> Option<(LeftToParse<'_>, &str)> {
move |input| {
let mut cur = parser(input)?;
while let Some(step) = parser(cur) {
cur = step;
}
Some((
cur,
&input[..(input.as_bytes().len() - cur.as_bytes().len())],
))
}
}
/// Parses with `basic` while `until` returns [`None`]. Returns [`None`] in case
/// `until` succeeded initially or `basic` never succeeded. Doesn't consume
/// [`char`]s parsed by `until`.
///
/// [`char`]: fn@char
fn take_until1(
mut basic: impl FnMut(&str) -> Option<&str>,
mut until: impl FnMut(&str) -> Option<&str>,
) -> impl FnMut(&str) -> Option<(LeftToParse<'_>, &str)> {
move |input: &str| {
if until(input).is_some() {
return None;
}
let mut cur = basic(input)?;
loop {
if until(cur).is_some() {
break;
}
let Some(b) = basic(cur) else {
break;
};
cur = b;
}
Some((
cur,
&input[..(input.as_bytes().len() - cur.as_bytes().len())],
))
}
}
/// Checks whether `input` starts with `s`.
fn str(s: &str) -> impl FnMut(&str) -> Option<LeftToParse<'_>> + '_ {
move |input| input.starts_with(s).then(|| &input[s.as_bytes().len()..])
}
/// Checks whether `input` starts with `c`.
fn char(c: char) -> impl FnMut(&str) -> Option<LeftToParse<'_>> {
move |input| input.starts_with(c).then(|| &input[c.len_utf8()..])
}
/// Checks whether first [`char`] suits `check`.
///
/// [`char`]: fn@char
fn check_char(
mut check: impl FnMut(char) -> bool,
) -> impl FnMut(&str) -> Option<LeftToParse<'_>> {
move |input| {
input
.chars()
.next()
.and_then(|c| check(c).then(|| &input[c.len_utf8()..]))
}
}
/// Checks whether first [`char`] of input is present in `chars`.
///
/// [`char`]: fn@char
fn one_of(chars: &str) -> impl FnMut(&str) -> Option<LeftToParse<'_>> + '_ {
move |input: &str| chars.chars().find_map(|c| char(c)(input))
}
/// Parses any [`char`].
///
/// [`char`]: fn@char
fn any_char(input: &str) -> Option<LeftToParse<'_>> {
input.chars().next().map(|c| &input[c.len_utf8()..])
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn text() {
assert_eq!(format_string(""), Some(FormatString { formats: vec![] }));
assert_eq!(
format_string("test"),
Some(FormatString { formats: vec![] }),
);
assert_eq!(
format_string("Минск"),
Some(FormatString { formats: vec![] }),
);
assert_eq!(format_string("��"), Some(FormatString { formats: vec![] }));
}
#[test]
fn argument() {
assert_eq!(
format_string("{}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: None,
}],
}),
);
assert_eq!(
format_string("{0}"),
Some(FormatString {
formats: vec![Format {
arg: Some(Argument::Integer(0)),
spec: None,
}],
}),
);
assert_eq!(
format_string("{par}"),
Some(FormatString {
formats: vec![Format {
arg: Some(Argument::Identifier("par")),
spec: None,
}],
}),
);
assert_eq!(
format_string("{Минск}"),
Some(FormatString {
formats: vec![Format {
arg: Some(Argument::Identifier("Минск")),
spec: None,
}],
}),
);
}
#[test]
fn spec() {
assert_eq!(
format_string("{:}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:^}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:-<}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{: <}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:^<}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:+}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:^<-}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:#}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:+#}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:-<#}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:^<-#}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:0}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:#0}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:-0}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:^<0}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:^<+#0}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:1}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: Some(Count::Integer(1)),
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:1$}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: Some(Count::Parameter(Argument::Integer(1))),
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:par$}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: Some(Count::Parameter(Argument::Identifier("par"))),
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:-^-#0Минск$}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: Some(Count::Parameter(Argument::Identifier("Минск"))),
precision: None,
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:.*}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: Some(Precision::Star),
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:.0}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: Some(Precision::Count(Count::Integer(0))),
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:.0$}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: Some(Precision::Count(Count::Parameter(
Argument::Integer(0),
))),
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:.par$}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: Some(Precision::Count(Count::Parameter(
Argument::Identifier("par"),
))),
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{: >+#2$.par$}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: Some(Count::Parameter(Argument::Integer(2))),
precision: Some(Precision::Count(Count::Parameter(
Argument::Identifier("par"),
))),
ty: Type::Display,
}),
}],
}),
);
assert_eq!(
format_string("{:x?}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::LowerDebug,
}),
}],
}),
);
assert_eq!(
format_string("{:E}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::UpperExp,
}),
}],
}),
);
assert_eq!(
format_string("{: >+#par$.par$X?}"),
Some(FormatString {
formats: vec![Format {
arg: None,
spec: Some(FormatSpec {
width: Some(Count::Parameter(Argument::Identifier("par"))),
precision: Some(Precision::Count(Count::Parameter(
Argument::Identifier("par"),
))),
ty: Type::UpperDebug,
}),
}],
}),
);
}
#[test]
fn full() {
assert_eq!(
format_string("prefix{{{0:#?}postfix{par:-^par$.a$}}}"),
Some(FormatString {
formats: vec![
Format {
arg: Some(Argument::Integer(0)),
spec: Some(FormatSpec {
width: None,
precision: None,
ty: Type::Debug,
}),
},
Format {
arg: Some(Argument::Identifier("par")),
spec: Some(FormatSpec {
width: Some(Count::Parameter(Argument::Identifier("par"))),
precision: Some(Precision::Count(Count::Parameter(
Argument::Identifier("a"),
))),
ty: Type::Display,
}),
},
],
}),
);
}
#[test]
fn error() {
assert_eq!(format_string("{"), None);
assert_eq!(format_string("}"), None);
assert_eq!(format_string("{{}"), None);
assert_eq!(format_string("{:x?"), None);
assert_eq!(format_string("{:.}"), None);
assert_eq!(format_string("{:q}"), None);
assert_eq!(format_string("{:par}"), None);
assert_eq!(format_string("{⚙️}"), None);
}
}
