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Delay parsing of localized formatting string until use
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@pitdicker
pitdicker committed Jun 23, 2023
1 parent dc0d401 commit ae4e8b2
Showing 1 changed file with 68 additions and 84 deletions.
152 changes: 68 additions & 84 deletions src/format/strftime.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -180,21 +180,10 @@ Notes:
China Daylight Time.
*/

#[cfg(feature = "unstable-locales")]
extern crate alloc;

#[cfg(feature = "unstable-locales")]
use alloc::vec::Vec;

#[cfg(feature = "unstable-locales")]
use super::{locales, Locale};
use super::{Fixed, InternalFixed, InternalInternal, Item, Numeric, Pad};

#[cfg(feature = "unstable-locales")]
type Fmt<'a> = Vec<Item<'a>>;
#[cfg(not(feature = "unstable-locales"))]
type Fmt<'a> = &'static [Item<'static>];

static D_FMT: &[Item<'static>] =
&[num0!(Month), lit!("/"), num0!(Day), lit!("/"), num0!(YearMod100)];
static D_T_FMT: &[Item<'static>] = &[
Expand All @@ -221,56 +210,33 @@ pub struct StrftimeItems<'a> {
remainder: &'a str,
/// If the current specifier is composed of multiple formatting items (e.g. `%+`),
/// `queue` stores a slice of `Item`s that have to be returned one by one.
queue: Fmt<'a>,
/// Date format
d_fmt: Fmt<'a>,
/// Date and time format
d_t_fmt: Fmt<'a>,
/// Time format
t_fmt: Fmt<'a>,
queue: &'static [Item<'static>],
#[cfg(feature = "unstable-locales")]
locale_str: &'a str,
#[cfg(feature = "unstable-locales")]
locale: Option<Locale>,
}

impl<'a> StrftimeItems<'a> {
/// Creates a new parsing iterator from the `strftime`-like format string.
#[must_use]
pub fn new(s: &'a str) -> StrftimeItems<'a> {
Self::with_remainer(s)
#[cfg(not(feature = "unstable-locales"))]
{
StrftimeItems { remainder: s, queue: &[] }
}
#[cfg(feature = "unstable-locales")]
{
StrftimeItems { remainder: s, queue: &[], locale_str: "", locale: None }
}
}

/// Creates a new parsing iterator from the `strftime`-like format string.
#[cfg(feature = "unstable-locales")]
#[cfg_attr(docsrs, doc(cfg(feature = "unstable-locales")))]
#[must_use]
pub fn new_with_locale(s: &'a str, locale: Locale) -> StrftimeItems<'a> {
let d_fmt = StrftimeItems::new(locales::d_fmt(locale)).collect();
let d_t_fmt = StrftimeItems::new(locales::d_t_fmt(locale)).collect();
let t_fmt = StrftimeItems::new(locales::t_fmt(locale)).collect();

StrftimeItems { remainder: s, queue: Vec::new(), d_fmt, d_t_fmt, t_fmt }
}

#[cfg(not(feature = "unstable-locales"))]
fn with_remainer(s: &'a str) -> StrftimeItems<'a> {
static FMT_NONE: &[Item<'static>; 0] = &[];

StrftimeItems {
remainder: s,
queue: FMT_NONE,
d_fmt: D_FMT,
d_t_fmt: D_T_FMT,
t_fmt: T_FMT,
}
}

#[cfg(feature = "unstable-locales")]
fn with_remainer(s: &'a str) -> StrftimeItems<'a> {
StrftimeItems {
remainder: s,
queue: Vec::new(),
d_fmt: D_FMT.to_vec(),
d_t_fmt: D_T_FMT.to_vec(),
t_fmt: T_FMT.to_vec(),
}
StrftimeItems { remainder: s, queue: &[], locale_str: "", locale: Some(locale) }
}
}

Expand All @@ -281,17 +247,16 @@ impl<'a> Iterator for StrftimeItems<'a> {

fn next(&mut self) -> Option<Item<'a>> {
// We have items queued to return from a specifier composed of multiple formatting items.
if !self.queue.is_empty() {
let item;
#[cfg(feature = "unstable-locales")]
{
item = self.queue.remove(0);
}
#[cfg(not(feature = "unstable-locales"))]
{
item = self.queue[0].clone();
self.queue = &self.queue[1..];
}
if let Some((item, remainder)) = self.queue.split_first() {
self.queue = remainder;
return Some(item.clone());
}

// We are in the middle of parsing the localized formatting string of a specifier.
#[cfg(feature = "unstable-locales")]
if !self.locale_str.is_empty() {
let (remainder, item) = self.parse_next_item(self.locale_str)?;
self.locale_str = remainder;
return Some(item);
}

Expand Down Expand Up @@ -339,31 +304,14 @@ impl<'a> StrftimeItems<'a> {

macro_rules! queue {
[$head:expr, $($tail:expr),+ $(,)*] => ({
#[cfg(feature = "unstable-locales")]
{
self.queue.clear();
$(self.queue.push($tail);)+
}
#[cfg(not(feature = "unstable-locales"))]
{
const QUEUE: &'static [Item<'static>] = &[$($tail),+];
self.queue = QUEUE;
}
const QUEUE: &'static [Item<'static>] = &[$($tail),+];
self.queue = QUEUE;
$head
})
}

macro_rules! queue_from_slice {
($slice:expr) => {{
#[cfg(feature = "unstable-locales")]
{
self.queue.clear();
self.queue.extend_from_slice(&$slice[1..]);
}
#[cfg(not(feature = "unstable-locales"))]
{
self.queue = &$slice[1..];
}
self.queue = &$slice[1..];
$slice[0].clone()
}};
}
Expand All @@ -387,12 +335,36 @@ impl<'a> StrftimeItems<'a> {
'U' => num0!(WeekFromSun),
'V' => num0!(IsoWeek),
'W' => num0!(WeekFromMon),
'X' => queue_from_slice!(self.t_fmt),
#[cfg(not(feature = "unstable-locales"))]
'X' => queue_from_slice!(T_FMT),
#[cfg(feature = "unstable-locales")]
'X' => {
if let Some(locale) = self.locale {
assert!(self.locale_str.is_empty());
let (fmt_str, item) = self.parse_next_item(locales::t_fmt(locale))?;
self.locale_str = fmt_str;
item
} else {
queue_from_slice!(T_FMT)
}
}
'Y' => num0!(Year),
'Z' => fix!(TimezoneName),
'a' => fix!(ShortWeekdayName),
'b' | 'h' => fix!(ShortMonthName),
'c' => queue_from_slice!(self.d_t_fmt),
#[cfg(not(feature = "unstable-locales"))]
'c' => queue_from_slice!(D_T_FMT),
#[cfg(feature = "unstable-locales")]
'c' => {
if let Some(locale) = self.locale {
assert!(self.locale_str.is_empty());
let (fmt_str, item) = self.parse_next_item(locales::d_t_fmt(locale))?;
self.locale_str = fmt_str;
item
} else {
queue_from_slice!(D_T_FMT)
}
}
'd' => num0!(Day),
'e' => nums!(Day),
'f' => num0!(Nanosecond),
Expand All @@ -419,7 +391,19 @@ impl<'a> StrftimeItems<'a> {
queue![nums!(Day), lit!("-"), fix!(ShortMonthName), lit!("-"), num0!(Year)]
}
'w' => num!(NumDaysFromSun),
'x' => queue_from_slice!(self.d_fmt),
#[cfg(not(feature = "unstable-locales"))]
'x' => queue_from_slice!(D_FMT),
#[cfg(feature = "unstable-locales")]
'x' => {
if let Some(locale) = self.locale {
assert!(self.locale_str.is_empty());
let (fmt_str, item) = self.parse_next_item(locales::d_fmt(locale))?;
self.locale_str = fmt_str;
item
} else {
queue_from_slice!(D_FMT)
}
}
'y' => num0!(YearMod100),
'z' => {
if is_alternate {
Expand Down Expand Up @@ -755,15 +739,15 @@ mod tests {
fn test_type_sizes() {
use core::mem::size_of;
assert_eq!(size_of::<Item>(), 24);
assert_eq!(size_of::<StrftimeItems>(), 80);
assert_eq!(size_of::<StrftimeItems>(), 32);
}

#[test]
#[cfg(feature = "unstable-locales")]
fn test_type_sizes() {
use core::mem::size_of;
assert_eq!(size_of::<Item>(), 24);
assert_eq!(size_of::<StrftimeItems>(), 112);
assert_eq!(size_of::<StrftimeItems>(), 56);
assert_eq!(size_of::<Locale>(), 2);
}
}

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