Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 938 insertions, 0 deletions

diff --git a/third_party/rust/chrono/src/format/mod.rs b/third_party/rust/chrono/src/format/mod.rs
new file mode 100644
index 0000000000..a641f196d3
--- /dev/null
+++ b/third_party/rust/chrono/src/format/mod.rs
@@ -0,0 +1,938 @@
+// This is a part of Chrono.
+// See README.md and LICENSE.txt for details.
+
+//! Formatting (and parsing) utilities for date and time.
+//!
+//! This module provides the common types and routines to implement,
+//! for example, [`DateTime::format`](../struct.DateTime.html#method.format) or
+//! [`DateTime::parse_from_str`](../struct.DateTime.html#method.parse_from_str) methods.
+//! For most cases you should use these high-level interfaces.
+//!
+//! Internally the formatting and parsing shares the same abstract **formatting items**,
+//! which are just an [`Iterator`](https://doc.rust-lang.org/std/iter/trait.Iterator.html) of
+//! the [`Item`](./enum.Item.html) type.
+//! They are generated from more readable **format strings**;
+//! currently Chrono supports [one built-in syntax closely resembling
+//! C's `strftime` format](./strftime/index.html).
+
+#![allow(ellipsis_inclusive_range_patterns)]
+
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
+#[cfg(feature = "alloc")]
+use alloc::string::{String, ToString};
+#[cfg(any(feature = "alloc", feature = "std", test))]
+use core::borrow::Borrow;
+use core::fmt;
+use core::str::FromStr;
+#[cfg(any(feature = "std", test))]
+use std::error::Error;
+
+#[cfg(any(feature = "alloc", feature = "std", test))]
+use naive::{NaiveDate, NaiveTime};
+#[cfg(any(feature = "alloc", feature = "std", test))]
+use offset::{FixedOffset, Offset};
+#[cfg(any(feature = "alloc", feature = "std", test))]
+use {Datelike, Timelike};
+use {Month, ParseMonthError, ParseWeekdayError, Weekday};
+
+#[cfg(feature = "unstable-locales")]
+pub(crate) mod locales;
+
+pub use self::parse::parse;
+pub use self::parsed::Parsed;
+pub use self::strftime::StrftimeItems;
+/// L10n locales.
+#[cfg(feature = "unstable-locales")]
+pub use pure_rust_locales::Locale;
+
+#[cfg(not(feature = "unstable-locales"))]
+#[derive(Debug)]
+struct Locale;
+
+/// An uninhabited type used for `InternalNumeric` and `InternalFixed` below.
+#[derive(Clone, PartialEq, Eq)]
+enum Void {}
+
+/// Padding characters for numeric items.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub enum Pad {
+    /// No padding.
+    None,
+    /// Zero (`0`) padding.
+    Zero,
+    /// Space padding.
+    Space,
+}
+
+/// Numeric item types.
+/// They have associated formatting width (FW) and parsing width (PW).
+///
+/// The **formatting width** is the minimal width to be formatted.
+/// If the number is too short, and the padding is not [`Pad::None`](./enum.Pad.html#variant.None),
+/// then it is left-padded.
+/// If the number is too long or (in some cases) negative, it is printed as is.
+///
+/// The **parsing width** is the maximal width to be scanned.
+/// The parser only tries to consume from one to given number of digits (greedily).
+/// It also trims the preceding whitespace if any.
+/// It cannot parse the negative number, so some date and time cannot be formatted then
+/// parsed with the same formatting items.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum Numeric {
+    /// Full Gregorian year (FW=4, PW=∞).
+    /// May accept years before 1 BCE or after 9999 CE, given an initial sign.
+    Year,
+    /// Gregorian year divided by 100 (century number; FW=PW=2). Implies the non-negative year.
+    YearDiv100,
+    /// Gregorian year modulo 100 (FW=PW=2). Cannot be negative.
+    YearMod100,
+    /// Year in the ISO week date (FW=4, PW=∞).
+    /// May accept years before 1 BCE or after 9999 CE, given an initial sign.
+    IsoYear,
+    /// Year in the ISO week date, divided by 100 (FW=PW=2). Implies the non-negative year.
+    IsoYearDiv100,
+    /// Year in the ISO week date, modulo 100 (FW=PW=2). Cannot be negative.
+    IsoYearMod100,
+    /// Month (FW=PW=2).
+    Month,
+    /// Day of the month (FW=PW=2).
+    Day,
+    /// Week number, where the week 1 starts at the first Sunday of January (FW=PW=2).
+    WeekFromSun,
+    /// Week number, where the week 1 starts at the first Monday of January (FW=PW=2).
+    WeekFromMon,
+    /// Week number in the ISO week date (FW=PW=2).
+    IsoWeek,
+    /// Day of the week, where Sunday = 0 and Saturday = 6 (FW=PW=1).
+    NumDaysFromSun,
+    /// Day of the week, where Monday = 1 and Sunday = 7 (FW=PW=1).
+    WeekdayFromMon,
+    /// Day of the year (FW=PW=3).
+    Ordinal,
+    /// Hour number in the 24-hour clocks (FW=PW=2).
+    Hour,
+    /// Hour number in the 12-hour clocks (FW=PW=2).
+    Hour12,
+    /// The number of minutes since the last whole hour (FW=PW=2).
+    Minute,
+    /// The number of seconds since the last whole minute (FW=PW=2).
+    Second,
+    /// The number of nanoseconds since the last whole second (FW=PW=9).
+    /// Note that this is *not* left-aligned;
+    /// see also [`Fixed::Nanosecond`](./enum.Fixed.html#variant.Nanosecond).
+    Nanosecond,
+    /// The number of non-leap seconds since the midnight UTC on January 1, 1970 (FW=1, PW=∞).
+    /// For formatting, it assumes UTC upon the absence of time zone offset.
+    Timestamp,
+
+    /// Internal uses only.
+    ///
+    /// This item exists so that one can add additional internal-only formatting
+    /// without breaking major compatibility (as enum variants cannot be selectively private).
+    Internal(InternalNumeric),
+}
+
+/// An opaque type representing numeric item types for internal uses only.
+pub struct InternalNumeric {
+    _dummy: Void,
+}
+
+impl Clone for InternalNumeric {
+    fn clone(&self) -> Self {
+        match self._dummy {}
+    }
+}
+
+impl PartialEq for InternalNumeric {
+    fn eq(&self, _other: &InternalNumeric) -> bool {
+        match self._dummy {}
+    }
+}
+
+impl Eq for InternalNumeric {}
+
+impl fmt::Debug for InternalNumeric {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "<InternalNumeric>")
+    }
+}
+
+/// Fixed-format item types.
+///
+/// They have their own rules of formatting and parsing.
+/// Otherwise noted, they print in the specified cases but parse case-insensitively.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum Fixed {
+    /// Abbreviated month names.
+    ///
+    /// Prints a three-letter-long name in the title case, reads the same name in any case.
+    ShortMonthName,
+    /// Full month names.
+    ///
+    /// Prints a full name in the title case, reads either a short or full name in any case.
+    LongMonthName,
+    /// Abbreviated day of the week names.
+    ///
+    /// Prints a three-letter-long name in the title case, reads the same name in any case.
+    ShortWeekdayName,
+    /// Full day of the week names.
+    ///
+    /// Prints a full name in the title case, reads either a short or full name in any case.
+    LongWeekdayName,
+    /// AM/PM.
+    ///
+    /// Prints in lower case, reads in any case.
+    LowerAmPm,
+    /// AM/PM.
+    ///
+    /// Prints in upper case, reads in any case.
+    UpperAmPm,
+    /// An optional dot plus one or more digits for left-aligned nanoseconds.
+    /// May print nothing, 3, 6 or 9 digits according to the available accuracy.
+    /// See also [`Numeric::Nanosecond`](./enum.Numeric.html#variant.Nanosecond).
+    Nanosecond,
+    /// Same as [`Nanosecond`](#variant.Nanosecond) but the accuracy is fixed to 3.
+    Nanosecond3,
+    /// Same as [`Nanosecond`](#variant.Nanosecond) but the accuracy is fixed to 6.
+    Nanosecond6,
+    /// Same as [`Nanosecond`](#variant.Nanosecond) but the accuracy is fixed to 9.
+    Nanosecond9,
+    /// Timezone name.
+    ///
+    /// It does not support parsing, its use in the parser is an immediate failure.
+    TimezoneName,
+    /// Offset from the local time to UTC (`+09:00` or `-04:00` or `+00:00`).
+    ///
+    /// In the parser, the colon can be omitted and/or surrounded with any amount of whitespace.
+    /// The offset is limited from `-24:00` to `+24:00`,
+    /// which is the same as [`FixedOffset`](../offset/struct.FixedOffset.html)'s range.
+    TimezoneOffsetColon,
+    /// Offset from the local time to UTC (`+09:00` or `-04:00` or `Z`).
+    ///
+    /// In the parser, the colon can be omitted and/or surrounded with any amount of whitespace,
+    /// and `Z` can be either in upper case or in lower case.
+    /// The offset is limited from `-24:00` to `+24:00`,
+    /// which is the same as [`FixedOffset`](../offset/struct.FixedOffset.html)'s range.
+    TimezoneOffsetColonZ,
+    /// Same as [`TimezoneOffsetColon`](#variant.TimezoneOffsetColon) but prints no colon.
+    /// Parsing allows an optional colon.
+    TimezoneOffset,
+    /// Same as [`TimezoneOffsetColonZ`](#variant.TimezoneOffsetColonZ) but prints no colon.
+    /// Parsing allows an optional colon.
+    TimezoneOffsetZ,
+    /// RFC 2822 date and time syntax. Commonly used for email and MIME date and time.
+    RFC2822,
+    /// RFC 3339 & ISO 8601 date and time syntax.
+    RFC3339,
+
+    /// Internal uses only.
+    ///
+    /// This item exists so that one can add additional internal-only formatting
+    /// without breaking major compatibility (as enum variants cannot be selectively private).
+    Internal(InternalFixed),
+}
+
+/// An opaque type representing fixed-format item types for internal uses only.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct InternalFixed {
+    val: InternalInternal,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+enum InternalInternal {
+    /// Same as [`TimezoneOffsetColonZ`](#variant.TimezoneOffsetColonZ), but
+    /// allows missing minutes (per [ISO 8601][iso8601]).
+    ///
+    /// # Panics
+    ///
+    /// If you try to use this for printing.
+    ///
+    /// [iso8601]: https://en.wikipedia.org/wiki/ISO_8601#Time_offsets_from_UTC
+    TimezoneOffsetPermissive,
+    /// Same as [`Nanosecond`](#variant.Nanosecond) but the accuracy is fixed to 3 and there is no leading dot.
+    Nanosecond3NoDot,
+    /// Same as [`Nanosecond`](#variant.Nanosecond) but the accuracy is fixed to 6 and there is no leading dot.
+    Nanosecond6NoDot,
+    /// Same as [`Nanosecond`](#variant.Nanosecond) but the accuracy is fixed to 9 and there is no leading dot.
+    Nanosecond9NoDot,
+}
+
+/// A single formatting item. This is used for both formatting and parsing.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum Item<'a> {
+    /// A literally printed and parsed text.
+    Literal(&'a str),
+    /// Same as `Literal` but with the string owned by the item.
+    #[cfg(any(feature = "alloc", feature = "std", test))]
+    OwnedLiteral(Box<str>),
+    /// Whitespace. Prints literally but reads zero or more whitespace.
+    Space(&'a str),
+    /// Same as `Space` but with the string owned by the item.
+    #[cfg(any(feature = "alloc", feature = "std", test))]
+    OwnedSpace(Box<str>),
+    /// Numeric item. Can be optionally padded to the maximal length (if any) when formatting;
+    /// the parser simply ignores any padded whitespace and zeroes.
+    Numeric(Numeric, Pad),
+    /// Fixed-format item.
+    Fixed(Fixed),
+    /// Issues a formatting error. Used to signal an invalid format string.
+    Error,
+}
+
+macro_rules! lit {
+    ($x:expr) => {
+        Item::Literal($x)
+    };
+}
+macro_rules! sp {
+    ($x:expr) => {
+        Item::Space($x)
+    };
+}
+macro_rules! num {
+    ($x:ident) => {
+        Item::Numeric(Numeric::$x, Pad::None)
+    };
+}
+macro_rules! num0 {
+    ($x:ident) => {
+        Item::Numeric(Numeric::$x, Pad::Zero)
+    };
+}
+macro_rules! nums {
+    ($x:ident) => {
+        Item::Numeric(Numeric::$x, Pad::Space)
+    };
+}
+macro_rules! fix {
+    ($x:ident) => {
+        Item::Fixed(Fixed::$x)
+    };
+}
+macro_rules! internal_fix {
+    ($x:ident) => {
+        Item::Fixed(Fixed::Internal(InternalFixed { val: InternalInternal::$x }))
+    };
+}
+
+/// An error from the `parse` function.
+#[derive(Debug, Clone, PartialEq, Eq, Copy)]
+pub struct ParseError(ParseErrorKind);
+
+/// The category of parse error
+#[derive(Debug, Clone, PartialEq, Eq, Copy)]
+enum ParseErrorKind {
+    /// Given field is out of permitted range.
+    OutOfRange,
+
+    /// There is no possible date and time value with given set of fields.
+    ///
+    /// This does not include the out-of-range conditions, which are trivially invalid.
+    /// It includes the case that there are one or more fields that are inconsistent to each other.
+    Impossible,
+
+    /// Given set of fields is not enough to make a requested date and time value.
+    ///
+    /// Note that there *may* be a case that given fields constrain the possible values so much
+    /// that there is a unique possible value. Chrono only tries to be correct for
+    /// most useful sets of fields however, as such constraint solving can be expensive.
+    NotEnough,
+
+    /// The input string has some invalid character sequence for given formatting items.
+    Invalid,
+
+    /// The input string has been prematurely ended.
+    TooShort,
+
+    /// All formatting items have been read but there is a remaining input.
+    TooLong,
+
+    /// There was an error on the formatting string, or there were non-supported formating items.
+    BadFormat,
+}
+
+/// Same as `Result<T, ParseError>`.
+pub type ParseResult<T> = Result<T, ParseError>;
+
+impl fmt::Display for ParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.0 {
+            ParseErrorKind::OutOfRange => write!(f, "input is out of range"),
+            ParseErrorKind::Impossible => write!(f, "no possible date and time matching input"),
+            ParseErrorKind::NotEnough => write!(f, "input is not enough for unique date and time"),
+            ParseErrorKind::Invalid => write!(f, "input contains invalid characters"),
+            ParseErrorKind::TooShort => write!(f, "premature end of input"),
+            ParseErrorKind::TooLong => write!(f, "trailing input"),
+            ParseErrorKind::BadFormat => write!(f, "bad or unsupported format string"),
+        }
+    }
+}
+
+#[cfg(any(feature = "std", test))]
+impl Error for ParseError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        "parser error, see to_string() for details"
+    }
+}
+
+// to be used in this module and submodules
+const OUT_OF_RANGE: ParseError = ParseError(ParseErrorKind::OutOfRange);
+const IMPOSSIBLE: ParseError = ParseError(ParseErrorKind::Impossible);
+const NOT_ENOUGH: ParseError = ParseError(ParseErrorKind::NotEnough);
+const INVALID: ParseError = ParseError(ParseErrorKind::Invalid);
+const TOO_SHORT: ParseError = ParseError(ParseErrorKind::TooShort);
+const TOO_LONG: ParseError = ParseError(ParseErrorKind::TooLong);
+const BAD_FORMAT: ParseError = ParseError(ParseErrorKind::BadFormat);
+
+/// Formats single formatting item
+#[cfg(any(feature = "alloc", feature = "std", test))]
+pub fn format_item<'a>(
+    w: &mut fmt::Formatter,
+    date: Option<&NaiveDate>,
+    time: Option<&NaiveTime>,
+    off: Option<&(String, FixedOffset)>,
+    item: &Item<'a>,
+) -> fmt::Result {
+    let mut result = String::new();
+    format_inner(&mut result, date, time, off, item, None)?;
+    w.pad(&result)
+}
+
+#[cfg(any(feature = "alloc", feature = "std", test))]
+fn format_inner<'a>(
+    result: &mut String,
+    date: Option<&NaiveDate>,
+    time: Option<&NaiveTime>,
+    off: Option<&(String, FixedOffset)>,
+    item: &Item<'a>,
+    _locale: Option<Locale>,
+) -> fmt::Result {
+    #[cfg(feature = "unstable-locales")]
+    let (short_months, long_months, short_weekdays, long_weekdays, am_pm, am_pm_lowercase) = {
+        let locale = _locale.unwrap_or(Locale::POSIX);
+        let am_pm = locales::am_pm(locale);
+        (
+            locales::short_months(locale),
+            locales::long_months(locale),
+            locales::short_weekdays(locale),
+            locales::long_weekdays(locale),
+            am_pm,
+            &[am_pm[0].to_lowercase(), am_pm[1].to_lowercase()],
+        )
+    };
+    #[cfg(not(feature = "unstable-locales"))]
+    let (short_months, long_months, short_weekdays, long_weekdays, am_pm, am_pm_lowercase) = {
+        (
+            &["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"],
+            &[
+                "January",
+                "February",
+                "March",
+                "April",
+                "May",
+                "June",
+                "July",
+                "August",
+                "September",
+                "October",
+                "November",
+                "December",
+            ],
+            &["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"],
+            &["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"],
+            &["AM", "PM"],
+            &["am", "pm"],
+        )
+    };
+
+    use core::fmt::Write;
+    use div::{div_floor, mod_floor};
+
+    match *item {
+        Item::Literal(s) | Item::Space(s) => result.push_str(s),
+        #[cfg(any(feature = "alloc", feature = "std", test))]
+        Item::OwnedLiteral(ref s) | Item::OwnedSpace(ref s) => result.push_str(s),
+
+        Item::Numeric(ref spec, ref pad) => {
+            use self::Numeric::*;
+
+            let week_from_sun = |d: &NaiveDate| {
+                (d.ordinal() as i32 - d.weekday().num_days_from_sunday() as i32 + 7) / 7
+            };
+            let week_from_mon = |d: &NaiveDate| {
+                (d.ordinal() as i32 - d.weekday().num_days_from_monday() as i32 + 7) / 7
+            };
+
+            let (width, v) = match *spec {
+                Year => (4, date.map(|d| i64::from(d.year()))),
+                YearDiv100 => (2, date.map(|d| div_floor(i64::from(d.year()), 100))),
+                YearMod100 => (2, date.map(|d| mod_floor(i64::from(d.year()), 100))),
+                IsoYear => (4, date.map(|d| i64::from(d.iso_week().year()))),
+                IsoYearDiv100 => (2, date.map(|d| div_floor(i64::from(d.iso_week().year()), 100))),
+                IsoYearMod100 => (2, date.map(|d| mod_floor(i64::from(d.iso_week().year()), 100))),
+                Month => (2, date.map(|d| i64::from(d.month()))),
+                Day => (2, date.map(|d| i64::from(d.day()))),
+                WeekFromSun => (2, date.map(|d| i64::from(week_from_sun(d)))),
+                WeekFromMon => (2, date.map(|d| i64::from(week_from_mon(d)))),
+                IsoWeek => (2, date.map(|d| i64::from(d.iso_week().week()))),
+                NumDaysFromSun => (1, date.map(|d| i64::from(d.weekday().num_days_from_sunday()))),
+                WeekdayFromMon => (1, date.map(|d| i64::from(d.weekday().number_from_monday()))),
+                Ordinal => (3, date.map(|d| i64::from(d.ordinal()))),
+                Hour => (2, time.map(|t| i64::from(t.hour()))),
+                Hour12 => (2, time.map(|t| i64::from(t.hour12().1))),
+                Minute => (2, time.map(|t| i64::from(t.minute()))),
+                Second => (2, time.map(|t| i64::from(t.second() + t.nanosecond() / 1_000_000_000))),
+                Nanosecond => (9, time.map(|t| i64::from(t.nanosecond() % 1_000_000_000))),
+                Timestamp => (
+                    1,
+                    match (date, time, off) {
+                        (Some(d), Some(t), None) => Some(d.and_time(*t).timestamp()),
+                        (Some(d), Some(t), Some(&(_, off))) => {
+                            Some((d.and_time(*t) - off).timestamp())
+                        }
+                        (_, _, _) => None,
+                    },
+                ),
+
+                // for the future expansion
+                Internal(ref int) => match int._dummy {},
+            };
+
+            if let Some(v) = v {
+                if (spec == &Year || spec == &IsoYear) && !(0 <= v && v < 10_000) {
+                    // non-four-digit years require an explicit sign as per ISO 8601
+                    match *pad {
+                        Pad::None => write!(result, "{:+}", v),
+                        Pad::Zero => write!(result, "{:+01$}", v, width + 1),
+                        Pad::Space => write!(result, "{:+1$}", v, width + 1),
+                    }
+                } else {
+                    match *pad {
+                        Pad::None => write!(result, "{}", v),
+                        Pad::Zero => write!(result, "{:01$}", v, width),
+                        Pad::Space => write!(result, "{:1$}", v, width),
+                    }
+                }?
+            } else {
+                return Err(fmt::Error); // insufficient arguments for given format
+            }
+        }
+
+        Item::Fixed(ref spec) => {
+            use self::Fixed::*;
+
+            /// Prints an offset from UTC in the format of `+HHMM` or `+HH:MM`.
+            /// `Z` instead of `+00[:]00` is allowed when `allow_zulu` is true.
+            fn write_local_minus_utc(
+                result: &mut String,
+                off: FixedOffset,
+                allow_zulu: bool,
+                use_colon: bool,
+            ) -> fmt::Result {
+                let off = off.local_minus_utc();
+                if !allow_zulu || off != 0 {
+                    let (sign, off) = if off < 0 { ('-', -off) } else { ('+', off) };
+                    if use_colon {
+                        write!(result, "{}{:02}:{:02}", sign, off / 3600, off / 60 % 60)
+                    } else {
+                        write!(result, "{}{:02}{:02}", sign, off / 3600, off / 60 % 60)
+                    }
+                } else {
+                    result.push_str("Z");
+                    Ok(())
+                }
+            }
+
+            let ret =
+                match *spec {
+                    ShortMonthName => date.map(|d| {
+                        result.push_str(short_months[d.month0() as usize]);
+                        Ok(())
+                    }),
+                    LongMonthName => date.map(|d| {
+                        result.push_str(long_months[d.month0() as usize]);
+                        Ok(())
+                    }),
+                    ShortWeekdayName => date.map(|d| {
+                        result
+                            .push_str(short_weekdays[d.weekday().num_days_from_sunday() as usize]);
+                        Ok(())
+                    }),
+                    LongWeekdayName => date.map(|d| {
+                        result.push_str(long_weekdays[d.weekday().num_days_from_sunday() as usize]);
+                        Ok(())
+                    }),
+                    LowerAmPm => time.map(|t| {
+                        #[cfg_attr(feature = "cargo-clippy", allow(useless_asref))]
+                        {
+                            result.push_str(if t.hour12().0 {
+                                am_pm_lowercase[1].as_ref()
+                            } else {
+                                am_pm_lowercase[0].as_ref()
+                            });
+                        }
+                        Ok(())
+                    }),
+                    UpperAmPm => time.map(|t| {
+                        result.push_str(if t.hour12().0 { am_pm[1] } else { am_pm[0] });
+                        Ok(())
+                    }),
+                    Nanosecond => time.map(|t| {
+                        let nano = t.nanosecond() % 1_000_000_000;
+                        if nano == 0 {
+                            Ok(())
+                        } else if nano % 1_000_000 == 0 {
+                            write!(result, ".{:03}", nano / 1_000_000)
+                        } else if nano % 1_000 == 0 {
+                            write!(result, ".{:06}", nano / 1_000)
+                        } else {
+                            write!(result, ".{:09}", nano)
+                        }
+                    }),
+                    Nanosecond3 => time.map(|t| {
+                        let nano = t.nanosecond() % 1_000_000_000;
+                        write!(result, ".{:03}", nano / 1_000_000)
+                    }),
+                    Nanosecond6 => time.map(|t| {
+                        let nano = t.nanosecond() % 1_000_000_000;
+                        write!(result, ".{:06}", nano / 1_000)
+                    }),
+                    Nanosecond9 => time.map(|t| {
+                        let nano = t.nanosecond() % 1_000_000_000;
+                        write!(result, ".{:09}", nano)
+                    }),
+                    Internal(InternalFixed { val: InternalInternal::Nanosecond3NoDot }) => time
+                        .map(|t| {
+                            let nano = t.nanosecond() % 1_000_000_000;
+                            write!(result, "{:03}", nano / 1_000_000)
+                        }),
+                    Internal(InternalFixed { val: InternalInternal::Nanosecond6NoDot }) => time
+                        .map(|t| {
+                            let nano = t.nanosecond() % 1_000_000_000;
+                            write!(result, "{:06}", nano / 1_000)
+                        }),
+                    Internal(InternalFixed { val: InternalInternal::Nanosecond9NoDot }) => time
+                        .map(|t| {
+                            let nano = t.nanosecond() % 1_000_000_000;
+                            write!(result, "{:09}", nano)
+                        }),
+                    TimezoneName => off.map(|&(ref name, _)| {
+                        result.push_str(name);
+                        Ok(())
+                    }),
+                    TimezoneOffsetColon => {
+                        off.map(|&(_, off)| write_local_minus_utc(result, off, false, true))
+                    }
+                    TimezoneOffsetColonZ => {
+                        off.map(|&(_, off)| write_local_minus_utc(result, off, true, true))
+                    }
+                    TimezoneOffset => {
+                        off.map(|&(_, off)| write_local_minus_utc(result, off, false, false))
+                    }
+                    TimezoneOffsetZ => {
+                        off.map(|&(_, off)| write_local_minus_utc(result, off, true, false))
+                    }
+                    Internal(InternalFixed { val: InternalInternal::TimezoneOffsetPermissive }) => {
+                        panic!("Do not try to write %#z it is undefined")
+                    }
+                    RFC2822 =>
+                    // same as `%a, %d %b %Y %H:%M:%S %z`
+                    {
+                        if let (Some(d), Some(t), Some(&(_, off))) = (date, time, off) {
+                            let sec = t.second() + t.nanosecond() / 1_000_000_000;
+                            write!(
+                                result,
+                                "{}, {:02} {} {:04} {:02}:{:02}:{:02} ",
+                                short_weekdays[d.weekday().num_days_from_sunday() as usize],
+                                d.day(),
+                                short_months[d.month0() as usize],
+                                d.year(),
+                                t.hour(),
+                                t.minute(),
+                                sec
+                            )?;
+                            Some(write_local_minus_utc(result, off, false, false))
+                        } else {
+                            None
+                        }
+                    }
+                    RFC3339 =>
+                    // same as `%Y-%m-%dT%H:%M:%S%.f%:z`
+                    {
+                        if let (Some(d), Some(t), Some(&(_, off))) = (date, time, off) {
+                            // reuse `Debug` impls which already print ISO 8601 format.
+                            // this is faster in this way.
+                            write!(result, "{:?}T{:?}", d, t)?;
+                            Some(write_local_minus_utc(result, off, false, true))
+                        } else {
+                            None
+                        }
+                    }
+                };
+
+            match ret {
+                Some(ret) => ret?,
+                None => return Err(fmt::Error), // insufficient arguments for given format
+            }
+        }
+
+        Item::Error => return Err(fmt::Error),
+    }
+    Ok(())
+}
+
+/// Tries to format given arguments with given formatting items.
+/// Internally used by `DelayedFormat`.
+#[cfg(any(feature = "alloc", feature = "std", test))]
+pub fn format<'a, I, B>(
+    w: &mut fmt::Formatter,
+    date: Option<&NaiveDate>,
+    time: Option<&NaiveTime>,
+    off: Option<&(String, FixedOffset)>,
+    items: I,
+) -> fmt::Result
+where
+    I: Iterator<Item = B> + Clone,
+    B: Borrow<Item<'a>>,
+{
+    let mut result = String::new();
+    for item in items {
+        format_inner(&mut result, date, time, off, item.borrow(), None)?;
+    }
+    w.pad(&result)
+}
+
+mod parsed;
+
+// due to the size of parsing routines, they are in separate modules.
+mod parse;
+mod scan;
+
+pub mod strftime;
+
+/// A *temporary* object which can be used as an argument to `format!` or others.
+/// This is normally constructed via `format` methods of each date and time type.
+#[cfg(any(feature = "alloc", feature = "std", test))]
+#[derive(Debug)]
+pub struct DelayedFormat<I> {
+    /// The date view, if any.
+    date: Option<NaiveDate>,
+    /// The time view, if any.
+    time: Option<NaiveTime>,
+    /// The name and local-to-UTC difference for the offset (timezone), if any.
+    off: Option<(String, FixedOffset)>,
+    /// An iterator returning formatting items.
+    items: I,
+    /// Locale used for text.
+    locale: Option<Locale>,
+}
+
+#[cfg(any(feature = "alloc", feature = "std", test))]
+impl<'a, I: Iterator<Item = B> + Clone, B: Borrow<Item<'a>>> DelayedFormat<I> {
+    /// Makes a new `DelayedFormat` value out of local date and time.
+    pub fn new(date: Option<NaiveDate>, time: Option<NaiveTime>, items: I) -> DelayedFormat<I> {
+        DelayedFormat { date: date, time: time, off: None, items: items, locale: None }
+    }
+
+    /// Makes a new `DelayedFormat` value out of local date and time and UTC offset.
+    pub fn new_with_offset<Off>(
+        date: Option<NaiveDate>,
+        time: Option<NaiveTime>,
+        offset: &Off,
+        items: I,
+    ) -> DelayedFormat<I>
+    where
+        Off: Offset + fmt::Display,
+    {
+        let name_and_diff = (offset.to_string(), offset.fix());
+        DelayedFormat {
+            date: date,
+            time: time,
+            off: Some(name_and_diff),
+            items: items,
+            locale: None,
+        }
+    }
+
+    /// Makes a new `DelayedFormat` value out of local date and time and locale.
+    #[cfg(feature = "unstable-locales")]
+    pub fn new_with_locale(
+        date: Option<NaiveDate>,
+        time: Option<NaiveTime>,
+        items: I,
+        locale: Locale,
+    ) -> DelayedFormat<I> {
+        DelayedFormat { date: date, time: time, off: None, items: items, locale: Some(locale) }
+    }
+
+    /// Makes a new `DelayedFormat` value out of local date and time, UTC offset and locale.
+    #[cfg(feature = "unstable-locales")]
+    pub fn new_with_offset_and_locale<Off>(
+        date: Option<NaiveDate>,
+        time: Option<NaiveTime>,
+        offset: &Off,
+        items: I,
+        locale: Locale,
+    ) -> DelayedFormat<I>
+    where
+        Off: Offset + fmt::Display,
+    {
+        let name_and_diff = (offset.to_string(), offset.fix());
+        DelayedFormat {
+            date: date,
+            time: time,
+            off: Some(name_and_diff),
+            items: items,
+            locale: Some(locale),
+        }
+    }
+}
+
+#[cfg(any(feature = "alloc", feature = "std", test))]
+impl<'a, I: Iterator<Item = B> + Clone, B: Borrow<Item<'a>>> fmt::Display for DelayedFormat<I> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        #[cfg(feature = "unstable-locales")]
+        {
+            if let Some(locale) = self.locale {
+                return format_localized(
+                    f,
+                    self.date.as_ref(),
+                    self.time.as_ref(),
+                    self.off.as_ref(),
+                    self.items.clone(),
+                    locale,
+                );
+            }
+        }
+
+        format(f, self.date.as_ref(), self.time.as_ref(), self.off.as_ref(), self.items.clone())
+    }
+}
+
+// this implementation is here only because we need some private code from `scan`
+
+/// Parsing a `str` into a `Weekday` uses the format [`%W`](./format/strftime/index.html).
+///
+/// # Example
+///
+/// ~~~~
+/// use chrono::Weekday;
+///
+/// assert_eq!("Sunday".parse::<Weekday>(), Ok(Weekday::Sun));
+/// assert!("any day".parse::<Weekday>().is_err());
+/// ~~~~
+///
+/// The parsing is case-insensitive.
+///
+/// ~~~~
+/// # use chrono::Weekday;
+/// assert_eq!("mON".parse::<Weekday>(), Ok(Weekday::Mon));
+/// ~~~~
+///
+/// Only the shortest form (e.g. `sun`) and the longest form (e.g. `sunday`) is accepted.
+///
+/// ~~~~
+/// # use chrono::Weekday;
+/// assert!("thurs".parse::<Weekday>().is_err());
+/// ~~~~
+impl FromStr for Weekday {
+    type Err = ParseWeekdayError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if let Ok(("", w)) = scan::short_or_long_weekday(s) {
+            Ok(w)
+        } else {
+            Err(ParseWeekdayError { _dummy: () })
+        }
+    }
+}
+
+/// Formats single formatting item
+#[cfg(feature = "unstable-locales")]
+pub fn format_item_localized<'a>(
+    w: &mut fmt::Formatter,
+    date: Option<&NaiveDate>,
+    time: Option<&NaiveTime>,
+    off: Option<&(String, FixedOffset)>,
+    item: &Item<'a>,
+    locale: Locale,
+) -> fmt::Result {
+    let mut result = String::new();
+    format_inner(&mut result, date, time, off, item, Some(locale))?;
+    w.pad(&result)
+}
+
+/// Tries to format given arguments with given formatting items.
+/// Internally used by `DelayedFormat`.
+#[cfg(feature = "unstable-locales")]
+pub fn format_localized<'a, I, B>(
+    w: &mut fmt::Formatter,
+    date: Option<&NaiveDate>,
+    time: Option<&NaiveTime>,
+    off: Option<&(String, FixedOffset)>,
+    items: I,
+    locale: Locale,
+) -> fmt::Result
+where
+    I: Iterator<Item = B> + Clone,
+    B: Borrow<Item<'a>>,
+{
+    let mut result = String::new();
+    for item in items {
+        format_inner(&mut result, date, time, off, item.borrow(), Some(locale))?;
+    }
+    w.pad(&result)
+}
+
+/// Parsing a `str` into a `Month` uses the format [`%W`](./format/strftime/index.html).
+///
+/// # Example
+///
+/// ~~~~
+/// use chrono::Month;
+///
+/// assert_eq!("January".parse::<Month>(), Ok(Month::January));
+/// assert!("any day".parse::<Month>().is_err());
+/// ~~~~
+///
+/// The parsing is case-insensitive.
+///
+/// ~~~~
+/// # use chrono::Month;
+/// assert_eq!("fEbruARy".parse::<Month>(), Ok(Month::February));
+/// ~~~~
+///
+/// Only the shortest form (e.g. `jan`) and the longest form (e.g. `january`) is accepted.
+///
+/// ~~~~
+/// # use chrono::Month;
+/// assert!("septem".parse::<Month>().is_err());
+/// assert!("Augustin".parse::<Month>().is_err());
+/// ~~~~
+impl FromStr for Month {
+    type Err = ParseMonthError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if let Ok(("", w)) = scan::short_or_long_month0(s) {
+            match w {
+                0 => Ok(Month::January),
+                1 => Ok(Month::February),
+                2 => Ok(Month::March),
+                3 => Ok(Month::April),
+                4 => Ok(Month::May),
+                5 => Ok(Month::June),
+                6 => Ok(Month::July),
+                7 => Ok(Month::August),
+                8 => Ok(Month::September),
+                9 => Ok(Month::October),
+                10 => Ok(Month::November),
+                11 => Ok(Month::December),
+                _ => Err(ParseMonthError { _dummy: () }),
+            }
+        } else {
+            Err(ParseMonthError { _dummy: () })
+        }
+    }
+}