add padding width

Author: BigPapa314

src/format/formatting.rs

@@ -127,89 +127,61 @@ impl<'a, I: Iterator<Item = B> + Clone, B: Borrow<Item<'a>>> DelayedFormat<I> {
     fn format_numeric(&self, w: &mut impl Write, spec: &Numeric, pad: Pad) -> fmt::Result {
         use self::Numeric::*;
 
-        fn write_one(w: &mut impl Write, v: u8) -> fmt::Result {
-            w.write_char((b'0' + v) as char)
-        }
+        // unpack padding width if provided
+        let (spec, mut pad_width) = match spec {
+            Numeric::Padded { numeric, width } => (numeric.as_ref().clone(), *width),
+            numeric => (numeric.clone(), 0),
+        };
 
-        fn write_two(w: &mut impl Write, v: u8, pad: Pad) -> fmt::Result {
-            let ones = b'0' + v % 10;
-            match (v / 10, pad) {
-                (0, Pad::None) => {}
-                (0, Pad::Space) => w.write_char(' ')?,
-                (tens, _) => w.write_char((b'0' + tens) as char)?,
+        let (value, default_pad_width, is_year) = match (spec, self.date, self.time) {
+            (Year, Some(d), _) => (d.year() as i64, 4, true),
+            (YearDiv100, Some(d), _) => (d.year().div_euclid(100) as i64, 2, false),
+            (YearMod100, Some(d), _) => (d.year().rem_euclid(100) as i64, 2, false),
+            (IsoYear, Some(d), _) => (d.iso_week().year() as i64, 4, true),
+            (IsoYearDiv100, Some(d), _) => (d.iso_week().year().div_euclid(100) as i64, 2, false),
+            (IsoYearMod100, Some(d), _) => (d.iso_week().year().rem_euclid(100) as i64, 2, false),
+            (Quarter, Some(d), _) => (d.quarter() as i64, 1, false),
+            (Month, Some(d), _) => (d.month() as i64, 2, false),
+            (Day, Some(d), _) => (d.day() as i64, 2, false),
+            (WeekFromSun, Some(d), _) => (d.weeks_from(Weekday::Sun) as i64, 2, false),
+            (WeekFromMon, Some(d), _) => (d.weeks_from(Weekday::Mon) as i64, 2, false),
+            (IsoWeek, Some(d), _) => (d.iso_week().week() as i64, 2, false),
+            (NumDaysFromSun, Some(d), _) => (d.weekday().num_days_from_sunday() as i64, 1, false),
+            (WeekdayFromMon, Some(d), _) => (d.weekday().number_from_monday() as i64, 1, false),
+            (Ordinal, Some(d), _) => (d.ordinal() as i64, 3, false),
+            (Hour, _, Some(t)) => (t.hour() as i64, 2, false),
+            (Hour12, _, Some(t)) => (t.hour12().1 as i64, 2, false),
+            (Minute, _, Some(t)) => (t.minute() as i64, 2, false),
+            (Second, _, Some(t)) => {
+                ((t.second() + t.nanosecond() / 1_000_000_000) as i64, 2, false)
             }
-            w.write_char(ones as char)
-        }
-
-        #[inline]
-        fn write_year(w: &mut impl Write, year: i32, pad: Pad) -> fmt::Result {
-            if (1000..=9999).contains(&year) {
-                // fast path
-                write_hundreds(w, (year / 100) as u8)?;
-                write_hundreds(w, (year % 100) as u8)
-            } else {
-                write_n(w, 4, year as i64, pad, !(0..10_000).contains(&year))
+            (Nanosecond, _, Some(t)) => ((t.nanosecond() % 1_000_000_000) as i64, 9, false),
+            (Timestamp, Some(d), Some(t)) => {
+                let offset = self.off.as_ref().map(|(_, o)| i64::from(o.local_minus_utc()));
+                (d.and_time(t).and_utc().timestamp() - offset.unwrap_or(0), 9, false)
             }
-        }
+            (Internal(_), _, _) => return Ok(()), // for future expansion
+            (Padded { .. }, _, _) => return Err(fmt::Error), // should be unwrapped above
+            _ => return Err(fmt::Error),          // insufficient arguments for given format
+        };
 
-        fn write_n(
-            w: &mut impl Write,
-            n: usize,
-            v: i64,
-            pad: Pad,
-            always_sign: bool,
-        ) -> fmt::Result {
-            if always_sign {
-                match pad {
-                    Pad::None => write!(w, "{:+}", v),
-                    Pad::Zero => write!(w, "{:+01$}", v, n + 1),
-                    Pad::Space => write!(w, "{:+1$}", v, n + 1),
-                }
-            } else {
-                match pad {
-                    Pad::None => write!(w, "{}", v),
-                    Pad::Zero => write!(w, "{:01$}", v, n),
-                    Pad::Space => write!(w, "{:1$}", v, n),
-                }
-            }
+        if pad_width == 0 {
+            pad_width = default_pad_width;
         }
 
-        match (spec, self.date, self.time) {
-            (Year, Some(d), _) => write_year(w, d.year(), pad),
-            (YearDiv100, Some(d), _) => write_two(w, d.year().div_euclid(100) as u8, pad),
-            (YearMod100, Some(d), _) => write_two(w, d.year().rem_euclid(100) as u8, pad),
-            (IsoYear, Some(d), _) => write_year(w, d.iso_week().year(), pad),
-            (IsoYearDiv100, Some(d), _) => {
-                write_two(w, d.iso_week().year().div_euclid(100) as u8, pad)
-            }
-            (IsoYearMod100, Some(d), _) => {
-                write_two(w, d.iso_week().year().rem_euclid(100) as u8, pad)
-            }
-            (Quarter, Some(d), _) => write_one(w, d.quarter() as u8),
-            (Month, Some(d), _) => write_two(w, d.month() as u8, pad),
-            (Day, Some(d), _) => write_two(w, d.day() as u8, pad),
-            (WeekFromSun, Some(d), _) => write_two(w, d.weeks_from(Weekday::Sun) as u8, pad),
-            (WeekFromMon, Some(d), _) => write_two(w, d.weeks_from(Weekday::Mon) as u8, pad),
-            (IsoWeek, Some(d), _) => write_two(w, d.iso_week().week() as u8, pad),
-            (NumDaysFromSun, Some(d), _) => write_one(w, d.weekday().num_days_from_sunday() as u8),
-            (WeekdayFromMon, Some(d), _) => write_one(w, d.weekday().number_from_monday() as u8),
-            (Ordinal, Some(d), _) => write_n(w, 3, d.ordinal() as i64, pad, false),
-            (Hour, _, Some(t)) => write_two(w, t.hour() as u8, pad),
-            (Hour12, _, Some(t)) => write_two(w, t.hour12().1 as u8, pad),
-            (Minute, _, Some(t)) => write_two(w, t.minute() as u8, pad),
-            (Second, _, Some(t)) => {
-                write_two(w, (t.second() + t.nanosecond() / 1_000_000_000) as u8, pad)
-            }
-            (Nanosecond, _, Some(t)) => {
-                write_n(w, 9, (t.nanosecond() % 1_000_000_000) as i64, pad, false)
+        let always_sign = is_year && !(0..10_000).contains(&value);
+        if always_sign {
+            match pad {
+                Pad::None => write!(w, "{:+}", value),
+                Pad::Zero => write!(w, "{:+01$}", value, pad_width + 1),
+                Pad::Space => write!(w, "{:+1$}", value, pad_width + 1),
             }
-            (Timestamp, Some(d), Some(t)) => {
-                let offset = self.off.as_ref().map(|(_, o)| i64::from(o.local_minus_utc()));
-                let timestamp = d.and_time(t).and_utc().timestamp() - offset.unwrap_or(0);
-                write_n(w, 9, timestamp, pad, false)
+        } else {
+            match pad {
+                Pad::None => write!(w, "{}", value),
+                Pad::Zero => write!(w, "{:01$}", value, pad_width),
+                Pad::Space => write!(w, "{:1$}", value, pad_width),
             }
-            (Internal(_), _, _) => Ok(()), // for future expansion
-            _ => Err(fmt::Error),          // insufficient arguments for given format
         }
     }
 

src/format/mod.rs

@@ -33,6 +33,8 @@
 
 #[cfg(all(feature = "alloc", not(feature = "std"), not(test)))]
 use alloc::boxed::Box;
+#[cfg(feature = "alloc")]
+use alloc::sync::Arc;
 use core::fmt;
 use core::str::FromStr;
 #[cfg(feature = "std")]
@@ -149,13 +151,46 @@ pub enum Numeric {
     /// For formatting, it assumes UTC upon the absence of time zone offset.
     Timestamp,
 
+    #[cfg(feature = "alloc")]
+    /// An extension to carry the width of the padding.
+    Padded {
+        /// The numeric to be padded.
+        numeric: Arc<Numeric>,
+        /// The width of the padding.
+        width: usize,
+    },
+
     /// 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),
 }
 
+impl Numeric {
+    #[cfg(feature = "alloc")]
+    fn with_padding(self, width: usize) -> Self {
+        if width != 0 {
+            // update padding
+            match self {
+                Numeric::Padded { numeric, .. } => Numeric::Padded { numeric, width },
+                numeric => Numeric::Padded { numeric: Arc::new(numeric), width },
+            }
+        } else {
+            // remove padding
+            match self {
+                Numeric::Padded { numeric, .. } => numeric.as_ref().clone(),
+                numeric => numeric,
+            }
+        }
+    }
+
+    #[cfg(not(feature = "alloc"))]
+    fn with_padding(self, _width: usize) -> Self {
+        self
+    }
+}
+
 /// An opaque type representing numeric item types for internal uses only.
 #[derive(Clone, Eq, Hash, PartialEq)]
 pub struct InternalNumeric {
@@ -555,3 +590,46 @@ impl FromStr for Month {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::format::*;
+
+    #[test]
+    #[cfg(feature = "alloc")]
+    fn test_numeric_with_padding() {
+        // No padding
+        assert_eq!(Numeric::Year.with_padding(0), Numeric::Year);
+
+        // Add padding
+        assert_eq!(
+            Numeric::Year.with_padding(5),
+            Numeric::Padded { numeric: Arc::new(Numeric::Year), width: 5 }
+        );
+
+        // Update padding
+        assert_eq!(
+            Numeric::Year.with_padding(5).with_padding(10),
+            Numeric::Padded { numeric: Arc::new(Numeric::Year), width: 10 }
+        );
+
+        // Remove padding
+        assert_eq!(Numeric::Year.with_padding(5).with_padding(0), Numeric::Year);
+    }
+
+    #[test]
+    #[cfg(not(feature = "alloc"))]
+    fn test_numeric_with_padding_disabled() {
+        // No padding
+        assert_eq!(Numeric::Year.with_padding(0), Numeric::Year);
+
+        // Add padding
+        assert_eq!(Numeric::Year.with_padding(5), Numeric::Year);
+
+        // Update padding
+        assert_eq!(Numeric::Year.with_padding(5).with_padding(10), Numeric::Year);
+
+        // Remove padding
+        assert_eq!(Numeric::Year.with_padding(5).with_padding(0), Numeric::Year);
+    }
+}

src/format/parse.rs

@@ -7,6 +7,8 @@
 use core::borrow::Borrow;
 use core::str;
 
+#[cfg(feature = "alloc")]
+use super::ParseErrorKind::BadFormat;
 use super::scan;
 use super::{BAD_FORMAT, INVALID, OUT_OF_RANGE, TOO_LONG, TOO_SHORT};
 use super::{Fixed, InternalFixed, InternalInternal, Item, Numeric, Pad, Parsed};
@@ -359,7 +361,9 @@ where
                     Nanosecond => (9, false, Parsed::set_nanosecond),
                     Timestamp => (usize::MAX, false, Parsed::set_timestamp),
 
-                    // for the future expansion
+                    #[cfg(feature = "alloc")]
+                    Padded { .. } => return Err(ParseError(BadFormat)),
+
                     Internal(ref int) => match int._dummy {},
                 };
 
@@ -1580,6 +1584,88 @@ mod tests {
         );
     }
 
+    #[test]
+    #[rustfmt::skip]
+    #[cfg(feature = "alloc")]
+    fn test_parse_padded() {
+        use crate::format::InternalInternal::*;
+        use crate::format::Item::{Literal, Space};
+        use crate::format::Numeric::*;
+        use crate::format::ParseErrorKind::BadFormat;
+
+        check(
+            "2000-01-02 03:04:05Z",
+            &[
+                nums(Year.with_padding(5))
+            ],
+            Err(ParseError(BadFormat)),
+        );
+
+        check(
+            "2000-01-02 03:04:05Z",
+            &[
+                nums(Year.with_padding(5)), Literal("-"), num(Month), Literal("-"), num(Day), Space(" "),
+                num(Hour), Literal(":"), num(Minute), Literal(":"), num(Second),
+                internal_fixed(TimezoneOffsetPermissive)
+            ],
+            Err(ParseError(BadFormat)),
+        );
+
+        check(
+            "2000-01-02 03:04:05Z",
+            &[
+                num(Year), Literal("-"), num(Month), Literal("-"), nums(Day.with_padding(5)), Space(" "),
+                num(Hour), Literal(":"), num(Minute), Literal(":"), num(Second),
+                internal_fixed(TimezoneOffsetPermissive)
+            ],
+            Err(ParseError(BadFormat)),
+        );
+    }
+
+    #[test]
+    #[rustfmt::skip]
+    #[cfg(not(feature = "alloc"))]
+    fn test_parse_padded_disabled() {
+        use crate::format::InternalInternal::*;
+        use crate::format::Item::{Literal, Space};
+        use crate::format::Numeric::*;
+        use crate::format::ParseErrorKind::TooLong;
+
+        check(
+            "2000-01-02 03:04:05Z",
+            &[
+                nums(Year.with_padding(5))
+            ],
+            Err(ParseError(TooLong)),
+        );
+
+        check(
+            "2000-01-02 03:04:05Z",
+            &[
+                nums(Year.with_padding(5)), Literal("-"), num(Month), Literal("-"), num(Day), Space(" "),
+                num(Hour), Literal(":"), num(Minute), Literal(":"), num(Second),
+                internal_fixed(TimezoneOffsetPermissive)
+            ],
+            parsed!(
+                year: 2000, month: 1, day: 2, hour_div_12: 0, hour_mod_12: 3, minute: 4, second: 5,
+                offset: 0
+            ),
+        );
+
+        check(
+            "2000-01-02 03:04:05Z",
+            &[
+                num(Year), Literal("-"), num(Month), Literal("-"), nums(Day.with_padding(5)), Space(" "),
+                num(Hour), Literal(":"), num(Minute), Literal(":"), num(Second),
+                internal_fixed(TimezoneOffsetPermissive)
+            ],
+            parsed!(
+                year: 2000, month: 1, day: 2, hour_div_12: 0, hour_mod_12: 3, minute: 4, second: 5,
+                offset: 0
+            ),
+        );
+    }
+
     #[track_caller]
     fn parses(s: &str, items: &[Item]) {
         let mut parsed = Parsed::new();