Support century when parsing/formatting year

Goorzhel · Oct 15, 2024 · 19120ac · 19120ac
1 parent a6c3243
commit 19120ac
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Showing 12 changed files with 275 additions and 31 deletions.
diff --git a/tests/formatting.rs b/tests/formatting.rs
@@ -391,6 +391,7 @@ fn format_date() -> time::Result<()> {
         (fd!("[year base:iso_week]"), "2020"),
         (fd!("[year sign:mandatory]"), "+2019"),
         (fd!("[year base:iso_week sign:mandatory]"), "+2020"),
+        (fd!("[year repr:century]"), "20"),
         (fd!("[year repr:last_two]"), "19"),
         (fd!("[year base:iso_week repr:last_two]"), "20"),
     ];

diff --git a/tests/meta.rs b/tests/meta.rs
@@ -154,7 +154,7 @@ fn size() {
     assert_size!(iso8601::FormattedComponents, 1, 1);
     assert_size!(iso8601::OffsetPrecision, 1, 1);
     assert_size!(iso8601::TimePrecision, 2, 2);
-    assert_size!(Parsed, 56, 56);
+    assert_size!(Parsed, 64, 64);
     assert_size!(Month, 1, 1);
     assert_size!(Weekday, 1, 1);
     assert_size!(Error, 56, 56);

diff --git a/tests/parse_format_description.rs b/tests/parse_format_description.rs
@@ -78,6 +78,7 @@ fn modifiers(
     week_number_repr: _,
     #[values(
         (YearRepr::Full, "repr:full"),
+        (YearRepr::Century, "repr:century"),
         (YearRepr::LastTwo, "repr:last_two"),
     )]
     year_repr: _,

diff --git a/tests/parsing.rs b/tests/parsing.rs
@@ -867,8 +867,8 @@ fn parse_date() -> time::Result<()> {
                 "[year padding:space]-W[week_number repr:sunday padding:none]-[weekday \
                  repr:sunday]",
             )?,
-            " 2018-W01-2",
-            date!(2018 - 01 - 02),
+            " 201-W01-2",
+            date!(201 - 01 - 06),
         ),
     ];
 
@@ -1124,10 +1124,10 @@ fn parse_offset_date_time_err() -> time::Result<()> {
 #[test]
 fn parse_components() -> time::Result<()> {
     macro_rules! parse_component {
-        ($component:expr, $input:expr,_. $property:ident() == $expected:expr) => {
+        ($component:expr, $input:expr, $(_. $property:ident() == $expected:expr);+ $(;)?) => {
             let mut parsed = Parsed::new();
             parsed.parse_component($input, $component)?;
-            assert_eq!(parsed.$property(), $expected);
+            $(assert_eq!(parsed.$property(), $expected);)+
         };
     }
 
@@ -1141,6 +1141,17 @@ fn parse_components() -> time::Result<()> {
         b"2021",
         _.year() == Some(2021)
     );
+    parse_component!(
+        Component::Year(modifier!(Year {
+            padding: modifier::Padding::Zero,
+            repr: modifier::YearRepr::Century,
+            iso_week_based: false,
+            sign_is_mandatory: false,
+        })),
+        b"20",
+        _.year_century() == Some(20);
+        _.year_century_is_negative() == Some(false);
+    );
     parse_component!(
         Component::Year(modifier!(Year {
             padding: modifier::Padding::Zero,
@@ -1161,6 +1172,17 @@ fn parse_components() -> time::Result<()> {
         b"2021",
         _.iso_year() == Some(2021)
     );
+    parse_component!(
+        Component::Year(modifier!(Year {
+            padding: modifier::Padding::Zero,
+            repr: modifier::YearRepr::Century,
+            iso_week_based: true,
+            sign_is_mandatory: false,
+        })),
+        b"20",
+        _.iso_year_century() == Some(20);
+        _.iso_year_century_is_negative() == Some(false);
+    );
     parse_component!(
         Component::Year(modifier!(Year {
             padding: modifier::Padding::Zero,

diff --git a/tests/quickcheck.rs b/tests/quickcheck.rs
@@ -1,7 +1,7 @@
 use num_conv::prelude::*;
 use quickcheck::{Arbitrary, TestResult};
 use quickcheck_macros::quickcheck;
-use time::macros::time;
+use time::macros::{format_description, time};
 use time::Weekday::*;
 use time::{Date, Duration, Month, OffsetDateTime, PrimitiveDateTime, Time, UtcOffset, Weekday};
 
@@ -56,6 +56,32 @@ fn date_ywd_roundtrip(d: Date) -> bool {
     Date::from_iso_week_date(year, week, weekday) == Ok(d)
 }
 
+#[quickcheck]
+fn date_format_century_last_two_equivalent(d: Date) -> bool {
+    let split_format = format_description!("[year repr:century][year repr:last_two]-[month]-[day]");
+    let split = d.format(&split_format).expect("formatting failed");
+
+    let combined_format = format_description!("[year]-[month]-[day]");
+    let combined = d.format(&combined_format).expect("formatting failed");
+
+    split == combined
+}
+
+#[quickcheck]
+fn date_parse_century_last_two_equivalent(d: Date) -> TestResult {
+    // There is an ambiguity when parsing a year with fewer than six digits, as the first four are
+    // consumed by the century, leaving at most one for the last two digits.
+    if !matches!(d.year().unsigned_abs().to_string().len(), 6) {
+        return TestResult::discard();
+    }
+
+    let split_format = format_description!("[year repr:century][year repr:last_two]-[month]-[day]");
+    let combined_format = format_description!("[year]-[month]-[day]");
+    let combined = d.format(&combined_format).expect("formatting failed");
+
+    TestResult::from_bool(Date::parse(&combined, &split_format).expect("parsing failed") == d)
+}
+
 #[quickcheck]
 fn julian_day_roundtrip(d: Date) -> bool {
     Date::from_julian_day(d.to_julian_day()) == Ok(d)

diff --git a/time-macros/src/format_description/format_item.rs b/time-macros/src/format_description/format_item.rs
@@ -425,6 +425,7 @@ modifier! {
     enum YearRepr {
         #[default]
         Full = b"full",
+        Century = b"century",
         LastTwo = b"last_two",
     }
 }

diff --git a/time-macros/src/format_description/public/modifier.rs b/time-macros/src/format_description/public/modifier.rs
@@ -131,6 +131,7 @@ to_tokens! {
 to_tokens! {
     pub(crate) enum YearRepr {
         Full,
+        Century,
         LastTwo,
     }
 }

diff --git a/time/src/format_description/modifier.rs b/time/src/format_description/modifier.rs
@@ -101,6 +101,8 @@ pub struct WeekNumber {
 pub enum YearRepr {
     /// The full value of the year.
     Full,
+    /// All digits except the last two. Includes the sign, if any.
+    Century,
     /// Only the last two digits of the year.
     LastTwo,
 }

diff --git a/time/src/format_description/parse/format_item.rs b/time/src/format_description/parse/format_item.rs
@@ -521,6 +521,7 @@ modifier! {
     enum YearRepr {
         #[default]
         Full = b"full",
+        Century = b"century",
         LastTwo = b"last_two",
     }
 }

diff --git a/time/src/formatting/mod.rs b/time/src/formatting/mod.rs
@@ -308,6 +308,7 @@ fn fmt_year(
     };
     let value = match repr {
         modifier::YearRepr::Full => full_year,
+        modifier::YearRepr::Century => full_year / 100,
         modifier::YearRepr::LastTwo => (full_year % 100).abs(),
     };
     let format_number = match repr {
@@ -316,7 +317,11 @@ fn fmt_year(
         #[cfg(feature = "large-dates")]
         modifier::YearRepr::Full if value.abs() >= 10_000 => format_number::<5>,
         modifier::YearRepr::Full => format_number::<4>,
-        modifier::YearRepr::LastTwo => format_number::<2>,
+        #[cfg(feature = "large-dates")]
+        modifier::YearRepr::Century if value.abs() >= 1_000 => format_number::<4>,
+        #[cfg(feature = "large-dates")]
+        modifier::YearRepr::Century if value.abs() >= 100 => format_number::<3>,
+        modifier::YearRepr::Century | modifier::YearRepr::LastTwo => format_number::<2>,
     };
     let mut bytes = 0;
     if repr != modifier::YearRepr::LastTwo {

diff --git a/time/src/parsing/component.rs b/time/src/parsing/component.rs
@@ -16,24 +16,62 @@ use crate::{Month, Weekday};
 
 // region: date components
 /// Parse the "year" component of a `Date`.
-pub(crate) fn parse_year(input: &[u8], modifiers: modifier::Year) -> Option<ParsedItem<'_, i32>> {
+pub(crate) fn parse_year(
+    input: &[u8],
+    modifiers: modifier::Year,
+) -> Option<ParsedItem<'_, (i32, bool)>> {
     match modifiers.repr {
         modifier::YearRepr::Full => {
             let ParsedItem(input, sign) = opt(sign)(input);
-            #[cfg(not(feature = "large-dates"))]
-            let ParsedItem(input, year) =
-                exactly_n_digits_padded::<4, u32>(modifiers.padding)(input)?;
-            #[cfg(feature = "large-dates")]
-            let ParsedItem(input, year) =
-                n_to_m_digits_padded::<4, 6, u32>(modifiers.padding)(input)?;
-            match sign {
-                Some(b'-') => Some(ParsedItem(input, -year.cast_signed())),
-                None if modifiers.sign_is_mandatory || year >= 10_000 => None,
-                _ => Some(ParsedItem(input, year.cast_signed())),
+
+            if let Some(sign) = sign {
+                #[cfg(not(feature = "large-dates"))]
+                let ParsedItem(input, year) =
+                    exactly_n_digits_padded::<4, u32>(modifiers.padding)(input)?;
+                #[cfg(feature = "large-dates")]
+                let ParsedItem(input, year) =
+                    n_to_m_digits_padded::<4, 6, u32>(modifiers.padding)(input)?;
+
+                Some(if sign == b'-' {
+                    ParsedItem(input, (-year.cast_signed(), true))
+                } else {
+                    ParsedItem(input, (year.cast_signed(), false))
+                })
+            } else if modifiers.sign_is_mandatory {
+                None
+            } else {
+                let ParsedItem(input, year) =
+                    exactly_n_digits_padded::<4, u32>(modifiers.padding)(input)?;
+                Some(ParsedItem(input, (year.cast_signed(), false)))
+            }
+        }
+        modifier::YearRepr::Century => {
+            let ParsedItem(input, sign) = opt(sign)(input);
+
+            if let Some(sign) = sign {
+                #[cfg(not(feature = "large-dates"))]
+                let ParsedItem(input, year) =
+                    exactly_n_digits_padded::<2, u32>(modifiers.padding)(input)?;
+                #[cfg(feature = "large-dates")]
+                let ParsedItem(input, year) =
+                    n_to_m_digits_padded::<2, 4, u32>(modifiers.padding)(input)?;
+
+                Some(if sign == b'-' {
+                    ParsedItem(input, (-year.cast_signed(), true))
+                } else {
+                    ParsedItem(input, (year.cast_signed(), false))
+                })
+            } else if modifiers.sign_is_mandatory {
+                None
+            } else {
+                let ParsedItem(input, year) =
+                    exactly_n_digits_padded::<2, u32>(modifiers.padding)(input)?;
+                Some(ParsedItem(input, (year.cast_signed(), false)))
             }
         }
         modifier::YearRepr::LastTwo => Some(
-            exactly_n_digits_padded::<2, u32>(modifiers.padding)(input)?.map(|v| v.cast_signed()),
+            exactly_n_digits_padded::<2, u32>(modifiers.padding)(input)?
+                .map(|v| (v.cast_signed(), false)),
         ),
     }
 }