1 files changed, 137 insertions, 0 deletions
diff --git a/third_party/rust/time-macros/src/date.rs b/third_party/rust/time-macros/src/date.rs
new file mode 100644
index 0000000000..574ef8ce6f
--- /dev/null
+++ b/third_party/rust/time-macros/src/date.rs
@@ -0,0 +1,137 @@
+use std::iter::Peekable;
+
+use proc_macro::{token_stream, TokenTree};
+use time_core::util::{days_in_year, weeks_in_year};
+
+use crate::helpers::{
+    consume_any_ident, consume_number, consume_punct, days_in_year_month, ymd_to_yo, ywd_to_yo,
+};
+use crate::to_tokens::ToTokenTree;
+use crate::Error;
+
+#[cfg(feature = "large-dates")]
+const MAX_YEAR: i32 = 999_999;
+#[cfg(not(feature = "large-dates"))]
+const MAX_YEAR: i32 = 9_999;
+
+pub(crate) struct Date {
+    pub(crate) year: i32,
+    pub(crate) ordinal: u16,
+}
+
+pub(crate) fn parse(chars: &mut Peekable<token_stream::IntoIter>) -> Result<Date, Error> {
+    let (year_sign_span, year_sign, explicit_sign) = if let Ok(span) = consume_punct('-', chars) {
+        (Some(span), -1, true)
+    } else if let Ok(span) = consume_punct('+', chars) {
+        (Some(span), 1, true)
+    } else {
+        (None, 1, false)
+    };
+    let (year_span, mut year) = consume_number::<i32>("year", chars)?;
+    year *= year_sign;
+    if year.abs() > MAX_YEAR {
+        return Err(Error::InvalidComponent {
+            name: "year",
+            value: year.to_string(),
+            span_start: Some(year_sign_span.unwrap_or(year_span)),
+            span_end: Some(year_span),
+        });
+    }
+    if !explicit_sign && year.abs() >= 10_000 {
+        return Err(Error::Custom {
+            message: "years with more than four digits must have an explicit sign".into(),
+            span_start: Some(year_sign_span.unwrap_or(year_span)),
+            span_end: Some(year_span),
+        });
+    }
+
+    consume_punct('-', chars)?;
+
+    // year-week-day
+    if let Ok(w_span) = consume_any_ident(&["W"], chars) {
+        let (week_span, week) = consume_number::<u8>("week", chars)?;
+        consume_punct('-', chars)?;
+        let (day_span, day) = consume_number::<u8>("day", chars)?;
+
+        if week > weeks_in_year(year) {
+            return Err(Error::InvalidComponent {
+                name: "week",
+                value: week.to_string(),
+                span_start: Some(w_span),
+                span_end: Some(week_span),
+            });
+        }
+        if day == 0 || day > 7 {
+            return Err(Error::InvalidComponent {
+                name: "day",
+                value: day.to_string(),
+                span_start: Some(day_span),
+                span_end: Some(day_span),
+            });
+        }
+
+        let (year, ordinal) = ywd_to_yo(year, week, day);
+
+        return Ok(Date { year, ordinal });
+    }
+
+    // We don't yet know whether it's year-month-day or year-ordinal.
+    let (month_or_ordinal_span, month_or_ordinal) =
+        consume_number::<u16>("month or ordinal", chars)?;
+
+    // year-month-day
+    #[allow(clippy::branches_sharing_code)] // clarity
+    if consume_punct('-', chars).is_ok() {
+        let (month_span, month) = (month_or_ordinal_span, month_or_ordinal);
+        let (day_span, day) = consume_number::<u8>("day", chars)?;
+
+        if month == 0 || month > 12 {
+            return Err(Error::InvalidComponent {
+                name: "month",
+                value: month.to_string(),
+                span_start: Some(month_span),
+                span_end: Some(month_span),
+            });
+        }
+        let month = month as _;
+        if day == 0 || day > days_in_year_month(year, month) {
+            return Err(Error::InvalidComponent {
+                name: "day",
+                value: day.to_string(),
+                span_start: Some(day_span),
+                span_end: Some(day_span),
+            });
+        }
+
+        let (year, ordinal) = ymd_to_yo(year, month, day);
+
+        Ok(Date { year, ordinal })
+    }
+    // year-ordinal
+    else {
+        let (ordinal_span, ordinal) = (month_or_ordinal_span, month_or_ordinal);
+
+        if ordinal == 0 || ordinal > days_in_year(year) {
+            return Err(Error::InvalidComponent {
+                name: "ordinal",
+                value: ordinal.to_string(),
+                span_start: Some(ordinal_span),
+                span_end: Some(ordinal_span),
+            });
+        }
+
+        Ok(Date { year, ordinal })
+    }
+}
+
+impl ToTokenTree for Date {
+    fn into_token_tree(self) -> TokenTree {
+        quote_group! {{
+            const DATE: ::time::Date = ::time::Date::__from_ordinal_date_unchecked(
+                #(self.year),
+                #(self.ordinal),
+            );
+            DATE
+        }}
+    }
+}