1 files changed, 92 insertions, 0 deletions
diff --git a/src/date.rs b/src/date.rs
new file mode 100644
index 0000000..d246579
--- /dev/null
+++ b/src/date.rs
@@ -0,0 +1,92 @@
+use crate::{
+    ext::LitIntExtension,
+    time_crate,
+    time_crate::{days_in_year, days_in_year_month, weeks_in_year},
+};
+use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+use syn::{
+    parse::{Parse, ParseStream},
+    Ident, LitInt, Result, Token,
+};
+
+pub(crate) struct Date {
+    year: i32,
+    ordinal: u16,
+}
+
+impl Parse for Date {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
+        let (year, year_span) = {
+            let year_sign = if input.peek(Token![+]) {
+                input.parse::<Token![+]>()?;
+                1
+            } else if input.peek(Token![-]) {
+                input.parse::<Token![-]>()?;
+                -1
+            } else {
+                1
+            };
+            let year = input.parse::<LitInt>()?;
+            (year_sign * year.value::<i32>()?, year.span())
+        };
+        input.parse::<Token![-]>()?;
+
+        // year-week-day
+        let (year, ordinal) = if input.peek(Ident) {
+            let week = {
+                let week = input.parse::<Ident>()?;
+                let week_str = week.to_string();
+                if week_str.starts_with('W') {
+                    LitInt::new(&week_str[1..], week.span())
+                } else {
+                    return error!(week.span(), "expected week value to start with `W`");
+                }
+            };
+            input.parse::<Token![-]>()?;
+            let day = input.parse::<LitInt>()?;
+
+            week.ensure_in_range(0..=weeks_in_year(year) as isize)?;
+            day.ensure_in_range(1..=7)?;
+
+            time_crate::Date::from_iso_ywd_unchecked(year, week.value()?, day.value()?).as_yo()
+        }
+        // year-month-day
+        else if input.peek2(Token![-]) {
+            let month = input.parse::<LitInt>()?;
+            input.parse::<Token![-]>()?;
+            let day = input.parse::<LitInt>()?;
+
+            month.ensure_in_range(1..=12)?;
+            day.ensure_in_range(1..=days_in_year_month(year, month.value()?) as isize)?;
+
+            time_crate::Date::from_ymd_unchecked(year, month.value()?, day.value()?).as_yo()
+        }
+        // year-ordinal
+        else {
+            let ordinal = input.parse::<LitInt>()?;
+            ordinal.ensure_in_range(1..=days_in_year(year) as isize)?;
+            (year, ordinal.value()?)
+        };
+
+        // TODO(upstream) Swap out the following when dtolnay/syn#748 is
+        // published on crates.io. Be sure to update Cargo.toml for the minimum
+        // version.
+        // LitInt::create(year).using_span(year_span).ensure_in_range(-100_000..=100_000)?;
+        if year < -100_000 || year > 100_000 {
+            return error!(year_span, "value must be in the range -100_000..=100_000");
+        }
+
+        Ok(Self { year, ordinal })
+    }
+}
+
+impl ToTokens for Date {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self { year, ordinal } = self;
+
+        tokens.extend(quote! {
+            ::time::internals::Date::from_yo_unchecked(#year, #ordinal)
+        })
+    }
+}