Expose equals and compare over FFI

temporal_capi/src/plain_date.rs

@@ -155,6 +155,35 @@ pub mod ffi {
                 .map_err(Into::into)
         }
 
+        pub fn equals(&self, other: &Self) -> bool {
+            self.0 == other.0
+        }
+
+        pub fn compare(one: &Self, two: &Self) -> i32 {
+            Self::compare_iso_date(
+                one.iso_year(),
+                one.iso_month(),
+                one.iso_day(),
+                two.iso_year(),
+                two.iso_month(),
+                two.iso_day(),
+            )
+        }
+
+        pub fn compare_iso_date(
+            year1: i32,
+            month1: u8,
+            day1: u8,
+            year2: i32,
+            month2: u8,
+            day2: u8,
+        ) -> i32 {
+            match (year1, month1, day1).cmp(&(year2, month2, day2)) {
+                std::cmp::Ordering::Less => -1,
+                std::cmp::Ordering::Equal => 0,
+                std::cmp::Ordering::Greater => 1,
+            }
+        }
         pub fn year(&self) -> i32 {
             self.0.year()
         }