rustc: Implement equality for option types

Author: pcwalton

src/libcore/option.rs

@@ -8,6 +8,8 @@
  * type.
  */
 
+use cmp::Eq;
+
 /// The option type
 enum Option<T> {
     None,
@@ -247,6 +249,25 @@ impl<T: copy> Option<T> {
     pure fn while_some(blk: fn(+T) -> Option<T>) { while_some(self, blk) }
 }
 
+impl<T: Eq> Option<T> : Eq {
+    pure fn eq(&&other: Option<T>) -> bool {
+        match self {
+            None => {
+                match other {
+                    None => true,
+                    Some(_) => false
+                }
+            }
+            Some(self_contents) => {
+                match other {
+                    None => false,
+                    Some(other_contents) => self_contents.eq(other_contents)
+                }
+            }
+        }
+    }
+}
+
 #[test]
 fn test_unwrap_ptr() {
     let x = ~0;