Add hashCode and equals to Option so that Options get handled properly in collections (or tests)

magro · magro · commit f03172c9fcc3 · 2011-09-22T00:32:46.000+02:00
diff --git a/core/src/main/java/fj/data/Option.java b/core/src/main/java/fj/data/Option.java
@@ -594,6 +594,22 @@ private static final class None<A> extends Option<A> {
     public A some() {
       throw error("some on None");
     }
+
+    @Override
+    public int hashCode() {
+       return 31;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+       if (this == obj)
+          return true;
+       if (obj == null)
+          return false;
+       if (getClass() != obj.getClass())
+          return false;
+       return true;
+    }
   }
 
   private static final class Some<A> extends Option<A> {
@@ -606,6 +622,32 @@ private static final class Some<A> extends Option<A> {
     public A some() {
       return a;
     }
+
+    @Override
+    public int hashCode() {
+       final int prime = 31;
+       int result = 1;
+       result = prime * result + ((a == null) ? 0 : a.hashCode());
+       return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+       if (this == obj)
+          return true;
+       if (obj == null)
+          return false;
+       if (getClass() != obj.getClass())
+          return false;
+       Some<?> other = (Some<?>) obj;
+       if (a == null) {
+          if (other.a != null)
+             return false;
+       } else if (!a.equals(other.a))
+          return false;
+       return true;
+    }
+
   }
 
   public static <T> F<T, Option<T>> some_() {
diff --git a/core/src/test/fj/data/CheckOption.scala b/core/src/test/fj/data/CheckOption.scala
@@ -16,6 +16,12 @@ object CheckOption extends Properties("Option") {
   property("orSome") = forAll((a: Option[Int], n: P1[Int]) =>
     a.orSome(n) == (if(a.isNone) n._1 else a.some))
 
+  property("hashCode") = forAll((a: Option[Int]) =>
+    if(a.isNone) a.hashCode == none.hashCode else a.hashCode == some(a.some).hashCode)
+
+  property("equals") = forAll((a: Option[Int]) =>
+    if(a.isNone) a == none else a == some(a.some))
+
   property("mapId") = forAll((a: Option[String]) =>
     optionEqual(stringEqual).eq(a.map((x: String) => x), a))
 
