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Implement hashCode, equals and toString in Maybe 

This brings Maybe's behavior closer to scala's Option.
This commit is contained in:
Martin Duhem 2016-08-19 15:41:56 +02:00
parent d760b15193
commit 432c93b0bb
1 changed files with 20 additions and 1 deletions
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21
internal/util-interface/src/main/java/xsbti/Maybe.java
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@ -14,6 +14,16 @@ public abstract class Maybe<t>
return new Maybe<s>() {
public boolean isDefined() { return true; }
public s get() { return v; }
public int hashCode() { return 17 + (v == null ? 0 : v.hashCode()); }
public String toString() { return "Maybe(" + v + ")"; }
public boolean equals(Object o) {
if (o == null) return false;
if (!(o instanceof Maybe)) return false;
Maybe<?> other = (Maybe<?>) o;
if (!other.isDefined()) return false;
if (v == null) return other.get() == null;
return v.equals(other.get());
}
};
}
public static <s> Maybe<s> nothing()
@ -21,10 +31,19 @@ public abstract class Maybe<t>
return new Maybe<s>() {
public boolean isDefined() { return false; }
public s get() { throw new UnsupportedOperationException("nothing.get"); }
public int hashCode() { return 1; }
public String toString() { return "Nothing"; }
public boolean equals(Object o) {
if (o == null) return false;
if (!(o instanceof Maybe)) return false;
Maybe<?> other = (Maybe<?>) o;
return !other.isDefined();
}
};
}
public final boolean isEmpty() { return !isDefined(); }
public abstract boolean isDefined();
public abstract t get();
}
}