1 files changed, 93 insertions, 0 deletions
diff --git a/src/main/java/bjc/data/Option.java b/src/main/java/bjc/data/Option.java
new file mode 100644
index 0000000..a180ef9
--- /dev/null
+++ b/src/main/java/bjc/data/Option.java
@@ -0,0 +1,93 @@
+package bjc.data;
+
+import java.util.function.Function;
+import java.util.function.UnaryOperator;
+
+/**
+ * A holder that may or may not contain a value.
+ *
+ * @author ben
+ *
+ * @param <ContainedType>
+ *        The type of the value that may or may not be held.
+ */
+public class Option<ContainedType> implements IHolder<ContainedType> {
+	private ContainedType held;
+
+	/**
+	 * Create a new optional, using the given initial value.
+	 *
+	 * @param seed
+	 *        The initial value for the optional.
+	 */
+	public Option(final ContainedType seed) {
+		held = seed;
+	}
+
+	@Override
+	public <BoundType> IHolder<BoundType> bind(final Function<ContainedType, IHolder<BoundType>> binder) {
+		if(held == null) return new Option<>(null);
+
+		return binder.apply(held);
+	}
+
+	@Override
+	public <NewType> Function<ContainedType, IHolder<NewType>> lift(final Function<ContainedType, NewType> func) {
+		return val -> {
+			return new Option<>(func.apply(val));
+		};
+	}
+
+	@Override
+	public <MappedType> IHolder<MappedType> map(final Function<ContainedType, MappedType> mapper) {
+		if(held == null) return new Option<>(null);
+
+		return new Option<>(mapper.apply(held));
+	}
+
+	@Override
+	public IHolder<ContainedType> transform(final UnaryOperator<ContainedType> transformer) {
+		if(held != null) {
+			held = transformer.apply(held);
+		}
+
+		return this;
+	}
+
+	@Override
+	public <UnwrappedType> UnwrappedType unwrap(final Function<ContainedType, UnwrappedType> unwrapper) {
+		if(held == null) return null;
+
+		return unwrapper.apply(held);
+	}
+
+	@Override
+	public String toString() {
+		return String.format("Option [held='%s']", held);
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+
+		int result = 1;
+		result = prime * result + (held == null ? 0 : held.hashCode());
+
+		return result;
+	}
+
+	@Override
+	public boolean equals(final Object obj) {
+		if(this == obj) return true;
+		if(obj == null) return false;
+		if(!(obj instanceof Option<?>)) return false;
+
+		final Option<?> other = (Option<?>) obj;
+
+		if(held == null) {
+			if(other.held != null) return false;
+		} else if(!held.equals(other.held)) return false;
+
+		return true;
+	}
+}