Add failed state.

diff --git a/src/main/java/net/pterodactylus/reactor/states/FailedState.java b/src/main/java/net/pterodactylus/reactor/states/FailedState.java
new file mode 100644 (file)
index 0000000..cfcbeef
--- /dev/null
+++ b/src/main/java/net/pterodactylus/reactor/states/FailedState.java
@@ -0,0 +1,81 @@
+/*
+ * Reactor - FailedState.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.reactor.states;
+
+import net.pterodactylus.reactor.State;
+
+/**
+ * {@link State} implementation that signals failure.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class FailedState extends AbstractState {
+
+       /** A failed state instance without an exception. */
+       public static final State INSTANCE = new FailedState();
+
+       /**
+        * Creates a new failed state.
+        */
+       public FailedState() {
+               super(false);
+       }
+
+       /**
+        * Creates a new failed state with the given exception
+        *
+        * @param exception
+        *            The exception of the state
+        */
+       public FailedState(Throwable exception) {
+               super(exception);
+       }
+
+       //
+       // STATIC METHODS
+       //
+
+       /**
+        * Returns a failed state for the given state. The failed state will be
+        * unsuccessful ({@link #success()} returns false) and it will contain the
+        * same {@link #exception()} as the given state.
+        *
+        * @param state
+        *            The state to copy the exception from
+        * @return A failed state
+        */
+       public static FailedState from(State state) {
+               if (state instanceof FailedState) {
+                       return (FailedState) state;
+               }
+               return new FailedState(state.exception());
+       }
+
+       //
+       // OBJECT METHODS
+       //
+
+       /**
+        * {@inheritDoc}
+        */
+       @Override
+       public String toString() {
+               return String.format("%s[exception=%s]", getClass().getSimpleName(), exception());
+       }
+
+}