add force checkout for cleanup

src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java

@@ -78,20 +78,20 @@ public class Repository {
     }
 
     /**
-     * Performs a checkout of the given {@link Commit}.
+     * Performs a checkout of the given {@link Reference}.
      *
-     * @param c
-     *         the {@link Commit} to checkout
+     * @param ref
+     *         the {@link Reference} to checkout
      * @return whether the checkout was successful
      * @see <a href=https://git-scm.com/docs/git-checkout>git checkout</a>
      */
-    public boolean checkout(Reference c) {
-        Optional<ExecRes> checkout = git.exec(dir, "checkout", c.getId());
+    public boolean checkout(Reference ref) {
+        Optional<ExecRes> checkout = git.exec(dir, "checkout", ref.getId());
         Function<ExecRes, Boolean> toBoolean = res -> {
             boolean failed = git.failed(res);
 
             if (failed) {
-                LOG.warning(() -> String.format("Checkout of %s failed.", c));
+                LOG.warning(() -> String.format("Checkout of %s failed.", ref));
             }
 
             return !failed;
@@ -100,6 +100,30 @@ public class Repository {
         return checkout.map(toBoolean).orElse(false);
     }
 
+    /**
+     * Performs a checkout of the given {@link Reference}. All changes since last commit will be discarded.
+     *
+     * @param ref
+     *         the {@link Reference} to checkout
+     * @return whether the checkout was successful
+     * @see <a href=https://git-scm.com/docs/git-checkout>git checkout</a>
+     */
+    public boolean forceCheckout(Reference ref) {
+        Optional<ExecRes> checkout = git.exec(dir, "reset", "--hard");
+        Function<ExecRes, Boolean> toBoolean = res -> {
+            boolean failed = git.failed(res);
+
+            if (failed) {
+                LOG.warning(() -> String.format("Reset of %s failed.", ref));
+                return false;
+            }
+
+            return checkout(ref);
+        };
+
+        return checkout.map(toBoolean).orElse(false);
+    }
+
     /**
      * Performs a fetch in this {@link Repository}.
      *