1 files changed, 127 insertions, 0 deletions
diff --git a/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/restapi/Response.java b/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/restapi/Response.java
new file mode 100644
index 0000000000..97c4cbc4cd
--- /dev/null
+++ b/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/restapi/Response.java
@@ -0,0 +1,127 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.extensions.restapi;
+
+/** Special return value to mean specific HTTP status codes in a REST API. */
+public abstract class Response<T> {
+  @SuppressWarnings({"rawtypes"})
+  private static final Response NONE = new None();
+
+  /** HTTP 200 OK: pointless wrapper for type safety. */
+  public static <T> Response<T> ok(T value) {
+    return new Impl<T>(200, value);
+  }
+
+  /** HTTP 201 Created: typically used when a new resource is made. */
+  public static <T> Response<T> created(T value) {
+    return new Impl<T>(201, value);
+  }
+
+  /** HTTP 204 No Content: typically used when the resource is deleted. */
+  @SuppressWarnings("unchecked")
+  public static <T> Response<T> none() {
+    return NONE;
+  }
+
+  /** HTTP 302 Found: temporary redirect to another URL. */
+  public static Redirect redirect(String location) {
+    return new Redirect(location);
+  }
+
+  @SuppressWarnings({"unchecked", "rawtypes"})
+  public static <T> T unwrap(T obj) {
+    while (obj instanceof Response) {
+      obj = (T) ((Response) obj).value();
+    }
+    return obj;
+  }
+
+  public abstract int statusCode();
+  public abstract T value();
+  public abstract String toString();
+
+  private static final class Impl<T> extends Response<T> {
+    private final int statusCode;
+    private final T value;
+
+    private Impl(int sc, T val) {
+      statusCode = sc;
+      value = val;
+    }
+
+    @Override
+    public int statusCode() {
+      return statusCode;
+    }
+
+    @Override
+    public T value() {
+      return value;
+    }
+
+    @Override
+    public String toString() {
+      return "[" + statusCode() + "] " + value();
+    }
+  }
+
+  private static final class None extends Response<Object> {
+    private None() {
+    }
+
+    @Override
+    public int statusCode() {
+      return 204;
+    }
+
+    public Object value() {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public String toString() {
+      return "[204 No Content] None";
+    }
+  }
+
+  /** An HTTP redirect to another location. */
+  public static final class Redirect {
+    private final String location;
+
+    private Redirect(String url) {
+      this.location = url;
+    }
+
+    public String location() {
+      return location;
+    }
+
+    @Override
+    public int hashCode() {
+      return location.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      return o instanceof Redirect
+        && ((Redirect) o).location.equals(location);
+    }
+
+    @Override
+    public String toString() {
+      return String.format("[302 Redirect] %s", location);
+    }
+  }
+}