1 files changed, 56 insertions, 0 deletions
diff --git a/java/com/google/gerrit/extensions/registration/DynamicItemProvider.java b/java/com/google/gerrit/extensions/registration/DynamicItemProvider.java
new file mode 100644
index 0000000000..d8dd1f925c
--- /dev/null
+++ b/java/com/google/gerrit/extensions/registration/DynamicItemProvider.java
@@ -0,0 +1,56 @@
+// 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.registration;
+
+import com.google.inject.Binding;
+import com.google.inject.Inject;
+import com.google.inject.Injector;
+import com.google.inject.Key;
+import com.google.inject.Provider;
+import com.google.inject.ProvisionException;
+import com.google.inject.TypeLiteral;
+import java.util.List;
+
+class DynamicItemProvider<T> implements Provider<DynamicItem<T>> {
+  private final TypeLiteral<T> type;
+  private final Key<DynamicItem<T>> key;
+
+  @Inject private Injector injector;
+
+  DynamicItemProvider(TypeLiteral<T> type, Key<DynamicItem<T>> key) {
+    this.type = type;
+    this.key = key;
+  }
+
+  @Override
+  public DynamicItem<T> get() {
+    return new DynamicItem<>(key, find(injector, type), PluginName.GERRIT);
+  }
+
+  private static <T> Provider<T> find(Injector src, TypeLiteral<T> type) {
+    List<Binding<T>> bindings = src.findBindingsByType(type);
+    if (bindings != null && bindings.size() == 1) {
+      return bindings.get(0).getProvider();
+    } else if (bindings != null && bindings.size() > 1) {
+      throw new ProvisionException(
+          String.format(
+              "Multiple providers bound for DynamicItem<%s>\n"
+                  + "This is not allowed; check the server configuration.",
+              type));
+    } else {
+      return null;
+    }
+  }
+}