Provide declarative support for listing components.

Fixes vaadin/framework8-issues#388


Change-Id: I4f8045bba51d308f4343a1f6d01b3f1ddca63e69

1 files changed, 52 insertions, 0 deletions

diff --git a/server/src/main/java/com/vaadin/ui/DeclarativeItemEnabledProvider.java b/server/src/main/java/com/vaadin/ui/DeclarativeItemEnabledProvider.java
new file mode 100644
index 0000000000..f16e54f1b2
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/DeclarativeItemEnabledProvider.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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.vaadin.ui;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import com.vaadin.server.SerializablePredicate;
+
+/**
+ * Item enabled provider class for declarative support.
+ * <p>
+ * Provides a straightforward mapping between an item and its enable state.
+ *
+ * @param <T>
+ *            item type
+ */
+class DeclarativeItemEnabledProvider<T> implements SerializablePredicate<T> {
+
+    private Set<T> disabled = new HashSet<>();
+
+    @Override
+    public boolean test(T item) {
+        return !disabled.contains(item);
+    }
+
+    /**
+     * Adds the {@code item} to disabled items list.
+     * 
+     * @param item
+     *            a data item
+     * @param caption
+     *            a caption for the {@code item}
+     */
+    protected void addDisabled(T item) {
+        disabled.add(item);
+    }
+
+}