1 files changed, 113 insertions, 0 deletions
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/DelegatingReaderRegistry.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/DelegatingReaderRegistry.java
new file mode 100644
index 000000000..387f3cc7c
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/DelegatingReaderRegistry.java
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.v3po.translate.util.read;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.LinkedListMultimap;
+import com.google.common.collect.Multimap;
+import io.fd.honeycomb.v3po.translate.read.ListReader;
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import io.fd.honeycomb.v3po.translate.read.ReaderRegistry;
+import io.fd.honeycomb.v3po.translate.util.RWUtils;
+import io.fd.honeycomb.v3po.translate.read.Reader;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Simple reader registry able to perform and aggregated read (ROOT read) on top of all provided readers. Also able to
+ * delegate a specific read to one of the delegate readers.
+ *
+ * This could serve as a utility to hold & hide all available readers in upper layers.
+ */
+public final class DelegatingReaderRegistry implements ReaderRegistry {
+
+    private static final Logger LOG = LoggerFactory.getLogger(DelegatingReaderRegistry.class);
+
+    private final Map<Class<? extends DataObject>, Reader<? extends DataObject>> rootReaders;
+
+    /**
+     * Create new {@link DelegatingReaderRegistry}
+     *
+     * @param rootReaders List of delegate readers
+     */
+    public DelegatingReaderRegistry(@Nonnull final List<Reader<? extends DataObject>> rootReaders) {
+        this.rootReaders = RWUtils.uniqueLinkedIndex(checkNotNull(rootReaders), RWUtils.MANAGER_CLASS_FUNCTION);
+    }
+
+    @Override
+    @Nonnull
+    public Multimap<InstanceIdentifier<? extends DataObject>, ? extends DataObject> readAll(
+        @Nonnull final ReadContext ctx) throws ReadFailedException {
+
+        LOG.debug("Reading from all delegates: {}", this);
+        LOG.trace("Reading from all delegates: {}", rootReaders.values());
+
+        final Multimap<InstanceIdentifier<? extends DataObject>, DataObject> objects = LinkedListMultimap.create();
+        for (Reader<? extends DataObject> rootReader : rootReaders.values()) {
+            LOG.debug("Reading from delegate: {}", rootReader);
+
+            if (rootReader instanceof ListReader) {
+                final List<? extends DataObject> listEntries =
+                        ((ListReader) rootReader).readList(rootReader.getManagedDataObjectType(), ctx);
+                if (!listEntries.isEmpty()) {
+                    objects.putAll(rootReader.getManagedDataObjectType(), listEntries);
+                }
+            } else {
+                final Optional<? extends DataObject> read = rootReader.read(rootReader.getManagedDataObjectType(), ctx);
+                if (read.isPresent()) {
+                    objects.putAll(rootReader.getManagedDataObjectType(), Collections.singletonList(read.get()));
+                }
+            }
+        }
+
+        return objects;
+    }
+
+    @Nonnull
+    @Override
+    public Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                                               @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        final InstanceIdentifier.PathArgument first = checkNotNull(
+                Iterables.getFirst(id.getPathArguments(), null), "Empty id");
+        final Reader<? extends DataObject> reader = rootReaders.get(first.getType());
+        checkNotNull(reader,
+                "Unable to read %s. Missing reader. Current readers for: %s", id, rootReaders.keySet());
+        LOG.debug("Reading from delegate: {}", reader);
+        return reader.read(id, ctx);
+    }
+
+    /**
+     * @throws UnsupportedOperationException This getter is not supported for reader registry since it does not manage a
+     *                                       specific node type
+     */
+    @Nonnull
+    @Override
+    public InstanceIdentifier<DataObject> getManagedDataObjectType() {
+        throw new UnsupportedOperationException("Root registry has no type");
+    }
+}