From 5376803e1c41d25f4c8e6e2ca38dc5e4d9fc18fb Mon Sep 17 00:00:00 2001
From: Robert Varga <robert.varga@pantheon.tech>
Date: Thu, 8 Nov 2018 15:01:07 +0100
Subject: [PATCH] Refactor DataObjectCodecContext.getBindingChildValue()

Using instanceof checks is an OOP anti-pattern, which we do not
want here anyways. Generalize NodeCodecContext.defaultObject()
to return null by default and refactor decoding to rely on it,
with LeafNodeCodecContext returning whatever it has as a default
value.

Change-Id: I2b58bc7f1a16496cf6bc93fd7a33aec38f864597
JIRA: MDSAL-18
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
---
 .../dom/codec/impl/DataObjectCodecContext.java        | 11 ++++-------
 .../binding/dom/codec/impl/LeafNodeCodecContext.java  |  9 ++-------
 .../binding/dom/codec/impl/NodeCodecContext.java      | 11 +++++++++++
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/DataObjectCodecContext.java b/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/DataObjectCodecContext.java
index e7961a546a..584ea26a6e 100644
--- a/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/DataObjectCodecContext.java
+++ b/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/DataObjectCodecContext.java
@@ -368,13 +368,10 @@ abstract class DataObjectCodecContext<D extends DataObject, T extends DataNodeCo
         final NodeCodecContext<?> childContext = byMethod.get(method).get();
         @SuppressWarnings("unchecked")
         final Optional<NormalizedNode<?, ?>> domChild = domData.getChild(childContext.getDomPathArgument());
-        if (domChild.isPresent()) {
-            return childContext.deserializeObject(domChild.get());
-        } else if (childContext instanceof LeafNodeCodecContext) {
-            return ((LeafNodeCodecContext)childContext).defaultObject();
-        } else {
-            return null;
-        }
+
+        // We do not want to use Optional.map() here because we do not want to invoke defaultObject() when we have
+        // normal value because defaultObject() may end up throwing an exception intentionally.
+        return domChild.isPresent() ? childContext.deserializeObject(domChild.get()) : childContext.defaultObject();
     }
 
     @SuppressWarnings("checkstyle:illegalCatch")
diff --git a/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/LeafNodeCodecContext.java b/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/LeafNodeCodecContext.java
index 9844149cc7..385c6095f0 100644
--- a/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/LeafNodeCodecContext.java
+++ b/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/LeafNodeCodecContext.java
@@ -17,7 +17,6 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
-import org.eclipse.jdt.annotation.Nullable;
 import org.opendaylight.mdsal.binding.dom.codec.api.BindingCodecTreeNode;
 import org.opendaylight.mdsal.binding.dom.codec.api.BindingNormalizedNodeCachingCodec;
 import org.opendaylight.yangtools.concepts.Codec;
@@ -230,12 +229,8 @@ final class LeafNodeCodecContext<D extends DataObject> extends NodeCodecContext<
         return ChildAddressabilitySummary.UNADDRESSABLE;
     }
 
-    /**
-     * Return the default value object.
-     *
-     * @return The default value object, or null if the default value is not defined.
-     */
-    @Nullable Object defaultObject() {
+    @Override
+    Object defaultObject() {
         return defaultObject;
     }
 }
diff --git a/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/NodeCodecContext.java b/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/NodeCodecContext.java
index 3311ae59de..868aa3a804 100644
--- a/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/NodeCodecContext.java
+++ b/binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/impl/NodeCodecContext.java
@@ -9,6 +9,7 @@ package org.opendaylight.mdsal.binding.dom.codec.impl;
 
 import com.google.common.collect.ImmutableMap;
 import java.util.List;
+import org.eclipse.jdt.annotation.Nullable;
 import org.opendaylight.mdsal.binding.dom.codec.api.BindingCodecTreeNode;
 import org.opendaylight.mdsal.binding.generator.util.BindingRuntimeContext;
 import org.opendaylight.yangtools.concepts.Codec;
@@ -94,5 +95,15 @@ abstract class NodeCodecContext<D extends DataObject> implements BindingCodecTre
         }
     }
 
+    /**
+     * Return the default value object. Implementations of this method are explicitly allowed to throw unchecked
+     * exceptions, which are propagated as-is upwards the stack.
+     *
+     * @return The default value object, or null if the default value is not defined.
+     */
+    @Nullable Object defaultObject() {
+        return null;
+    }
+
     protected abstract Object deserializeObject(NormalizedNode<?, ?> normalizedNode);
 }
-- 
2.36.6