Add a hasExtension method to ExtendableMessageNano.

It allows checking for the presence of an extension without having to
deserialize the field.

Change-Id: Id542d20274b2435b7bc2b322740e9984cb8639a1

1 files changed, 12 insertions, 0 deletions

diff --git a/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java b/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
index 5984d35..46cd86f 100644
--- a/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
+++ b/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
@@ -68,6 +68,18 @@ public abstract class ExtendableMessageNano<M extends ExtendableMessageNano<M>>
     }
 
     /**
+     * Checks if there is a value stored for the specified extension in this
+     * message.
+     */
+    public final boolean hasExtension(Extension<M, ?> extension) {
+        if (unknownFieldData == null) {
+            return false;
+        }
+        FieldData field = unknownFieldData.get(WireFormatNano.getTagFieldNumber(extension.tag));
+        return field != null;
+    }
+
+    /**
      * Gets the value stored in the specified extension of this message.
      */
     public final <T> T getExtension(Extension<M, T> extension) {