HONEYCOMB-431: add validation support to Writers

This patch introduces FlatWriterRegistry.validateModifications.
Implementation iterates over writersOrder following bulkUpdate logic
to properly support subtree writers case.

Writers are now cabable of validating modifications.
Commonly used implementations (GenericWriter and GenericListWriter)
delegate validation capbility to Validators.

Change-Id: If7a0bb0838c0b8f2c0393c989f3b03853a2ea679
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/infra/translate-api/src/main/java/io/fd/honeycomb/translate/write/Writer.java b/infra/translate-api/src/main/java/io/fd/honeycomb/translate/write/Writer.java
index 18573e58a..f3265a39b 100644
--- a/infra/translate-api/src/main/java/io/fd/honeycomb/translate/write/Writer.java
+++ b/infra/translate-api/src/main/java/io/fd/honeycomb/translate/write/Writer.java
@@ -33,6 +33,20 @@ import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 public interface Writer<D extends DataObject> extends SubtreeManager<D> {
 
     /**
+     * Validates data modification.
+     *
+     * @param id Identifier of data being validated
+     * @param dataBefore Old data
+     * @param dataAfter New, updated data
+     * @param ctx Write context enabling writer to get information about candidate data as well as current data
+     */
+    default void validate(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                          @Nullable final DataObject dataBefore,
+                          @Nullable final DataObject dataAfter,
+                          @Nonnull final WriteContext ctx) throws DataValidationFailedException {
+    }
+
+    /**
      * Process modifications and translate them as create/update/delete operations to lower level
      *
      * @param id         Identifier of data being written