Add OnDemandSchemaTreeStorageNode

[yangtools.git] / yang / yang-parser-spi / src / main / java / org / opendaylight / yangtools / yang / parser / spi / meta / NamespaceBehaviour.java

diff --git a/yang/yang-parser-spi/src/main/java/org/opendaylight/yangtools/yang/parser/spi/meta/NamespaceBehaviour.java b/yang/yang-parser-spi/src/main/java/org/opendaylight/yangtools/yang/parser/spi/meta/NamespaceBehaviour.java
index 86b687d917052ee5d312fe880ab924d9fb5f2e4a..2139cd55623debd712cb18efb8a2eeeb3d00b7d8 100644 (file)
--- a/yang/yang-parser-spi/src/main/java/org/opendaylight/yangtools/yang/parser/spi/meta/NamespaceBehaviour.java
+++ b/yang/yang-parser-spi/src/main/java/org/opendaylight/yangtools/yang/parser/spi/meta/NamespaceBehaviour.java
@@ -9,6 +9,7 @@ package org.opendaylight.yangtools.yang.parser.spi.meta;
 
 import static java.util.Objects.requireNonNull;
 
+import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects.ToStringHelper;
 import com.google.common.base.Verify;
 import java.util.Map;
@@ -17,6 +18,9 @@ import java.util.Optional;
 import org.eclipse.jdt.annotation.NonNull;
 import org.eclipse.jdt.annotation.Nullable;
 import org.opendaylight.yangtools.concepts.AbstractIdentifiable;
+import org.opendaylight.yangtools.yang.common.QName;
+import org.opendaylight.yangtools.yang.model.api.meta.DeclaredStatement;
+import org.opendaylight.yangtools.yang.model.api.meta.EffectiveStatement;
 import org.opendaylight.yangtools.yang.model.api.meta.IdentifierNamespace;
 
 /**
@@ -107,6 +111,30 @@ public abstract class NamespaceBehaviour<K, V, N extends IdentifierNamespace<K,
                 V value);
     }
 
+    /**
+     * Interface implemented by {@link NamespaceStorageNode}s which support dynamic addition of child elements as they
+     * are requested. This means that such a node can, defer creation of child namespace storage nodes, in effect lazily
+     * expanding this namespace on an if-needed basis.
+     */
+    @Beta
+    public interface OnDemandSchemaTreeStorageNode extends NamespaceStorageNode {
+        /**
+         * Request that a new member of this node's schema tree statement be added. Implementations are required to
+         * perform lookup in their internal structure and create a child if tracktable. Resulting node is expected to
+         * have been registered with local storage, so that it is accessible through
+         * {@link #getFromLocalStorage(Class, Object)}.
+         *
+         * <p>
+         * This method must not change its mind about a child's presence -- once it returns non-present, it has to be
+         * always returning non-present.
+         *
+         * @param qname node identifier of the child being requested
+         * @return Requested child, if it is present.
+         */
+        <D extends DeclaredStatement<QName>, E extends EffectiveStatement<QName, D>>
+            @Nullable StmtContext<QName, D, E> requestSchemaTreeChild(QName qname);
+    }
+
     protected NamespaceBehaviour(final Class<N> identifier) {
         super(identifier);
     }