Topology related util class.

- We may need them to adapt Immutable*Topology as Mutable*Topology.

Part of ONOS-1925

Change-Id: I5782ef9f9b9441946b112e374a87059ab0a0df01
diff --git a/src/main/java/net/onrc/onos/core/topology/ImmutableTopologyWrapper.java b/src/main/java/net/onrc/onos/core/topology/ImmutableTopologyWrapper.java
new file mode 100644
index 0000000..c44dc3b
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/ImmutableTopologyWrapper.java
@@ -0,0 +1,150 @@
+package net.onrc.onos.core.topology;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Collection;
+
+import net.floodlightcontroller.util.MACAddress;
+import net.onrc.onos.core.util.Dpid;
+import net.onrc.onos.core.util.OnosInstanceId;
+import net.onrc.onos.core.util.PortNumber;
+import net.onrc.onos.core.util.SwitchPort;
+
+/**
+ * Wrapper to access {@link ImmutableTopology} as {@link MutableTopology}.
+ */
+public final class ImmutableTopologyWrapper implements MutableTopology {
+
+    private final ImmutableTopology wrapped;
+
+    /**
+     * Constructor.
+     *
+     * @param toWrap {@link ImmutableTopology} to wrap
+     */
+    public ImmutableTopologyWrapper(ImmutableTopology toWrap) {
+        this.wrapped = checkNotNull(toWrap);
+    }
+
+    @Override
+    public void acquireReadLock() {
+        // no-op
+    }
+
+    @Override
+    public void releaseReadLock() {
+        // no-op
+    }
+
+    @Override
+    public Switch getSwitch(Dpid dpid) {
+        return wrapped.getSwitch(dpid);
+    }
+
+    @Override
+    public Iterable<Switch> getSwitches() {
+        return wrapped.getSwitches();
+    }
+
+    @Override
+    public Port getPort(Dpid dpid, PortNumber portNumber) {
+        return wrapped.getPort(dpid, portNumber);
+    }
+
+    @Override
+    public Port getPort(SwitchPort port) {
+        return wrapped.getPort(port);
+    }
+
+    @Override
+    public Collection<Port> getPorts(Dpid dpid) {
+        return wrapped.getPorts(dpid);
+    }
+
+    @Override
+    public Link getOutgoingLink(Dpid dpid, PortNumber portNumber) {
+        return wrapped.getOutgoingLink(dpid, portNumber);
+    }
+
+    @Override
+    public Link getOutgoingLink(Dpid dpid, PortNumber portNumber, String type) {
+        return wrapped.getOutgoingLink(dpid, portNumber, type);
+    }
+
+    @Override
+    public Link getOutgoingLink(SwitchPort port) {
+        return wrapped.getOutgoingLink(port);
+    }
+
+    @Override
+    public Link getOutgoingLink(SwitchPort port, String type) {
+        return wrapped.getOutgoingLink(port, type);
+    }
+
+    @Override
+    public Collection<Link> getOutgoingLinks(SwitchPort port) {
+        return wrapped.getOutgoingLinks(port);
+    }
+
+    @Override
+    public Link getIncomingLink(Dpid dpid, PortNumber portNumber) {
+        return wrapped.getIncomingLink(dpid, portNumber);
+    }
+
+    @Override
+    public Link getIncomingLink(Dpid dpid, PortNumber portNumber, String type) {
+        return wrapped.getIncomingLink(dpid, portNumber, type);
+    }
+
+    @Override
+    public Link getIncomingLink(SwitchPort port) {
+        return wrapped.getIncomingLink(port);
+    }
+
+    @Override
+    public Link getIncomingLink(SwitchPort port, String type) {
+        return wrapped.getIncomingLink(port, type);
+    }
+
+    @Override
+    public Collection<Link> getIncomingLinks(SwitchPort port) {
+        return wrapped.getIncomingLinks(port);
+    }
+
+    @Override
+    public Link getLink(Dpid srcDpid, PortNumber srcPortNumber, Dpid dstDpid,
+            PortNumber dstPortNumber) {
+        return wrapped.getLink(srcDpid, srcPortNumber, dstDpid, dstPortNumber);
+    }
+
+    @Override
+    public Link getLink(Dpid srcDpid, PortNumber srcPortNumber, Dpid dstDpid,
+            PortNumber dstPortNumber, String type) {
+        return wrapped.getLink(srcDpid, srcPortNumber, dstDpid, dstPortNumber, type);
+    }
+
+    @Override
+    public Iterable<Link> getLinks() {
+        return wrapped.getLinks();
+    }
+
+    @Override
+    public Host getHostByMac(MACAddress address) {
+        return wrapped.getHostByMac(address);
+    }
+
+    @Override
+    public Iterable<Host> getHosts() {
+        return wrapped.getHosts();
+    }
+
+    @Override
+    public Collection<Host> getHosts(SwitchPort port) {
+        return wrapped.getHosts(port);
+    }
+
+    @Override
+    public OnosInstanceId getSwitchMaster(Dpid dpid) {
+        return wrapped.getSwitchMaster(dpid);
+    }
+}