1 files changed, 30 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IProvider.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IProvider.java
new file mode 100644
index 00000000..cd25dc95
--- /dev/null
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/IProvider.java
@@ -0,0 +1,30 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2015, Zoltan Ujhelyi, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.matchers.util;
+
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import tools.refinery.viatra.runtime.matchers.psystem.queries.PQuery;
+
+/**
+ * A provider interface useful in various registry instances.
+ * 
+ * @author Zoltan Ujhelyi
+ *
+ */
+public interface IProvider<T> extends Supplier<T>{
+    
+    public final class ProvidedValueFunction implements Function<IProvider<PQuery>, PQuery> {
+        @Override
+        public PQuery apply(IProvider<PQuery> input) {
+            return (input == null) ? null : input.get();
+        }
+    }
+}