1 files changed, 29 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/yql/JavaListTypeChecker.java b/container-search/src/main/java/com/yahoo/search/yql/JavaListTypeChecker.java
new file mode 100644
index 00000000000..86e2cbf01ff
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/yql/JavaListTypeChecker.java
@@ -0,0 +1,29 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.yql;
+
+import com.google.common.base.Preconditions;
+
+import java.util.List;
+
+class JavaListTypeChecker extends OperatorTypeChecker {
+
+    private final Class<?> elementType;
+
+    public JavaListTypeChecker(Operator parent, int idx, Class<?> elementType) {
+        super(parent, idx);
+        this.elementType = elementType;
+    }
+
+    @Override
+    public void check(Object argument) {
+        Preconditions.checkNotNull(argument, "Argument %s of %s must not be null", idx, parent);
+        Preconditions.checkArgument(argument instanceof List, "Argument %s of %s must be a List<%s>", idx, parent, elementType.getName(), argument.getClass().getName());
+        List<?> lst = (List<?>) argument;
+        for (Object elt : lst) {
+            Preconditions.checkNotNull(elt, "Argument %s of %s List elements may not be null", idx, parent);
+            Preconditions.checkArgument(elementType.isInstance(elt), "Argument %s of %s List elements must be %s (is %s)", idx, parent, elementType.getName(), elt.getClass().getName());
+        }
+    }
+
+}
+